抄録
In this paper, in order to develop the spatial electrocutaneous communication system with minimum size of hardware, fundamental experiments were performed to provide with various locations on the skin a continuously variable sensation by utilizing the phantom sensation. Two sets of electrodes were located on the skin just above the biceps brachii and stimuli were presented to each electrodes either simultaneously or with time delay. The effect of relative magnitudes and time delay on the phantom sensation was experimentally studied. The following results were obtained. (1) The magnitude-difference cue was found more distinct than the temporal-difference cue. The phantom sensation caused by a magnitude-difference cue becomes less clear as the energy level becomes high (above 40erg/channel), and as the interval of pulse stimuli becomes short (under 50ms). (2) The relation between the mental location of the relative magnitude phantom sensation and the ratio of the magnitude of stimuli E0/E1, in which E0 and E1 are the energy levels of stimuli simultaneously presented to adjacent locations respectively, is linear, and does not depend on the stimulus energy level (E0+E1) except in the vicinity of each electrode, where the relation depends on the energy level. (3) The just noticeable difference (jnd) of mental location has a maximum value at the central position between the two electrodes and a minimum value at the neighborhoods of the electrodes. The maximum information transmission rate calculated from jnd of mental location depends on the distance d between the two electrodes and ranges from 2.0 to 3.0 bits for d between 50 and 150mm. (4) The advantages of employing the technique of the phantom sensation are that it can reduce the number of electrodes required for spatial electrocutaneous stimulation and also that it can distribute stimuli more densely without the restriction of electrode sizes.
