Photography – Camera detail – Diaphragm
Reexamination Certificate
2000-02-04
2002-01-08
Perkey, W. B. (Department: 2851)
Photography
Camera detail
Diaphragm
Reexamination Certificate
active
06336753
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention concerns an optical device suitable, for example, to display apparatus for conducting display of numericals or characters or X-Y matrix display, as well as an optical filter capable of controlling light transmissivity or light reflectivity in a visible light region (wavelength at 400 to 700 nm), as well as a fabricating method thereof, a driving method thereof and a camera system.
2. Description of the Related Art
An electrochromic display device employed in display apparatus such as digital watches (hereinafter simply referred to as “ECD”) is a non-light emission type display device which conducts display by reflection light or transmission light as a light control device by electrochemical operation, so that it has a merit giving less feeling of fatigue even in long time observation, as well as a merit that if requires relatively low driving voltage and less consumption power.
For instance, as disclosed in Japanese Published Unexamined Patent Application No. Sho 59-24879, a liquid type ECD using organic molecule type viologen molecule derivatives that reversibly form states of coloration/color extinction as the electrochromic material (EC material) has been known. However, ECDs using the viologen molecule derivatives involve a problem that response speed or degree of shielding is insufficient. In addition, as a light amount control device, it is necessary that the light transmissivity can be controlled in a visible light vision (wavelength at 400 to 700 nm), and no sufficient characteristics can be obtained with the ECD material as described above.
In view of the above, the present inventor has noted on a light control device utilizing deposition/dissolution of a metal salt, instead of ECD, and has found that it can provide more excellent characteristics than the EC material with respect to the response speed and the degree of shielding in the course of research and development thereof.
While various metals salts can be used for such an optical device, those systems using deposition/dissolution of silver particles are excellent in view of optical characteristics. That is, an electrolyte is used as the material for a reversible plating, that is, RED (Reversible Electro-Deposition) in which a solution for the electrolyte shows no absorption spectrum in a visible light region (wavelength at 400 to 700 nm) upon preparation and causes deposition/solution of silver particles from a silver salt (including silver complex salt) capable of forming substantial uniform shielding in the visible light region upon coloration. Further, the silver salt has a possibility of deposition/solution by control for driving. Meanwhile, a cyan type solution has been used so far as a plating bath regarding deposition of silver particles from a silver salt but, since the cyan type solution is fatally poisonous, it is preferred to use a non-cyan type silver salt in the optical device of the present invention in view of safety for operation environment and discarding of liquid wastes.
Under the situations described above, it is possible to provide a non-light emitting type optical device such as an optical filter which consumes less electric power and which is suitable to a visible light region.
FIG.
1
A and
FIG. 1B
, and
FIG. 2
show a cell structure of an existent electrochemical light control device described above.
As shown in FIG.
1
A and
FIG. 2
, a pair of transparent glass substrates
4
and
5
are disposed at a predetermined distance as a display window. As shown in
FIG. 1A
, working electrodes
2
and
3
each comprising an indium tin oxide (ITO) film obtained by doping tin to indium oxide are opposed to each other on the inner surfaces of the substrates
4
and
5
, and an electrolyte
1
containing a metal salt dissolved therein is sealed between the opposed working electrodes
2
and
3
. Counter electrodes
6
are disposed at the circumferential edges between the substrates
4
and
5
that function also as spacers, by which the sealed electrolyte
1
is sealed between the substrates
4
and
5
.
In the optical device described above, when a DC driving voltage is applied for a predetermined period of time, as shown in
FIG. 1B
, between the counter electrode
6
as an anode and the working electrodes
2
and
3
as the cathode, metal ions dissolved in the electrolyte take place the oxidation/reduction reaction at the cathode as shown by the following formula (1):
M
n+
+ne
−
→M (1)
(n: natural number)
and the working electrodes
2
and
3
on the cathode change from transparent to colored states by deposited metal particles.
FIG. 1B
is a conceptional view illustrating the electrochemical mechanism in this reaction.
When the foregoing reaction is explained specifically to a case of using a silver salt solution as the electrolyte
1
, a silver plate is used for the counter electrodes
6
and the silver salt solution is formed, for example, by dissolving silver bromide into dimethyl sulfoxide (DMSO). As shown in
FIG. 1B
when a DC driving voltage is applied for a predetermined period of time between the counter electrode
6
as the anode and the working electrodes
2
and
3
as the cathode, oxidation/reduction reaction is taken place for silver ions at the cathode as shown by the following equation (2):
Ag
+
+e
−
→Ag (2)
and the working electrodes
2
and
3
on the cathode change from transparent to colored states by deposited Ag particles.
When the metal particles are deposited on the working electrodes
2
and
3
as described above, a specified reflection color with the deposited metal particles is observed through the display window. The filter effect due to the coloration, namely, the transmissivity for the visible light (or density of coloration) changes depending on the level of voltage or the application time thereof. Accordingly, the cell can function as a variable transmissivity display device or an optical filter by controlling the factors.
On the other hand, in a state where the cell is in the colored state, when a DC voltage is applied in the opposite direction between the counter electrode
6
and the working electrodes
2
and
3
, the working electrodes
2
and
3
on which the metal particles are deposited now act as the anode to cause a reaction of the following formula (3):
M→M
n+
+ne
−
(3)
and Ag particles deposited on the working electrodes
2
and
3
are restored from the colored state to the transparent state.
This is to be explained to a case of using a silver salt solution for the electrolyte
1
. When a DC voltage is applied in the direction opposite to the above between the counter electrode
6
and the working electrodes
2
and
3
in a state where the cell is in the colored state, the working electrodes
2
and
3
on which Ag particles are deposited now act as the anode to take place the reaction of the following formula (4):
Ag→Ag
+
+e
−
(4)
and Ag particles deposited on the working electrodes
2
and
3
are restored from the colored state to the transparent state.
FIG.
3
and
FIG. 4
show another electrochemical light control device of the prior art.
In this example, as shown in the cross sectional view of
FIG. 3
, working electrodes
8
a,
8
b,
8
c,
8
d,
8
e
and
9
a,
9
b,
9
c,
9
d,
9
e
each comprising a pair of ITO films are opposed to each other on the inner surfaces of a pair of transparent glass substrates
11
and
12
constituting a cell. Counter electrodes
7
a,
7
b
each comprising a silver plate are disposed to the outer circumference of the outer working electrodes
8
e
and
9
e.
The substrates
11
and
12
are kept and sealed at a predetermined distance by a spacer
13
and an electrolyte
1
is sealed between the substrates.
As shown in a plan view of
FIG. 4
, the working electrodes
8
a
-
8
e
and
9
a-
9
e,
and counter electrodes
7
a
and
7
b
are planer electrodes formed in a coaxial pattern. Each of the electro
Kihira Toru
Udaka Toru
Perkey W. B.
Sonnenschein Nath & Rosenthal
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