Voltage-to-frequency TDMA digital light-emitting cardiography using photosynchronization

The measurement of the potential on the living body is very vulnerable to electric induction noise. To avoid such induction, a novel principle for cardiography is proposed. In electrography, the cardiography sensing signal is transmitted in open air by the light from an LED. The electrocardiograph transmits 12-channel signals of electrical potential on a living body. In this report, the multichannel transmission is realized by a TDMA system. This requires synchronization (sync). In this system, a new method of optical acquisition of sync is utilized. Many kinds of modulated light sources can be used as the sync light source. The light of a fluorescent lamp can also be utilized as a syncsource. To avoid such induction and to utilize the photosynchronization, a new light emitting cardiography is proposed. In this system, the sync jitter of a fluorescent lamp is negligible owing to the frequency stability of the power company. A voltage-to-frequency conversion (V/F) TDMA light-emitting cardiograph by using the sync of a fluorescent lamp is proposed here. It is promising for practical clinical use.