JPH01159623A - Finder device - Google Patents

Abstract

PURPOSE:To visually and artificially recognize the way that a photographing optical system forms an image in a finder without complicating or scaling up a device by controlling a arraying state of liquid crystals in an optical phase filter and forming a out-of-focus image of an object in response to the image formed by the system. CONSTITUTION:The title device is provided with the optical phase filter 1 and a controlling means 2 for the arraying state of the liquid crystals of the filter 1. A modulation transfer function characteristic which takes the object depth of the photographing system and the distance difference between an object and a main object in each area into account is set to an area in the finder, and a signal complying with the characteristic is outputted to the optical phase filter 1 form the arraying state control circuit 2. As a result, the main object is visually recognized as being focused, while its surrounding object is visually recognized as being out-of-focus in response to its distance. Thus, the way that the photographing optical system forms an image can be recognized in the finder artificially and visually.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to a finder device that pseudo-displays the imaging state of a photographing optical system using an optical phase filter that utilizes the birefringence of liquid crystal. be.

(Background of the Invention) Conventionally, in the finder optical system of an eye-reflex camera, a diffuser plate made of acrylic or the like is placed at a position equivalent to the imaging plane of the photographing optical system, or as disclosed in Japanese Patent Publication No. 61-60420, etc. A diffuser plate that utilizes the diffusivity of the liquid crystal described (in the in-focus state, it forms a transparent state with no diffusivity at all, and in the out-of-focus state, it has diffusivity and displays a blurred image) ) are arranged. Therefore, it is possible to visually confirm the imaging state of the subject by the photographing optical system within the finder.

However, the finder optical system of a lens-shutter camera consisting of a real image finder or a virtual image finder,
It has a configuration independent of the photographing optical system. Therefore, there is no diffuser plate placed in the finder optical path.
Therefore, it has been impossible to visually check the image formation state of the photographing optical system through the finder optical system.

In addition, in a lens shutter camera having a finder optical system consisting of a real image finder, by arranging a diffuser plate on the image forming surface, it becomes possible to visually confirm the image forming state of the photographing optical system through the finder optical system. For this purpose, it is essential to move the objective lens of the finder optical system in conjunction with the photographing lens, which poses a problem in that the apparatus becomes complicated and large.

(Object of the Invention) An object of the present invention is to solve the above-mentioned problems and to provide a finder device that allows the imaging state of the photographic optical system to be visually confirmed in a pseudo viewfinder without complicating or increasing the size of the device. The goal is to provide the following.

(Features of the Invention) In order to achieve the above object, the present invention provides a transparent electrode which is a common electrode having irregularly arranged non-conductive regions disposed on one opposing surface of a pair of transparent substrates; It consists of transparent electrodes, which are segment electrodes having one or more regions, arranged on the other opposing surface of the substrate, and liquid crystal filled between these transparent electrodes, and arranged between the objective lens and the eyepiece. an optical phase filter, and an array state control means that receives information on the amount of extension of the photographing lens to be moved to the in-focus position and controls the array state of the liquid crystal of the optical phase filter based on the information, and the following is provided. The imaging state of the photographing optical system, which changes over time, is input as an electrical signal, and the alignment state of the liquid crystal of the optical phase filter is controlled according to the signal to blur the subject image according to the imaging state at that time. It is characterized by forming a state.

(Embodiments of the Invention) Hereinafter, the present invention will be described in detail based on illustrated embodiments.

FIG. 1 is a block diagram showing one embodiment of the present invention. In the figure, 1 is an optical phase filter using liquid crystal (details will be described later); 2 is an arrangement state control circuit that controls the arrangement state of liquid crystals in the optical phase filter 1 based on a signal from a distance measuring device, which will be described later; 3 is an objective lens that forms part of a real-image finder optical system that is provided independently of the photographic lens described later; 4 is a known Porro prism that plays the role of returning an inverted image by the objective lens 3 to an erect image; 5 is an eyepiece. The optical phase filter 1 to the eyepiece lens 5 constitute a finder display device.

