JPS6127725B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical diaphragm device using an electro-optic material, and provides an automatic optical diaphragm device suitable for EE cameras, especially television cameras.

Generally, electro-optical materials include organic liquid crystals and artificial liquid crystals in which crystalline organic particles such as helavatite or crystalline inorganic particles are suspended in a certain type of solution. In a thin film of such an electro-optic material, the molecular arrangement is easily disturbed in a relatively low electric field and exhibits a unique optical phenomenon. For example, several to several tens of μ
When a pair of losses facing each other is sandwiched with a distance of m, an electric field of several to 15 volts is usually applied between the electrodes to separate the electro-optic material.
The child array is disordered and exhibits a unique optical phenomenon, and the power consumption required at this time is only about a few to 20 μW/1 cm ² . Such electro-optic materials are extremely widely useful in various electro-optic devices.

Now, a pair of transparent substrates facing each other is provided, a transparent flat thin film electrode is provided in a portion of the opposing inner surfaces of both substrates, and an electro-optic electrode is provided between the two substrates. An electro-optic cell is constructed in which a substance is sandwiched and each molecule of the electro-optic substance is arranged vertically in an orderly manner in the absence of an electric field, and this electro-optic cell is arranged between a pair of linear polarizing plates whose polarization planes are orthogonal to each other, When an electric field is applied between the opposing thin film electrodes while irradiating diffused light from the back side, the molecules of the electro-optic material in the area where no electric field is not applied become ordered and vertically arranged, making them optically isotropic. The area where the electric field is applied is displaced or turbulent, exhibiting optical anisotropy, and transmitted light is partially transmitted. In addition, an electro-optic cell is constructed in which each molecule of an electro-optic substance is orderedly twisted and horizontally aligned in the absence of an electric field. When an electric field is applied between the electrodes, the arrangement of each molecule is displaced only in the area where the electric field is applied, making it optically opaque.

The present invention provides an optical diaphragm device that automatically reduces the amount of transmitted light by utilizing this principle.

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

As shown in the first and second figures, in an electro-optic cell, a plurality of annular electrodes a ₁ , a _{2 .} . . with areas S ₁ , S ₂ . ... are provided concentrically, and furthermore, these first
A thin film-like internal impedance element 14 is provided in a layered manner on the lower surface of the electrodes a ₁ , a ₂ . . . .

These electrodes a ₁ , a _{2 .} . . can be connected to the outside as terminals via electrical circuits b ₁ , b ₂ . Further, a transparent second thin film electrode c is provided on the upper surface of the transparent back substrate 2 such as glass or plastic.

The first thin film electrodes a ₁ , a ₂ . . . and the second thin film electrode c are formed by, for example, using a metal such as tin oxide or indium oxide or a compound of these metals by a vacuum evaporation method, a sputtering method, a spraying method, a chemical conversion method, etc. The film thickness is usually from several hundred to 2000 Å.

The lower surface of the front substrate 1 and the upper surface of the back substrate 2 are stacked so as to face each other, and a thin film 3 of an electro-optic material is sandwiched between the front substrate 1 and the back substrate 2 to form an electro-optic cell. Usually, the thickness of the thin film 3 of electro-optic material is determined by a spacer provided therebetween.

Here, as the electro-optical material, we use a liquid crystal whose optical anisotropy changes electrically, such as an organic liquid crystal or an artificial liquid crystal, that is, a colloidal suspension artificially produced by dispersing inorganic or organic fine particles in a solvent. be able to.

