Nidek Medical CP-690, Service Manual

Page: 49 / 70

6 - 5
6.5 Adjustment of the Chart and Mask Positions
1. Remove the top and bottom cover ASSYs and disk cover (M030). (See 5.1.)
2. Turn the power switch ON, project the chart onto the screen and adjust the focus.
3. Loosen SB4 × 10 (n=4) , SW4
(n=4) and PW4 (n=4) fixing the mask motor. Make fine
adjustments of the mask motor position to satisfy the following conditions.
* If the adjustment can not be completed by moving the mask motor, move the chart position
by making fine adjustments of the chart sensor position. However, when the chart sensor is
moved, perform “6.4 Adjustment of the fixed mask position”.
• Single letter mask position
When applying the single letter mask to the following charts [the parenthesized numbers are
visual acuity], the alphabetical letter shall be in about the center of the mask.
U type: Alphabet (70), M type: Alphabet (100), F type: Alphabet (0.3), T type: Alphabet
(0.2), P type: Alphabet (0.2), I type: Number (0.25), UK type: Alphabet (24), A type:
Hiragana (0.3)
• R/G filter position
The boundary between the red and green filters shall be in the middle of the chart
horizontally.
As a guide, the boundary is within about 3 mm from the center at the refractive distance of 5
m.
• Blocking of the astigmatism clock dial chart
The projected astigmatism clock dial chart shall be not blocked.
• Positions of the horizontal and vertical line masks
When applying the horizontal or vertical line mask to the following charts [the parenthesized
numbers are visual acuity], the mask shall not incline and the next chart shall not be seen (for
checking the light leakage).
U type: Alphabet (70 to 50), M type: Alphabet (100 to 20), F type: Alphabet (0.3 to 0.5), T
type: Alphabet (0.2 to 0.4), P type: Alphabet (0.2 to 0.32), I type: Number (0.25 to 0.4),
UK type: Alphabet (24 to 15), A type: Hiragana (0.2 to 0.4)
4. Tighten the loosened screws and check to satisfy the above conditions.
5. Perform “6.1 Adjustment of the initialized position” and “6.2 Adjustment of the sensor
voltage”.