The present invention provides an information storage apparatus that generates a tracking error signal based on a detection signal, and performs various control operations based on the tracking error signal. The pigment dispersing resin consists essentially of the carboxylic acid salt of an aminated bisphenol epoxy resin and an alkoxylated styrenated phenol. The output signals of the integrator circuit are periodically compared, and based on the comparison, output signals having a voltage representative of a value are generated. The buffer layer preferably is a silicon oxide layer with a thickness substantially smaller than a thickness of the passivation layer. In another embodiment, a node listens on a first frequency for a wireless CSDA signal regarding a second frequency, and in response to receiving a CSDA signal, may refrain from transmitting a wireless signal on the second frequency for the particular duration, or else, may allow transmission of a wireless signal on the second frequency, accordingly. The optical filter has excellent environmental resistance and low reflection.