ISO/IEC TR 13841:1995
(Main)Information technology — Guidance on measurement techniques for 90 mm optical disk cartridges
Information technology — Guidance on measurement techniques for 90 mm optical disk cartridges
Provides guidance on measurement techniques for 90 mm rewritable/read only optical disk cartridges. This technical report is to aid the understanding of interchangeability between disks and drives.
Technologies de l'information — Lignes directrices pour les techniques de mesurage des cartouches de disque optique de diamètre 90 mm
General Information
Standards Content (Sample)
TECHNICAL
ISO/IEC
REPORT TR 13841
First edition
1995-07-01
Information technology - Guidance on
measurement techniques for 90 mm
Optical disk cartridges
Technologies de I ’informa tion - Lignes directrices pour /es techniques
de mesurage des cartouches de disque optique de diametre 90 mm
Reference number
ISO/lEC 7-R 13841 :1995(E)
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ISO/IEC TR 13841:1995(E)
Contents
1. General
1.1 Scope
1.2 Purpose
1.3 Reference
1.4 Definitions
2 Measurement environments
2.1 General
2.2 Measurement environment A
2.3 Measurement environments B
2.4 Measurement environment C
3 Measurement set up
3.1 General
3.2 Measurement accuracy
3.3 Calibration disk
3.4 Measurement area
3.5 Reference Servo
4 Items for measurement techniques
3
4.1 General
3
4.2 List of measurement items
3
5 Measurement techniques
3
5.1 Shutter opening forte
3
5.1.1 Definition
4
5.1.2 Measurement procedure
4
5.2 Clamping forte
4
5.2.1 Introduction
4
5.2.2 Measurement procedure
4
5.3 Tilt
5.3.1 Introduction
5.3.2 Measurement method 1
5.3.3 Measurement method 2
5.4 Axial and Radial acceleration
5.4.1 Introduction
5.4.2 Measurement System
5.4.3 Procedure 1: Low-pass measurement System
High-pass Measurement System
5.4.4 Procedure 2:
Total measurement System
5.4.5 Procedure 3:
5.5 Reflectance
o ISO/IEC 1995
All rights reserved. Unless otherwise specified, no part of this publication may be
reproduced or utilized in any form or ‘by any means, electronie or mechanical, including
photocopying and microfilm, without Permission in writing from the publisher.
ISO/IEC Copyright Office l Case postale 56 l CII- 1211 Geneve 20 l Switzerland
Printed in Switzerland
ii
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ISO/IEC TR 13841:1995(E)
0 ISO
15
5.6 Capture cylinder
15
5.7 Signals from grooves
15
5.7.1 Measurement equipment
15
5.7.2 Measurement conditions
15
5.7.3 Measuring procedure
16
5.8 Signals from headers
16
5.8.1 General
16
5.8.2 Amplitude measurement
21
5.9 Read power
21
5.9.1 Definition
21
5.9.2 Measurement conditions
211
5.9.3 Measuring procedure
21
5.9.4 Analysis
22
5.10 Write power and erase power
22
5.10.1 Definition
22
5.10.2 Measurement conditions
22
5.10.3 Measuring procedure
22
5.10.4 Analysis
25
5.11 Imbalance of the magneto-Optical Signal
25
5.11.1 Measurement condition
25
5.11.2 Measuring procedure
25
5.12 Narrow-Band Signal-to-Noise Ratio (NBSNR)
25
5.12.1 Definition
25
5.12.2 Measurement conditions
25
5.12.3 Measuring procedure
Annexes
27
A - The flow Chart for determining write power and erase power
29
B - Averaging Times and Spectrum Analyzer Data
31
C - Measurement Frequency Point for Noise Level
36
D - Notes on Measuring Noise Level
38
E - Example of measurement procedure of Signals from grooves
41
F - The Measuring Method of The Capture Cylinder Radius for the Hub
50
G - Better noise measurement with the HP3585A & HP3589A
70
H - An example of measurement equipment and data for shutter opening forte
. . .
111
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ISO/IEC TR 13841:1995(E) o ISO/IEC
Foreword
ISO (the International Organization for Standardization) and IEC (the Inter-
national Electrotechnical Commission) form the specialized System for worldwide
standardization. National bodies that are members of ISO or IEC participate in the
development of International Standards through technical committees established
by the respective organization to deal with particular fields of technical activity.
