Huvitz CRK-1 Service Manual
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Huvitz CRK-1 Service Manual

Auto ref/keratometer
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Auto Ref/Keratometer CRK-1

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Summary of Contents for Huvitz CRK-1

  • Page 1 Service Manual Auto Ref/Keratometer CRK-1...
  • Page 2 Shanghai Huvitz has the right to make any kind of modification to this product or pr oduct specs anytime without prior notice and modification may not be renewed on thi...
  • Page 3 Shanghai Huvitz Co., Ltd. Building 1, No. 150, Renjie Road, Fengxian, Shanghai, 201401, China All rights reserved. Under copyright laws, this manual may not be copied, in whole or in part, without the prior written consent of Shanghai Huvitz Co., Ltd...

  • Page 4: Table Of Contents

    ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 3 Contents 1. Important Notice....................................5 2. Safety Information..................................6 2.1. Introduction.................................... 6 2.2. Safety Symbol..................................7 2.3. Environmental Considerations............................10 2.4. Safety Precaution................................12 3. Product Outline................................... 14 3.1. Nomenclature..................................14 3.2. Optical System................................... 18 3.3. Electrical System................................22 3.4. Mode Setting..................................30 3.5.
  • Page 5 4 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ 4.9. Software upgrade................................66 5. Disassembly and Assembly Procedure..........................68 5.1. Removing the Cover.................................68 5.2. Disassembling the Moving Base Assy......................... 70 5.3. Disassembling the Front-Cover-Assy (LCD-Assy)......................71 5.4. Disassembling the OPTICAL HEAD ASSY......................... 73 5.5. Disassembling the MAIN FRAME ASSY........................74 6.

  • Page 6: Important Notice

    Shanghai Huvitz reserves the right to make changes in its products or product specificati ons at any time and without prior notice, and is not required to update this documentatio...

  • Page 7: Safety Information

    6 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ 2. Safety Information 2.1. Introduction Safety is everyone’s responsibility. The safe use of this equipment is largely dependent u pon the installer, user, operator, and maintainer. It is imperative that personnel study and become familiar with this entire manual before attempting to install use, clean, service or adjust this equipment and any associated accessories.

  • Page 8: Safety Symbol

    ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 7 WARNING "Warning,” indicates the presence of a hazard that could result in severe person al injury, death or substantial property damage if ignored. NOTE "Note,” describes information for the installation, operation, or maintenance of w hich is important but hazard related if ignored.
  • Page 9 8 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ for medical electronic equipment, which classify a connection or warn of any potential hazards. The classifications and symbols are shown below. I and O on power switch represent ON and OFF respectively. Type B Isolated patient connection This symbol identifies a safety note.
  • Page 10 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 9 lth. 4. For more detailed information about disposal of your old applian ce, please contact your city office, waste disposal service or the sh op where you purchased the product. Alternating Current Warning: Crushing or insert of hand (Attention: écrasement ou insertion de la main)

  • Page 11: Environmental Considerations

    10 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ Use no hooks (N'utilisez aucun crochet) Consult instructions for use (Consulter les instructions d'utilisation) COM Connector cable Symbol (COM Connector cable Symbole) Serial Number Symbol (Symbole du numéro de série) 2.3. Environmental Considerations Please avoid the environment below for the operation and storage of the equipment...
  • Page 12 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 11 Where any heaters are at t Do not close the thermal he close distance to the m ventilation outlet. achine. Do not connect the AC Where the humidity is high power plug into the o...

  • Page 13: Safety Precaution

    The equipment must be operated only by, or under direct supervision of properly trained and qualified person/s. Modifications of this equipment may only be carried out by Shanghai Huvitz’s ser vice technicians or other authorized persons. Customer maintenance of this equipment may only be performed as stated in the User’s Manual and Service Manual.
  • Page 14 The equipment may only be used together with accessories supplied by Shangha i Huvitz’s. If the customer makes use of other accessories, use them only if ther e are usability under technical safety aspects has been proved and confirmed by Shanghai Huvitz or the manufacturer of the accessory.

