JPH01105924A - Active screen - Google Patents

Abstract

PURPOSE:To speedily confirm the state of an object to be photographed by providing a photoconductive layer generating resistance distribution corresponding to the light intensity distribution of an object image formed on a focused surface and a liquid crystal layer overlapped with said photoconductive layer and possessing storing actions. CONSTITUTION:Since an R filter 33 is fitted to the position corresponding to the R filter 30 of a glass substrate 27, a liquid crystal layer 25 in the position corresponding to the R filter 30 can be observed on the side of the glass substrate 27 through an R filter 33. Thus, red-colored components of light for an object image are formed as an liquid crystal image composed of red components corresponding to said light on the side of the glass substrate 27. Other green and blue components are formed similarly, and these three components form one picture element. When a photographing lens 10 is directed toward a white plate or a white cloud, etc. being light to reflect scattered light or when said lens is removed to point a camera toward a white light source for lighting a room to peep through an eye contact lens, an object image stored on an active screen 1 and being ready for exposure can be recognized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an active type screen that is provided on the focusing surface of the finder optical system of a camera so that the photographed subject image can be confirmed immediately after photographing. (hereinafter referred to as an active screen).

[Conventional technology]

In conventional cameras, the viewfinder optical system observes the subject image, determines the composition, and adjusts the focus (for models with an autofocus mechanism, this is done automatically in conjunction with pressing the release button, etc.). Photographs are taken by pressing the button, and the judgment of success or failure of the photograph immediately after the photograph is taken depends on the intuition and experience of the photographer.

[Problem that the invention seeks to solve]

In other words, with conventional cameras, in order to judge the success or failure of a photograph, one must wait for the film to be developed, which takes time, and the focus of the photographed subject image, the facial expressions of the person, blinking, etc. cannot be determined immediately after the photograph is taken. cannot be confirmed. Therefore, in order to avoid this failure as much as possible, multiple shots of the same subject have been taken. However, such a method is troublesome and costly, and there are problems in that it is impossible to confirm the state of the subject image at the time of photographing.

(Purpose of the Invention) The present invention was made to solve the above-mentioned problems, and includes an active screen that allows you to check the focus and composition of the subject image immediately after shooting. The purpose is to provide.

[Means for solving problems]

In order to achieve the above object, the active screen of the present invention is provided on the focus plane of a finder optical system included in a camera, and has a resistance distribution corresponding to the intensity distribution of light of a subject image formed on the focus plane. The liquid crystal layer is composed of a resulting photoconductive layer and a liquid crystal layer having a memory function, which is superimposed on the photoconductive layer and to which a voltage is applied in accordance with the resistance distribution.

[Function] According to the above configuration, the subject is captured through the finder, the focus is adjusted, the composition is determined, and the release button is pressed in the same way as in a conventional camera. Then, a resistance distribution corresponding to the intensity distribution of the light of the subject image is generated in the photoconductive layer of the active screen provided on the focus surface of the finder optical system, and a voltage is applied to the liquid crystal layer that has a memory function in response to this. Therefore, an image corresponding to the subject image is stored in the liquid crystal layer of the active screen. Therefore, by looking through the finder immediately after photographing is completed, the subject image at the time of photographing can be confirmed within the field of view of the finder.

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

[Embodiment] In FIG. 1 showing the main parts of a camera 1 equipped with an active screen 15 which is an embodiment of the present invention, the camera 1 is a well-known 35 mm eye reflex camera, and a photographic lens 1
A well-known movable mirror 11 is arranged behind the movable mirror 11, and a finder optical system is constructed above the movable mirror 11. This finder optical system consists of an active screen, 15° condenser lens, 16. Pentaprism 17.
It consists of an eyepiece lens 18 which is a two-piece achromatic lens, and a film 12 is loaded behind the movable mirror 11.

In FIG. 2 showing the structure of the active screen 15 of the present invention, the active screen 15 includes a glass substrate 20 whose inner surface has a matte finish and a glass substrate 27 made of transparent glass, and between these glass substrates 20 and 27. Transparent electrodes 21, 24, 26. Photoconductive layer (Ph
oto Conductor) 22, transparent glass plate 2
3 and a liquid crystal layer 25.

The photographic lens 1 is mounted on the matte surface of the glass substrate 20.
0 forms the subject image. The transparent electrode 21.
26 is attached to the inside of each of the glass substrates 20 and 27, and the transparent electrode 24 is attached to the transparent glass plate 23. On the outer surface of each of the glass substrates 20.27, there is a minute R filter 30.degree. G filter 31. that transmits red, green, and blue light respectively. A filter group including the B filter 32, and the R filter 33. A group of filters including a G filter 34 and a B filter 35 are pasted on one side in correspondence with each other.

As the photoconductive layer 22, a Cds deposited layer with a thickness of 2 to 12 μm is used, and the liquid crystal used in the liquid crystal layer 25 is a ferroelectric smectic liquid crystal having a memory function. Here, the resistance RL per unit area of the liquid crystal layer 25 is
C is the resistance per unit area of the photoconductive layer 22 with and without light irradiation, that is, the bright resistance R0N and the dark resistance R8
For FF.

ROFF) RLC) Selected to become RoN.

A power source 40 for applying a DC voltage and a switch 42 are connected to the transparent electrodes 21.26, and the transparent electrodes 24
．． A power supply 41 and a switch 43 are connected to 26. The transparent electrode 24 is provided to erase the image stored in the liquid crystal layer 25, and the transparent electrode 24.26
The voltage applied between them is of opposite polarity to the voltage applied between the transparent electrodes 21 and 26. Note that the switch 42
is turned on in conjunction with pressing the release button (not shown) of the camera 1.