Examples of organic liquid crystals include p-anisal-
p'-cyanoaniline, p-methylbenzal-p'-
n-butylaniline, p-ethoxybenzal-
p'-cyanoaniline, p-cyanobenzal-p'-
n-butylaniline, p-cyanobenzal-p'-
Anisidine, p-cyanobenzalphenetidine,
p-cyanophenyl-p-n-butylbenzoate, p-cyanophenyl-p'-n-heptylbenzoate, ethyl p-(p-anisalamino)-cinnamate, ethyl p-(p-ethoxybenzalamino)-cinnamate, Ethyl p-(p-cyanobenzalamino)-cinnamate, ethyl p-(p
-n-butylanisalamino)-cinnamate,
n-butyl p-(p-ethoxybenzalamino)-
Cinnamate, isonoamyl-p-(p-anisalamino)-cinnamate, p-n-hexylbenzal-p-cyanoaniline, p-n-propylobenzal-p'-cyanoaniline, p-azoxyanisole, anisalazoxif Enetol, p-
(anisalamino)-phenylacetate, p-methoxybenzal-p'-n-butylaniline, p-
Methoxyformyloxybenzal-p-n-butylaniline, N-(p-methoxybenzylidene)-p
-(2-propoxycarbonyl-1-propenyl)-aniline, p-ethoxybenzal-p'-n
-butylaniline, p-methoxy-p'-n-benzylcarboxyazobenzene, p-ethoxy-
p'-butoxycarbonylazobenzene, butyl p
-(p-ethoxyphenoxycarbonyl)-phenyl carbonate, 2-(p-methoxybenzalamino)-5-n-butylphenol, p-(p-ethoxyphenylazo)-phenylhexanoate, Bis-(4-n-octyloxybenzal)-
〓〓〓〓
2-chlorophenylenediamino, 4,4'-bis-
(Hexyloxy)-azoxybenzene, 4,4'-bis-(heptyloxy)-azoxybenzene, 4-caproxybenzoic acid-4'-ethoxyphenyl ester, 4-caproxybenzoic acid-4-butoxyphenyl ester, etc. A nematic liquid crystal substance or a mixture liquid crystal containing two or more of these nematic liquid crystal substances is used. As will be discussed below, in some cases a nematic liquid crystal material may be mixed with a small amount of a cholesteric liquid crystal material. In some cases, nematic liquid crystal materials may be mixed with dipole additives. Further, a mixture of 4-alkoxyphenyl-acetyl chloride, 4-alkyl phenyl-acetyl chloride, and 4-acetoxyphenylacetyl chloride may be used.

Artificial liquid crystals include, for example, anisotropic needle-like crystals such as tungsten oxide, vanadium oxide, and quartz, or layered crystals such as blue lead carbonate, lead crystals, and glass pieces, or inorganic fine particles such as herabatite and polyvinylidene fluoride. Alternatively, a colloidal suspension in which organic fine particles are dispersed in a solvent such as diptylphthalate, diphenyl, alcohol, or water can be used. In some cases, these colloidal suspensions may be mixed with dipole type adducts.

Note that the thickness of the electro-optical thin film 3 is usually set to about several to 20 μm.

The internal impedance element 14 is SiO,
A thin film of MgO, GeO, _MgF2 , etc. is used. Further, the dielectric constant of the impedance element 14 may be increased by mixing Ti, Ta, BaTiO ₃ , Ba.SrTiO ₃ or the like into these thin films. Alternatively, a thin film of TiO ₂ may be used. Alternatively, laminated films of polyolefin resins, solution-coated films of acetyl cellulose, polycarbonate, polystyrene, polyurethane, polyester, or acrylic, films formed by a dispersion method of tetrafluoroethylene, and photocurable resin films, etc., usually have a low dielectric constant. The higher the price, the better. In the illustrated example, the film thickness of the element 14 is partially changed to change its impedance, but it is also possible to keep the thickness constant and partially change the material.

As shown in the third diagram, _the first electrodes a ₁ , a _{2 .} . . It is connected to one pole of the external power source E, and the second electrode c is connected to the other pole of the external power source E.

Next, the operation of this device will be explained. Now the above area
If S ₁ , S ₂ ... are S ₁ > S ₂ > S ₃ ... > S ₁₁ , then the first electrode a ₁ ,
The capacitances c ₂₁ , c ₂₂ , ... between a ₂ ... and the second electrode c are c ₂₁ > c ₂₂ > c ₂₃ ... and the internal resistances r ₂₁ , r ₂₂ ... between them are r ₂₁ < r ₂₂ <r ₂₃ ... Therefore, the effective impedance Z ₂₁ , Z ₂₂ ... of the field effect type due to these capacitors and resistances is greatly influenced by the value of the capacitance component, and Z ₂₁ > Z ₂₂ > ....

Further, the impedances Z ₁₁ , Z _{12 .} . . of the internal impedance element 14 are set to have the following relationship: Z ₁₁ ≦Z ₁₂ ≦Z ₁₃ ≦ .

Therefore, _the voltages eZ ₂₁ , eZ ₂₂ . . . acting on the first electrodes a ₁ , _{a 2} .

As the amount of light now hitting the light receiving element 4 increases, its internal resistance decreases _, and the voltages eZ ₂₁ , eZ ₂₂ . _2. Electro-optical phenomena occur sequentially in the following order. That is, as the amount of external light increases, the amount of transmitted light gradually decreases, producing an automatic aperture effect.

FIG. 4 shows another embodiment of the present invention, in which the first electrodes a ₁₁ , a ₁₂ . . . have a square frame shape. Note that in the devices shown in the first and fourth figures, it may be better to provide a mask d that does not transmit light, as shown by a chain line, in this electric circuit portion.

