JPH0727161B2 - Display device in the finder - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a display device, and more particularly to a display device for displaying various information at the time of shooting in a viewfinder of a shooting device such as a camera or a video.

(2) Conventional Technology Conventionally, when displaying predetermined photographing information in a finder of a photographing device such as a camera or a video, an LED or a liquid crystal arranged outside the photographing field frame has been used. However, with such a mechanism, there is a possibility of overlooking the display that warns of an inappropriate exposure state, and it is impossible to display a focus area, an appropriate exposure area, and the like within the field of view.

In view of the above-mentioned drawbacks, the applicant of the present application has proposed that the liquid crystal display or the like is overlapped with the field of view for display. For example, in JP-A-52-110626, a TN (twisted nematic) liquid crystal display is used. However, in this type of display, since a polarizing plate is usually used, the maximum light utilization efficiency was about 50%.
Further, JP-A-58-62626 uses a GH (guest-host) type liquid crystal display, and although a polarizing plate is unnecessary, light absorption efficiency by dye molecules is always present, resulting in a decrease in light utilization efficiency. .

Therefore, the conventional method has a drawback in that the brightness in the finder cannot be sufficiently obtained although the display device in the field of view in the finder is highly useful.

(3) Outline of the Invention An object of the present invention is to eliminate the above-mentioned conventional drawbacks and to arrange the light beam at a position that covers almost all the light flux in the finder optical path, while maintaining the brightness inside the finder all the time. , It is to provide a display device in the finder that can display a clear image in any place.

In order to achieve the above object, a display device in a finder according to the present invention is a display device in a finder that displays shooting information, a pattern, etc. in a finder of a camera, and is substantially perpendicular to an optical path of a subject light in the viewfinder. A grating in which first and second optically anisotropic substances are alternately arranged along a flat plane, and the optical axis directions of the first and second optically anisotropic substances substantially coincide with each other. The subject light is diffracted by the grating because the subject light passes through the grating in a first state and the optical axis directions of the first and second optically anisotropic substances are parallel to the plane and different from each other. Means for controlling the optical axis direction of the optically anisotropic substance to generate the second state.

The optically anisotropic substance is a substance whose optical axis can be changed by an electric field, a magnetic field, heat, pressure, light, or the like, or a substance whose refractive index can be changed. Crystal, ie PLZT, LiNbO ₃ , LiTa
O ₃ , TiO ₂ , PMMA, CCl ₄ , KDP, ADP, ZnO, BaTiO ₃ , Bi ₁₂ SiO ₂₀ ,
Ba ₂ NaNb ₅ O ₁₅ ,, MnBi, EuO, CS ₂ , Gd ₂ (MoO ₄ ) ₃ , Bi ₄ Ti ₃ O ₁₂ ,, Cu
Cl, GaAs, ZnTe, As ₂ Se ₃ , Se, AsGeSeS, DKDP, MNA, mNA, UREA,
Photoresist, nematic liquid crystal, cholesteric liquid crystal, smectic liquid crystal, ferroelectric liquid crystal and the like can be mentioned. In particular, liquid crystals are suitable materials because they are inexpensive and easy to control.

In addition to displaying a monochrome pattern by transmitting and blocking (diffracting) the subject light, this display device can also perform color display using a color filter or the like, color display using the spectral transmittance characteristic of grating, etc. .

Further, as a method for creating the above-mentioned grating, a method using a resist, a method by photolithography and dry etching, a replica method using a thermosetting resin or an ultraviolet curable resin, a cutting method using a ruling engine or embossing is used. There are various methods such as the method.

Hereinafter, the display device will be described in detail with reference to the drawings.

(4) Example FIG. 1 shows an example of the basic constitution of a display element used in the display device in a fan according to the present invention and also serves as an explanatory view of the operating principle.
Here, 1 and 2 are optically anisotropic substances, 3 is a transparent electrode,
Reference numeral 4 denotes a transparent optical member, 5 denotes incident light, and 6 and 6 ′ denote arbitrary orthogonal polarization components in the incident light 5.