To use the camera 1 equipped with the active screen 15 of the present invention, the user presses the release button after pointing the photographing lens 10 at the subject and adjusting the focus. In conjunction with this, the switch 42 of the active screen 15 is turned OFF.
N, and a predetermined voltage is applied between the transparent electrodes 21 and 26. On the other hand, the subject image is formed on the matte surface of the glass substrate 20 of the active screen 15 via the movable mirror 11 by the photographing lens 10 . Then, a resistance distribution corresponding to the light intensity distribution of this subject image is generated in the photoconductor N22.

For example, to explain the light of the subject image that has passed through one R filter 30, the light that passes through this R filter 30 is only the red component of one minute point in the subject image, and the R filter 30 After passing through the glass substrate 20.
The light passes through the transparent electrode 21 and enters the photoconductive layer 22 . Depending on the brightness of the red component light incident on the photoconductive layer 22, R
The resistance value of the photoconductive layer 22 at a position corresponding to the filter 30 decreases. A voltage corresponding to the amount of drop in the resistance value is applied from the transparent electrode 21.26 to the liquid crystal layer 25 at a position corresponding to the R filter 30, and the molecular arrangement changes due to the electro-optic effect.

On the other hand, since the R filter 33 is attached to the glass substrate 27 at a position corresponding to the R filter 30, the liquid crystal layer 25 at the position corresponding to the R filter 30 from the glass substrate 27 side passes through the R filter 33. observed.

As a result, the red component light of the subject image is formed as a corresponding red component liquid crystal image on the glass substrate 27 side.

The other green and blue components are formed in the same way, and one pixel is formed by these three color components. By forming these pixels at high density over the entire surface of the active screen 15 on the glass substrate 27 side, an image corresponding to the subject image is formed on the glass substrate 27 side. At the next moment, the movable mirror 11 is flipped up and evacuated from the photographing optical path, the shutter (not shown) is opened and closed, and the film 1 is
2, exposure is performed. As soon as the exposure of the film 12 is completed, the movable mirror 11 is returned to its original position.

You can point the photographic lens 10 at a white plate or white cloud that is hit by light and reflect scattered light, or remove the photographic lens 10 and point the camera 1 at a white light source for indoor lighting, etc., and look through the eyepiece 18. (The image of the subject just before exposure stored on the active screen 15 can be viewed 6 meters away. By observing this image of the subject, the state of focus, composition, etc. just before shooting can be confirmed. It is possible to almost accurately judge the success or failure of photography without developing the exposure film.

Note that since the liquid layer 25 is a smectine liquid crystal layer that has a memory function, even if the switch 42 is turned off by stopping pressing the release button, the movable mirror 11 will jump up again and the subject image will no longer be incident. However, the image formed on the liquid crystal layer 25 is preserved without being lost. Further, to erase the stored image, turn on the erase switch 43. When the switch 43 is turned on, a voltage of opposite polarity is applied between the transparent electrodes 24 and 26, the molecular arrangement state of the liquid crystal layer 25 is returned to the initial state, and the stored image is erased.

When the stored image is erased, the liquid crystal layer 25 becomes transparent and the active screen 15 returns to function as a focusing plate with a matte surface as before. The subject image is formed by the photographing lens 10 on the matte surface of the active screen 15 via the movable mirror 11, and is condensed by the condenser lens 16 to the pentaprism 1.
7. As is well known, the pentaprism 17 inverts the left and right images of the incident subject image and guides it to the eyepiece 18 as an erect image. The subject image incident on the eyepiece lens 18 is magnified and focused at a position where it can be easily viewed. Therefore, the subject image formed by the photographing lens 10 can be observed in the viewfinder field of view as before photographing.

Note that a mode may be provided in which the switch 42 is always kept in the OFF state when there is no need to memorize the subject image during photographing. Furthermore, it goes without saying that the active screen 15 can be incorporated into a finder optical system of a compact camera or the like.

Furthermore, by applying the active screen 15 of the present invention, it is also possible to confirm the subject image fixed on the film without waiting for the film to be developed. For example, installing an active screen inside the camera's exposure chamber,
A subject image incident from the photographing lens 10 is guided to this active screen via a sub-mirror or the like.

Then, the subject image may be stored in the active screen in conjunction with the opening of the shutter, and displayed on a display device such as an external screen.

〔Effect of the invention〕

As described above, the active screen of the present invention is provided on the focusing surface of the finder optical system provided in the camera, and
It has a photoconductive layer that generates a resistance distribution corresponding to the intensity distribution of the light of the object image formed on the focal plane, and a memory function that is superimposed on this photoconductive layer and applies a voltage corresponding to the resistance distribution. Because it consists of a liquid crystal layer, you can quickly and easily check the focus and composition of the subject image immediately after shooting, without having to wait for the time-consuming film development process, and make it possible to judge whether the shooting was successful or not. It also makes it possible to avoid costly and time-consuming layering and the use of instant film.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a camera including an embodiment of the present invention. FIG. 2 is an enlarged sectional view of one embodiment of the present invention. 1... Camera 10... Photographing lens 11... Movable mirror 12... Film 15... Active screen 16... Condenser lens 17... Pentaprism 18... Eyepiece.

Claims (2)

[Claims] (1) A photoconductive layer that is provided on the focusing surface of the finder optical system of the camera and that produces a resistance distribution corresponding to the intensity distribution of the light of the subject image formed on this focusing surface; An active screen comprising a liquid crystal layer having a memory function which is superimposed and a voltage is applied in accordance with the resistance distribution. (2) The focus plane of the finder optical system is located between a movable mirror provided in the photographic optical system and a pentaprism for guiding the subject image reflected by the movable mirror to the eyepiece. An active screen according to claim 1.