A head shield device having a frame and a replaceable lens. In the electrophoretic display device, a distribution state of the electrophoretic particles is changed to effect display, and the first electrode has an area substantially equal to or larger than an area of the second electrode. The torque monitoring device is configured as a function of a result of the power take-off monitoring. A reproduction section reproduces the content data read from the temporary memory. The electronic document is delivered in response to receiving a reply to the acknowledgment from the requestor accepting the identification of the payment amount.