ISO and IEC technical committees collaborate in fields of mutual interest. Other
international organizations, governmental and non-governmental, in liaison with
ISO and IEC, also take part in the work.
In the field of information technology, ISO and IEC have established a joint
technical committee, ISO/IEC JTC 1.
The main task of technical committees is to prepare International Standards, but in
exceptional circumstances a technical committee may propose the publication of a
Technical Report of one of the following types:
type 1, when the required support cannot be obtained for the publication of an
International Standard, despite repeated efforts;
- type 2, when the subject is still under technical development or where for any
other reason there is the future but not immediate possibility of an agreement on
an International Standard;
- type 3, when a technical committee has collected data of a different kind from that
which is normally published as an International Standard ( “state of the art ”, for
example).
Technical Reports of types 1 and 2 are subject to review within three years of
publication, to decide whether they tan be transformed into International Standards.
Technical Reports of type 3 do not necessarily have to be reviewed until the data they
provide are considered to be no longer valid or useful.
ISOIIEC TR 1384 1, which is a Technical Report of type 3, was prepared by Joint
Technical Committee ISO/IEC JTC 1, Infornzation technology.
1v
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TECHNICAL REPORT o ISO/IEC
ISO/IEC TR 13841:1995(E)
Information technology - Guidance on measurement techniques for 90 mm Optical disk cartridges
1 General
11 0 Scope
This technical report provides Guidance on Measurement Techniques for 90 mm Rewritable/Read-only Optical Disk
Cartridges.
12 Purpose
0
This technical report provides guidance on measurement techniques which are not well understood in industry. The basic
concept of this report is to aid in the understanding of interchangeability between disks and drives. This report gives
guidance and provides some examples of measurement techniques to aid this understanding.
13 l Reference
ISOIIEC 10090: 1992, Information technology - 90 mm Optical disk cartridges, rewritable and read only, for data interchunge.
14 0 Definitions
The definitions of this report are the same as the definitions of ISO/IEC 10090.
2 Measurement environments
21 0 General
This report recommends 3 kinds of measurement environments. Esch clause in section 5 may use 1 of 3 measurement
environments as specified in this section. Basically, Measurement environment A is used for each clause in section 5 unless
noted. Additional environments or conditions are recommended in each clause.
Measurement environment A
22 0
Measurement environment A is the same as the testing environment of ISO/IEC 10090 i.e.
temperature : 23 “Ck2 “C
relative humidity : 45% to 55%
atmospheric pressure : 60kPato 106kPa
air cleanliness : Class 100 000
magnetic field strength : 32 000 A/m max.
23 . Measurement environments B
Measurement environments B are used for the highest temperature marginal test
temperature : 50 “C+2 “C
relative humidity : Not significant on this environment
atmospheric pressure : Not significant on this environment
air cleanliness : Class 100 000
magnetic field strength : 32 000 A/m max. (unless noted)
24 0 Measurement environments C
Measurement environments C are used for temperature marginal tests. The range of these environments arc the same as tbe
operating environment of ISOAEC 10090.
temperature : 5 ”C+2 OC, 23 ”C+2 “C,50°C+2 “C
relative humidity : Not significant in this environment
atmospheric pressure : Not significant in this environment
air cleanliness : Class 100 000
magnetic field strength : 32 000 A/m max. (unless noted)
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ISO/IEC TR 13841 : 1995 (E) OISO/IEC
3 Measurement set up
31 0
General
An Optical drive which is used for measuring disks should be calibrated before measuring disks. A typical calibration disk
which is suitable for laser power calibration is mentioned in 3.3.
32 0 Measurement accuracy
The measuring equipment should have high reproducibility and repeatability and the recommended Performance tolerante
ratio (P/T) ;
P/T = 6*SD/Tolerance < 0,2
where SD is the Standard deviation and Tolerante is the upper limit minus the lower limit of the specification.
For example:
In the case of reflectance
PA’ = 6* SD/(0,29-0,14) < 0,2 i.e. SD < 0,005
In the case of Single ended specifications, the System should be capable of resolving the number of significant digits in the
Parameter specification.
