Liquid crystal display device with polarizer cutout for constantly diplayed information for camera finder

A liquid crystal display device for use in a camera finder is provided which is capable of enabling a camera user to constantly observe a predetermined information by peeping into the finder. Said liquid crystal display device is formed by a liquid crystal display plate and one or more polarizing plates, at least one polarizing plate is formed with a notch corresponding to an information constantly displayed on the liquid crystal display plate, thereby rendering a user to constantly observe a predetermined information without consuming any electric energy.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to a liquid crystal display device for use in
 a camera finder, in particular to a liquid crystal display device capable
 of displaying constant normal information and information needed in
 photographing operation.
 2. Description of the Related Art
 In general, there have been known a liquid crystal display device for use
 in a camera finder, particularly for use in a lighting type finder
 apparatus, such as that disclosed in Japanese Unexamined Patent
 Publication Nos. 57-173824 and 63-128331.
 With a lighting type finder apparatus employing the above mentioned liquid
 crystal display device, since a target mark of distance measurement may be
 displayed by a liquid crystal, there is not any inconvenience when
 responding to a release signal to display a target mark. However, if a
 target mark is to be displayed constantly, the driving of liquid crystal
 will cause a consumption of electric energy, resulting in a problem that
 buttery inserted therein will be used up too soon.
 On the other hand, if a liquid crystal display plate is a glass plate on
 which a target mark has been printed, a constant displaying does not cause
 any electric consumption. However, since the target mark can only be seen
 through a polarizing plate, there is a problem that such target mark can
 not be seen clearly.
 SUMMARY OF THE INVENTION
 is an object of the present invention to provide an improved liquid crystal
 display device for use in a camera finder, which allows a user to clearly
 and constantly see a target mark of distance measurement, and is able to
 avoid an electric consumption which is otherwise unavoidable for driving
 the liquid crystal.
 In order to solve the above problem, according to the present invention,
 there is provided an improved liquid crystal display device for use in a
 camera finder, said display device being capable of displaying a
 predetermined information within an image of a photographing object and in
 the vicinity of said image, characterized in that said liquid crystal
 display device is formed by a liquid crystal display plate and at least
 one polarizing plate, said liquid crystal display plate is provided with
 an information constantly displayed and an information needed only at a
 time of performing a photographing operation, the at least one polarizing
 plate is formed with a notch corresponding to the information constantly
 displayed.
 Further, with the liquid crystal display device of the present invention,
 it is possible that only one side of the above liquid crystal display
 plate is provided with a polarizing plate, alternatively, both sides of
 the liquid crystal display plate are provided with polarizing plates, at
 least one polarizing plate is formed with a notch corresponding to the
 information constantly displayed on the liquid crystal display plate.
 With the use of the present invention, a camera user is allowed to peep
 into the finder to constantly observe a predetermined information such as
 a target mark in the liquid crystal display device, without consuming any
 electric energy. Further, during a process of photographing operation,
 since the liquid crystal display device is driven, it is possible for a
 user to observe all of the displayed information by peeping into the
 finder.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
 An embodiment of the present invention shown in the accompany drawings will
 be described in detail below.
 FIG. 1 is a perspective view schematically illustrating a whole structure
 of a camera finder which is equipped with a liquid crystal display device
 made according to the present invention, FIG. 2 is an explanatory view
 schematically illustrating one example of liquid crystal displaying within
 the camera finder when the camera is OFF, FIG. 3 is an explanatory view
 schematically illustrating one example of liquid crystal displaying within
 the camera finder when the camera is ON, FIG. 4 is an explanatory view
 schematically indicating the liquid crystal display device, FIG. 5 is a
 cross sectional view schematically indicating the liquid crystal display
 device, FIG. 6 is an exploded view schematically indicating the liquid
 crystal display device of the present invention, FIG. 7 is an explanatory
 view schematically illustrating polarizing plates for use in the liquid
 crystal display device of the present invention, FIG. 8 is an explanatory
 view schematically illustrating a full displaying state within the finder
 apparatus under a full lighting condition.
 As shown in FIG. 1, a liquid crystal display device made according to the
 present invention is used in a lighting type finder apparatus, an image
 light of a photographing object having passed through an objective lens 2
 and movable lens 3 is input into a first Porro prism 4 and is changed in
 its travelling direction by about a right angle. After passing through a
 full visual field mask 5, the image light of the photographing object is
 allowed to arrive at a second Porro prism 6, in which the above image
 light is changed again in its travelling direction by about a right angle.
 Then, the image light is passed through a half mirror 7 and is allowed to
 proceed in the same direction as the image light which is passing through
 the above objective lens 2, and further pass through a diopter correction
 lens 8 and an ocular lens 9.
 On the other hand, the information displayed on the liquid crystal display
 device 1 within the finder is positioned on the outside of the image of
 the photographing object. In the present embodiment, predetermined
 informations are displayed on both sides of the image of a photographing
 object.
 The above liquid crystal display device 1 can be understood in further
 detail with reference to FIGS. 4-7. Namely, on one surface of the glass
 plate 11 there is formed a pattern surface (liquid crystal) 12 capable of
 displaying predetermined informations. Provided on the pattern surface 12
 are another glass plate 13 and a liquid crystal display plate 14. Further,
 on the outer surfaces of the two glass plates 11 and 13, there are
 provided polarizing plates 15 and 16, thereby forming the liquid crystal
 display device 1.
