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)

- 8 -
(4) Cylinder Form
There are three kind of the cylinder form.
－: displaying form measured by minor meridian. Refractive power of the minor
meridian
is displayed as SPH and the axis AX. And Difference between the major and minor
meridian is displayed as –CYL.
＋ : displaying form measured by major meridian. Refractive power of the major meridian
is displayed as SPH and the axis AX. And Difference between the major and minor
meridian is displayed as –CYL.
－/＋ : “-“ sign will be attached in case of the myopic astigmatism and the mixed
astigmatism. On the other hand, “+” sign in case of the hyperoptic astigmatism.
According to the setting in the setting mode, the above-mentioned data will be displayed.
(5) Axis
Axis is expressed counterclockwise from the ear side of the left eye as the origin(0°). 0° is
expressed as 180°.
Right Left
(6) Pupil Distance (PD)
Pupillary distance (PD) is the distance between the centers of the lenses of glasses.
Conviniently, it is said that the distance between the pupils is the distance between the
center of the lenses.
Average PD of Korean is about 62∼63mm for men and about 60mm for woman. In General, 3mm
for hyperopia, myopia of the youth, and 1~2mm for myopia of the aged people will be
shortened as the PD of hyperopia.
(7) Eccentricity (e)
Eccentricity is one of the integers of the conic sections. It is calculated by the
following equation.
e ＝ √1-(b/a)2 a ＝ major axis of the ellipse b ＝ minor axis of the ellipse
e＝0·················circle
e 〈 0 or e 〉 0···· · ellipse(The number ‘e’ represents the degree of closeness from
circle)

- 9 -
MRK-2000 classifies the data according to the signs (+, -) as follows.
－ : when the curvature of the peripheral area of cornea is greater than the curvature
of the center of cornea.
＋ : when the curvature of the peripheral area of cornea is smaller than the curvature
of the center of cornea.
Generally, eccentricity is used to prescribe the contact lens.

- 10 -
2.3 Electrical system
2.3.1 Electrical wiring

- 11 -
2.3.2 Initialization and Error
After connecting the power supply, MRK-2000 will initialize the system and perform the
following functions. Completing all of these, it enters the K-R mode. Exact procedures are as
follows.
(1) Initialization of the Thermal Printer
To initialize the Thermal Printer in the eyesight machine.
(2) EEPROM
To read the modifying value in need to perform a measurement from the EEPROM. Error
Messages will be displayed on the monitor if there are some errors in the EEPROM.
(3) Diaphragm Motor of keratometry
To Initialize the diaphragm motor of keratometry and performs self test.
(4) Motor of the Eye Fixation Target
To take the mechanic origin by moving the motor to the Photo Interrupter side. And then
move the motor to the position ‘0D’ set in the EEPOM. Error Messages will be displayed
on the monitor if there are some errors in the Photo Interrupter (REF-PI).
2.3.3 Eyeball Diagram Generated by the REF Measurement
It is possible to print the refrection state diagram regarding the result of the REF
measurement to the internal printer. This function will be performed when ‘PRINT=ALL’ in the
Page 2/4 of the SETUP MODE. See the following table and diagram for further information.
Classification of Data NORM
AL
MYOP
IA
HYPE
ROPI
A
ASTI
GMAT
ISM
NORMAL -0.5 =< S <= +0.5 -0.5 =< C <= 0.0 ◎
MYOPIA S < -0.5 -0.5 =< C <= 0.0 ◎
SIMPLE
MYOPIC
ASTIGMATISM
-0.5 =< S <= 0.0 C < -0.5 ◎ ◎
COMPOUND
MYOPIC
ASTIGMATISM
S < -0.5 C < -0.5 ◎ ◎
MIXED
ASTIGMATISM 0.0 < S C < -0.5 S+C < 0.0 ◎
HYPEROPIA +0.5 < S -0.5 =< C <= 0.0 0.0 < S+C ◎
SIMPLE
HYPEROPIC
ASTIGMATISM
+0.5 < S C < -0.5 0.0 =< S+C <= +0.5 ◎ ◎
COMPOUND
HYPEROPIC
ASTIGMATISM
+0.5 < S+C ◎ ◎
Table2-1 Eyeball Output by REF Measurement

- 12 -
(a) EMMETROPIA/NORMAL (e) MIXED ASTIGMATISM
(b) MYOPIA/NEAR SIGHTEDNESS (f) HYPEROPIA/ FAR SIGHTEDNESS
(c) SIMPLE MYOPIC ASTIGMATISM (g) SIMPLE HYPEROPIC ASTIGMATISM
(d) COMPOUND MYOPIC ASTIGMATISM (h) COMPOUND HYPEROPIC ASTIGMATISM
Figure 2-1 Diagram of the eye ball output by REF Measurement