33 b Calibration disk
The laser power of the Optical drive a.nd/or the measurement equipment on the recording layer tan be calibrated from the
calibration disk which is provided by the Reliability Center for Electronie Components of Japan (RCJ)
Note - This calibration disk cartridge has been established by RCJ, l-1-2 Hachiman Higashikurume Tokyo, Japan, and tan be ordered under Part number
JCM6272 until2002.
Measurement area
34 l
ISO/IEC 10090 requires disks to satisfy specifications in all the areas of the disk unless noted. (See annex R in ISO/IEC
10090). This report Shows the most critical measurement areas in each clause, as follows:
(A) Innermost diameter is critical (R=24mm) for Read power, NBSNR, Signal from headers (Ivfo , Idmax /Idmin), Push-pull
Signal and Cross-track Signal in ROM area
(B) Correspond to control track data ( R=24mm, 30mm, 40mm) Write power, Erase power
(C) Outermost diameter is critical (R=40mm) for Tilt, Axial and radial accelerations,
(D) Outermost and innermost diameters are critical (R=24mm, 40mm) for Reflectance, Imbalance of the MO Signal
(E) Inner and outer test zones and control zones. Signal from grooves and headers
35 . Reference Servo
ISO/IEC 10090 specifies a disk rotational frequency of 30Hz for testing conditions and specifies the transfer functions of the
Reference Servo for axial and radial tracking of the recording layer. (See 9.5 and 11.4 of ISO/IEC 10090.)
During the measurement of the Signals, the radial tracking error between the focus of the optical beam and the Center of a
track is made smaller than during the measurement of the radial acceleration. This is achieved by a strong servo as provided
in 20.2.4. Therefore the 0,l Pm value of the radial tracking error is increased below the acceleration Cross-over frequency
and is not changed in the fiequency range higher than the acceleration Cross-over frequency. There arc various strong servos
using various Phase compensators. If one uses the same type of compensator (C=3) as the reference servo, the 0 Cross
frequency of this strong servo on the rotational Speed of 30 Hz is 1 500 Hz. And this strong servo has an acceleration cross-
over fiequency of 870 Hz.
For other rotational frequencies, see table 1.
2
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0 1s0/II3c ISO/IEC TR 13841: 1995 (E)
Table 1. Constants table for the measurement servos
0 Cross freq. for
Rot. Acceleration at low Example servo for Signals. Cross over
reference servo (Hz)
freq. freq. (Hz)
frequency (m/s2)
0 Cross freq. (Hz)
Acceleration (m/s2)
Axial Radial Axial Radial Axial Radial Axial radial Radial
1500 10,o 370 870
30 Hz 870 1230 10,o 390 870
593 1160 2000 18,0 593 1160
40 Hz 1160 1640 18,0
28,0 82 1450 2500 28,O 83 1450
50 Hz 1450 2050
2460 40,o 12,0 1740 3000 40,o 12,0 1740
60 Hz 1740
b
Note: The bold vaiues are the values calculated for the reference servo.
Items for measurement techniques
4
41 l General
The following list Shows the Status of each item. The list classifies these items into 2 groups :
1) guidance on definition and measurement techniques,
2) guidance on measurement techniques.
42 . List of measurement items
Clause number Title status Clause
in ISOLIEC 10090 number
10.45 Shutter opening forte 5.1
(1)
12.2 Clamping forte 5.2
(2)
11.4.9 Tilt 5.3
(1)
11.4.8 Radial and axial acceleration 5.4
(2)
11.54 Reflectance 5.5
(2)
12.3 Capture cylinder 5.6
(2)
21 Signals from grooves 5.7
(2)
22 Signals fiom headers 5.8
(2)
24.2.2 Read power 5.9
(1)
24.3.2124.4.1 Write power and Erase power 5.10
(1)
25.2 Imbalance of the MO 5.11
(2)
26.2 Narrow-band signal-to-noise ratio 5.12
(2)
5 Measurement techniques
51 l Shutter opening forte
5.1.1 Definition
The shutter opening forte is defined as the maximum forte including shutter weight and fiction between the cartridge and shutter
when opening and/or closing the shutter. It is measured as the forte in pushing or pulling the shutter parallel to the shutter movement.
But the fkiction forte caused by the shutter-opener in the drive mechanism is not included in the definition.