Reference numeral 101 is a distance measuring device that detects distance measurement information of a plurality of areas corresponding to the finder image of the camera and generates signals to be output to each circuit. A light emitting lens 103 that emits light, a light receiving lens 104, and a plurality of light receiving areas (three in the embodiment) that receive reflected light from a subject that enters through the light receiving lens 104.
The light receiving element 105 has a plurality of light receiving areas) and a signal processing circuit 106 that processes signals from the light receiving element 105. Reference numeral 107 denotes a photographing lens driving device that moves the photographing lens 108 based on a signal from the distance measuring device 101.

In the above configuration, the object light incident on the objective lens 3 passes through the optical phase filter 1 disposed between the exit pupil plane of the objective lens 3 and the imaging plane of the object light, and then reaches the entrance surface of the Porro prism 4. After the image is formed, it is guided to the photographer's eye through the Porro prism 4 and the eyepiece lens 5.

Here, the viewfinder display of a camera equipped with the real-image viewfinder display device as described above will be explained using the flowchart shown in FIG.

First, distance information to each subject located in n (three in the example) distance measurement areas is detected (#1). Here, the distance information on the closest distance side is regarded as the main subject, and this is distance information L1, and other distance information L2. L3 is distance information to a background object located around it. Next, the photographing lens 108 is moved to the subject at a position conjugate to the film surface at the reference position (for example, an initial position such as a close position) of the photographing lens 108, that is, at the initial position before the photographing lens 108 starts to extend. The known distance information L◇ to the subject that is in focus is RO
#2), calculate the total extension amount ΔX1 ("Lo Ll") of the photographing lens 108 from the distance information LO and the distance information L1 of the main subject, and then calculate the total extension amount ΔX1 for one tooth. Calculate how many cars it corresponds to by setting the amount of feed out to ΔX (#3).Next, proceed to #4,
A signal corresponding to the amount of extension (ΔX) for both sides is output to the photographic lens driving device 107, and then the count value of the amount of extension, ie, the value of P (number of teeth), is incremented by 1 (#5). Next, the process proceeds to #6, and a signal corresponding to the filter applied voltages 1 to v3 to be output from the array state control circuit 2 to the optical phase filter 1 is output to the array state control circuit 2 based on the feeding amount ΔX ( (Details will be described later). The process then proceeds to #7, where it is checked whether the count value P has reached the number of teeth P1 determined in #3, and the routines from #4 to #6 are repeated until the relationship P≧P1 is satisfied.

By performing the above operations, the photographing lens 108 is moved from the reference position to a position where the main subject is in focus, and in the finder there is an optical system divided according to the distance measurement area. In each region of the phase filter 1,
MT F (Modul) according to the focus state of the main subject
The voltages v1 to v3 that provide the characteristics of the photographing lens 108
Since it is applied in accordance with the movement of the main subject, the image of the main subject gradually comes into focus, allowing the photographer to see the main subject image in a clear state. In addition, a background object with a distance difference from the main object can be visually recognized as a blurred image, which indicates depth of field display (details will be described later).
.

Hereinafter, the above-mentioned supplementary explanation will be given using FIGS. 3 to 5.

FIG. 3 is an MTF characteristic diagram of the optical phase filter 1 using liquid crystal. The states x, n, and m are determined by the voltage Vi (Vi
-1, Vi-2, Vi-3), and in state I, the subject light incident on the objective lens 3 is not modulated at all in the optical phase filter 1, so it is equivalent to passing through. The subject image is visually recognized (the main subject area finally reaches this state), which is recognized by the photographer as if the image forming state of the photographic optical system is satisfied (Vi-1=O). In state II, the subject light is somewhat modulated by the optical phase filter 1, and the visible subject image also deteriorates and becomes blurred.
This is perceived by the photographer as if the image forming state of the photographic optical system is not satisfied (Vi-1<Vi-2)
. The same is true for state (2), and since the subject light is significantly modulated by the optical phase filter 1, the photographer perceives that the image forming state of the photographic optical system is not satisfied at all (Vi-2<Vi- 3). Furthermore, as described above, the optical phase filter 1 has a configuration that can partially modulate the subject light passing through the finder optical system (a configuration in which a voltage is applied according to the distance information of the subject located in each area). ), it is possible to display the imaging state of the photographing optical system in a pseudo manner according to the depth of field. As is clear from the foregoing, the degree and modulation area of the subject light by the optical phase filter 1 are determined by the array state control circuit 2 which operates based on the signal from the signal processing circuit 106.

