JPH06175010A - Optical device - Google Patents

Abstract

PURPOSE:To prevent a ghost from being brought into focus by obtaining the form of a corresponding diaphragm value in a storage device based on information from a diaphragm position detecting device and excluding an area having a form similar to the obtained form from an autofocusing reference area. CONSTITUTION:The image of an object formed on a CCD 205 is turned into an image pickup signal by performing signal processing such as amplification and gamma correction in a camera circuit 213. Only a signal in a specified area within an image plane, out of the image pickup signal, is selected by a gate 214 and fetched in a CPU 215. The CPU 215 detects the ghost from the fetched signal by a ghost detection part 216 based on a diaphragm form memory 217 and information on a diaphragm value at that time. Furthemore, when the detected ghost has higher luminance than the luminance signal of the other area, the signal of that area is removed from a signal for AF by a ghost removing part 218. Thereafter, focusing or non-focusing is judged by an AF circuit 219.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device such as a camera, an interchangeable lens and an observation instrument.

[0002]

2. Description of the Related Art Conventionally, as an optical device equipped with an automatic focusing device, an entire or part of a photographing screen is used as reference data for the automatic focusing device, and the increase / decrease in the amount of high frequency components in that area is determined and confirmed. However, it is known that the focused state is recognized.

Almost all lenses generate a diaphragm-shaped surface reflection ghost in a backlit state.

In recent years, miniaturization of video cameras and still cameras has progressed, and so-called rear focus lenses, which have a focusing function for a lens close to a focus surface, have been increasing as an optical system thereof. Since cameras having this optical system can focus on a super close range, many of them can focus on a super close range.

Further, as a conventional video camera, a part of the image pickup light flux is allocated to a focus detection device separately from the image pickup element,
Some have automatic focus adjustment, the video camera,
In order to prevent the light beam incident on the automatic focus detection device from being disturbed by the diaphragm device which is a light quantity adjusting device, the light from the image pickup light beam is dispersed before the diaphragm. In the video camera, focusing also needs to be performed before the spectroscopy, and the optical system of the video camera is inevitably configured as shown in FIG.

In FIG. 12, 10 is a front lens of a focusing lens, 11 is a variator for changing the focal length, 12 is a compensator for a lens for correcting a focus position change due to movement of the variator 11, and 13 is an afocal for a fixed lens. Reference numeral 14 is a lens, 14 is a spectroscopic prism which is a spectroscopic element, 15 is a diaphragm device which is a light amount adjusting device, 16
Is a master lens which is an image forming optical system, 17 is an image pickup element arranged on the focus surface, 18 is an AF image forming lens for forming an AF light flux on the AF sensor, and 19 is an AF sensor for detecting a focus shift. ,.

Based on the distance information from the AF sensor 19, the front lens 10 is controlled to move and a focusing operation is performed. 13 is the same as FIG.
FIG. 6 is a movement locus diagram of lens groups by zooming of the respective lens groups. The movement of the variator 11 causes a change in the focal length, the focus movement caused thereby is corrected by the compensator 13, and the movement of the front lens 10 is controlled by the distance information of the AF sensor 19.

FIG. 14 shows another conventional example, in which 20 is a front lens of a fixed lens, 21 is a variator for changing the focal length, 22 is a compensator for correcting the focus movement due to the movement of the variator 21 at a fixed position, and 23 is A focusing lens that performs a focusing action, 24 a spectral prism that is a spectral element, 25 a diaphragm device that is a light amount adjusting device, 26 a relay lens that is an imaging optical system, and 27 a focusing surface. An image pickup element arranged, 28 is an AF for focusing an AF light flux on the AF sensor
An image forming lens 29 is an AF sensor that detects a focus shift.

The focus lens 23 is controlled to move based on the distance information of the AF sensor 29 and the position information of the variator 10 to perform a focusing operation. FIG. 15 is a movement locus of the lens group due to zooming of each lens in FIG. The focal length is changed by the movement of the variator 21, the focus movement caused thereby is corrected at a fixed position by the compensator 22, and the movement of the focus lens 23 is controlled based on the distance information of the AF sensor 29 and the position information of the variator 21. A focusing operation is performed by.

[0010]

The above-mentioned conventional optical device has the following problems.

(I) When a diaphragm-shaped surface reflection ghost occurs in the reference data area of the automatic focusing device in the backlit state as described above, if the contrast of the ghost is high, the ghost will be in focus, and originally, The subject is greatly blurred.