The device shown here forms a triangular wave-shaped grating at the interface between the anisotropic substance 1 and the anisotropic substance 2, and the respective optical axes are oriented in the arrow directions (groove direction and arrangement direction of the grating) in the figure. And are orthogonal to each other. The layer forming the grating is sandwiched by the two transparent optical members 4 on which the transparent electrodes 3 are formed to form an element.

In general, light having random polarization characteristics can be divided into two polarization components 6, 6'that are orthogonal to each other as shown in FIG. When the display device shown in the figure is driven by an electric field, the polarization direction of the polarization component 6 of the incident light 5 is anisotropic when the electric field is not applied between the transparent electrodes 3 facing each other.
Coincides with the optical axis direction of, and the polarization component 6 feels the extraordinary refractive index n _e of the anisotropic substance 1. Also, since the orthogonal to the optical axis direction of the anisotropic material 2, the polarization component 6 feel ordinary refractive index n _o 'of the anisotropic material 2. Further, based on the same principle, the polarization component 6 of the incident light 5 'each ordinary refractive index n _o and the extraordinary refractive index n _e with respect to anisotropic materials 1 and 2' feel. Therefore, there exists a phase type grating having refractive indexes n _e , n _o ′ and n _o , n _e for the polarization components 6 and 6 ′, respectively. Next, in a state where an electric field is applied between the transparent electrodes 3 facing each other,
The optical axis directions of the anisotropic substances 1 and 2 change according to the amount of electric field, and at the same time, the refractive indexes felt by the polarization components 6 and 6'of the incident light 5 also change, and the modulation degree of the grating changes. At this time, by controlling so that the refractive indices of the anisotropic substances 1 and 2 sensed by the polarization components 6 and 6'are equal, there is no grating for the incident light 5, and the incident light 5 Passes through a grating consisting of anisotropic substances 1 and 2.

For example, when the same positive dielectric nematic liquid crystal is used for the anisotropic substances 1 and 2 (n _o = n _o ′, n _e = n _e ′), the liquid crystal is aligned in the direction of the electric field by applying an electric field. The alignment direction of the liquid crystal and the optical axis coincide with each other. Therefore, the polarization component 6 of the incident light 5 with respect to the liquid crystal aligned substantially perpendicular to the transparent electrode 3
Both 6 and 6'perceive the ordinary index of refraction n _o of the liquid crystal and transmit the grading composed of the liquid crystal. Further, in the static state where no electric field is applied, the liquid crystal is oriented in the direction of the arrow, and the polarization components 6 and 6'of the incident light 5 both feel a grating consisting of the refractive indices n _e and n _o . Here, the wavelength of the incident light 5 is λ, the refractive index difference between the anisotropic substances 1 and 2 made of liquid crystal is Δn,
If the thickness of the liquid crystal (grading height) is T,
The diffraction efficiency η _o of the zero-order transmitted diffracted light diffracted by the grading formed by the liquid crystal can be expressed by the following formula 1.

However, Δn _max = | n _e −n _o |, Δn _min = 0, and Δn · T
= Mλ (m = 1,2,3, ...) Is satisfied, ηo = 0. That is, the polarization components 6 and 6'of the incident light 5 are both diffracted by the grating, and the emitted light in the zero-order direction does not exist.
Further, when Δn = 0, that is, when the refractive indices of the anisotropic substances 1 and 2 are equal to the polarization components 6 and 6 ′, the incident light 5 as described above is used.
Passes through the grating and becomes zero-order transmitted light.
Since Δn changes according to the amount of electric field applied between the transparent electrodes 3, the diffraction efficiency η _{o in the} above equation is variable by controlling the amount of electric field.

As can be seen from the above description, even light having random polarization characteristics such as natural light can be modulated without decreasing the light utilization efficiency by individually controlling the transmission of the polarization components orthogonal to each other. I can.

FIG. 2 shows another example of the grating shape in the above display element. FIG. 2 (A) is a rectangular element, and FIG. 2 (B) is an element having a sinusoidal grating. All refer to the same members as in FIG.