  • Page 15: Product Outline

    14 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ 15. Do not obstruct any ventilation outlet for proper heat dissipation. In case of any presence of smoke, spark or abnormal noise/smell from the machine, ple ase power off immediately and pull out the plug.
  • Page 16 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 15 1. Forehead rest: location for placing the forehead to prevent test subject from mo ving the face (Type B attachment part) 2. Measuring window: object lens for measuring the image that is formed in the ey e retina 3.
  • Page 17 16 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ 1. Power supply socket (Fuse holder): Socket that connects with the outside power plug (250V T3.15AL) 2. Serial interface connector: Connector for connecting outside device connector 3. RGB connector: Connector for connecting with the outside monitor of the RGB method 4.
  • Page 18 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 17 Use signal amplifier if the distance with the outside monitor is significant.

  • Page 19: Optical System

    18 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ 3.2. Optical System...
  • Page 20 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 19 List of Optical Components Patient’s eye 2-1, -2: LED for lightening cornea 3-1, -2: Ring unit of the Keratometry 4-1: White LED 4-2: Blue LED 5: Objective lens 6: Half mirror 7: Relay lens 8: IR filter (K measurement)
  • Page 21 20 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ 22: Collimation lens 23: Light source(R) 24: Relay lens 25: Reflection mirror 26: Relay lens 27: Moving lens to compensate refractive power 28: Imaging Lens for Refractometer Signal 29: TV camera(R) 30: Moving module to compensate refractive power...
  • Page 22 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 21 Ｄ : Pr o j e c ti o n sy s t e m of th e RE F li g ht so ur c e (2 3 22 21 20 19 18 17 11 651) Ｅ...

  • Page 23: Electrical System

    22 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ 3.3. Electrical System Electrical construction diagram 3.3.1.1. System functional block diagram...
  • Page 24 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 23 3.3.1.2. Power input electrical block diagram SMPS Output DC Output +5V, 4A +5V, 2A +12V, 1.8A DC12V Dual Line Fuse Power switch AC 100-240~ (DPST) SMPS...
  • Page 25 24 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ Electrical wiring 3.3.1.3. Main Board 14 13...
  • Page 26 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 25 3.3.1.4. Description of wire harness connection of MAINBOARD Connect No. Description Target connector 1 (CCN1) REF CMOS CAMERA AR1030 CAMERA BOARD COLORCMOS CAMERA BOAR 2 (CN17) KER CMOS CAMERA 3 (CN18) LCD INTERFACE LCD ASSY...
  • Page 27 26 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ 15 (CN11) Y MOTOR Y MOTOR HARNESS 16 (CN1) SMPS INPUT SMPS OUT CONNECTOR 17 (CN15) CHART LED CHART LED BOARD 18 (CN14) REF LED REF LED HARNESS 19(CN7) LCD TOUCH LCD ASSY 20 (CN13)
  • Page 28 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 27 3.3.1.5. MIRERING BOARD 3.3.1.6. Description of wire harness connection of MIRERING BO Connect No. Description Target connector 1 (CN1) OPTIC LED INTERFACE MAIN BOARD CN13 2 (CN3) FOCUS LED ( L ) FOCUS LED ASSY...
  • Page 29 28 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ 3 (CN13) EXTERNAL LED ( L ) EXTERNAL LED BOARD 4 (CN5) COLOR LED ( L ) WHITE,BLUE LED HARNESS 5 (CN4) COLOR LED ( R ) WHITE,BLUE LED HARNESS 6 (CN12) EXTERNAL LED ( R )
  • Page 30 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 29 3.3.1.8. Description of Mainboard Part Ref No. Part name Description AM1808 TI ARM9 CPU XC6SLX25-2FGG484C Xillinx FPGA (Logic Array) THC63LVDF84 LVDS Receiver DS92LV1212A LVDS Deserializer ADC101S021CIMF MDIN241 VGA Coverter DRV8825 STEP Motor Driver U5,U25 K4T51163QQ...

  • Page 31: Mode Setting

    30 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ 3.4. Mode Setting Turn-on the system with pressing button as following content of table Start Key Description [S/W Upgrade Mode] Download OS program into ROM via serial port Joystick Button (Ex. COM) permanently. After downloading, always CR...

