Vision tester with color corrected illuminating system

Claim 2

In a vision testing apparatus wherein a light-occluding housing includes vision testing transparencies movable into a viewing position relative to a viewing area and light source means positioned relative to said transparencies to illuminate same for viewing, the improvement comprising; blue filtering means interposed between said light source means and said viewing area, said light source means is an incandescent bulb with said blue filtering means positioned on the light transmitting surface thereof; and said blue filtering means include a coating having a coloration shade, a thickness and a density that, in cooperation with said light source means , provides ilumination of said transparencies in the range of approximately 5000 to 5500 degrees K and maintains substantially consistent illumination of said transparencies throughout variations in line voltage input to the vision testing apparatus of beween about 110 and about 135 volts, said substantially consistent illumination being white in color and avoiding off-color illumination experienced by blue filters other than said blue filtering means, including the development of orange and yellow tinged illumination of the transparencies at input line voltage variations beween said about 110 and about 135 volts.

Claim 3

The vision testing apparatus of claim 1, wherein said transparencies are mounted on a rotatable drum within which there are a pair of said light source means and said filtering means that establish a near point testing station and a far point testing station.

Claim 4

The vision testing apparatus of claim 2, wherein said light source means include tungsten filaments.

Claim 5

The vision testing apparatus of claim 1, wherein said light source means include tungsten filaments.

Claim 6

The vision testing apparatus of claim 2, wherein said filtering and light source means cooperatively provide illumination in the range of approximately 5000 to 5200 degrees K.

Claim 7

The vision testing apparatus of claim 1, wherein filter means are provided between said light source means and said viewing area, said filter means being for reducing contrast on the test pattern.

Claim 8

In a vision testing apparatus including: a base, a light-occluding casing carried by said base; a drum member rotatably supported in said casing, means for rotating said drum member, said drum member having a periphery, said drum member having a vision test station disposed along said periphery of the drum member; a test pattern carried by said drum member in position to be selectively moved into alignment with the vision test station, said test pattern having a plurality of characters; viewing means carried by said casing including lens means adapted for optical alignment with said test pattern, the improvement comprising: said vision test station including a tungsten filament light source, and blue colored filtering means is interposed beween said light source and an internal test pattern, said colored filtering means correcting the color of said light source to approximate the color temperature that is generally charcateristic of daylight lighting conditions said colored filtering means includes a coating having a coloration shade, a thickness and a density that, in cooperation with said light source, provides illumination of said internal test pattern at a color temperature value that is in the range of approximately 5000 to 5500 degrees K and imparts substantially consistent illumination of said internal test pattern throughout variations in line voltage input to the vision testing apparatus of between about 110 and about 135 volts, said substantially consistent illumination being white in color and avoiding off-color illumination experienced by blue filters other than said colored filtering means, including the development of orange and yellow tinged illumination of the internal test pattern an input line voltage variations between said about 110 and about 135 volts.

Claim 9

In a vision testing apparatus including: a base, a light-occluding casing carried by said base; a drum member rotatably supported in said casing, means for rotating said drum member, said drum member having a periphery, said drum member having a vision test station disposed along said periphery of the drum member; a test pattern carried by said drum member in position to be selectively moved into alignment with the vision test station, said test pattern having a plurality of characters; viewing means carried by said casing including lens means adapted for optical alignment with said test pattern, the improvement comprising: said vision test station including a tungsten filament light source, and blue colored filtering means is interposed beween said light source and an internal test pattern, said colored filtering means correcting the color of said light source to approximate the color temperature that is generally charcateristic of daylight lighting conditions said colored filtering means includes a coating having a coloration shade, a thickness and a density that, in cooperation with said light source, provides illumination of said internal test pattern at a color temperature value that is in the range of approximately 5000 to 5500 degrees K and imparts substantially consistent illumination of said internal test pattern throughout variations in line voltage input to the vision testing apparatus of between about 110 and about 135 volts, said substantially consistent illumination being white in color and avoiding off-color illumination experienced by blue filters other than said colored filtering means, including the development of orange and yellow tinged illumination of the internal test pattern an input line voltage variations between said about 110 and about 135 volts.

Claim 10

The vision testing apparatus of claim 7, wherein said light source is in the form of a bulb of clear glass with said coating on the surface thereof.

Claim 11

The vision testing apparatus of claim 7, wherein said color temperature value is within the general range of approximately 5000 to 5200 degrees K.

Claim 14

The vision testing method according to claim 10, wherein said interposing step is carried out at a location between the light source and the test pattern.

Claim 15

The vision testing method according to claim 10, wherein the vision testing that is carried out measures the contrast sensitivity characteristics of the eyes, and wherein said method includes varying the contrast of the test pattern in a controlled manner.

Claim 16

The vision testing method according to claim 12, wherein said varying is carried out by providing a plurality of test patterns that are characterized by differing contrast attributes thereof.

Claim 17

The vision testing method according to claim 12, wherein said varying is carried out by filter means for reducing the contrast of the test pattern.

Claim 18

The vision testing method according to claim 10, wherein said interposing step is carried out on a surface of the light source.

Claim 19

The vision testing method according to claim 10, wherein said interposing step is carried out at a location separate from the light source.