Biosignal measurement apparatus

1. A biosignal measurement apparatus used by being affixed on a living body, the biosignal measurement apparatus comprising:

a sheet formed with a plurality of electrodes and a plurality of wirings connected to the plurality of electrodes respectively, the sheet being freely expanded, contracted and bent and being adhesive; and

a substrate connected to the plurality of wirings and equipped with a signal processing circuit for wirelessly transmitting a biosignal acquired via the plurality of wirings,

wherein the sheet has a flexible connecting part comprising the plurality of wirings, wherein the sheet is bent such that the sheet is folded back, wherein the flexible connecting part has a tip connected to the signal processing circuit, wherein the flexible connecting part increases in hardness from a portion close to the plurality of electrodes toward a portion close to the tip of the flexible connecting part,

the plurality of electrodes are exposed on a front surface of the sheet,

the sheet and the substrate are stacked so that a back surface of the sheet faces the substrate, and

the plurality of wirings extend respectively and correspondingly from the electrodes to the of the flexible connecting part.

2. The biosignal measurement apparatus according to claim 1 , wherein each of the sheet and the substrate under a state of the front surface of the sheet affixed on the living body has an outer shape in plan view of a size falling within a rectangle of 5 cm×15 cm.

3. The biosignal measurement apparatus according to claim 1 , wherein

the plurality of electrodes include a reference electrode and a plurality of measurement electrodes.

4. The biosignal measurement apparatus according to claim 3 , wherein

reference electrode is attachable to and detachable from the sheet, and is affixed on the sheet.

5. The biosignal measurement apparatus according to claim 1 , wherein

the plurality of electrodes include electrodes arranged parallelly in at least two rows, and each of the rows includes a plurality of electrodes in line.

6. The biosignal measurement apparatus according to claim 1 , wherein

the signal processing circuit includes an analog circuit for processing an analog signal acquired via the plurality of electrodes to convert the analog signal into a digital signal,

a digital circuit for processing the digital signal acquired by the analog circuit to transmit the digital signal wirelessly, and

a power source circuit for supplying power to the analog circuit and the digital circuit, and

the analog circuit, the digital circuit and the power source circuit are respectively mounted in a first region, a second region and a third region obtained by dividing a mounting surface of the substrate into three regions.

7. The biosignal measurement apparatus according to claim 6 , wherein the analog circuit has an A/D converting section for converting the analog signal into a digital signal having a bit number of 20 bits or more.

8. The biosignal measurement apparatus according to claim 6 , wherein the analog circuit has a contact state-detecting circuit for detecting a contact state between the plurality of electrodes and the living body by measuring a contact impedance between the plurality of electrodes and the living body.

9. The biosignal measurement apparatus according to claim 6 , wherein the power source circuit includes:

a rechargeable battery;

a connection terminal provided on the substrate; and

a charging circuit for charging the battery with power supplied through the connection terminal.