Mirae CHAROPS MRK-2000 User manual

SERVICE MANUAL
AUTO REF/KERATOMETER MRK-2000
AUTO REFRACTOMETER MR-2000
Revision 1.1 www.charops.com

CONTENTS
1. Structure of this machine ······················································
1
2. Operational Discription
2.1 Measurement Principle
2.1.1 Measurement Principle of the Reflex system ························································
·· 2
2.1.2 Measurement Principle of the Keratometer system ··················································
· 3
2.1.3 Measurement Principle of the IOL Observation ······················································
· 5
2.2 Optical system and Operation Principle ··········································
6
2.3 Electrical System
2.3.1 Electrical wiring ·····················································································
···· 10
2.3.2 Initialization and Error ···············································································
···· 11
2.3.3 Eyeball Diagram Generated by the REF Measurement ···············································
11
3. Repair Standard
3.1 Disassembly and Assembly Procedure
3.1.1 Removing the Head rest ass’y ······································································
··· 13
3.1.2 Removing the Head front cover assembly ···························································
· 14
3.1.3 Removing the Ker led ass’y and the Ker diaphragm assembly ······································
15
3.1.4 Removing the Mirror box assembly ··································································
·· 1 6
3.1.5 Removing the Motor base assembly ································································
·· 1 7
3.1.6 Removing the Prism lens assembly ·································································
·· 1 8
3.1.7 Removing the Head unit assembly ··································································
·· 1 9
3.1.8 Removing the Body front cover assembly ···························································
·· 2 1
3.1.9 Removing the CRT assembly ·······································································
··· 22
3.1.10 Removing the Joystick assembly ··································································

··· 23
3.1.11 Removing the Base1 assembly ····································································
··· 24
3.1.12 Removing the Y-pole housing assembly and the Head guide pole assembly ·····················
25
3.1.13 Removing the Base2 assembly ····································································
··· 26
3.2 Checking and Control
3.2.1 TEST MODE ·························································································
····· 28
3.2.2 How to Change INC-R into Unit 0.01 ································································
·· 2 9
3.2.3 Adjustment of the Origin of the Eye Fixation Target ··················································
30
3.2.4 Checking the REF-DATA ············································································
··· 31
3.2.5 Modifying the REF-Measured Value ··································································
·· 3 2
3.2.6 Checking the KER-DATA ············································································
··· 34
3.2.7 Modifying the KER-Measured Value ·································································
··· 35
3.2.8 Important Notice to Service ··········································································
··· 37
3.2.9 Voltage of Each Part in the Normal Condition························································
· 37

1. Structure of this machine
- 1 -

2. Operational Discription
2.1 Measurement Principle
2.1.1 Measurement Principle of the Reflex system
(1) Light beam from the light source is reflected from the examinee’s retina.
(2) According to the refraction condition of the examinee’s eye, parallel light beam will be
projected in case the examinee is emmetropia, and divergent light beam in case of myopia.
(3) The light beam projected from the examinee’s eye will be divided, projected and imaged
on the TV camera as six bright points.
(4) Do the Ellipsoidal Fitting of the coordinate of this six bright points by the
distance between the center and each point, and SPH, CYL, AX can be derived.
Diagram of measurement Principle
H
yp
ero
p
ia
M
y
o
p
ia
Emmetro
p
i
Minor axis
of elli
p
se
Major axis
of ellipse
Diaphragm for measuring
Objective Lens
Camera for measuring
Diaphragm
Hole Mirror
- 2 -

About the function of the IOL
Cornea and iris can be deformated in case of eyes with intraocular lens(IOL). Thus there
can be measurement error due to the bad Light wave. Also, IOL has high transmitance of light
than the crystalline lens of human. Thus if you measure the eyes with IOL in the same amount of
light as human, the light reflected from retina is too strong. It may cause some errors. To prevent
this measurement error, there is the IOL switch.
2.1.2 Measurement Principle of the Keratometer system
If the ring light source of the keratometry is projected on cornea, it is reflected as a circle or
an ellipse (in case of astigmatism), the size and the shape changed according to the radius of
curvature of cornea in each direction because cornea is not a sphere. On TV, make image the
relflected light (mire image) from cornea and read the data as coordinates (figure 1). Input this
data to the MPU and calculate the diameter of major axis(2a), the diameter of minor axis(2b) and
the rotational angle(θ , axis on the minor meridian) (figure 2). Furthermore, there is correlation
between the radius of cornea (R), the height of the projected ring image(h), the projection
angle of ring light (θ). The correlation is as follows. Therefore, small and large radius of
curvature of cornea can be calculated with respect to the minor and major axis.
H
R ＝ sin(θ/2)
Diaphragm for the correction
(of magnification)
Lens for measuring
Ring type light source for measuring
CCD Camera
Objective glass for Keratometer
(Mire Ring)
〔 Figure 1〕
- 3 -