(Ii) In the above-mentioned two conventional examples, since the spectral prism is arranged in front of the diaphragm, the diaphragm and the front lens are distant from each other, and the front lens becomes large. The cost and weight increase, which leads to an increase in the size and weight of an optical device such as a camera.

An object of the present invention is to provide an optical device which solves the above problems.

That is, a first object of the present invention is to provide an optical device having a function of preventing a ghost from being in focus and causing an original subject to be greatly blurred. It is a second object of the present invention to provide an optical device which prevents the size of the front lens of the photographing optical system from increasing and does not increase the cost and weight of the photographing optical system.

[0015]

In the optical device according to the present invention, the aperture shape used for the lens is stored in advance in a memory for each aperture value or for each aperture shape, and aperture position detection at the time of photographing is performed. The shape corresponding to the detected value of the device can be called from the memory, and based on the shape information, it is determined whether there is an area of the same shape or a similar shape in the screen, and the similar shape area is similar. When the brightness is higher than the other areas close to the shape area, the automatic focusing device is operated in the area where the extraction area is deleted from the reference data area of the automatic focusing apparatus, thereby focusing on the ghost due to surface reflection. It is characterized in that it is designed to prevent that

Further, in the optical device according to the present invention, the light is adjusted by the focus position detecting device from between the aperture which is the light amount adjusting device and the image pickup surface, and the light flux is incident from the aperture to the automatic focus detecting device. (That is, the portion corresponding to the pupil of the AF sensor) is composed of a polarizing element, and another polarizing element having a different phase from the polarizing element is arranged between the image sensor and the diaphragm, and the diaphragm and the AF It is characterized in that a focusing lens, which is a focusing optical element, is arranged between the sensor and a spectral prism that splits light.

[0017]

According to the optical device of the present invention, it is possible to prevent the original subject from becoming out of focus due to the focusing of the surface reflection ghost which is likely to occur particularly in the backlit state on the wide side of the zoom lens.

Further, according to another optical device of the present invention, it is possible to split the light beam into the AF system behind the diaphragm device while using the phase difference detection AF sensor which requires pupil division, and as a result, rear It has become possible to apply high-performance phase difference detection AF to compact cameras with focus zoom lenses.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) A first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a block diagram of a video camera according to the first embodiment of the present invention. In the figure, 206 is a zoom switch, 207 is a zoom motor drive circuit, 208 is an aperture drive circuit, 209 is a focus motor drive circuit,
210 is a zoom encoder, 211 is an aperture value encoder, 212 is a focus encoder, 213 is a camera circuit, 214 is a gate, 215 is a CPU, 216 is a ghost detector, 217 is an aperture-shaped memory unit, 218.
Is a ghost removing unit, 219 is an AF circuit, 220 is a zoom motor, and 221 is a focus motor. or,
In this example, the photographing lens has a group structure of convex, concave, and convex in order from the subject side, and 201 is a fixed first group, and 202 is a fixed first group.
Is a variator lens for zooming, 203 is a fixed relay lens, and 204 is a focus lens group as a focus and compensator. 205 is a CCD
A solid-state image sensor such as 222 is a diaphragm.

In FIG. 2, 41 is a photographing screen, 42 is a surface reflection ghost generated at the time of backlighting, and 43 is an autofocus reference range. FIG. 2 is a situation diagram in which a surface reflection ghost is generated on the screen in a state where the sun or the like which is a high-intensity light source is present outside the upper right screen.

FIG. 4 is a reference data table in which the shape of the aperture of the diaphragm device used in the optical system is stored in advance for each aperture value, and such a data table is stored in the memory unit 217 in advance. Has been done.

Next, the operation of the camera of this embodiment will be described with reference to FIG.

The image of the subject formed on the CCD 205 through the taking lens composed of the lens groups 201 to 204 is subjected to signal processing such as amplification and gamma correction in the camera circuit 213, and is converted into an image pickup signal. Become. Of these, the contrast of the subject is extracted as a Y signal.
Of the signals, only the signal in a predetermined area (distance measuring frame) on the screen is selected by the gate 214 and taken into the CPU 215.

In the CPU 215, based on the fetched Y signal, based on the aperture shape memory 217 and the aperture value information at that time (loaded from the aperture value encoder 211).
The ghost detecting section 216 detects a ghost. Furthermore, the ghost detected by the ghost removing unit 218 is
When the luminance is higher than the luminance signal of the other area, the Y signal of that area is removed from the signal for AF. After that, the AF circuit 219 determines whether or not focus is achieved.
At this time, the zoom encoder 210 and the focus lens position encoder 212 are used for zoom tracking.
The detection result of is also taken in, and finally a drive command is transmitted from the CPU to the focus motor drive circuit 209.

