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Model
DV-560H (serv.man6)
Pages
48
Size
432.55 KB
Type
PDF
Document
Service Manual
Brand
Device
DVD / DVD Technical Manual (Based on the DV560H)
File
dv-560h-sm6.pdf
Date

Sharp DV-560H (serv.man6) Service Manual ▷ View online

6
DVD-Series
2. DVD Features
2-1 DVD is not a Digital Video Disc
“DVD” is often considereed the abbreviation for Digital Video Disc, but as the unified standard
for the next generation of high density optical fiber discs, the term “DVD” is not used in that way.
It has been adopted as the name of the unified standard.
2-2 Amazing Mega-Capacity
Although the DVD’s size is the same as a 12cm CD, one DVD side can record huge capacity, about
4.7GB, equivalent to approximately 7 CDs. This disc can be recorded to 133 minutes for full a
movie film, with high quality picture and sound which like a movie theater.
Additionally, it is only the capacity for one side.  The 1 side 2 layer type can record 8.5GB, the 2
sides with 1 layer type can record 9.4 GB and an amazing maximum 17GB can be recorded on 2
side 2 layers type.
4.7
GB               
=
    
688
MB
 Comparison of DVD data capacity
DVD
(one side) 
CD
X 6.8 CDs
 7 times as more
than a CD    
DVD
(one side) 
CD
2.2 (side)
2.2 times as much a
s an LD   
133
MIN
                       
     
60
MIN
 Comparison of DVD recording times (approximate)
The memory capacity of a disc is determined by the time of information and amount of data per
second (data rate).  In the case of CDs, the number of quantization bits is 16, and the sampling
wavelength is 44.1kHz with 2 channels.  So, the amount of data is 16 
×
 44.1k 
×
 2 = approx.1,411k
bits/second = 1.411M bits/second.
The maximum length of a CD is 74 minutes.  If the same sound from a CD is recorded on the DVD,
it comes to 4.7GB.  That means, 37.6 (4.7 
×
 8), and it will come to 37.6 
×
 1,000 
÷
 1.411 = approx.
26,648 (seconds) for one side.
That is approximately 444 minutes (7 hours 24 minutes).
2-3 Secrets of Producing Large Capacity Recording and Long Hour Replay
1. Realization of large capacity recording
The track pitch is less than half of that of a CD, making it longer.
Also, the recorded amount of information is increased due to the smaller pit (less than half of
that of a CD)
Because the pit is smaller, the laser focus needs to be smaller.  To do this, the wavelength of the
laser beam is shortened and the opening of the object lens (NA) is increased.
This bigger NA increases the influence of the aberration of laser beam from the protection film
(the transparent plastic part).  This causes blurring of the laser focus against the disc inclination,
or its slippage when the pit becomes bigger, lowering the signal reading precision (increasing
noise).
To decrease the influence of this laser beam aberration from protection film (transparent plastic
part), we decreased the thickness of the disc.
(one-half that of a CD, 0.6mm)  Also ensure CD compatibility, we put 2 of the discs together.
By putting 2 of these 0.6mm thick discs together, the evenness of the disc is increased, warping
due to heat and humidity is decreased and the signal reading precision is improved.2.
7
DVD-Series
λ
2. Comparison of CDs and DVDs
Item
CD
DVD
DVD(CD)
Track Pitch
1.60
µ
m
0.74
µ
m
1.60
µ
m
Minimum Pit
0.87
µ
m
0.40
µ
m
0.87
µ
m
 Laser Beam Wavelength
780nm
 (Infrared Light)
650nm
(Red)
650nm
(Red)
Opening of the Object Lens
0.45
0.6
0.38
Laser Focus
1.8
µ
m
1.0
µ
m
1.7
µ
m
*CD mode of DVD
3. Decreasing the Laser Beam Focus Wavelength
The size of the laser beam focus 
Φ
 has small 
λ
, When NA increases, it becomes smaller.
 It is determined using the following formul:
NA (Opening of the object lens) = DVD : 0.6
CD(DVD) : 0.38
Φ
 =  
NA
λ 
(laser beam wavelength) = 650nm
DVD
 Φ
 = 
 
