JPH0368927A - Photographing lens driving device for camera - Google Patents

Abstract

PURPOSE:To make a finder part low in height and to obtain a small-sized and easy-to- handle camera by providing an image pickup lens, a finder focusing plate, a storage means, a lens driving quantity control means and a lens driving means. CONSTITUTION:A light beam is made incident on an automatic focus sensor 10 through a main mirror 4 and an auxiliary mirror 4. The output of the sensor is inputted in a computer 30 through an interface 11 and an arithmetic circuit 12 makes a correction means 12a correct a focusing state based on the output from a memory 20 and a lens information output circuit 21. A power source switch 18 and a release switch 19 are connected to a control circuit 13, which causes a driving circuit 14 to drive a lens or a focusing optical system in an optical axis direction by a motor 15 through a transmitting means 17. A pulse generator 16 detects the rotation of the motor 15 and generates a pulse to perform the feedback to the control circuit. The number of pulses for moving the lens 1 and moving an image-formation surface by deviation D is stored in a memory. Since the positional deviation between a film surface and the focusing surface of the finder is corrected by driving the image pickup lens, the degree of freedom in constituting the finder is increased and the camera is miniaturized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a driving device for a photographing lens in an eye reflex camera.

(Conventional technology) In a conventional single-lens reflex camera, the film surface and the viewfinder! 1? It was necessary to place the i-point plate at a conjugate position with respect to the photographic lens. This will be explained using the first [K. (Note that FIG. 1 shows an embodiment of the present invention, and parts that are not related to the explanation of the prior art are omitted here.) A light beam from the subject (the optical axis of this light beam is shown with a reference numeral) is reflected by the main mirror 4 and bent upward. The light beam reflected by the main mirror 4 is guided to conventional finder optical systems 5', 6', and 7' shown by phantom lines.

That is, the light beam passes through the focus plate 5° which is conjugate with the film plane 8, is reflected within the pentaprism 6' as shown at 1''A, is emitted backward, and passes through the eyepiece lens 7'. If we observe a ray of light coming from an eyepiece of 7°,
You can see the object image formed on the 12-point sieve surface a' of the focusing plate 5''.The reference number 2 is a lens bayonet for connecting the photographing lens l to the camera body. This lens bayonet 2 has a joining reference surface 2a with the camera body.On the other hand, the body side bayonet 3 that joins with the lens bayonet 2 has a /Am 3 surface.

As shown in the figure, when the photographic lens is attached, this reference surface 3a comes into contact with the reference surface 2a of the lens bayonet 2.

[Problem to be solved by the invention]

In such conventional cameras, body bayonet 3
The distance L1+L2(L
l=distance from the reference reference a to the intersection P of the light beam and the main mirror, L2=distance from the intersection P to the film surface 8. )and,
From the reference plane 3a of the body bayonet to the focal plane 5a of the focusing plate
'Distance aLl+L3 (L3=from intersection P;, jj
It was necessary that the distance between the points 5a' and 2) was exactly the same. This is because - if the two distances do not match, even if it is in focus on the reticle, it will not be in focus on the film surface, and conversely, it will not be in focus on the film plane. - This is because if you focus on a plane, it will be out of focus on the focal plate. Therefore, the vertical position of the focusing plate 5 is the main mirror 4.
It must be uniquely determined by the position of the intersection point P, which intersects the optical axis of the photographing lens. This means that
- This was a constraint when downsizing the part of the viewfinder that protruded from the camera body. In particular, this has been a major constraint when reducing the height dimension of the eye reflex camera body and downsizing the camera as a whole.

The present invention has been made in view of these conventional problems, and it is an object of the present invention to provide a camera that is compact and easy to handle, in which the height of a portion of the finder of the camera is lower than that of the conventional camera.

