WO1994000789A1

WO1994000789A1 - Sunglasses having electro-optical screens

Info

Publication number: WO1994000789A1
Application number: PCT/FR1993/000572
Authority: WO
Inventors: Jean-Pierre Girard
Original assignee: Girard Jean Pierre
Priority date: 1992-06-26
Filing date: 1993-06-15
Publication date: 1994-01-06
Also published as: EP0601158A1

Abstract

A light beam filtering device comprising a light sensor (2), an electronic circuit (3) and two positive-operating electro-optical screens (5, 6) arranged on a spectacle frame (1). Each electro-optical screen comprises a correspondingly-shaped active area located in front of the eye and connected via electrical connections (4) to the ouput of the electronic circuit (3). The device is characterized in that two or more of the contacts between the electrical connections and the respective active area are separated by a distance equivalent to over a quarter of the largest dimension of said active area.

Description

The present invention presents sunglasses with electro-optical screens controlled automatically as a function of the light which reaches them.

In particular, the present invention applies to electronic cameras, sunglasses and anti-fog and to the protection of the eyes of welders.

The filters known to date produced chemically or mechanically carry out a predetermined and invariable filtering as a function of the light which reaches them. The present invention intends to remedy this drawback by presenting a device having a photo-sensitive sensor controlling the transparency of electro-optical screens as a function of the decreasing light intensity it receives. In particular, the present invention presents an assembly of liquid crystal screens and polarizers adapted to have a very uniform contrast in a solid angle corresponding to the vision of the eye through glasses.

In addition, the present invention presents a mode of electrical connection of liquid crystal screens adapted to avoid the feeling of wave due to the progressive obscuration laterally of a liquid crystal screen.

The device which is the subject of the present invention is therefore a device for filtering light rays comprising a photo-sensitive sensor adapted to emit a continuous primary signal of increasing power as a function of the light intensity reaching it, an electronic circuit electrically connected to the

ISA / EP REPLACEMENT SHEET photo-sensitive sensor and emitting an alternating secondary signal of increasing power with the power of the signal emitted by the photo-sensitive sensor and two electro¬ optical screens operating in positive and placed on spectacle frames and comprising "each an active zone, of connected form, adapted to be placed in front of an eye and connected by electrical connections to the output of the electronic circuit, characterized in that at least two of the contacts between the electrical connections with the associated active area are distant from each other by a distance greater than a quarter of the largest dimension of the associated active area.

The description which follows, given for explanatory purposes and in no way limiting, allows a better understanding of the advantages, aims and characteristics of the invention. Figure 1 shows a front view of the pair of glasses according to the invention.

FIG. 2 represents a sectional view of one of the electro-optical screens incorporated in the device represented in FIG. 1. FIG. 3 represents an active area and electrical connections incorporated in the device presented in FIG. 1.

FIG. 4 represents polarizers which can be incorporated in the device presented in FIG. 1.

FIG. 5 represents a block diagram of an electronic circuit incorporated in the device presented in FIG. 1.

FIG. 6 represents an electronic diagram realizing the functions of the block diagram presented in FIG. 5. In FIG. 1 are shown a spectacle frame 1, a photo-sensitive sensor 2, an electronic circuit 3, two electro-optical filters 5 and 6 comprising active zones 7 and 8, respectively, and electrical connections 4 connecting the circuit electronics 3 and the active zones 7 and 8 of the electro-optical filters 5 and 6.

The spectacle frame 1 is of known type. It is suitable for mechanically holding the other components shown in FIG. 1. In particular, the frame 1 can be produced by molding or by machining of plastic, metal or artificial material parts.

The photo-sensitive sensor 2 is adapted to emit a continuous signal whose power is an increasing function of the total light intensity which is incident to it. For example, the photo-sensitive sensor 2 can consist of a photo-diode, a photo-resistance powered by an electric cell or a solar cell.

The electronic circuit 3 is electrically connected to the photo-sensitive sensor 2 and is adapted to emit an alternating signal of increasing power with the power of the signal emitted by the photo-sensitive sensor 2. An example of electronic circuit 3 is given in FIG. 6.

The electro-optical filters 5 and 6 are presented with reference to FIGS. 2, 3 and 4. They operate in positive, that is to say that their transparency decreases with the power of the electrical signal applied to them. The electro-optical filters 5 and 6 respectively comprise the active zones 7 and 8 presented in FIG. 3. These active zones 7 and 8 are adapted to be positioned each in front of one of the eyes of the user of the device which is the subject of the present invention. The active areas 7 and 8 are related in the mathematical sense of the term, that is to say that all the line segments connecting any two points of each active area are integrally in the active area.

The electrical connections 4 are presented with reference to FIG. 3. They electrically connect the electronic circuit 3 and each of the electro-optical filters 5 and 6.

For each related active area 7 or 8, at least two of the contacts between the electrical connections 4 with the related active area are distant from each other by a distance greater than a quarter of the largest dimension of the related active area. 2 shows a sectional view of one of the electro-optical screens incorporated in the device shown in Figure 1. In Figure 2 are shown successively from top to bottom, an anti-scratch treatment 9, a polarizer 10, a layer glue 11, a glass slide 52, an electrode 13, an orientation layer 14, a liquid crystal 15, an orientation layer 53, an electrode 17, a glass slide 19, a layer of glue 20, a polarizer 21, an active area 7 and, laterally positioned around the liquid crystal 15 and between the orientation layers 14 and 53, a strip of adhesive 22. The anti-scratch treatment 9 is carried out on the polarizer 10 in a known manner. The polarizers 10 and 21 are of known type. They are glued to the glass slides 52 and 19 by the adhesive layers 11 and 20. The electrodes 13 and 17 are transparent and of known type and produced on the glass slides 52 and 19. The orientation layers 14 and 53 and the adhesive tape 22 are of known type in the production liquid crystal displays. The liquid crystal 15 is of the nematic helical type with a helix making a quarter of its pitch, that is to say ninety degrees. The orientations of the polarizers and the orientation layers are presented in FIG. 4.

