The invention relates to a screen which is particularly intended for a non-invasive functional unit measuring the function of at least one organ through skin contact, the functional unit comprising a supporting structure, an electrical circuit for operation, and electrodes for the skin contact, the electrodes being operatively coupled to the electrical circuit and mechanically attached to the supporting structure.
Vital functions can be measured telemetrically using a non-invasive measuring device. An example of such a measuring device is, for example, a system which measures human heart rate and usually comprises as functional units a transmitter unit, a receiver unit and a data transfer unit. The transmitter unit refers to a transmitter unit equipped with electrodes and worn on the human body, particularly on the chest, the transmitter unit usually being implemented in the form of a transmitter belt attached around the body. The receiver unit refers for instance to a watch-like receiver unit which is worn on the wrist, the receiver unit having a telemetric or wired coupling with the transmitter unit. The data transfer unit transfers data received in the receiver unit to a computer, for example. The computer can also control the transmitter unit and the receiver unit via the data transfer unit.
Heart rate measurement is based on monitoring the function of the heart. When the heart contracts, it generates a series of electric impulses that can be measured in the body. The measurement and analysis of this signal is called electrocardiography (ECG). The signal itself is called an ECG signal. Different phases of the heart cycle can be discerned in the ECG signal. These are called P, Q, R, S, T and U waves.
The transmitter part located next to the body suffers from electromagnetic interference, and particularly from problems caused by static electricity. A typical problem situation occurs when a user exercises with a shirt on. When the user moves, the shirt moves, flapping against the user""s body and the transmitter unit. Synthetic fiber textiles in particular that are poor at conducting electricity attract electric charges specifically in dry weather, at least before the user starts sweating. In terms of electrical engineering, a great amount of charge at random amplitude and at random frequency then moves in the vicinity of the transmitter unit. Such a random movement of a great amount of charge is capacitively coupled to the transmitter unit, interfering with its operation.
An object of the invention is thus to provide a screen so as to solve the above problems caused by static electricity. This is achieved with a screen described in the introduction, the screen being characterized by being arranged to closely follow the electrode or the supporting structure at least at the electrode.
A plurality of advantages can be achieved by the screen of the invention. The screen prevents disturbance from being connected to the functional unit; hence, the operation of the functional unit becomes more reliable.