The present invention can be achieved with any shape including the grating shape as shown in FIG. 2. However, when the grating shape is different, the formula of the diffraction efficiency as shown in the formula (1) is different. . For example, in the rectangular grating, the diffraction efficiency of zero-order transmitted light is expressed by the following equation (2).

Next, the difference in the spectral characteristics depending on the shape of the grating will be shown as an example.

FIG. 3 shows the spectral transmittance characteristics of the zero-order transmitted light in the visible wavelength range of 400 to 700 nm in this device when triangular wave-shaped and rectangular-shaped gratings are used. Here, the vertical axis is the transmittance η
_o , the horizontal axis is the wavelength λ, 7 and 7'in the figure show the characteristics of the triangular and rectangular gratings when transmitting light, and 8 and 8'the triangular wave and rectangular gratings when the light is blocked. It shows the characteristics. As shown in the figure, the rectangular grating has strong wavelength selectivity and the triangular wave grating has almost no wavelength selectivity.

Therefore, the grating shape is selected in consideration of the ease of manufacture, the purpose of use of the photographing device, the system around the display device, specifications and the like.

Hereinafter, an example of a method of manufacturing a display device using the display element shown in FIG. 1 will be shown.

FIG. 4 shows a process of manufacturing the display device of FIG. 1, 9 is a wavy transparent spacer, 10 is a liquid crystal aligned in the groove direction of the grating, 10 'is a liquid crystal aligned in the array direction of the grating, and 11 is SiO. The same members as those in FIG. 1 are designated by the same reference numerals. Here, a positive dielectric nematic liquid crystal is used as the anisotropic substance.

Corning 7059 Glass Substrate 4 (Corning, 37 × 26
X 1 mm ³ ) both sides are polished to form a transparent flat surface, and the substrate 4
An ITO film having a thickness of 1000 Å was formed on the entire surface of to prepare a transparent electrode 3. Next, SiO11 was obliquely vapor-deposited on the transparent electrode 3 for orientation treatment so that the liquid crystal was oriented as shown by the arrow in FIG. 4 (A). Further, a glass substrate 4 of the same kind as the above glass substrate
After forming the patterned transparent electrode 3 as shown in FIG. 4 (C) on the ITO film, SiO is obliquely vapor-deposited on the transparent electrode 3 for alignment treatment, and the liquid crystal is changed to FIG. 4 (C). The orientation is as indicated by the arrow. On the other hand, a wavy transparent spacer 9 as shown in FIG. 4 (B) was formed by pressure processing. The height T of the peaks and valleys of the waves in this wavy transparent spacer 9 is 2.3 μm.
Is. Subsequently, the above-mentioned 2
The glass substrates 4 were opposed to each other with the transparent electrodes 3 facing each other, and the positive dielectric nematic liquid crystals 10 and 10 'were filled in the gaps and then sealed to complete the display device shown in FIG. 4 (D).

FIG. 5 is a view showing an example of the display device in the finder according to the present invention, in which 12 is the display device, 13 is a focusing plate with a Fresnel lens, 14 is a condenser lens, 15 is a pentaprism,
Reference numeral 16 is an eyepiece lens, and 17 is a reflecting mirror.

The subject light guided into the finder by the reflecting mirror 17 is
The pentaprism 15 forms an erect image through the display device 12, the Fresnel lens / focus plate 13 and the condenser lens 14, and enters the eye of the photographer through the eyepiece lens 16. Here, in the display device 12, while the rectangular wave AC electric field is being applied between both electrodes, the entire visual field in the finder is in a light transmitting state, and the subject image can be clearly seen through the eyepiece lens 16. Things can be done. On the other hand, in the case of displaying an underexposure warning or a warning such as an in-focus state, the electric field of the warning display portion is patterned to 0 according to a signal from a detection device such as exposure or focus, and the display portion is displayed as a light-blocking state. Can be done.

An example thereof is shown in FIG. In the figure, reference numeral 18 denotes a transparent optical member having a semi-transparent mirror having an inclined surface of 45 ° in the central portion, and a part of light passing through the photographing lens is used as a light receiving element 21 for exposure detection or focus detection.
To send to. 22 is an exposure amount detection circuit or a focus detection circuit that receives and analyzes the output of the light receiving element 21, and 23 is a voltage generation circuit that receives the detection signal from the detection circuit 22 and the output of this circuit is the main display. Applied to the device 12.

