ES2244275B1 - POSITIONING SYSTEM OF THE ELECTRODES ON THE SUBJECT FOR THE OBTAINING OF ELECTROOCULOGRAPHICAL SIGNS. - Google Patents

Abstract

Electrode positioning system on the subject to obtain electroographic signals. It comprises a mask (1), a conduction cable (4), for at least two electrodes (2) fixed to said mask (1), connection means (3) of the electrodes with said conduction cable (4) and means for fixing (6) the mask on the subject, and is characterized by the fact that it comprises a differential amplification circuit (5) fixed to the mask (1) and a flexible and absorbent element (7) disposed between the electrodes ( 2) and the mask (1). It allows some freedom of facial movements without altering the electrooculography.

Description

Electrode Positioning System on the subject to obtain signals electrooculographic

The present invention relates to a system of  electrode positioning on the subject for Obtaining electroographic signals.

Background of the invention

Techniques based on utilization are known  of electrodes to detect eye movements. Between them, electrooculography (E.O.G) is a method based on the recording of the potential difference between the cornea and the retina. To capture these variations of the field current, which produce with the oscillations of the look, a system is used of periodic electrodes, fixed on a mask. A electrode placed in the vicinity of the eye, acquires a potential more positive when the eye rotates towards him, and less positive, if it rotates in the opposite direction. This method is quite linear in a range of ± 30 ° from the central position of the eyes, and allows detection eye movements with accuracies of approximately 2º.

One of the disadvantages of the electrooculography are the high inconvenience for the user that It involves the use of electrodes.

Another drawback is the alterations of the electrooculographic signal that have their origin in the rigidity of the mask on which the electrodes are mounted. The contact between the electrodes and the skin depends on the pressure of the mask on the skin, so that any movement of the mask involves a movement of the electrode contact surface with the skin. In addition, the fact that the mask adjusts precisely over the face, causes any movement of the muscles facial (blinking, eyebrow movement, etc ...) alter the signal electrooculographic.

Another source of alterations on the electrooculographic signal are the movements of the cables, and of the electrodes themselves, very sensitive to small movements. For example, the connection cable between the mask and the amplification equipment introduced
Noise in the signal due to the rigidity of the cable, which also causes the movement of the mask to move.

Description of the invention

The objective of the present invention is to solve  the mentioned disadvantages, developing a system of electrode positioning on the subject to obtain electrocardiographic signals that allow some freedom of facial movements without permanently altering the electrooculography

In accordance with this objective, the system of electrode positioning on the subject to obtain of electroographic signals of the present invention are characterized by the fact that it comprises a circuit of differential amplification fixed to the mask and an element flexible and absorbent disposed between the electrodes and the mask.

Thanks to these characteristics the fixing time of the electrodes on the subject, the records they are more reliable since the position of the electrodes in the subject does not vary significantly between each of the registrations made, and interference caused by cable movements on the signal and on them electrodes

Preferably, said fixing means of the  mask on the subject comprise the arrangement of a material flexible and absorbent arranged on the internal edges of the mask.

Preferably, said flexible material and absorbent disposed on the inner edges of the mask are neoprene strips

Neoprene strips on the inner edges of the mask allow to fix said mask comfortably and absorb the pressure of it on the face. In this way, the contact between the electrodes and the skin does not depend on the pressure of the mask on the skin and, being the flexible fasteners, the Mask or face movements are also not transmitted at contact surfaces, being buffered or absorbed.

Advantageously, the mask comprises four measuring electrodes and one reference.

The existence of a greater number of electrodes makes it possible to obtain an electroographic signal of greater quality.

Preferably, said material element flexible and absorbent between the electrodes and the mask is of foam.

The spongy material arranged between electrodes and the mask, facilitates the mobility of the electrode to the Once you put some pressure on it.

Advantageously, the mask is made of aluminum.

Aluminum is a malleable material, it weighs little and, being a metal, it performs the shielding function of the mask.

Brief description of the drawings

For greater understanding of how much has been exposed some drawings are accompanied in which, schematically and only to non-limiting example title, a case study of realization.

In these drawings,

Figure 1 shows an exterior view of the electrode positioning system of the present invention, arranged on a plaster reproduction of the face of a user.

Figure 2 shows an interior view of the electrode positioning system of the present invention.

Figure 3 shows a detail of the system of electrode clamping on the mask.

Description of a preferred embodiment

Figure 1 shows the outside of a mask 1, made with 1.5 mm aluminum plate, which has been molded to adapt to the face of the individual.

Figure 2 shows the inner surface of the  mask 1 in which five electrodes 2 are appreciated with their tweezers contact pressure 3, a conduction cable 4, a circuit differential amplification 5 installed on the inner face of said mask 1, and neoprene strips 6 on the edges Inner mask.

The pressure contact pliers 3 ensure the optimal contact of electrodes 2 on the subject's face, at the once they connect said signal with the conduction cable 4.

The neoprene strips 6 constitute means of flexible fastening that allows the mask to be fixed comfortably on the subject and absorb the pressure of the face on the mask. In this way, the contact between the electrodes and the skin does not it depends on the pressure of the mask on the skin, and being flexible fasteners, mask or face movements nor are they transmitted to the contact surfaces, being cushioned or absorbed.

The installation of an amplification circuit differential 5 on the same mask 1 makes it possible to obtain an electroographic signal of greater amplitude and with less noise, since interference is greatly diminished caused by the movement of the connecting cable between the mask 1 and amplification equipment 5.

Figure 3 shows a detail of the system of clamping of the electrodes on the mask 1, in which it is appreciated the spongy material 7 disposed between the electrodes 2 and the mask 1. Said material facilitates the mobility of electrode 2 a while exerting some pressure on it.

The electrode positioning system 2 described in the drawings allows records as well obtained conform to the maximum to the movement patterns. He system, compared to others existing in the state of the technique, reduces the drift effect in almost all records

Although it has been described and represented a  concrete embodiment of the present invention, it is evident that the subject matter expert may introduce variants and modifications, or replace the details with technically equivalent ones, without depart from the scope of protection defined by the attached claims.

Claims (6)

1. Electrode positioning system on the subject for obtaining electroographic signals comprising a mask (1), a conduction cable (4), at least two electrodes (2) fixed to said mask (1), means of connection (3) of the electrodes with said conduction cable (4) and fixing means (6) of the mask on the subject, characterized in that it comprises a differential amplification circuit (5) fixed to the mask ( 1) and a flexible and absorbent element (7) disposed between the electrodes (2) and the mask (1). 2. System according to claim 1 characterized in that said means for fixing the mask (1) on the subject comprise the provision of a flexible and absorbent material disposed on the inner edges of the mask (1). 3. System according to claim 1 characterized in that the mask comprises 4 measuring electrodes and 1 reference. 4. System according to claim 2 characterized in that said flexible and absorbent material disposed on the inner edges of the mask are neoprene strips (6). 5. System according to claim 1 characterized in that said flexible and absorbent material element between the electrodes (2) and the mask (1) is made of foam (7). 6. System according to claim 1 characterized in that the mask is made of aluminum.