 As information to be displayed on the liquid crystal display device 1,
 there may be a target mark located on the central area thereof, and
 various other informations (for example, informations indicating if there
 is a flashing) to be displayed on both sides of the target mark.
 Namely, on both incidence surface and emitting surface of the liquid
 crystal display plate 14, there are provided a polarizing plate 15 and a
 polarizing plate 16. The two polarizing plates 15 and 16 have through
 holes in their central areas so that both the polarizing plates 15 and 16
 will not cover a position of the target mark located in the center of the
 liquid crystal display plate 14.
 In more detail, in the present embodiment, each of the polarizing plates 15
 and 16 has a through hole 17 in the central position thereof. In this way,
 a part of the liquid crystal display plate 14 corresponding to the holes
 17 will not be affected by the polarizing plates 15 and 16.
 In this condition, it is either allowable to form a through hole 17 on each
 of the polarizing plates 15 and 16, or allowable to form a through hole 17
 on only one of the polarizing plates 15 and 16.
 On the other hand, referring to FIG. 8, a reference numeral 18 is used to
 represent a transparent portion on which a photographing object image is
 displayed, while a reference numeral 19 is used to represent a
 non-transparent portion which is adapted to display an information such as
 a scale information.
 Further, as shown in FIG. 1, there is provided a light guide 20 adjacent to
 the objective lens 2. Such light guide 20 is used to render an outside
 incident light to proceed in a direction parallel to a proceeding
 direction of an image light passing through the objective lens 2. Ahead of
 the light guide 20 and on one side of the Porro prism 6, there is provided
 the liquid crystal display device 1.
 Further, on both sides of the light guide 20 there are provided a pair of
 lighting elements such as LED (Light Emitting Diode), so as to illuminate
 the informations being displayed on both sides of the image of a
 photographing object.
 The operation of the finder apparatus constructed in the manner as
 described above will be explained in detail below.
 At first, an image light of a photographing object is input into the
 objective lens 2, passed through the movable lens 3, and changed in its
 travelling direction in the Porro prism 4. Further, the image light is
 passed through the full visual field 5 and enter the other Porro prism 6
 in which its travelling direction is again changed. Finally, the image
 light is caused to pass through the half mirror 7 and the diopter
 correction lens 8, before passing through the ocular lens 9.
 Upon peeping into the finder, a target mark is visible together with an
 image of a photographing object on the central area of the liquid crystal
 plate 14, by virtue of the through holes 17, 17 of the polarizing plates
 15 and 16. Further, the target mark and the image are clearly visible also
 by virtue of the light guide 20.
 Namely, a target mark provided on the liquid crystal display plate 14 may
 be clearly seen by peeping into the finder, without a necessity of seeing
 through the polarizing plates 15 and 16.
 Therefore, the target mark is allowed to be clearly and constantly seen by
 peeping into the finder, irrespective of whether or not there is existing
 an image of photograph object.
 On the other hand, on both sides of the above light guide 20 there are
 provided a pair of lighting elements such as LED (Light Emitting Diode)
 which are used to illuminate the liquid crystal display device 1.
 In this way, during a photographing operation, as fast as the camera is ON,
 the lighting elements 21 may be actuated to illuminate the photographing
 information displayed on both sides of the image of the photographing
 object, thereby rendering the interior of the finder to be clearly visible
 (as shown in FIG. 8).
 Under a condition as described above, since the polarizing plates 15 and 16
 are not provided on an area of the liquid crystal display plate 14 which
 contains the target mark, even when the camera is OFF, it is still
 possible to render the target mark visible upon peeping into the finder.
 Therefore, the target mark may be constantly displayed without consuming
 an electric energy which is otherwise unavoidable for driving the liquid
 crystal (as shown in FIG. 2).
 Further, when displaying some other marks provided on the liquid crystal
 display plate 14 such as a mark representing whether there is a flash, the
 camera may be made ON and the liquid crystal may thus be driven, so that a
 user is allowed to peep into the finder while at the same time ensuring
 that the portions covered by the polarizing plates 15 and 16 will not
 receive any unfavourable influences from the polarizing plates 15 and 16
 (as shown in FIG. 2).
 Accordingly, when peeping into the finder, a predetermined mark such as a
 target mark may be constantly observed without consuming any electric
 energy. In this way, an electric energy is consumed only during a
 photographing operation for driving a liquid crystal, thereby permitting a
 considerable reduction in electric consumption.
 The present invention, having been constructed in the above described
 manner, can provide the following effects. Namely, since a notch is formed
 on each polarizing plate, and since such notch is corresponding to a
 position on the liquid crystal display plate which involves a mark to be
 constantly displayed, it is sure that a mark to be constantly displayed
 will not be obstructed by the polarizing plates, thereby ensuring a
 desired observation into the finder. Therefore, it is allowed to dispense
 with a necessity of driving the liquid crystal, so as to greatly reduce an
 electric consumption.
 Further, since the above effect may be achieved only by cutting notch
 portions on the polarizing plates, the liquid crystal display device may
 be made simple in its structure, thereby permitting the manufacture
 thereof with a low cost.