The zoom motor 220 is driven by the zoom motor drive circuit 207 when the zoom switch 206 is operated by the photographer. Also, as is known,
The diaphragm 222 provides feedback to the diaphragm drive circuit from the level of the Y signal so as to obtain optimum exposure.

FIG. 5 is a flowchart showing a ghost removing function which is a feature of the optical device of the present invention, and is executed by the camera circuit 213 and the CPU 215.

The operations of the camera circuit 213 and the CPU 215 will be described below with reference to the flowchart of FIG.

First, the diaphragm position is detected from [START], and the diaphragm position is confirmed. Next, the diaphragm aperture shape corresponding to the diaphragm position is extracted from the storage memory. next,
An image shape search is performed to find out a similar shape portion to the memory shape on the screen, and a similar shape portion is found. When there is a similar shape, the brightness of the portion where the area is close to the area is compared, and when the similar shape portion has a higher brightness than the portion where the area is close to the area, the similar shape portion is deleted from the automatic focus reference range.

In other words, the automatic focusing device is operated by the information from the area of the similar shape portion excluding the portion having the higher brightness than the other portions.

In the present embodiment, the surface reflection ghost is brought into focus by deleting the portion whose brightness is higher than the other portion due to the unnecessary surface reflection ghost riding on the image by the original effective light ray from the automatic focus reference range. Can be prevented.

In the case of a zoom lens, the zoom position at the time of shooting may be detected, and this operation may be stopped at the telephoto end. This is because there are many inconveniences that the ghost is in focus at the time of widening, and there is little problem even if it is operated only there.

(Embodiment 2) FIG. 6 shows a second embodiment of the present invention.

In FIG. 6, 1 is a front lens which is a fixed lens, 2 is a variator for changing the focal length, 3 is a diaphragm device which is a light amount adjusting device, and 4 is an afocal lens which is a fixed lens. 5 is variator 2
A focus relay lens for correcting the focus movement due to the movement of the lens and a focusing operation, 6a a spectral prism as a spectral element, 7 a polarizing element, 8 an image sensor for converting an optical image into an electric signal, 9 AF Senor,
Is. FIG. 7 is a movement locus of each lens group in FIG. 6 due to zooming. In zooming, the focal length is changed by the movement of the variator 2, so the movement locus of the variator 2 is as shown by 2a. Focus relay lens 5
Is controlled by the distance information of the AF sensor 9 and the position information of the variator 2.

FIG. 8 is a view of the diaphragm device 3 seen from the optical axis direction in the optical system of FIG. 6, which is in an open state.

3a and 3b are diaphragm blades for controlling light shielding, 3c is a driving device for driving the diaphragm blades, 3d is a blade driving lever for converting the rotational movement of the driving device 3c into linear movement of the diaphragm blades 3a and 3b, Reference numerals 3e and 3f are areas in which a part of the diaphragm blades 3a and 3b is formed by a polarizing element, and 3i is an AF light flux area that passes through the diaphragm portion.

In FIG. 9, the driving device 3c rotates to rotate the diaphragm blades 3.
It is a state where a and 3b are closed. Even in this state, since the area of the AF light flux 3i is covered by the areas of the polarization elements 3e and 3f, the passing polarized light flux of the AF light flux enters the spectroscopic prism 6 and is guided to the AF sensor 9 by the reflecting surface.
The polarizing element 7 is the polarizing element region 3 of the diaphragm blades 3a and 3b.
Since the light beams passing through the spectroscopic prism 6a are arranged in polarization directions different from those of the polarization element regions 3e and 3f.
Rays that have passed f are cut.

(Embodiment 3) FIG. 10 is a third embodiment of the present invention, which is different from FIG. 6 in that the reflecting surface of the spectral prism 6b covers the entire surface of the transmitted light beam, and the polarization characteristic of the surface causes 6
The polarizing element 7 is abolished.

(Embodiment 4) FIG. 11 is another embodiment relating to the light quantity adjusting device, in which the entire blade itself is constituted by a polarizing element. In addition, the operation direction of the blade is also the AF light flux 3i.
On the other hand, the arrangement is performed by rotating by 90 ° with respect to the arrangements of FIGS. 8 and 9, and there is an advantage that the AF light flux 3i does not overlap with a plurality of blades when the blades are closed and the loss of the AF light flux is small.