(Means for Solving Problem J) In order to solve Problem L, the photographing lens drive device according to the first invention has the following features: a finder focus plate (5) disposed at a position displaced by a predetermined amount from m control means (12) for calculating and outputting the driving force of the m shadow lens (1) necessary for correcting the focusing error on the film surface caused by the displacement of the finder focus plate from the predetermined gutter; , 13) and #M shadow lens driving means (14, 15, 16° 17) for driving the photographic lens based on the output regarding the amount of entanglement from the control means (12, 13);
It was decided to consist of

A photographic lens driving device according to a second invention is an application of the TI shadow lens driving device according to the first invention to an automatic focusing camera. In such a photographic lens driving device, focus detection means (10, 11) are provided for detecting the out-of-focus of an image formed on a film surface by the photographic lens (1).
Included in 4. The control means (12°13) also controls the deviation 1 detected by the focus detection means (10, 11).
．． [to the predetermined h() stored in the storage means (20>),
(including a correction means (12a) for correcting the
When the camera or viewfinder is observed, the supplementary 1f
The driving stitch of the photographing lens (1) is calculated based on the shifted star, and the photographing lens driving means (14, 15, 16° 17)
Output to.

[Effect]

That is, in the device according to the first invention, the control means (12, 1
3) determines that the camera has been operated and the second digit has changed from the viewfinder observing state to the shooting ready state, and stores the memory means (20
), the photographing lens is driven based on the value stored in the camera to correct the amount of positional deviation between the film plane and the focus plate in the optical axis direction (that is, the above-mentioned predetermined amount). As a result, the object image formed on the focus plate by the photographing lens in the viewfinder observation state is formed on the film plane or at a position conjugate thereto in the photographable state.

In addition, in the device according to the second aspect of the present invention, during viewfinder observation, the control means (12, 13) drives the photographing lens (1) according to the in-focus state on the focus plate. result.

When observing through the finder, by continuing to heat the focus plate, it is possible to focus on the film surface when photography is possible.

To summarize, the misalignment between the film plane and the focusing plate can be corrected by driving the photographic lens, and there is no need for the film plane and the focusing plate to be in optically conjugate positions.

(Example) FIG. 1 shows an embodiment of the present invention.

In FIG. 1, a photographing lens l, a lens bayonet 2,
The reference plane 2a, the body insert head 3, the reference plane 3a, and the main mirror 4 are the same as those in the prior art, and their explanations will be omitted.

In this embodiment, the positions of the focusing plate 5, pentaprism 6, and eyepiece 7 shown by solid lines are different from those of the prior art 5.
°, 6' and 7'. In other words, the entire finder optical system is placed at a position D lower than in the case of a conventional camera.

A part of the main mirror 4 is provided with a semi-transparent part through which light can pass, and the light that enters here is guided via a sub-mirror 9 to an AF full sensor 0 for automatic focus detection. The AF sensor IO is driven by the sensor interface 11. The output of the sensor interface 11 is input to the microcomputer 30.

The microcomputer consists of an arithmetic circuit 12, a control circuit 1
3, and a memory circuit 20. The arithmetic circuit 12 is an AF
Based on the signal from the sensor 11, the amount of focus shift is calculated. Note that the arithmetic circuit detects the focusing state of the photographing lens 1 on the film surface. A memory circuit 20 and a lens information output circuit 21 are connected to the arithmetic circuit 12 . A correction means 12a is provided in the arithmetic circuit, and the correction means 12a includes a memory circuit 20 and a lens information output circuit 21.
The arithmetic circuit 12 is also connected to the control circuit 13, which corrects the in-focus state (defocus ψ) detected in the output. This control circuit 13 is a circuit for controlling one rotation of the motor 15, and is connected to a power switch 18 and a release switch 19.

The output of the 11111 circuit 13 is output to the drive circuit 14. The drive circuit 14 is a circuit for the motor 15'NA drive circuit. The motor 15 drives the I&L shadow lens (or the focusing optical system within the photographic lens) in the optical axis direction via the transmission means 17.

The pulse generator 16 is composed of a photocoupler and an interrupter, and detects the rotation of the motor 15 and generates pulses. The signal from the pulse generator is foothacked into the control circuit 13.

The contents stored in the memory circuit 20 will now be explained.

As shown in FIG. 1, the film surface 8 is separated from the body base surface 3a.
The distance fiL1+L2 and the distance from the bodeino, tpemo surface 3a to the point i5a on the fish point plate 5 @ L l +
The difference between L4 and positional deviation bLD is stored in the memory 4-way 20. Because +iii As mentioned above, L2
Since =L3, the following relationship holds true.