An example of the display is shown in FIG. In the figure, (a) is an underexposure warning, (b) is an overexposure warning, (c) is a proper exposure display, (d) is a front focus state, (e) is a rear focus state,
(F) represents focusing. As described above, the display in the photographing field frame can be performed with a high contrast without impairing the brightness of the image, and when the display is not performed, there is no influence on the observation of the subject image.

In the above embodiment, the display device 12 is arranged between the condenser lens 14 and the focusing plate 13, but it is clear that the eyepiece 16 may be arranged in the vicinity depending on the system configuration in the finder. is there. Further, since this display device uses diffraction development by grating, it is also possible to take measures such as a means for removing diffracted light that becomes flare light, such as providing a fiber plate or the like on the light exit side of the display device. It is valid.

FIG. 8 shows a manufacturing process of another constitutional example in the present display device, and FIG. 9 is an explanatory diagram of a driving method of the display device shown in FIG. Here, 24 is a ferroelectric liquid crystal, and 25 and 25 'are comb-like electrodes, and the same members as those in the above-mentioned embodiment are designated by the same reference numerals. The creation process will be described in detail below.

As in the previous embodiment, Corning 7059 glass substrate 4 (37 × 26
Two pieces of × 1 mm ³ ) were prepared. One sheet is shown in Fig. 8 (A)
The ITO transparent electrode 3 is formed with a thickness of 1000 Å as shown in Fig. 4, and the other one is formed by comb-shaped IT only in the pattern part as shown in Fig. 8 (B).
O transparent electrodes 25, 25 'were formed with a thickness of 1000Å. The comb-shaped electrodes 25, 25 'are provided alternately as shown in FIG. 8 (C). Further, a PVC (polyvinylcarbazole) film was formed on the two glass substrates 4 and then subjected to rubbing treatment to align the liquid crystal alignment axes in the direction along the comb-shaped electrodes 25, 25 '. Then, as shown in FIG. 8 (C), the two glass substrates 4 are bonded to each other so that the electrode surfaces 3, 25, 25 'face each other via a spacer, and the ferroelectric liquid crystal MORA is provided in the gap. After filling with -8, it was sealed.

Next, a method of driving the display device created by the above method will be described with reference to FIG.

When the display is not performed first, the transparent electrode 3 and the comb-shaped electrode
No voltage is applied to both 25 and 25 '. Therefore, the ferroelectric liquid crystal
The optical axis of 4 is aligned in one direction in the initial state as shown in FIG. 9 (A), the anisotropy of the refractive index is uniform in the plane, no grating is formed, and the incident light passes through. To do. On the other hand, in the case of displaying, a voltage with opposite positive and negative absolute values, for example ± 5, is applied to the comb-shaped electrodes 25, 25 'forming the display pattern.
V is applied across the transparent electrode 3. At this time, the optical axis of the ferroelectric liquid crystal 24 is alternately tilted as shown in FIG. 9 (B), and only the display pattern portion is formed with a grating for the incident light. Therefore, if the relationship between the thickness T of the liquid crystal layer, the refractive index difference Δn ′, and the wavelength λ of the incident light is adjusted so as to satisfy the equation (2), the subject light passing through the display pattern portion is blocked. To be done. Therefore, the display within the field of view frame can be displayed with high contrast while maintaining the brightness of the entire image.

The above-mentioned ferroelectric liquid crystal does not have a memory function, but if the liquid crystal has a memory property, it is added to the electrode of either 25 or 25 'after making the initial alignment state uniform. The function described above is achieved only by switching the sign of the electric field.

The display devices in the above two embodiments are provided with patterns to be displayed in advance in the device, but it is naturally possible to drive the matrix display device in the finder, and various types of cameras can be used. If matrix driving is performed in combination with a detection device, focusing area display, exposure appropriate area display, and the like are possible, and various display forms can be obtained.