In the distance measuring device 101, light emitted from one of the three light sources 102 passes through a projection lens 103 and illuminates a part of the subject in an area corresponding to the finder image.

The reflected light from the object passes through the light receiving lens 104 and enters the light receiving element 105 having three light receiving areas, and the signal processing circuit 106 converts the incident spot light to the light source 1 of the light receiving element 105.
The subject distance L (=fXs/d) is calculated based on the deviation amount d from the center position of the light receiving area corresponding to 02, the focal length f of the light receiving lens 104, and the base line length S.

The light source 102 is switched in chronological order to illuminate each area corresponding to the finder image, and each object distance information is calculated from the reflected light of the object in each area, and a signal based on the information is output from the signal processing circuit 106. Ru.

By outputting a signal from the signal processing circuit 106 to control the position of the photographing lens 108, the photographing lens 108 is gradually extended based on the signal, and at the same time, the optical phase filter 1 is moved in the viewfinder. The MTF of the area corresponding to the main subject is finally set to the state shown in FIG. 3, resulting in an almost transparent state. In the areas within the viewfinder corresponding to the subjects surrounding the main subject, MTF characteristics are set that take into account the depth of field of the photographic optical system and the distance difference between the subject and the main subject in each area, and a signal (voltage V2 , V3 = Vi-2 or Vi-3)
is output from the array state control circuit 2 to the optical phase filter 1. As a result, the main subject appears to be in focus in the viewfinder, while surrounding subjects appear blurred depending on their distance, making it possible to pseudo-recognize the image formation state of the photographic optical system. becomes. At this time, it is also possible to intentionally increase the amount of image blur to emphasize the image formation state. Further, by making the MTF of the optical phase filter 1 correspond to the aperture value of the camera, it is also possible to display the depth of field in a pseudo manner.

In addition, since the optical phase filter 1 is not placed on the image forming plane of the real image finder, it is possible to place a superimposed display element on the image forming plane, and even when this device is applied to a conventional single-lens reflex camera, the image forming Since there is a diffuser plate on the image plane, the display element must be shifted from the image formation plane, and the problem that the subject image plane and the display plane do not match and the display quality deteriorates can be solved. can. Furthermore, when the present embodiment device is applied to a camera having an evaluation distance measurement mechanism that detects distances in a plurality of areas, automatically evaluates the distance information, and extends the photographing lens 108, the evaluation distance measurement mechanism The image that has been recognized as the main subject can be visually recognized in the viewfinder as a transparent image, and it can also be compared with the main subject intended by the photographer.

FIG. 4 is a functional explanatory diagram of the optical phase filter 1. 11
．． Reference numerals 12 denote glass substrates on the common electrode side and the segment electrode side, which are arranged parallel to each other. 13.14
are transparent electrodes on the common side and segment side, respectively, and the right side of the transparent electrode 13 is cut off. Reference numeral 15 denotes an alignment film formed by a rubbing method, which is provided on the transparent electrodes 13 and 14. 16 is a positive nematic liquid crystal, and 17 is a sealing member.

When a voltage Vi is applied to the positive nematic liquid crystal 16 by the alignment state control circuit 2, the molecular axis of the liquid crystal becomes perpendicular to the transparent electrode, and when no voltage Vi is applied, the molecular axis of the liquid crystal becomes a homogeneous alignment parallel to the transparent electrode. The molecular axis is alignment film 1
5 to face the same direction.