[0041]

According to the optical device of the present invention, the automatic focusing device erroneously measures the distance to the surface reflection ghost which is likely to occur in the backlit state on the wide side of the zoom lens, and the ghost is in focus. It is possible to prevent the original subject from becoming out of focus.

Further, according to another optical device of the present invention, it is possible to split the light flux into the AF system behind the diaphragm device while using the phase difference detection AF sensor which requires pupil division, and the rear focus zoom lens It has become possible to apply high-performance phase-difference detection AF to a compact camera with a built-in camera.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an optical device according to a first exemplary embodiment of the present invention.

FIG. 2 is a diagram showing a shooting screen state of the optical device according to the first embodiment of the present invention.

FIG. 3 is a diagram in which a ghost region is deleted from an autofocus device reference area after the operation of the optical device according to the present invention.

FIG. 4 is a diagram showing a diaphragm aperture shape memory in the optical device of the present invention.

FIG. 5 is an operation flowchart of the optical device according to the first embodiment of the present invention.

FIG. 6 is an optical layout diagram of a second embodiment of the optical device of the present invention.

FIG. 7 is a lens block movement diagram by zooming in the second embodiment.

8 is a diagram of a diaphragm device section of the optical device of FIG.

FIG. 9 is a diagram in which the blade operates from the state of FIG.

FIG. 10 is an optical layout diagram of a third embodiment of the optical device of the present invention.

FIG. 11 is a diagram of a diaphragm device according to a third embodiment of the present invention.

FIG. 12 is an optical layout diagram of a fourth embodiment of the optical device of the present invention.

FIG. 13 is a lens block movement diagram of the fourth embodiment of the present invention.

FIG. 14 is an optical layout diagram of a conventional optical device.

15 is a lens block movement diagram of the optical device of FIG.

[Explanation of symbols]

41 ... Shooting screen 42 ... Surface reflection ghost 43 ... Distance measuring area of automatic focusing device 44 ... Region where ghost region is deleted from automatic focusing device reference area 1 ... Front lens 2 ... Variator 3 ... Aperture device 3a / 3b ... Aperture blade 3c ... Driving device 3d ... Driving lever 3e, 3f, 3g, 3h ... Polarizing element area 3i ... AF luminous flux area 4 ... Afocal lens 5 ... Focus relay lens 6a ... Spectral prism 7 ... Polarizing element 8 ... Imaging element 9 ... AF sensor 10.20 ... Front lens 11.21 ... Variator 12.22 ... Compensator 13 ... Afocal lens 14.24 ... Spectral prism 15.25 ... Diaphragm device 16.26 ... Relay lens 17.27 ... Imaging element 18.28 ... AF imaging lens 19/29 ... AF sensor 23 ... Focus lens 201 ... Fixed first lens group 202 ... Variator lens 203 ... Fixed relay lens 204 ... Focus lens 205 ... Solid-state image sensor 206 ... Zoom lens 207 ... Zoom motor drive circuit 208 ... Aperture drive circuit 209 ... Focus motor drive circuit 210 ... Zoom position encoder 211 ... Aperture value encoder 212 ... Focus encoder 213 ... Camera circuit 214 ... Gate 215 ... CPU 216 ... Ghost detection section 217 ... Aperture shape memory section 218 ... Ghost removal section 219 ... AF circuit 220 ... Zoom motor 221 ... Focus motor 222 ... Aperture

Claims (3)

[Claims] 1. An aperture shape of an aperture is recorded in a storage device for each aperture value, and a shape of a corresponding aperture value of the storage device is determined by information from an aperture position detection device at the time of operation of an automatic focusing device. An optical device characterized in that a basin having a similar shape to that shape is excluded from the autofocus reference area. 2. The optical device according to claim 1, wherein the region having the similar shape is excluded from the auto-focus reference region when the brightness is higher than that of a region having a similar shape. 3. A polarizing element is arranged at a position where a light beam which is split into a focus position detecting device from between the light amount adjusting device and the imaging surface and which is incident on the focus position detecting device passes through the light amount adjusting device, and , Another polarizing element having a phase different from that of the polarizing element is arranged between the image pickup element and the light amount adjusting device, and a focusing optical element is arranged between the light amount adjusting device and the position where the light is dispersed in the focus detection device. An optical device characterized in that