  • Page 32: Principles Of Measurement

    ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 31 3.5. Principles of Measurement Measurement principle of refractometry (1) Light beam from the ring source is incident on the examinee’s eye and refle cted from it’s retina as in the Figure below. (2) According to the refraction condition of the examinee’s eye, that is, if the ex aminee’s eye is emmetropia, hyperopia or myopia, the reflected light from th...
  • Page 33 32 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ Measurement principle of keratometry When the ring light source of the keratometry is projected on to the cornea, it i s reflected as a circle or an ellipse in the case of the eye with corneal astigmatis m, the size and the shape of reflected light are different according to the radius of curvature of the cornea because the cornea is not a sphere.
  • Page 34 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 33 n ＝ 1.3375, 1.336, 1.332 The principle of Retro-Illumination observation 3.5.1.1. Principle of retro-illumination observation The incident lights of the infrared LED (spot light) onto the fundus of the eye are retro-scattered from it. The scattered lights from the fundus illuminate the vitreou s humor and some of it go through the crystalline lens and the iris.
  • Page 35 34 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------...

  • Page 36: Repair Standard

    ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 35 4. Repair Standard 4.1. Checking and Control If your device shows suspicious measurement result repeatedly, you can suspect internal problem. In that case, checking internal status at Engineer Mode can be helpful. 4.1.1. Enter the Engineer Mode To enter the Engineer Mode, take following steps.
  • Page 37 REF signal has a ring shape. If there are apparent defects at the signal, you can suspect that the optic module has b een damaged or contaminated. In that case, you should report it to the FA Team of Shanghai Huvitz.
  • Page 38 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 37 4.1.3. Check REF calibration data If the signal quality is not bad, you can check calibration data in the second place. 1) Enter the “1-2. REF DATA SETUP” 2) Touch “> GRAPH” button. 3) Check the shape of data current.
  • Page 39 38 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ Regarding calibration data, ascending or descending current is important. If there are any points stand against the current, you should take a re-calibration REF calibration If some problems are found in calibration data, you should take a calibration again.
  • Page 40 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 39 Run calibration The number of calibration points are thirteen. (-30.0D ~ +25.0D) REF calibration should be taken for all of them. Save the result After calibration, you have to save it to FRAM.
  • Page 41 40 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------...
  • Page 42 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 41 4.1.4. Check KER signal If there are some problems in KER measurement, the first thing you can check is KER s ignal quality. Mire led quality can be checked with following steps. 1) Touch “> CAPT” button to capture current signal.
  • Page 43 42 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ 4) If the yellow marked area is too small, and there are relatively big white areas, you could increase Mire duty at SYSTEM settings to cover it.
  • Page 44 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 43 4.1.5. Check KER calibration data If KER signal has no apparent problem, you can check calibration data. Checking KER calibration data is available at “1-4. KER DATA SETUP”. Like REF calibration data, ascending or descending current is important.
  • Page 45 44 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ In that case you should take a calibration again.
  • Page 46 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 45 KER calibration If some problems are found in calibration data, you should take a calibration again. Or though the calibration data has no problem, if the physical condition of the device is changed from initial status, re-calibration can be a solution.
  • Page 47 46 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ [On-focus calibration] The first thing you have to do is on-focus calibration. On-focus calibration is for yellow points on KER data graph. 1) Set KER 0D model eye on the chin rest and enter the KER TEST MODE.
  • Page 48 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 47 3) Control working distance to match “HR”. 4) Touch SETUP button.
  • Page 49 48 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ 5) Touch 0D target. 6) Set real target diopter and touch START SETUP button.
  • Page 50 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 49 7) Calibration for target diopter would run automatically. 8) Repeat this process to other diopters.
  • Page 51 50 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ [De-focus calibration] De-focus calibration is for these points. 1) Set KER 0D model eye on the chin rest and enter the KER TEST MODE. 2) Touch FOCUS button.
  • Page 52 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 51 3) Select 0D target. 4) Run calibration for each points from -1.5 to 1.5. Repeat this to all other diopters.
  • Page 53 52 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ [Save] After calibration, you have to save it to FRAM.

  • Page 54: Auto Tracking Setup

    ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 53 4.2. Auto Tracking Setup If auto tracking power is too big or too weak, you can adjust coefficients to control the tr acking power. Menu for tracking coefficients control is “2-2. TRACKING SETUP” Bottom two items are for auto tracking.
  • Page 55 54 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ 1) Start with default value. 2) Test tracking performance. Move focus cross to outer mire ring edge. Leave the joystick out, and watch the tracking action. C. If the cross passed the center of mire ring then you can say that the test is fail...
  • Page 56 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 55 D. If the cross stopped at the center of mire ring without passing, then the test is success. 3) If Step 2. is failed, increase setting value and retry. 4) If Step 2. is succeed current values are the answer.