FIG. 5 shows a case in which an electro-optic material whose polarization plane is changed by the application of an electric field is used, and a polarizing plate 6 and an analyzer plate 7 are provided on both sides of an electro-optic cell 5. When using an electro-optic cell in which each molecule in the electro-optic material is regularly twisted and horizontally aligned when the electric field is zero, a polarizing plate 6 and an analyzer plate 7 are used.
The planes of polarization are orthogonal to each other.

〓〓〓〓
With this device, when the outside world is dark, the first
the voltage between the electrode and the second electrode is below the threshold;
As shown in FIG. 5A, all light rays pass through, but as the outside world becomes brighter, the voltage between the first electrode and the second electrode exceeds the threshold voltage one after another, As shown in FIG. 5B, the transmitted light is centered and focused.

In the circuit configuration shown in the fourth diagram, the light receiving element 4
are connected in series to the first electrodes a ₁ , a ₂ . , the internal impedance element 14 and the first electrode a ₁ of the cell in parallel with the light receiving element 4a,
a ₂ ... may be connected. In this case, when using an electro-optic cell in which each molecule in the electro-optic substance is uniformly aligned perpendicular to the electrode surface when the electric field is zero, the polarization planes of the polarizing plate 6 and the analyzing plate 7 should be perpendicular to each other. When using an electro-optic cell in which each molecule of the electro-optic material is regularly twisted and horizontally aligned when the electric field is zero, the polarizing planes of the polarizing plate θ and the analyzing plate 7 are arranged parallel to each other. This will automatically limit the light when the outside world becomes bright.

FIG. 6 shows a thin film internal impedance element 14.
This shows an example in which the electro-optic cell is used as a light-receiving element, and the concentric first electrode of the electro-optic cell
a ₂₂ , a ₂₂ ... are internal impedance elements 14 (impedances Z ₁₁₁ , Z ₁₁₂ ...) made of photoconductive elements.
) are each layered.

In the present invention, a series circuit consisting of an independent internal impedance element is provided for each region, and no current circuit that does not pass through the electro-optic substance impedance is formed, so that it is consumed in electro-optical devices using liquid crystals, suspensions, etc. It does not consume any power other than electric power, does not damage the characteristics of electro-optic devices using liquid crystals or suspensions, and even if the impedance within the electro-optic material changes abnormally in any region, it will not dissipate in other regions. It has no effect on the operation of the

Furthermore, in the second invention of the present application, the thin film-like internal impedance element provided within the electro-optic cell also functions as an optical element, so that the circuit can be further simplified.

[Brief explanation of the drawing]

FIG. 1 is a plan view of one embodiment of the present invention, FIG. 2 is a sectional view taken along the line of FIG. 1, FIG. 3 is an equivalent circuit diagram thereof, and FIG. 4 is a plan view of another embodiment of the present invention. Fifth
Figures A and B are cross-sectional views of still another embodiment, and Figure 6 is a circuit diagram when a thin film internal impedance element is used as an optical element. a ₁ , a ₂ ... are the first electrodes, c is the second electrode, 3
1 is an electro-optical material, 14 is a thin film internal impedance element, 4 is a light receiving element, and E is a power source. 〓〓〓〓

Claims (1)

[Scope of Claims] 1 A plurality of first electrodes and a second electrode that are provided concentrically through an electro-optic material are arranged to face each other in parallel, and the above-mentioned forming a plurality of series circuits in which thin-film internal impedance elements are individually layered on each of the first electrodes and configured in series with the second electrode;
Both of these series circuits are connected to a variable voltage source that changes depending on the surrounding brightness via a light receiving element, and each of the adjacent series circuits has an electric current between the first electrode and the second electrode. The impedance of the optical substance and the partial pressure ratio of the thin film-like internal impedance element are made different in sequence, and the electro-optical behavior threshold between the first electrode and the second electrode is set to the first electrode.
An optical aperture device characterized in that the electrodes are different from each other, and the series circuits are configured so that there is no electrical interference between the series circuits. 2 A plurality of first electrodes provided concentrically through an electro-optic material and a second electrode facing the electrodes are arranged to face each other in parallel, and each of the first electrodes has a Forming a plurality of series circuits configured in series with the second electrode by individually layering thin film internal impedance elements,
A thin film-like internal impedance element has the function of an optical element, and is constructed by connecting a plurality of series circuits provided for each first electrode to a fixed voltage source. The impedance of the electro-optic material between the two electrodes and the partial pressure ratio of the thin film-like internal impedance element are sequentially made different, and the electro-optic behavior threshold between the first electrode and the second electrode is set to be the same as that of the first electrode. An optical diaphragm device characterized in that the electrodes are different from each other and configured so that there is no electrical interference between the series circuits.