3
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ISO/IEC TR 13841 : 1995 (E) OISO/IEC
5.1.2 Measurement procedure
The measurement is done by using a tension gauge as shown in figure 1. This measurement method does not include shutter
weight. Therefore, the shutter weight must be added to the result of the measurement. Another method and measurement data
arc shown in annex H.
Cartridge
Tension gauge
Type; Teclock DT-1OOG
Figure 1 - An example of measurement setup
. Clamping forte
52
5.2.1 Introduction
The maximum allowable forte is within a range from clamping a disk without deterioration mechanical characteristics of the
disk to unloading the disk by a forte of the loading motor or mechanism. The clamping forte is checked by the disk with an
upper or lower limit of hub which meets the requirement of annex K in ISO/IEC 10090. This item is determined by the drive
design.
5.2.2 Measurement procedure
1. Prepare the magnetizable material for a hub which is able to provide the adsorbent forte of 4,5 N on the tester in annex K
in ISO/IEC 10090.
2. Adhere the material on the non-magnetizable hub with height accuracy of 1,20+0,01 mm including parallelism of the
Substrate and the material.
3. Clamp the disk on the tumtable of the test drive.
4. Measure tbe clarnping forte by pulling off the disk.
53 l Tilt
5.3.1 Introduction
Tilt is defined as the angle between the reference plane of a disk and the entrance surface in the text of the ISO/IEC 10090.
The accuracy of the Substrate thickness is also considered when the reflectance light is utilized from the recording layer in
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0 ISO/IEC
ISO/IEC TR 13841: 1995 (E)
the real measurement. There exist several methods and this report Shows following two methods of the measurement. The
first method is of the similar method defined in the sentence of the ISOAEC 10090, that is, to measure the tilt with a parallel
light beam directly. The second one is to measure the tilt with a special head utilized over the measurement of the
mechanical characteristics.
5.3.2 Measurement methd 1
This has been used for long time and the principle of the measurement is depicted in figure 3. When a small He-Ne laser, for
example, is used as a light Source, the spot size of the measurement is approximately 1 mm. Therefore, this method is mostly
close to the sentence defined in ISO/IEC 10090. However, following conditions should be considered in this measurement.
(A)The spot size should be kept in the range of 1 mm when the outermost area is measured.
(B)The error increase depends on the Substrate thickness, when the tilt increases.
5.3.3 Measurement method 2
This is a method to measure tilt by the axial deflection values. In Order to measure the axial deflection, the Position of the
objective lens is detected either with a head, which is specially designed within a micro-Sensor or by an electric current to the
lens actuator. These methods are more convenient for measurement method 1 because the other mechanical characteristics
are also measured simultaneously. The method to determine a tilt by the axial deflection is explained in figure 2. Assuming a
small Square within a few mm2 as a flat plane, the tilt along the radius (er) or along tangential (@) direction is calculated by
the axial direction differente of separated two Points (A 1, B 1 or A2, Al) and the distance (lr or 19) respectively.
Tangential tilt angle $e= tan - l(AdWle)
= tan - l((DAl-DA2)/ 1)
Radial tilt angle er= t-an - 1 (Adr /lr)
= tan - l((DAl-DBl)/ 1,)
Therefore, compounded solid angle (tilt angle) is,
Tilt angle l+l= SQRT (+e2++ 2,
r
However, this equation must be used carefully for the following reasons.
(A)Tilt is determined by the axial deflection differente as function of the distance. That is, the shorter the distance of the
separated Points (le,lr) is, the more estimated error increases. Oppositely, in the case of the longer distance, the surface
roughness disturbs the measurement. Therefore, the measurement conditions must be well considered.
(B)The axial deflection value of 5 Pm should correspond to 5 mrad of the specification when tilt is measured every 1 mm
pitch. Therefore, the measurement accuracy must be also considered.