FIG. 4 corresponds to a state in which a voltage Vi is applied between the transparent electrodes 13 and 14, and the liquid crystal molecules are arranged as shown by the double-headed arrow. Light transmitted through the non-conductive region B where the voltage Vi is not applied and the liquid crystal molecules are homogeneously aligned will cause birefringence due to the optical anisotropy of the liquid crystal. Of the transmitted light, light (extraordinary light) having a vibration plane parallel to the molecular axis of the liquid crystal molecules is transmitted through the liquid crystal layer with an optical path length of ned (ne is the refractive index of the liquid crystal for extraordinary light). Further, light (ordinary light) having a vibration plane perpendicular to the molecular axis of the liquid crystal molecules (vibration plane perpendicular to the plane of the paper) is transmitted through the liquid crystal layer with an optical path length of nod (no is the refractive index of the liquid crystal with respect to ordinary light). Here, an optical path length difference of 5=ned-nod=Δnd occurs between the extraordinary light and the ordinary light, but since the vibration planes of the six lights are orthogonal, no interaction occurs. Note that Δn(=ne −
no) is the birefringence of the liquid crystal.

Next, in the conductive region A, the liquid crystal molecules are aligned perpendicularly and parallel to the optical axis. The light passing through this region has a vibration plane perpendicular to the liquid crystal molecular axis, so the optical path length when passing through the liquid crystal layer is no.
d. At this time, the thickness of the transparent electrodes 13 and 14 is ignored because it is sufficiently thinner than the thickness d of the liquid crystal layer 16.

Of the light transmitted through the conductive region A, the light having the same vibration plane as the extraordinary light transmitted through the non-conductive region B is δ=Δn
They have an optical path length difference of d, and interaction occurs. If the non-conductive regions B are island-like circular openings (described later) and are irregularly arranged in the conductive region A, the MTF value will decrease and the finder image will be blurred. Further, the optical path length difference of the extraordinary light transmitted through each region can be controlled by the voltage Vi applied between each transparent electrode, and as a result, the MTF value can be controlled by the voltage Vi. Furthermore, unless a voltage Vi is applied between the transparent electrodes, no difference in optical path length occurs, so the MTF value does not decrease (state 3 in FIG. 3).

FIG. 5 shows transparent electrodes 13 and 14 of the optical phase filter 1.
The transparent electrode 13 on the common side has a pattern in which island-like circular openings, which are non-conductive areas, are irregularly arranged in a --like transparent conductive film. The transparent electrode 14 on the segment side has a pattern in which a --like transparent conductive film is divided into three regions, which correspond to the distance measurement regions (of the light receiving element 105) of the distance measurement device 101.

FIG. 6 shows another embodiment of the present invention, in which the same parts as in FIG. 1 are given the same reference numerals. In the figure, 6 is 1
7 is an objective lens independent of the photographing lens 108; 8 is an eyepiece. Also 109
110 is one light source, 110 is a light receiving element consisting of one area,
Reference numeral 111 outputs the extension amount ΔX of the photographic lens 108 from the light reception signal from the light receiving element 110 to the photographic lens driving device 107, and also outputs a voltage V corresponding to the extension amount ΔX.
This is a signal processing circuit that outputs an instruction signal for applying i to the optical phase filter 1 to the array state control circuit 2.

The distance measuring operation and finder display of a camera equipped with a virtual image finder device as described above will be explained with reference to FIG.

The objective lens 7 and the eyepiece lens 8 constitute a substantially afocal optical system, and the subject light incident on the objective lens 7 is guided to the human eye through the eyepiece lens 8. An optical phase filter 6 is arranged between the objective lens 7 and the eyepiece 8.

In the distance measuring device 101, light emitted from a light source 109 passes through a projection lens 103 and illuminates a subject in a specific area corresponding to a finder image. Reflected light from the subject enters the light receiving element 110 through the light receiving lens 104. The light intensity distribution detected by the light receiving element 110 is transmitted from the light source 109. Coupled with the positional relationship between the light emitting lens 103 and the light receiving lens 104, the signal processing circuit 106 converts this into information on the amount of extension of the photographing lens 108 (#11 to #13). Based on the information from the signal processing circuit 106, the photographic lens drive circuit 8 starts extending the photographic lens 108, and at the same time, within the viewfinder, a signal corresponding to the amount of extension of the photographic lens 108 is sent from the array state control circuit 2 to the liquid crystal display. The voltage is applied as a voltage Vi to the optical phase filter 1, which controls the MTF of the finder optical system (#14 to #17). Therefore, the imaging state of the photographic optical system can be visually confirmed within the finder.