And there is the following relation between the radius of cornea (R), the refractive power of
cornea (D), and the refration rate (n). Thus, strong and weak refractive powers of cornea (D)
are calculated in regard to large and small radius of curvature (R) (figure 3).
1000 (n-1) The following 3 values can be selected
D ＝
R(mm) for corneal equivalent refractive index (n)
n ＝ 1.3375 , 1.336 , 1.332
[Peripheral Measurement of Cornea]
You can measure the radius of peripheral cornea R, the refrative power of cornea D and so
on by the stated measurement principle lightening the illumination lamp located to eight
directions (up, down, right, left and each interval of the stated directions) on the 45°of
the circumference. Peripheral mesurement about 30°of meridial direction is also measured by
changing the target point(tilt angle 18°in regard to examinee’s eye) with the peripheral
lamp.
X^2/a^2 + Y^2/b^2 = 1 R = h/sin(θ/2)
Ring light
Examinee
θ
When measuring the peripheral
d = R sin(θ/2)
The Line of View
Optical Axis of
measuremen
t
When measuring the central area
Minor axis
of elli
p
se
Major axis
of ellipse
[Figure 2]
[Figure 3]
〔Figure 4〕
- 4 -

2.1.3 Measurement Principle of the IOL Observation
(2) Using the IOL observation
(1) Principle of the IOL observation
Give light to the fundus of the eye by lightening the infrared LED(spot light) used to
measure the Auto Reflex and lightening the crystalline lens with the reflected light. And
then confusing shape of the intermediate transparent body can be captured by TV camera.
Relay Lens Camera for observing
Collimator Lens Illumination LED
zYou can observe the wounded part of the contact lens and stainning form, etc.
zIt is possible to measure the eye with the cataract by finding the penetrating part
observing IOL. It was impossible to measure or there were some errors before.
zThe confusing shape of the cataract and the frontal glass can be observed. Thus the
change of the disease can be taken up with. Therefore, the cause of the degradation of
eyesight can be known whether it is because of the simple refractive derangement or
because of the confusion in the eye.
- 5 -

- 6 -
2.2 Optical System and Operation Principle
Terminology of Optical system
1 : patient’s eye 8 : light source (R)
2-1, -2 : LED for lightening cornea 9 : diffraction prism (R)
3 : ring unit of the keratometry 9-1 : diaphragm measuring relfex
4-1 : protective glass 11 : relay lens measuring reflex
4-2 : half mirror 12 : TV camera (R)
4-3 : half mirror 13 : relay lens for keratometry
4-4 : reflection mirror 14 : TV camera (K)
5 : objective Lens 16 : moving lens used to modify the eyesight
6 : diaphragm 17 : internal chart
7 : project group of measurement chart (R) 18 : illumination lamp
7-1 : hole mirror
7-2 : diaphragm projecting relfex
R = Ref
K = Keratometer
Light Source of the Optic System
Ａ: External illuminator (2-1, 2-2)
Ｂ: Corneal observation system (1→4-1→ 4-2→4-3→13→14)
Ｃ: Ker measurement system (3→1→4-1→4-2→4-3→13→14)
Ｄ: Projection system of the REF measurement chart (8→7-2→7-1→6→5→4-2→4-1→1)
Ｅ: Projection system of the REF measurement (1→4-1→4-2→5→6→7-1→9-1→10→11→12)
Ｆ: Projection system of the light source for the fine observation (8→7-2→7-1→6→ 5→ 4-2→ 4-1→ 1)
Ｇ: Fine observation system (1→4-1→4-2→4-3→13→14)
Ｈ: Projection system of the target chart (18→17→16→4-4→4-3→4-2→4-1→1)
1
2-2
2-1
4-4
4-3
4-24-1
4
3
5
13 14
181
7
16
9
6
7
8
12
11
7-1
9-1
7
-2
Diagram Illustrating the Operation principle

- 7 -
Appendix- Terminology
(1) Foggy Method
It is recommaned that the refractive power is measured when the examinee’s eye is in the
hyperopia-state. But there can be some errors due to the interruption of the controllerbility
if it is measured in the eye refraction system of internal optical target method (mechanic
myopia).
Foggy method is the method that the size of the target is modified to be greater than the
eyesight of the examinee by ＋1∼2D in order to reduce the error caused by this
controllerability. There is another method – controllerbility paralysis method. Generally,
mechanic myopia occurs to the youth in a great deal. At this point, controllerbility is one of
the functions of the eye. It controls the thickness of crystalline lens according to the
movement of the ciliary body and changes the refractive power of crystalline lens. As a result,
it makes clear images on retina.
(2) Standard Value
If you measure continuously more than three times, you can get the measured value in a high
confidence level through the statistics of the newest 3~5 measured value.
(3) Vertex Distance (VD)
Vertex Distance is the distance between the backward vertex of the correcting lens (eye
side) and the vertex of cornea.
If Vertex Distance influences the refractive power and Vertex Distance is incresed, minus
diaphragm is needed, if decreased, plus diaphragm is needed.
H
d
F2 ＝ 1+
1000
F1
F2 : Refractive Power in the movement position (D)
d : movement distance (mm)
F1 : Refractive Power in the standard position (D)
(example) F1 ＝+13D, d＝+3mm : F
2 ＝+12.5D
F
1 ＝ +13D, d＝-3mm : F 2 ＝ +13.5D
F
1 ＝ -10D, d＝+2mm : F 2 ＝ -10.2D
F
1 ＝ -10D, d＝-2mm : F 2 ＝ - 9.8D
The following three kind of data will be displayed as the setting in the setting mode.
VD ＝ 0mm : hard contact lens
VD ＝12. 0mm : lens of glasses (oriental people)
VD ＝13. 5mm : lens of glasses (western people)