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ISO/IEC TR 13841: 1995 (E)
Harf \ - Position
I
mirror \ L Sensor
jlaser] /
Figure 2 - Direct measuring of tilt (Measurement method 1)
Or Al
\l/ Bl
AdRj]
@ A+-
Axial
deflection DB1
DA1 DA1
DA2
IPI
Beference plane
+Qr-+
+Q B-+
of the disk
Figure 3 - Measurement tilt calculated by axial deflection (Measurement method 2)
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0 ISOmw ISO/IEC TR 13841: 1995 (E)
54 l Axial and Radial acceleration
5.4.1 Introduction
The ISO/IEC 10090 assumes that a light spot traces tracks on a disk by the use of axial and radial servos. Although this
tracing must be accurate to the extent that playback is adequately performed, movement in the axial and radial directions tan
act as an obstacle to this requirement. At low frequencies, in which the servo responds, the Object lens traces disk movement
and the servo-loop gain decreases the distance between the track and the light spot by a Füraction, which means that the
fractual distance Shows up in tracing performante. On the other hand, at high frequencies in which the servo does not
respond, disk movement itself corresponds to tracking performante. As for typical servo characteristics in an Optical disk
drive, in the range up to the lead break frequency of the Phase compensation filter inside the servo loop, doubling the
frequency results in 25% of the loop gain. In the same way, when the disk exhibits sinusoidal motion under the condition
that the maximum acceleration is constant, the relationship between the frequency and amplitude is such that doubling the
frequency results in 25% increase in amplitude. Thus, because servo gain and disk acceleration are given, tracing
characteristics tan be estimated at low frequencies (see figures 4 and 5). Accordingly, if we limit ourselves to disk
acceleration for low fiequencies and disk displacement for high frequencies, track tracing performante of the light spot tan
be determined to a certain extent. However, the following Problems arise if we attempt to make them precise rules. First, the
necessity of measuring the two physical quantities of acceleration and displacement independent of the fiequency tan be
complicated, and second, excess movement of the Object lens near the Zero-Cross frequency cannot be accurately ascertained
by acceleration and displacement. For example, figure 4 Shows that the loop gain at 600 Hz allows the acceleration of
17,5 m/s2 and that the loop gain at 1000 Hz allows the disk displacement of only 0,8 Pm. Taking the above into
consideration, ISO/IEC 10090 prescribes a servo deviation specification using a reference servo having fixed characteristics.
This is Chosen because servo deviation appears directly in tracing performante, and consequently the same physical quantity
tan be evaluated throughout the entire frequency range.
5.4.2 Measurement System
A measurement System for performing measurements is shown in figure 6 (this figure combines figures C.2 and C.4 of
annex C in ISOLIEC 10090). In figure C.2. the output of a non-contact electrostatic capacity Sensor is added to the actual
servo ’s error Signal and the resultant is input into a filter having the transfer characteristics of the reference servo. For typical
non-contact Sensors, however, it is not so simple to carry out accurate measurements from low frequencies up to high
frequencies. It is generally felt that Operation at less than 1 kHz is desirable. As a result, the Object lens moves in excess of
the disk displacement near the servo ’s Zero-Cross frequency, and even if this appears in the error Signal, it carmot be
compensated by the non-contact sensor ’s output, and measurement accuracy falls. In figure C.4, the actual servo ’s transfer
function is identified and the servo ’s error Signal is input into a filter whose characteristics represent the multiplication of the
inverse of the actual servo ’s transfer function with the reference servo ’s transfer function. Here, however, it is generally not
easy to measure accurately the servo System transfer characteristics from high frequencies down to low frequencies. In
particular, for a leaf-spring type of actuator, resonance frequency due to the spring and the mass of the movable parts of the
actuator is several tens of Hz, and characteristics are difficult to identify accurately. Moreover, even for a slide-able type of
actuator, the large influence of stick and Slip at low frequencies makes it difficult to identify characteristics well. For this
reason, using figure C.2 for low frequencies and figure C.4 for high frequencies, a Systems proposed in which the output
from both of the above tan be accurately measured in both the low frequency interval and the high frequency interval
independent of frequency. Here, we use weil-placed crossover filters having inverse characteristics. These are 1st Order
filters having tut-off frequencies of 600 Hz. In addition, since Object-lens displacement is measured directly in the low
frequency interval, the low fiequency component of disk displacement stored in memory should be used for feed forward
control in the actual servo System. Gl is a sensor-system element transfer function having a band of 100 kHz. G2 and G3 are
a servo-loop Phase-compensation element and actuator transfer function, respectively, whose characteristics are dependent
on the type of equipment used.