Further, in the above-mentioned embodiment, an example in which liquid crystal is applied as an optically anisotropic substance is shown, but the anisotropic substance is not limited to liquid crystal, and electro-optical effect such as electro-optical crystal, thermo-optical effect, magnetic effect, etc. Various anisotropic substances having an optical effect can be applied.

(5) Effects of the Invention As described above, the display device in the finder according to the present invention does not need a polarizing plate because it does not have a polarization characteristic, and allows the subject light to pass with a high transmittance in a normal state. This is a device capable of displaying with high contrast when displaying shooting information and the like. Therefore, the device is capable of displaying the warning pattern, the region, and the like on the entire surface regardless of the inside and the outside of the field frame within the finder while maintaining the field structure and brightness.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic configuration example of a display element used in a display device in a finder according to the present invention. FIG. 2 is a diagram showing another example of the grating shape of the display element. FIG. 3 is a diagram showing the spectral transmittance characteristics in the visible wavelength region in the case of triangular wave-shaped and rectangular gratings, which are shown when light is transmitted and when light is blocked. FIG. 4 is a diagram showing a manufacturing process of a display device using the display element shown in FIG. 1. FIG. 5 is a diagram showing an example of a display device in a finder according to the present invention. FIG. 6 is a diagram showing an example in which an exposure amount or focus detection device and this display device are combined. FIG. 7 is a diagram showing an example of a display pattern by this display device. FIG. 8 is a diagram showing a production process of another configuration example of the display device. FIG. 9 is an explanatory diagram showing a driving method of the display device shown in FIG. 1,2 ...... Optically anisotropic substance 3 ...... Transparent electrode 4 ...... Transparent optical member (substrate) 5 ...... Incident light 6,6 '…… Polarizing components in incident light orthogonal to each other 7 ...... Light Spectral transmittance characteristic of triangular wave grating when transmitting 7 '... Spectral transmittance characteristic of rectangular grating when transmitting light 8 ...... Spectral transmittance characteristic of triangular wave grating when blocking light 8' ... Light Spectral transmittance characteristics in rectangular grating when cut off 9 Wavy transparent spacer 10,10 '…… Liquid crystal 11 …… SiO 12 …… Display device 13 …… Focus plate 14 …… Condenser lens 15 …… Penta prism 16 ...... Eyepiece 17 ...... Reflecting mirror 18 ...... Transparent optical member having a semi-transparent mirror with a 45 ° inclined surface in the center 19 …… Lens 20 …… Mirror 21 …… Detecting light receiving element 22 …… Detecting circuit 23 ...... Voltage generator 24 …… Ferroelectric liquid crystal 25,25 '…… Comb shaped electrode

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location G02F 1/141

Claims (3)

[Claims] 1. A viewfinder display device for displaying shooting information, patterns, etc. in a viewfinder of a camera, wherein first and second optical differences are provided along a plane substantially perpendicular to an optical path of subject light in the viewfinder. The first state and the first state in which the subject light passes directly through the grating due to the optical axes of the first and second optically anisotropic substances being substantially aligned with each other The optical difference between the optical axes of the first and second optically anisotropic substances is parallel to the plane and different from each other so that a second state in which the subject light is diffracted by the grating is generated. And a means for controlling the optical axis direction of the isotropic substance. 2. The first and second optically anisotropic substances each comprise a nematic liquid crystal, and the control means comprises means for applying an electric field to the first and second optically anisotropic substances. The optical axis directions of the first and second optically anisotropic substances in a predetermined portion of the grating are parallel to the plane and orthogonal to each other when the electric field is not applied, and The display device in the finder according to claim (1), characterized in that both of them coincide with the direction of the electric field. 3. The first and second optically anisotropic substances are each made of a ferroelectric liquid crystal, and the control means comprises the first and second
Means for applying an electric field to the optically anisotropic substance, and the optical axis directions of the first and second optically anisotropic substances in a predetermined portion of the grating are the planes when the electric field is not applied. The display device in a finder according to claim (1), characterized in that they are parallel to each other and coincide with each other, and are oriented in a direction parallel to the plane and orthogonal to each other by applying the electric field.