EP1007389A1

EP1007389A1 - Electrochrome mirror

Info

Publication number: EP1007389A1
Application number: EP98945278A
Authority: EP
Inventors: Falko Von Unger; Klaus Grosskopf
Original assignee: Bayer AG
Current assignee: Bayer AG
Priority date: 1997-08-30
Filing date: 1998-08-24
Publication date: 2000-06-14
Also published as: AU730556B2; AU9264498A; CA2302225A1; JP2001514117A; US6280041B1; WO1999011489A1; TW466363B; DE19737978C2; DE19737978A1; KR20010023393A; BR9812147A; PL338896A1

Abstract

The invention concerns electrochrome mirrors comprising, as central component, an optically active cell consisting of two glass plates (1, 2) arranged as a laminate, each provided, on the inside, with a plane electrode, an electrochromic substance (5) being placed between the two plane electrodes. The two glass plates (1, 2) are sealingly connected to each other, by means of an adhesive bead (6) enclosing the perimeter of said glass plates (1, 2) at their peripheral edge, while leaving free a narrow edge strip. In order to ensure that a connection wire (8a, 8b) is more securely fixed without modifying the dimensions of the mirror, each edge strip of the plane electrodes is divided in two by a separating trench (9a, 9b), thereby forming an edge strip section (11a, 11b) such that the edge strip section isolated from one of the plane electrodes is opposite to the edge strip section not isolated from the other plane electrode. In each space included between said edge strip sections, is incorporated a connection wire (8a, 8b), using an electroconductive material.

Description

Electrochromic mirror

description

The invention relates to an electrochromic mirror with an optically active cell, consisting of two transparent, laminate-like disks shaped according to the mirror configuration,

which are each provided on the inclined side with an electrically conductive electrode layer extending over the entire pane surface, each of which is contacted with a connecting wire, of which the pane facing away from the light is mirrored, which is spaced apart from one another by means of an edge region of the Disks surrounding a narrow bead of adhesive bead are sealingly connected to each other, and between which an electrochromic medium is arranged.

Electrochromic mirrors, also abbreviated to EC mirrors, have the property that they change their reflectivity under the influence of an electrical voltage. They are preferably used in the automotive industry, in particular as an automatically dimming rear view mirror in motor vehicles. Such automatically dimmable rear view mirrors increase traffic safety when driving at night and help to prevent accidents.

In the darkness in the area, the driver's pupil works like a wide-open camera shutter in order to supply the optic nerve with as much light signals as possible. In this state, the eye is extremely sensitive to suddenly glaring light. The headlight light from passing or following vehicles reflected by conventional rear view mirrors dazzles the driver so strongly that his eyesight is currently greatly reduced. For a fraction of a second, the driver is virtually blind due to the optical effects of the flash of light and his reaction time to those that become visible

Obstacles on the road ahead are increased by more than a second.

In systematic braking distance measurements, this so-called Troxler effect e.g. to double the braking distance of a test car under night driving conditions at 100 km / h on a dry road.

The effect affects all drivers in the dark regardless of gender, age or eye color. It represents an uncertainty factor when driving at night, which is only compensated for by the conventional, mechanically adjustable anti-glare interior mirrors. When the inside mirror is tilted, the reflection is reduced from approx. 90% to 4%. The low residual reflection of the tilted interior mirror reduces the glare, but only shows the headlights and not the contours of the overtaking or following vehicles. In the case of the mostly curved exterior mirrors, such tilting does not exist as glare protection when driving at night.

However, the vehicle equipment with automatically dimmable rear view mirrors, whose electro-optical sensors detect the risk of glare at lightning speed and by slidingly reducing the amount, demonstrably helps Defuse mirror reflection to about 10% within a few seconds. When the risk of glare is over, the specular reflection immediately increases to the initial value. This automatic interplay of darkening and brightening the rear-view mirror repeats itself at every risk of glare and without fatigue during the entire life of the vehicle.

To change the reflection behavior of the automatically dimmable

The rearview mirror has been using the electrochromic behavior of certain chemicals that are arranged in front of the actual reflector of the EC mirror for more than ten years. Some inorganic and organic electrochromic "dyes" change their absorption depth if they are limited

Electrodes are supplied with an electrical potential.

Such reversible absorption changes in some inorganic oxides of transition metals (e.g. tungsten) in thin solid layers are known and systematically researched. On the other hand, thin liquid cells with organic dyes (e.g. liquid crystals or viologens) have been successfully investigated in this context. For functional and cost reasons, liquid cells with viologens have prevailed for the commercially available EC mirrors.