5.4.3 Procedure 1: Low-pass measurement System
la Calibrate non-contact Sensor gain
Ib Measure error Signal gain
Method A (Axial Gain)
* Stop disk.
* Turn axial and radial servos OFF.
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ISO/IEC TR 13841: 1995 (E) OISO/IEC
Coarsely move the disk using a mechanical slow-motion facility and place the disk around the Center of the axial error
Signal ea .
Slowly move the disk using a piezo element and search for the Center of the axial error Signal ea
When the differente between the axial S-Signals for land and groove becomes large, place radial serve ON.
Using a piezo element, move the disk $r 1 micron fiom the Center of the error Signal and measure the gain at this Point.
Method B (Axial Gain)
* Stop disk.
* Tun axial and radial servos ON. While applying an offset voltage to Z, detect the Object lens motion with an electrostatic
capacity non-contact Sensor and measure the gain at 1 micron.
Method C (Radial Gain)
* Stop disk.
* Turn axial servo on.
* Apply a chopping wave to the radial actuator to move.
* For the radial error Signal ea obtain a wave form in which the deviation between adjacent periods is within 3%, and
treating one period as 1,6 micron, measure the gain at =r 0,l micron from land centre. Note that by observing the cross-
track Signal at this time, land and groove tan be distinguished.
Method D (Radial Gain)
*
Stop disk.
*
Turn axial and radial servos on. Whole applying an offset voltage to Zero, detect the Object lens motion with an
electrostatic capacity non-contact Sensor and measure the gain at 1 micron.
lc Adjust the variable gain AMP so as to match the error Signal gain with that of the non-contact Sensor. If method B tan be
used for gain measurement, it is recommended to input a 1OOHz sine wave into z and adjust the variable gain so that
Signal S, becomes 0.
ld Implementing a reference-servo Simulation filter. In Order for the l/( l+Hs) filter to accurately simulate low-pass
characteristics, and analog filter is preferred despite the fact that a digital Elter is relatively easy to construct. Figures 7
and 8 show examples of analog filters for axial use and radial use, respectively. Figures 9 and 10 are the Simulation
results of each filter.
le Implementing a low-pass filter A 1st Order filter which acts as crossover band-limiting filter having a tut-off frequency of
600 Hz is desirable. The tut-off frequency and gain here must be uniform with the high-pass filter of the high-pass
measurement System within an accuracy of 3%.
Caution: When performing measurements while the disk is not revolving, deformation of the illuminated part of theplastic
disk Substrate tan be prevented by lowering laser power.
5.4.4 Procedure 2: High-pass Measurement System
2a Sensor-System gain
Adjust the variable-gain AMP as in the low-pass measurement System.
2b Transfer function derivation
*
Apply an excitation Signal from z and measure the transfer characteristics from z to ea :
ea /z = l/(l+Gl*G2*G3) = l/(l+H&
Measurements should be performed in a fiequency domain above 200 Hz since the 600 Hz tut-off high-pass filter is
employed here for the high-pass measurements.
*
Determine the transfer function Erom the transfer characteristics using the curve-fitting function of an FFT analyzer.
Caution: Considering the wide measurement frequency range, measurement accuracy tan be improved by varying the
excitation Signal amplitude in a step-like fashion for each frequency. During measurement, it is necessary to
tonfirm that each section within the servo loop is not being saturated.
2c Implement the (l+Ha)/( l+H,) correction filter.
8
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ISO/IEC TR 13841: 1995 (E)
0 ISO/IEC
2d Implement the high-pass filter
A 1st Order filter which acts as a Cross over band-limiting filter having a tut-off frequency of 600 Hz is desirable. The
tut-off frequency and gain must be uniform with the low-pass filter of the low-pass measurement System within an
accuracy of 3%.
5.4.5 Procedure 3: Total measurement System
3a Add the output Signal of the low-pass measurement System to the output Signal of the high-pass measurement System at
the same gain. Under these conditions, rotate the test disk, apply the axial and radial servos and observe the es output
Signal.
400
300
200
Max acce 1 l : 18 m/s/s
10 ’0
8
5
1
Acceleration peak value, : 11, 3 m/s’
r -
4 El
idual servo error 1 um
30
20
n
E
10
3
u
:e
:a,
l ‘.
E
W -.