  • Page 57: Pupil Distance Calibration (Pd Setup)

    56 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ 4.3. Pupil distance calibration (PD Setup) PD Setup is available at 3-2. PD TEST & SETUP.
  • Page 58 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 57 Engineer mode of the PD Setup begins. PD Setup in the menu is as follows. 1) SAVE - Changed the temporary storage of PD are set. 2) CENT - The current value of the X-axis encoder center position.
  • Page 59 58 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ e screen. The machine optical head moved to about the middle position, record scale valu e.（e.g.The screen is displayed at 8cm.），click ”CENT” and “SETUP”. The focu s is adjusted on the screen and prees joystick button.

  • Page 60: Factory Data Setup

    ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 59 4.4. Factory Data Setup 1) MAKE SYSTEM BACKUP It is for our factory worker. Please do not touch it. 2) VERIFY BACKUP DATA Check if the valid system backup is stored. 3) RESTORE SYSTEM Restore all system data to factory backup.

  • Page 61: Color Test

    60 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ Copy backup data to another FRAM. 4.5. Color Test Verify the LCD Color temperature 1) Each number on the screen is color temperature. 2) Bigger number is warmer color.

  • Page 62: Touch Setup

    ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 61 4.6. Touch Setup 1) Start touch setup button in the engineer mode. 2) Press start button or touch LCD a few seconds. 3) Press the cross marker (9 section) until beep sound.
  • Page 63 62 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ 4) Touch APPLY button to apply the result of calibration.

  • Page 64: Dpc (Dead Pixel Correction) Setup

    ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 63 4.7. DPC (Dead Pixel Correction) Setup DPC Setup begins in engineer mode. DPC Setup in the menu is as follows. VIEW The selected Pixel color camera and the location of the Dead Pixel is displa yed as a rectangle on the screen.
  • Page 65 KER CCD’s Black Pixel in COLOR CCD's White Pixel COLOR CCD’s Black Pixel in After DPC Setup, engineer mode by pressing the SAVE SYS DATA is stored. CRK-1 restarts, and were being corrected by the camera from the screen Dead Pixel Check.

  • Page 66: Iqc Mode

    ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 65 4.8. IQC mode Test procedure Start IQC Mode in the engineer mode. Test the each mode. If Test is success or fails, select pass or fail on pass and fail button. Menu NO DISP All of the sections disappear on the screen.

  • Page 67: Software Upgrade

    Start DNW program, set your PC’s COM port number, 115200 Bps. Connect PC to CRK-1 with serial cable. Pressing the 5th key, then turn on CRK-1. DNW program will show the following screen. Select Serial Port => Transmit menu, then File Dialog box pops up.
  • Page 68 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 67 After downloading, turn off and on the HRK-9000A. Confirm the changed SW version on boot screen.

  • Page 69: Disassembly And Assembly Procedure

    68 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ 5. Disassembly and Assembly Procedure 5.1. Removing the Cover Remove the screws (10) of the Main body (1) and then separate the Head Rest A ssy (11). (2) Remove the BOLTCAP and screws (2, 4), and then separate Right/Left Side Cove...
  • Page 70 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 69 (1) Remove the screws(4) and then separate the moving-base-front-cover(5) (2) Remove the screws(4) and then separate the moving-base-rear-cover(6) (3) Remove the screws(2) and then separate the optical-head-assy(3) (4) Remove the screws(7) and then separate the moving-base-assy(8) from fixing...

  • Page 71: Disassembling The Moving Base Assy

    70 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ 5.2. Disassembling the Moving Base Assy (1) Removal Method Remove the screws(1)(2) and then remove the os-connect-brk(3)  Remove the screws(6) and then remove the joystick-assy(5)  Remove the set screws and then remove the gear(8) ...