These cells, hereinafter called optically active cells, form the heart of the EC mirror. They typically consist of two panes shaped in accordance with the mirror configuration, which preferably consist of glass, ie a front glass and a rear glass, which are connected to one another at a distance from one another and are sealed along their circumference in a manner sealed off from the environment. The electrochromically active medium, in particular a liquid with viologens, is located between the two disks. Each disc is on the side facing the EC medium with an electrically conductive electrode layer covering the entire disc surface provided, to each of which a connecting wheel is attached. The "actual" mirror layer is on the back glass.

If a voltage is applied to the two connecting wires of the two surface electrodes, e.g. the voltage generated by a light sensor due to the light of a rear car, then the depth of absorption of the EC medium arranged in front of the mirror pane changes and with it the

Reflectivity of the optically active cell.

These relationships are state of the art and have become known through numerous writings.

A particular problem with such a typical cell is the mutually insulated contact between the connecting wires and the associated surface electrode, since the surface electrodes lie congruently on one another, only separated by a very narrow gap of approximately 0.1 to 0.2 mm.

It has become known from US-A-5, 151, 824 to solve the problem in such a way that the front and rear glasses are arranged offset from one another by a predetermined amount, so that an exposed zone of the surface electrode is formed on each glass, which can be used for contacting. On each of these edge zones there is an elongated contact clip with resiliently yielding contact pins that surround the glass with the free-standing edge zones of the surface electrodes, to which the connecting wire is soldered.

Due to the edge offset in the known EC mirror, the edge zone of the mirror is disadvantageously relatively large, which is not desirable. The demands of the automotive industry are aimed at EC mirrors, which practically do not differ in size from conventional mirrors. In addition, the spring or clamp contact is very complex and cumbersome to install, and only in the relatively narrow

Area makes contact with the surface electrode. This adversely affects the speed with which the absorption depth of the EC medium changes.

From EP 0 434 453 B1 (= US-A-5,066, 112) an EC mirror of the generic type has become known, which has no offset of the disks of the optically active cell and no spring contacts in the form of brackets, in the in the peripheral zones an additional conductive contact layer is applied to the surface electrode of the disks, including the end face thereof, to which the connecting wire is then soldered on the end face.

Such an EC mirror is once very complex to manufacture and on the other hand the front contact zone for attaching the connecting wire is very narrow, so that it can easily tear off and on the other hand only allows a narrow contact area, which also has a negative effect on the speed , with which the absorption depth of the EC medium changes.

The invention is based on the object of constructing the electrochromic mirror described in the introduction in such a way that no offset of the edges with complex contact clamps is necessary, and nevertheless reliable large-area contacting is possible with simple means.

The solution of the invention is achieved according to the invention in that on the one disc in the associated electrode layer on the lower half and on the other disc in the associated electrode layer in the upper half, one at the level of the adhesive bead covered by it, one isolated Edge strip section is formed in the respective electrode layer defining separating trench that in the space between one insulating edge strip section and the non-insulated edge strip section on the opposite electrode layer, the one connecting wire, and between the other insulating edge strip section and the non-insulating edge strip section on the opposite electrode layer, the second connecting wire is embedded, in each case by means of an electrically conductive compound.

The electrochromic mirror according to the invention has congruent panes of the optically active cell, i.e. has no external widening of the mirror, avoids complex spring contacts and ensures a safe, stable and large-area power supply, which causes the EC mirror to darken and bleach quickly.

According to a development of the invention, the separating trench is preferably formed by means of a laser beam. This makes it possible to separate the associated edge strip section from the rest of the surface electrode with a very narrow cutting line.

In order to make the pane facing away from the light reflecting, there are basically two possibilities. According to a first embodiment of the invention, both electrode layers consist of indium tin oxide (ITO), a mirror layer additionally being applied on the disc facing away from the light.

According to the second embodiment of the invention, the electrode layer applied to the windshield facing the light consists of

Indium tin oxide (ITO) and the electrode layer made of a chromium / rhodium compound on the disc facing away from the light.

In order to easily specify the predetermined distance between the two panes of the optically active cell, the adhesive bead contains preferably glass spheres with a diameter which corresponds to the predetermined distance between the panes of the cell.

A number of possibilities are available to the person skilled in the art as a conductive mass which is introduced into the intermediate space between the surface electrodes and which the lead wires are embedded. The electrically conductive composition is preferably a conductive conductive lacquer.