In this embodiment of the virtual image finder optical system,
Since it is not possible to distinguish between the distance information of the main subject and the distance information of other subjects, it is not possible to display each condition in the viewfinder. This can be visually recognized throughout the viewfinder as a change in the blur of the subject image.

In the embodiments shown in FIGS. 1 to 7, an optical phase filter using a liquid crystal is placed between the objective lens and the eyepiece, and the MTF characteristics of the optical phase filter are measured based on the distance determined by the distance measuring device. The amount of extension of the photographing lens based on the information, that is, the amount of movement of the photographic lens, is changed by voltage control according to the focus state of the photographic lens on the main subject, so the imaging state of the photographic optical system can be visually confirmed in the viewfinder in a pseudo manner. It becomes possible to do so.

(Modified example) In this embodiment, calculations (#6 in FIG. 2, #16 in FIG. 7) for setting the voltage ■i to be applied to the optical phase filter 1 according to the amount of extension of the photographic lens 108 are measured. Distance device 101
The array state control circuit 2 applies a voltage Vi to the optical phase filter 1 according to the calculation result from the device, and the MT
Although the F characteristic is changed, the calculations in #6 in FIG. 2 and #16 in FIG. 7 may also be performed within the array state control circuit 2.

(Effects of the Invention) As explained above, according to the present invention, the transparent electrode, which is a common electrode having irregularly arranged non-conductive regions, arranged on one opposing surface of a pair of transparent substrates; It consists of transparent electrodes, which are segment electrodes having one or more regions, arranged on the other opposing surface of the substrate, and liquid crystal filled between these transparent electrodes, and arranged between the objective lens and the eyepiece. an optical phase filter, and an array state control means that receives information on the amount of extension of the photographing lens to be moved to the in-focus position and controls the array state of the liquid crystal of the optical phase filter based on the information, and the following is provided. The imaging state of the photographing optical system, which changes over time, is input as an electrical signal, and the alignment state of the liquid crystal of the optical phase filter is controlled according to the signal to blur the subject image according to the imaging state at that time. Since the state is formed, it is possible to visually confirm the imaging state of the photographing optical system in a pseudo manner within the finder without complicating or increasing the size of the apparatus.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of the main parts of a camera equipped with an apparatus according to an embodiment of the present invention, and FIG. 2 is a flowchart showing its operation.
FIG. 3 is a diagram explaining the MTF characteristics of the optical phase filter shown in FIG. 1, FIG. 4 is a diagram explaining its function, FIG. 5 is a pattern diagram of its transmission electrode, and FIG. FIG. 7 is a block diagram of the main parts of the camera equipped with the device, and is a flowchart showing its operation. 1... Optical phase filter, 2... Array state control circuit, 3... Objective lens, 5...
...Eyepiece, 6...Optical phase filter, 7
...Objective lens, 8...Eyepiece lens,
101... Distance measuring device. Patent applicant Canon Co., Ltd.

Claims (1)

[Claims] (1) In a finder device equipped with an objective lens that takes in light reflected from an object and an eyepiece that allows the image formed by passing through the objective lens to be observed as an image of the object, one side of a pair of transparent substrates facing each other is a transparent electrode that is a common electrode having irregularly arranged non-conductive regions; a transparent electrode that is a segment electrode having one or more regions disposed on the other opposing surface of the transparent substrate; The optical phase filter, which is made of liquid crystal filled between transparent electrodes and is placed between the objective lens and the eyepiece lens, and information on the amount of extension of the photographic lens moved to the in-focus position are input. A finder device comprising an arrangement state control means for controlling an arrangement state of liquid crystals of the optical phase filter based on the arrangement state of the liquid crystals of the optical phase filter.