Ceiling-Mounted Type Lighting Device

A ceiling-mounted type lighting device, comprising:

• a light-receiving unit containing four optical sensors arranged crosswise and a light-shielding body through which four through-holes are cut as positions that are respectively opposite to light-receiving surfaces of the optical sensors;
• and
• a tilt adjustment mechanism containing first and second movable bodies which are mounted on first and second rotation shafts arranged on a same plane to cross at right angles,
• wherein the light shielding body is arranged so as to be opposite to the optical sensors with any possible small clearance being kept;
• wherein single tilt adjustment light emitted from a light emitter of a side of the treatment table passes through the through-holes to form four spotted tilt adjustment lights which are respectively concentrated to the sensors;
• wherein the tilt adjustment mechanism is mounted in a housing constituting the ceiling-mounted type lighting device;
• and
• wherein the light-receiving unit and a lighting lamp illuminating a side of the light emitter are mounted on a rotational center axis of the second moving body, whereby a tilt of the light-receiving unit is adjusted on the basis of outputs from the optical sensors.