This conductive varnish not only ensures a good electrical connection between the surface electrode and the connecting wire, but also gives the cell a certain stability.

As an alternative to this, the electrically conductive mass, in which the connecting wires are embedded, can also be a solidifying conductive solder or the like.

According to a further development of the invention, the connecting wire is embedded in the electrically conductive mass over the entire length of the associated non-insulating edge section. This enables a good current transfer and thus a quick darkening and bleaching of the mirror.

To ensure safe protection from the environment, the

The faces of the panes of the cell are preferably sealed with an insulating and adhesive mass.

Glass, preferably float glass, but also plastic can be used for the material of the panes of the cell.

Further design features and advantages of the invention result from an exemplary embodiment shown in the drawing.

Show it: Fig. 1 in an exploded view of the structure of the optically active cell of the EC mirror according to the invention

Fig. 2 in a greatly enlarged cross-sectional view

Layer structure of the finely mounted optically active cell with the contacting of the connecting wires

1 shows an exploded view of the structure of the optically active cell according to the invention as the basis of the EC mirror according to the invention in connection with a cross-sectional view according to FIG. 2 for a finely mounted optically active cell along an imaginary section line in FIG. 1, the center and runs parallel to the narrow side edges of the cells.

The optically effective cell of the mirror consists of two, the mirror configuration - here that of a car exterior mirror - correspondingly shaped transparent flat panes, which in the exemplary embodiment consists of glass, preferably float glass, namely the front glass 1, which is assigned to the direction of light incidence, and the rear glass 2nd

In principle, it is possible to manufacture the panes from a transparent plastic material.

The front glass 1 is provided on the side facing away from the light with an electrically conductive surface electrode 3, which extends over the entire surface of the front glass 1. Likewise, the rear glass 2 is on the

Provide light-facing side with an electrically conductive surface electrode 4, which also extends over the entire surface of the rear glass 2. In the present embodiment, the electrically conductive

Surface electrode 3 is formed by an ITO layer (indium tin oxide), which is transparent. whereas the surface electrode 4 is formed by a chrome / rhodium layer, which specifies a reflective surface.

An embodiment is also possible in which the surface electrode 4 is likewise formed by an ITO layer, an additional mirror layer then being applied to the back of the rear glass 2.

The electrochromic medium 5 is located between the two disks 1 and 2 with their associated surface electrodes 3 and 4, preferably in the form of an electrochromic solution of the one mentioned at the beginning

On. For this purpose, the two disks 1, 2 with the sides on which the surface electrodes 3, 4 are located are circumferentially bonded to one another at the edge, so as to form a closed cell into which liquid can be poured. The corresponding composite adhesive, which must consist of an electrically insulating adhesive so that there is no internal short circuit of the two surface electrodes, forms an adhesive bead 6, as can be seen particularly well from FIG. 2. This adhesive bead 6 is located at the surface electrode 3 on the side facing the EC medium 5. The caterpillar 6 of the surface electrode 4 is also located on the

Medium 5 facing side.

The composite adhesive contains small glass balls, which specify the distance between the two cell walls, which is typically in the range from 0.1 to 0.2 mm.

The adhesive bead 6 forms an electrically conductive edge strip 7a in the surface electrode 3 assigned to the front glass and an electrically conductive edge zone 7b in the surface electrode 4 which is assigned to the rear glass 2. With the edge zone 7a is a connecting wire 8a and with the edge zone 7b, a lead wire 8b is attached. So like that

Fig. 2 shows a large-area, the space between the discs 1 and 2 with their surface electrodes 3 and 4 filling contact to the contact strips 7a and 7b by means of a conductive paint, solder or other conductive paste 10, in each of which Connection wire 8a, 8b is embedded, can be produced, insulation of the congruent surface electrodes 3 and 4 must be provided. This isolation is carried out by separating trenches 9a and 9b, which are each formed spatially opposite the adhesive bead 6 on the other surface electrode, so that, as can be seen from FIG. 2, the insulating adhesive bead 6 covers the separating trench 9a and 9b, respectively , so that by filling the edge zones of the electrode surfaces between the glasses, only the outer edge region 11a, 11b of the respective opposite surface electrode is covered, but not the part of this surface electrode lying inside.