  • Page 72: Disassembling The Front-Cover-Assy (Lcd-Assy)

    ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 71 5.3. Disassembling the Front-Cover-Assy (LCD-Assy) (1) Removal Method Remove the screws (8) and then remove the main-board (7).  Remove the the board PC film (6) and tape.  Remove the screws (5) and then remove the lcd-brk (4).
  • Page 73 72 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ (2) Point for Assembly Assembly is the reverse procedure of disassembly ...

  • Page 74: Disassembling The Optical Head Assy

    ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 73 5.4. Disassembling the OPTICAL HEAD ASSY ) Removal Method Remove the screws (1) and then separate the Y-AXIS-GUIDE-PLATE (2).  Remove the screws(3) and then remove the OPTIC-COVER(4)  Point Assembly Assembly is the reverse procedure of disassembly.

  • Page 75: Disassembling The Main Frame Assy

    74 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ 5.5. Disassembling the MAIN FRAME ASSY. Removal Method Remove the screws (19) and then separate the XZ-RAIL-ASSY (17).  Remove the set screws , knob (13) and then separate the FOOT (12).  Remove the screws(18) and then separate the base-plate (9) and bottom- ...
  • Page 76 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 75...

  • Page 77: Troubleshooting

    76 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ 6. Troubleshooting Phenomenon 1: When Power is ON, there is no action Check whether power cable is inserted well Check fuse in the bottom side Take off the head cover Check whether the cable from SMPS to...
  • Page 78 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 77 Take off the head cover Check whether the cable from Mainboard t o LCD is inserted well. Mainboard CN18  Make correct connection Connection is OK? External LCD is O Replace the Mainboard Replace the LCD...
  • Page 79 78 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ Phenomenon 3: Key or Joystick does not work Take off the cover 1. Check whether the cable from Mainboard to LCD is inserted well. 2. When pressing the button, check whethe r the voltage goes to ‘L’ level. Default is ‘H igh’...
  • Page 80 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 79 Phenomenon 5: When printing out, paper is not fed correctly Take off the head cover Unconnect the cable from mainboard to the thermal printer board Connect new printer module to mainboard, then execute printing, again...
  • Page 81 80 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ Phenomenon 6: Cannot see the eye fixation target Take off the head cover Take off the optic cover Check whether led is out Replace Mainboard Is LED out? Replace LED board...
  • Page 82 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 81 Phenomenon 7: The result of Refractometry of TEST MODEL EYE is very different from the original value when the focusing bright spot i s some that out-focused Enter into REF TEST MODE in engineer mode Enter into ‘CCD’...

  • Page 83: Technical Materials

    82 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ 7. Technical Materials (1) Fogging Method It is recommended that the refractive power of eye is measured when it is in the hypero pia-state. There happens some measurement error called mechanic myopia due to the ac commodation of eye when it is measured by locating the internal eye-fixing target to the position corresponding to the eyesight of examinee.
  • Page 84 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 83 : Refraction Power with the standard VD in diopter : Refraction Power with changed VD in diopter (example) ＝ +1 0 D, d ＝ +3 m m ＝ +9 . 71 D ＝ +1 0 D, d ＝...
  • Page 85 84 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ ajor and minor meridian is displayed as +CYL. MIX : “-“ sign will be attached in the case of the myopic astigmatism whereas, “+” sign in the case of the hyperoptic astigmatism. The above-mentioned option can be chose in ‘User Setup Mode’...
  • Page 86 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 85 (6) Eyeball Diagram representing refraction power It is possible to print the refraction state diagram regarding the result of the REF measur ement to the internal printer. This function will be performed when ‘PRINT=EYE: ON’ in t he Page 3/4 of the SETUP MODE.
  • Page 87 86 Auto Ref/Keratometer CRK-1 ------------------------------------------------------------------------------------------------ COMPOUND H ◎ ◎ YPEROPIC AS +0.5 < S+C TIGMATISM Eyeball Output by REF Measurement (a) EMMETROPIA/NORMAL (e) MIXED ASTIGMATISM (b) MYOPIA/NEAR SIGHTEDNESS (f) HYPEROPIA / FAR SIGHTEDNESS (c) SIMPLE MYOPIC ASTIGMATISM (g) SIMPLE HYPEROPIC ASTIGMATIS...
  • Page 88 ---------------------------------------------------------------------------------------------- Auto Ref/Keratometer CRK-1 87 MATISM Diagram of the eye ball output by REF Measurement...

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