5
-
Cl r
- -
4 * ‘@.
1
l l *
l l *
Servo loop gain
3’ 5
l-
l 6
l 5
.
H
l
l *.
. .
/J
-l 2
0
a *
x
* _ y>b\- - - - _
a
m------w-v
1
l
/
0
*
l
Acceleration
0 5 l
0
0
0 4
0
4
e
3
l
.
.
0
0
0 2
l
b
0
l 1
Cs) 6l 6m
.
FREQ. Cl-kl
Figure 4 - Ratio between acceleration and servo loop gain
9
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OISO/IEC
ISO/IEC TR 13841 : 1995 (E)
Case A : A disk with only low frequency components of the axial deflection.
axial deflect Ions (pm )
DEFLECT. 8
Cum1
.
RCCEL. 0
CrnAUsJ
-20
axial tracking error (pm)
1
RESIDURL. 0
cum3
-1
150 me 218
mdCLE
A dlsk wlth low and high frequency components of the axial deflectlon.
Case B :
axial defleetions (pm)
DWLECT. 0
CUd
-10
28
(m/s*)
axial acceletation
RCCEL. e
Cmh0s J
180 210
150
RNGLE
Figure 5 - Simulation of mechanicd characteristics of the disk
10
---------------------- Page: 14 ----------------------
Lens Movement
f
,
Sensor
t 1
Sm
-----
1 +Hs
1 L
1 4
1 I
t- -
I
t
Low Pass Filter
I
1
600Hz
I
I
I
I
73
I
I
I
I
x
Compensator - Error Sensor
f 1 r 1
l+Ha
ea
Se
L
1 +Hs
1 1
/ Variable
Hi Pass Filter
Gain Amp.
6OOHz
---------------------- Page: 15 ----------------------
OISO/IEC
ISOAEC TR 13841 : 1995 (E)
s
i% 3
3
5
.-
-6
--
7Y
2
z
L
0
u
Cc
-
b
5
d
- d
-
.-
.-
Cc
-
n
n
2
;
+
-t
7
T
T
z
z
cv
a
a
a
E
E
0
0
l2
w
r\
KJ
cj,
ti
.-
.-
G
G
Figures 7,8 - Examples of l/(l+Hs) filters for axial and radial use
---------------------- Page: 16 ----------------------
0 ISOAEC
ISO/IEC TR 13841: 1995 (E)
Ftequency charaateristics of l/(l+Hs) fitter (Radial)
I
-120
20
! IIIII *
! 1 l 1,
1 ! I I--r -
1
1111 ’1 I 1 I
10
-180
0
1 11. l
-10
-240%
-20
L
F
g
I I IIIlIII I IiIlt+tl
i IIIl+J.+l/I u
I 1 I 1/
- 30
c-
.L
-360
-60
-70 /
1
i i
*
1 1 l! 1 1 1
11 l I 11 , I 1 1 I.1
1 -420
-80
0.01
0 . 1
1 10
100
f requency (kHz)
Frequency character istics of l/(l+Hs) filter (Axial)
20
10
-180
0
, -
1 1 I,,,- IN 1 1 I ' l/yri , . .II 4 I I .n,, . l 1 1 -
-10
I I I !,, I il
-20 -240
2
1 ! ! i-. 1
iii
7
%a 1. I 1 IIIW I
Q)
- 30
E-
.-
6
u3
0300 z
-50
-60 -360
-70
-80 -420
1
frequency (kHz)
Figures 9,10 - Frequency characteristics of l/(l+Hs) filters
13
---------------------- Page: 17 ----------------------
ISOAEC TR 13841 : 1995 (E)
55 l Reflectance
Note: The value of baseline reflectance should exclude the reflectance of disk surface. When the baseline reflectance is measured by Optical pick up i.e.
with concentrated beam, the disk surface reflectance is small when the length of light pass of the Optical pick up is very large.
See figure 11.
3. 2
g 2.4
0
c
3
8
G
2 1.6
0. 8
10 20 30 50 60 i0
40
Distance between Objective lens and Photo detector [mm]
Figure 11 - Reflectance from the disk surface
14
---------------------- Page: 18 ----------------------
ISO/IEC TR 13841: 1995 (E)
56 0 Capture cylinder
Note: Captur
...
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