The trenches 9a, 9b are expediently formed by means of a

Laser, preferably by means of a neodymium-YAG laser. As can be seen from Fig. 1, the laser trench 9a pulls on the transparent

Electrode 3 at the bottom to slightly below the middle. It isolates an edge strip 11a on which the electrical contact to the opposite reflecting electrode 4 is located. In this reflective electrode 4, the laser separating trench 7b extends from the upper edge to slightly below the center on both sides. It isolates an edge strip 11b on which the electrical contact is located on the opposite transparent electrode 3. In this way, the surface electrodes 3, 4 can be provided with two connecting wires 8a and 8b which are electrically insulated from one another and which, due to the covering with a conductive medium, are in intimate and mechanically stable contact with their associated surface electrodes. If the optically active cell is filled with the EC solution 5, its light transmission can be achieved by applying an electrical potential between the

Change surface electrodes 3, 4. For this purpose, the two surface electrodes, electrically insulated from one another, are connected to a DC voltage source with the connecting wires 8a and 8b.

In order to avoid an internal short circuit, the conductive lacquer 10 is in each case on the

Transitions from the isolated edge strips 11a, 11b to the non-insulation edge strips are interrupted by an insulating mass.

As can be seen in FIG. 2, the edge between the two disks 1, 2 glued together is provided with a seal 12 which hermetically seals the interior of the optically active cell from the surroundings.

The thickness of the disks 1, 2 is in the range of 1 to 2 mm, whereas the electrode layers typically have a thickness of the order of 1000 angstroms. The width of the edge strips 7a, 7b and 11a, 11b is of the order of 0.8 mm.

Instead of an ITO layer, the transparent surface electrode can also be formed by a tin or zinc oxide layer.

The optically active cell can be accommodated in a corresponding mirror holder with known constructions, for example as shown in US Pat. No. 5,151,824.

Claims

claims

Electrochromic mirror with an optically active cell, consisting of two transparent, laminate disks (1, 2) shaped in accordance with the mirror configuration, each of which on the inclined side with an electrically conductive electrode layer (3. 4) are provided, each of which is connected to a connecting wire (8a, 8b), of which the disk (2) facing away from the light is designed to be reflective, which is spaced apart from one another by means of a narrow one in the peripheral area of the disks (1, 2) Edge strips leaving the adhesive bead (6) sealed together and between which an electrochromic medium (5) is arranged, characterized in that on the one disc (1) in the associated electrode layer (3) on the lower half and on the other disc (2) in the associated electrode layer (4) in the upper half at the level of Kl A caterpillar (6) forms a separating trench (9a, 9b), which is covered by this and defines an isolated edge strip section (11a, 11b) in the respective electrode layer (3, 4), that in the space between the one isolated edge strip section (11a) and the non-insulating edge strip section (7b) on the opposite electrode layer (4) the one connecting wire (8b), and between the other insulated edge strip section (11b) and the non-insulating edge strip section (7a) on the opposite electrode layer (3) second connecting wire (8a), each by means of an electrically conductive mass (10), is embedded.

2. Mirror according to claim 1, characterized in that the

Separation trench (9a, 9b) is in each case formed by means of a laser beam.

3. Mirror according to claim 1 or 2, characterized in that both

Electrode layers (3, 4) consist of indium tin oxide (ITO), and additionally a mirror layer is applied on the back of the pane (2) facing away from the light.

4. Mirror according to claim 1 or 2. characterized in that the. on the front window (1) facing the incident light (3) made of indium tin oxide (ITO) and the electrode layer (4) on the facing away from the light made of a chrome

/ Rhodium compound exists.

5. Mirror according to one of claims 1 to 4, characterized in that the adhesive bead (6) contains glass beads with a diameter which corresponds to the predetermined distance between the disks (1, 2) of the cell.

6. Mirror according to one of claims 1 to 5, characterized in that the electrically conductive mass (10), in which the connecting wires (8a, 8b) are embedded, is a curable conductive lacquer.

7. Mirror according to one of claims 1 to 5, characterized in that the electrically conductive mass (10), in which the connecting wires (8a, 8b) are embedded, is a solidifying conductive solder.

8. Mirror according to one of claims 1 to 7, characterized in that the connecting wires (8a, 8b) are each embedded over the entire length of the associated non-insulated edge portion (7a, 7b) in the electrically conductive mass (10).

9. Mirror according to one of claims 1 to 8, characterized in that the end faces of the discs (1, 2) of the optically active cell are sealed with an insulating and aushäπenden mass (12).

10. Mirror according to one of claims 1 to 9, characterized in that the disks (1, 2) of the optically active cell consist of float glass.