| US 7,549,751 B2 | ||
| Optotype presenting apparatus | ||
| Yuichiro Kanazawa, Okazaki (Japan); and Ryoji Suzuki, Toyohashi (Japan) | ||
| Assigned to Nidek Co., Ltd., Gamagori-shi (Japan) | ||
| Filed on Jan. 31, 2008, as Appl. No. 12/10,975. | ||
| Claims priority of application No. 2007-045564 (JP), filed on Feb. 26, 2007. | ||
| Prior Publication US 2008/0204662 A1, Aug. 28, 2008 | ||
| Int. Cl. A61B 3/02 (2006.01) | ||
| U.S. Cl. 351—243 [351/237; 351/242] | 7 Claims |
| 1. An optotype presenting apparatus which presents an optotype for visual acuity test, the apparatus comprising:
a display that is illuminated by a backlight and includes a light intensity changing device which changes backlight intensity;
a background luminance selecting device which selects background luminance of the optotype among a plurality of preset levels,
in which background luminance at each level corresponds to standard light intensity changing data in a changeable range determined
by the light intensity changing device; and
a correction device which corrects the standard light intensity changing data in the background luminance selecting device,
the correction device including:
an input device which inputs the background luminance measured by an illuminance meter, the measured background luminance
being background luminance obtained when the light intensity changing device is operated based on the preset light intensity
changing data; and
a calculation device which determines correction light intensity changing data by comparing the background luminance input
by the input device and the preset light intensity changing data.
|