D= (Ll+L2)-(Ll+L4)=L2-L4 =L3-L4 The lens information output circuit 12 has a function that moves the IM shadow lens 1 in the optical axis direction to form an image (for example, position shift ID).
), data indicating which pulse of the pulse generator 16 corresponds to that movement is stored. It is desirable to provide a lens information output circuit 21 for each interchangeable lens to prevent malfunctions even when the photographing lens is replaced.

Next, the operation of this embodiment will be explained using the flowchart shown in FIG.

1. When the camera's autofocus operation starts when the glare source switch 18 is turned on (ON) and the camera's autofocus operation is started, the photographic lens 1, main mirror 4. Through the sub-mirror 9,
Capture the subject image with AF sensor 10.

In step #lO1, based on the output of the AF sensor 10, the arithmetic circuit 12 calculates the focus deviation 1ijE of the subject image with respect to the film surface.

Then, in step #102, the arithmetic circuit 12 calculates the amount of motor drive required to focus on the film plane based on this arithmetic result and the data from the lens information output circuit 21. Does the amount correspond to the drive tI) of the photographing lens optical system?
In the case of this embodiment, a value Nl is calculated by converting the rotational speed of the motor into the number of pulses of the pulse generator 16.

Next, in step #103, the arithmetic circuit 12
0 and the data from the lens information output circuit 21, the pulse generator 16 calculates the drive amount of the motor necessary to move the imaging lens of the photographing lens by the distance i, lD.
It is calculated as the value N2 converted into the number of pulses.

Then, in step #104, the sewing photographic lens is driven by correcting the pulse ft1N1 by the pulse correction N.

To explain step #104 in detail, when the arithmetic circuit 12 sends the N pulse as the drive jJ to the control 111 path 13, the control WI! dk1313 controls the motor to rotate by Ii). At this time, the rotation of the motor is fed back to the control circuit 13 by the pulse generator 16, and if the necessary lens is driven, the motor is stopped. In the conventional single focus mode, the value N1 is given as the drive amount, and the motor is controlled so as to focus on the film surface. However, in the embodiment, the positional deviation fil D is further forward than the position where it is aligned with the film surface (the photographic lens (or
The motor is controlled so as to focus on the position in the direction in which the optical system moves out (in other words, the number of pulses is N2). As a result, the tl&' plane of the photographing lens when the drive is completed coincides with the focal plane 5a of the fish point plate, and it can be confirmed that the image is in focus on the finder.

Next, in step #105, turn on the release switch 19.
Check whether it is ONL or not, and if it is not ONL, return to step #101 and repeat this operation. In other words, the focusing operation before release (ie, finder tracking) is controlled so that the image formation of the photographing lens coincides with the focal plane of the finder, not with the film plane. On the other hand, if it is detected in step #105 whether the release or the switch 19 is ON, the process advances to step #106.

In step #106, the motor is controlled to renormalize the lens by N2 pulses calculated in step #11j.

This operation corrects the difference between the focal plane 5a of the finder and the film plane 8 to what extent j+l:D. In other words, the image formed by the photographing lens of the release button (i.e., shooting "T fm") is not focused on the focal plane 5a of the focusing plate, but on the film plane 8.The operation of step #106 is from the release to the film plane. It is desirable to perform other operations in parallel with mirror up and lens aperture before the exposure starts.
Pressing the F function button is the viewfinder observation state and 11
It is also possible to set the function to ++7 by pressing this button from the outside (that is, the release button does not switch between the viewfinder observation state and the photographing function).

When these operations are completed, exposure of the film is started in step #107. Then, in step #108, the process waits for the completion of the exposure operation.

In step #109, the motor is controlled to extend the lens by the previously calculated N2 pulses. As a result, the image formed by the 1st lens matches the dot curve 5a at j+ and b on the dot plate, and it can be confirmed in the finder whether the image is in focus. Then, he lies down in Sudep well 101 and repeats the same action.

