Samsung patents eye test device using a lens that changes shape electronically

1. An apparatus configured to measure a visual acuity (VA) by a focus-tunable lens, the apparatus comprising: a display engine configured to project light comprising a VA measuring image; an image combiner configured to guide the light projected from the display engine; the focus-tunable lens provided on a path of the light guided by the image combiner; an input device configured to receive a user's input with respect to the VA measuring image; a storage configured to store one or more instructions; and a processor configured to execute the one or more instructions to: control the focus-tunable lens to assign a first optical power to a first lens region and a second optical power that is different from the first optical power to a second lens region, the first lens region and the second lens region being included in a lens surface of the focus-tunable lens; control the display engine to display the VA measuring image through a first output region and a second output region of the image combiner, which respectively correspond to the first lens region and the second lens region of the focus-tunable lens; control the input device to receive the user's input; specify one optical power of the first optical power and the second optical power based on the user's input; and determine a VA of a user based on the specified optical power, wherein the focus-tunable lens comprises a first liquid crystal lens comprising a first strip electrode array and divided into a plurality of first zones, and a second liquid crystal lens comprising a second strip electrode array and divided into a plurality of second zones, wherein the first strip electrode array comprises a plurality of first strip electrodes having a linear shape extending along a first direction, and the second strip electrode array comprises a plurality of second strip electrodes having a linear shape extending along a second direction perpendicular to the first direction, wherein the plurality of first strip electrodes and the plurality of second strip electrodes overlap each other orthogonally, wherein the processor is further configured to assign the first optical power to the first lens region by setting a first voltage profile applied to at least one first strip electrode included in a first zone among the plurality of first zones corresponding to the first lens region and at least one second strip electrode included in a second zone among the plurality of second zones corresponding to the first lens region, and assign the second optical power to the second lens region by setting a second voltage profile applied to at least one first strip electrode included in a first zone among the plurality of first zones corresponding to the second lens region and at least one second strip electrode included in a second zone among the plurality of second zones corresponding to the second lens region, wherein the first optical power has a first cylindrical lens optical power with the first direction, placed on the lens surface of the focus-tunable lens, as an axial direction, and the second optical power has a second cylindrical lens optical power with the second direction, placed on the lens surface of the focus-tunable lens and orthogonal to the first direction, as the axial direction based on measuring astigmatism of the user, and wherein the measuring of the VA of the user comprises determining an astigmatism direction of the user based on the axial direction of each of the first cylindrical lens optical power and the second cylindrical lens optical power.