Patent ID: 7057154

Claim:
An external force detecting device comprising: an action section to receive an external force; a support section to support the action section; and at least one optical displacement sensor including a light source, a light receiving element, and a light reflecting means, wherein the light source and the light receiving element are disposed at one of the action section and the support section while the light reflecting means is disposed at the other one thereof at which the light source and the light receiving element are not disposed, and wherein light emitted from the light source is reflected at the light reflecting means and received at the light receiving element, whereby displacement of the action section in relation to the support section is detected and outputted as a signal according to which an external force applied to the action section is calculated, and wherein the optical displacement sensor is capable of detecting displacement with respect to two-axis directions of a plane perpendicular to an optical central axis of light emitted from the light source, and wherein the light reflecting means defines two reflection surfaces which make an angle of 90 degrees with each other, and which respectively make an angle of 45 degrees with the optical central axis of light emitted from the light source, and wherein a direction in which the two reflection surfaces oppose each other coincides with an intermediate direction between the two-axis directions with respect to which displacement is detected.