In addition, in the above embodiment, the memory circuit 20 is
A removable ROM with 11 functions may also be used. In this case, it is possible to imprint the image i of position n shift early-D for each camera as a fixed image. As a result, 1) the rod according to the present invention can be used not only to downsize a part of the finder, but also to precisely adjust the position of the j, jj black dot board, which was required in conventional cameras. available to do. That is, instead of j11i dense position A adjustment, it is sufficient to write n deviation filD of 1-11if with respect to the film equivalent surface of the focus plate for each camera into the 1 degree ROM. In this case, depending on the positional deviation of fixed f + the sign of il and D, etc., the lens is moved forward by a certain amount or retracted by a certain amount during exposure (i.e., shooting n (in the active state)).This changes the conventional focal point. Since the number of parts and components required for adjusting the position of the plate can be reduced, the cost of the camera can be reduced (this also holds true for the embodiment of Figure 1).

In the above embodiments, only the autofocus operation has been described, but the present invention is also applicable to manual focus operation.
, and ) can also be applied to power focus battles. In this case, the processing of the 21st M Sudep I lot to Sudebu #104 can be replaced with manual focus using the finder, etc., or (well, replace it with the known power focus process, and the processes from Sudep #105 onwards can be performed in the same way. Good. In the case of manual focus, the first correction stage 12a in the MoriC calculation circuit 10 does not function.

Therefore, the calculation 11j circuit 12 outputs the lens information I
According to the information from the jjl path 21 and the memory circuit 20, only the number of pulses N2 for driving the motor is calculated. According to this number of pulses, the motor 15 is driven.

(Effects of the invention) As mentioned above, according to Unreleased 1, the film surface and j,
%-Sunspot board, -2 points The positional deviation between the surface and the film surface can be corrected by driving the photographic lens when the camera or finer observation samurai moves to 1III shadow + + l function, and then the film surface and ;, j% focus plate! , there is no longer a need for point-pointing or optical positioning, and the configuration of the camera's viewfinder has increased.

We can achieve miniaturization of cameras.

Furthermore, by eliminating the need to adjust the position of the point plate in the optical axis direction, it is possible to reduce the number of parts and components used to adjust the position of the point plate in conventional cameras, thereby reducing the cost of the camera. I can achieve it.

4. IA (7) M'It a II FIG. 1 shows the configuration of an embodiment of the present invention, and FIG. 21-A is a flowchart showing the operation of the embodiment.

<Explanation of symbols for main expense departments> Photographing lens 5...Finder j, % focus plate I11.11... ...
...No point detection - [stage 12° 13 ...... Control means + 2a Correction means 14° + 5°! 6 17......Photographing lens drive F-stage shipping person 0 Nikon Co., Ltd. Yasui Yuki Asai Shin, /-7,'!

Claims (1)

[Scope of Claims] 1. A photographing lens; a finder focus plate disposed at a position displaced by a predetermined amount in the optical axis direction from a position conjugate with the film plane; and a storage means for storing information regarding the predetermined amount; When the camera transitions from the viewfinder observing state to the photographing ready state, the driving amount of the photographing lens necessary to correct the focus error on the film plane caused by the displacement of the finder focus plate is stored in the storage means. a control means for calculating and outputting the calculated amount from the stored predetermined amount;
A photographic lens driving device for a camera, comprising: photographing lens driving means for driving the photographing lens based on an output regarding the drive amount from the control means. 2. The photographing lens driving device according to claim 1, further comprising a focus detection means for detecting the amount of defocus of the image formed on the film surface by the photographing lens, and the control described above. The means further includes a correction means for correcting the amount of deviation detected by the focus detection means based on the predetermined amount stored in the storage means, and when the camera is in the viewfinder observation state, the corrected amount of deviation is detected by the focus detection means. Claim 1, wherein the driving amount of the photographing lens is calculated based on the amount of deviation and is output to the photographing lens driving means.
The photographing lens drive device described in . 3. The control means outputs a driving amount of the photographic lens necessary for correcting a focus error on the film surface in response to the release operation, and upon completion of photographing, moves the photographic lens to the release operation surface. 3. The photographing lens driving device according to claim 1, wherein the photographing lens driving device outputs a driving amount necessary to return to the state of.