- 14 -
3. Repair Standard
3.1 Disassembly and Assembly Procedure

- 28 -
3.2 Checking and Control
3.2.1 TEST MODE
Turn on the power button of the MRK-2000 and wait a few minutes until the ‘Measurement
Window’ is displayed. Press the following buttons in the following order. Check the ‘Beep’ sound.
◀ Æ ◀ Æ ▶ Æ MODE
Then it enters the ‘TEST MODE’ as the following figure.
TEST MODE
REF-M SYSV
KER REF
K-DAT R-DAT
RET
AUTO SHIFT
The title ‘TEST MODE’ will be shown on top line. In the middle 3 line, corresponding
functions to the six buttons in the right side of the keypad of the MRK-2000 will be displayed.
And the functions of the three buttons in the right side of the MRK-2000 will be displayed in the
bottom 2 line. Here is brief description of each function.
(1) REF-M
REF-MOTOR TEST. Checking or controlling the initial point of the ‘Eye Fixation
Target’.
(2) SYSV
Restoring the values set in the User Setup as a basic value.
(3) KER
Modifying the KER accuracy of measurement to be in the tolerance.
(4) REF
Modifying the REF accuracy of measurement to be in the tolerance.
(5) K-DAT
Checking the KER data set in the system and deleting certain items if necessary.
(6) R-DAT
Checking the REF data set in the system and deleting certain items if necessary.
(7) AUTO
Setting the variables related to the Auto-Start and the size of cornea.
(8) SHIFT

- 29 -
Setting the Shift amount of the KER-RAD, the KER-CYL, and the REF-CYL.
(9) RET
Returning to the ‘Measurement Window’ from ‘TEST MODE’.
3.2.2 How to Change INC-R into Unit 0.01
REF measured value will be displayed as unit 0.12 or 0.25 in the normal ‘Measurement
Window’. However, it is possible to change into unit 0.01 by the following order.
(1) Enter the ‘TEST MODE’.
(2) Press the ◀ button to select ‘AUTO’ and the following window will be shown.
AIM
-
PXL
:
32
AUTO START
INC* ----
D -- D ++
APX- APX+
RET
REF-INC: 0.25
DOTS/MM: 44.5
(3) In the top line of the right bottom area, the value set in the present ‘SETUP MODE’ will
be displayed.
(4) Press the MODE button to change the INC-R beside the REF-INC. Then the INC-R will
be changed into unit 0.01.
(5) Press the PRINT button to escape. There will be message, “SAVE SYS-VARS?” in the
left bottom of the window. Press the PRINT button again twice.
(6) You can measure when the ‘Measurement Window’ appears. From this point, REF
measured value will be displayed as unit 0.01.
<Notes> If disconnect the power supply, unit 0.01 of INC-R will be canceled.

- 30 -
3.2.3 Adjestment of the Origin of the Eye Fixation Target
[Purpose]
To locate the electric 0D to the optical 0D of the eye fixation target in the MRK-2000.
[Procedure]
(1) Enter the TEST.
(2) Press the MODE button in order to select ‘REF-M’ and it enters ‘REF-MOTOR TEST’
as the following figure. The position of the REF-MOTOR will move to the present
electric 0D and the value of it will be displayed beside ‘SM_0D:’.
M_POS: 135
SM_0D: 135
REF-MOTOR TEST
TEST STOP
SM0D M-EP
-1 +1
RET
-5 +5
M_END: 600
(3) Align the end part of the lens of the TV Camera Set for adjustment to the objective
glass.
(4) Press the AUTO, DISP, ◀, or ▶ to move the motor to make the chart of the eye
fixation target clear. Whenever the buttons are pressed, the present value of the REF-
MOTOR will be shown beside ‘M_POS:’.
(5) Press the IOL button to change the eletric 0D into the present value of REF-MOTOR. At
this point, the value beside ‘SM_0D:’ will be the same as the value beside ‘M_POS:’.
(6) If the PRINT is pressed, the message, “SAVE SYS-VARS?” will be shown in the left
bottom of the window. Press the ILLUM button to save the data. If the other button is
pressed, it returns to the ‘TEST MODE’ without saving.
(7) Press the MODE button to return to the REF-MOTOR TEST from the ‘TEST MODE’.
After the REF-MOTOR moves to the 0D position, check if the chart of the eye fixatoin
target is clear.
(8) Repeat the procedures from (2) to (6) until the chart of the eye fixation target becomes
clear.

- 31 -
3.2.4 Checking the REF-DATA
[Purpose]
To check the data of REF model eye stored in the MRK-2000.
[Procedure]
(1) Enter the ‘TEST MODE’.
(2) Press the DISPLAY button to select the ‘R-DAT’. Then the following window will be
displayed.
DIOPTER VALUE TO DELETE: +00.000
200: 309.80 307.10 309.30 +05.000
180: 282.80 281.70 282.30 +02.500
140: 261.20 261.90 259.10 -02.500
120: 228.40 229.80 227.80 -05.000
IDX: L0 L1 L2 DIOPTER
(3) Only the data about the model eye of Diopter stored in the MRK-2000 will be displayed.
(4) Press the PRINT button to return to the ‘TEST MODE’.
(5) If you want to delete certain values about Diopter, first, press the ◀ or the ▶ button
to change the number in the bottom line into the Diopter you want to delete. The
message “SAVE SYS-VARS?” will be popped up in the left bottom line if the ILLUM
button is pressed. And if the ILLUM button is pressed again, the value about the given
Diopter will be deleted. The window returns to the ‘TEST MODE’ automatically.