The connected active area 7 is the largest connected part of the superposition of the electrodes 13 and 17.

FIG. 3 represents an active zone and electrical connections incorporated in the device presented in FIG. 1.

In FIG. 3 are shown the electro-optical filter 5, comprising the electrodes 13 and 17, the active area 7 between parts of electrodes 26 and 27 and segments of electrodes 23, 24 and 25, and the electrical connections 4 .

The electrode 13 is made up of the segments 23 and 24, on the one hand, and of the electrode part 26, on the other hand.

The electrode 17 consists of the segment 25, on the one hand, and the electrode part 27, on the other hand.

The electrode parts 26 and 27 exactly overlap, are identical to the related active area 7 and define it.

In Figure 4 are represented four arrows F10, F14, F53 and F21. The arrow F10 represents the direction of polarization of the polarizer 10. The arrow F14 represents the direction of orientation of the orientation layer 14. The arrow F53 represents the direction of the orientation layer 53. The arrow F21 represents the direction of polarization of the polarizer 21. The arrows F14 and F53 are perpendicular, which is known in the manufacture of helical nematic liquid crystal displays. The arrow F10 is inclined to the left and has with the arrow F14 an angle of 5 degrees in the counterclockwise direction. The arrow F21 is inclined downward and has with the arrow F53 an angle of 5 degrees in the direction opposite to the trigonometric direction. The angle between the polarization directions of the polarizers 10 and 21 is therefore 100 degrees. It should be noted that other values of inclinations with respect to the directions of the orientation layers are also in accordance with the spirit of the invention and that the values of the angles between the orientation layers and the polarizers can be different. or in the same trigonometric direction.

FIG. 5 represents a block diagram of an electronic circuit incorporated in the device presented in FIG. 1. In FIG. 5 are shown the electro-optical filters 5 and 6, the parts of electrodes 26 and 27 the electrical connections 4, an electrical power source 28, the photo-sensitive sensor 2 and two oscillators 50 and 51. The electrical power source 28 can consist of a battery or be incorporated into the photo-sensitive sensor 2, in the form of solar cells .

Electric oscillators 50 and 51 are connected - 1 -

electrically to the electric power source 28 and to the photo-sensitive sensor, respectively, on the one hand, and to the electrodes 26 and 27, respectively, via the electrical connections 4, on the other hand. The electric oscillators 50 and 51 deliver alternating signals of the same amplitude and the same frequency but in phase opposition. In this way, the signals received by the liquid crystal 15, between the electrode parts 26 and 27, have the same frequency as the signals emitted by the oscillators 50 and 51 but with a doubled amplitude.

FIG. 6 represents an electronic diagram realizing the functions of the block diagram presented in FIG. 5.

In FIG. 6 are shown solar cells 30, a capacitor 31, a resistor 32, a resistor 33, a capacitor 34, a potentiometer 35, two transistors 36 and 37, a capacitor 38, four inverting schmit triggers 39, 40, 41 and 42 and electrical connections 12 and 16.

The potentiometer 35 controls the gain of the variable gain amplifier consisting of the two transistors 36 and 37. The electronic circuit, the diagram of which is given in FIG. 6, is easy to understand and to realize for the man of the art. Its description is therefore not more detailed.

The electrical connections 12 and 16 are respectively connected to the electrode portions 26 and 27 and thus constitute the connections 4 presented in FIGS. 1 to 5.

The solar cells 30 constitute the photo-sensitive sensor 2 and the electric power source 28. Preferably, the polarization axis of the front polarizers of each of the electro-optical screens 5 and 6 is vertical.

Also preferably, the birefringence of the liquid crystal 15 and its thickness are jointly adapted to the first minimum of the Gooch and Tarry curve, their product being substantially equal to 500 nm.

Claims

1 / Light ray filtering device comprising a photo-sensitive sensor (2) adapted to emit a continuous primary signal of increasing power depending on the light intensity which reaches it, an electronic circuit (3) electrically connected to the sensor photo-sensitive (2) and emitting an alternating secondary signal of increasing power with the power of the signal emitted by the photo-sensitive sensor (2) and two electro-optical screens (5,6) operating in positive and placed on a mounting of eyewear (1) and each comprising an active area (7,8), of connected shape, adapted to be placed in front of an eye and connected by electrical connections (4) to the output of the electronic circuit characterized in that at least two of contacts between the electrical connections (4) with the associated active area are distant from each other by a distance greater than a quarter of the largest dimension of the connected active area.

2 / Device according to claim 1 characterized in that the electro-optical screens (5,6) consist of liquid crystal screens comprising orientation layers (14,53) and polarizers (10,21), at minus an angle between a direction (F14, F53) of an orientation layer and a direction (F10, F21) of a polarizer being greater than two degrees. 3 / Device according to claim 2 characterized in that the liquid crystal has a birefringence index and a thickness jointly adapted to the first minimum of the Gooch and Tarry curve, their product being approximately equal to 500 nm. 4 / Device according to any one of the preceding claims, characterized in that the electronic circuit (3) comprises two oscillators (50,51) operating in phase stripping. 5 / Device according to any one of the preceding claims, characterized in that the directions of the front polarizers of the electro-optical screens are substantially vertical. 6 / Device according to any one of the preceding claims, characterized in that the electronic circuit comprises a variable gain amplifier (36,37) whose gain is controlled by a potentiometer (35).

7 / Device according to any one of the preceding claims, characterized in that the photo-sensitive sensor is a set of solar cells (30).