Eyeglass rating with respect to protection against UV hazard
AssigneeEssilor International
InventorsKarl Citek, Gilles Baillet, Francisco De Ayguavives, Gabriel Keita
Life of this patent
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Abstract
An index value is calculated for rating an eyeglass with respect to protection against UV hazard. The index value is based on an integrated UV transmission value through the eyeglass and an integrated UV reflection value related to a back face of the eyeglass. Thus, the index value takes into account actual wearing conditions where UV eye exposure is due either to transmission through the eyeglass or reflection on the eyeglass back face. Respective index values obtained for a set of eyeglasses allow easy sorting of the eyeglasses with respect to UV protection efficiency.
Claims32
A method of providing to a customer of an eyeglass a rating of the eyeglass with respect to protection provided by the eyeglass against UV hazard, the rating based on an index value, which quantifies a reduction in a total UV amount impinging onto an eye for a wearer of the eyeglass with respect to UV exposure without the eyeglass, the method comprising the steps of:
- measuring UV intensity with a photometer for light reflecting from a back face of the eyeglass;
- providing a value of UV transmission for the eyeglass;
- providing a value of UV reflection on a back face of the eyeglass;
- combining both values of the UV transmission and the UV reflection of the eyeglass using an addition formula with non-zero positive factors respectively for the UV transmission and UV reflection;
- and
- calculating the index value from a non-zero base number divided by a result obtained in the combining step, the index value being based in part on measurements obtained in the measuring step and accounting for incident light that reaches an eye of the wearer from the back face of the eyeglass;
- and
- providing to a customer the rating for the eyeglass.
An eyeglass rated for quantifying an amount of UV light exposure on eyes of a wearer, the eyeglass comprising:
- a front face that transmits light;
- a back face that reflects light;
- and
- an indication of a visual rating associated with the eyeglass whereby the wearer is informed, the rating including an index value that quantifies a reduced UV light exposure amount to the eyes of the wearer, the index value being based on
- an amount of UV light transmitted through the front face of the eyeglass, and
- an amount of UV light reflected from the back face of the eyeglass.
A method of rating an eyeglass with respect to protection provided by the eyeglass against UV hazard, whereby an index value is calculated, which quantifies a reduction in a total UV amount impinging onto an eye for a wearer of the eyeglass with respect to UV exposure without the eyeglass, the method comprising the steps of:
- measuring UV intensity with a photometer for light reflecting from a back face of the eyeglass;
- providing a value of UV transmission for the eyeglass;
- providing a value of UV reflection on a back face of the eyeglass;
- combining both values of the UV transmission and the UV reflection of the eyeglass using an addition formula with non-zero positive factors respectively for the UV transmission and UV reflection;
- and
- calculating the index value from a non-zero base number divided by a result obtained in the combining step, the index value being based in part on measurements obtained in the measuring step.
Dependencies are inferred from the claim text.