  
0.6
 
  
 = about 1
µ
m  
 
CD(DVD) 
Φ =
 
0.38
    = about 1.7
µ
m
NA shows the brightness of the lens.  When the focal distance of the lens becomes shorter and
the diameter increases, the NA becomes bigger.  It is determined using the following formul:
4. Longer Track, Smaller Pit
650nm
650nm
NA =  
f
 a
a
Disk
f
Laser Beam Focus
0.74  Track Width
Minimum Pit
0.4  
8
DVD-Series
5. Thinner Disc
Decreasing the thickness of a disc can cause less focus movement against similar disc inclination
and less focus disorder.
6. Realization of Long Hour Reproduction
Even by making the track longer and the pit smaller to expand capacity, it is not possible to
record one whole movie on one side (1 layer) of a 12cm DVD disc if using current image data
information.  To reproduce 133 minutes on a 1 layer on 1 side disc, it is necessary to digitally
compress the image data.
Most digital compression technology of data is done is the audio field.
It is already routinely used in personal computers and MD.
To make comparisons with the audio field, digital compression technology for images, which
contain far more information, were processed by the MPEG (Moving Picture Image Coding
Expert Group) committee of ISO, and became the world standard.
First, MPEG1 (a fixed bit rate system) was standardized and made practical for use in video CDs
(karaoke, etc.).
Then, MPEG2, DVD actualization, became standardized.  MPEG2 is called “Variable Bit Rate
System”.
It compresses information while changing the amount of data, depending on the amount of data
on the image.  That means, it compares the former and latter images, then records the amount
of change as data.
2-4 Realization of High Quality Images
1. High Quality Imaging and Resolving Rate through Full Digitalization
The image performance of DVD actualizes 500 horizontal lines of resolution, an increase from
traditional recording media.
Currently, it is superior to the “the media with the highest quality image”, an LD (430 horizontal
lines of resolution).  It matches master tapes made to professional specifications.
With its high quality imaging and high number of resolution lines, image outlines are sharp.
Even in dark scenes, there is less noise and clearer perspective.
Compared with to horizontal lines of resolition / recording system of DVD and traditional media
Object Lens
Laser Beam Focus
 Horizontal Lines of Resolution 
|
Recording System
s
500
DVD
Digital (MPEG2)
400 
240
S-VHS Video Tape
/VHS Video Tape
Analogue
430
LD
Analogue
240
VideoCD
Digital (MPEG1) 
  
9
DVD-Series
DVD responds to wide sized screens
From the beginning of its development, DVD was meant to be applicable for wide sizes.
When zoom reproduced (expanding the  mage in vertical and horizontal directions) on a
wide screen monitor, the picture quality isn’t weakened.  Instead, a beautiful and delicate
image is reproduced.
[Full Mode]
[Zoom Mode]
2-5 Super Digital Sound That Surpasses CDs
1. 144dB Dynamic Range can be recorded
To use its large capacity equivalent to 7 times the time available on a CD in an effective way,
the 96kHz/24bit high sampling/high bit can record a dynamic range of 144dB super hi-fi digital
audio.  It also reproduces sounds beyond the range of human hearing, restoring subtle nuance
to original sounds.
This DVD reproduced by wide TV.
It realize of high quality images.
This video reproduced by wide TV.
But, it worries about weakness of 
picture of quality.
*This picture is image illustration 
for identification effects.
146MB
(24bit)
96dB
(16bit)
DVD Range
    20kHz              40kHz
Natural Sound
An example of a dynamic range comparison on DVD and CD
Dynamic Range
Wavelength Band Range
2. Sound Equivalent to Movie Theaters
DVD adopts Dolby AC-3, 5.1ch.
In addition to the 4 channels on front, back, right and left, a center channel used mainly for
dialogue and a heavy lower sound are included, to make 5.1 channels.
With these, fully digital sound can be recorded and reproduced with this unit.2-6
2-6 Various Advanced Functions of DVD
These functions are able to be included on DVD discs, and the content is decided on the disc side.
Therefore, there are various contents available, depending on the DVD disc used.  Only included
functions can be reproduced by remote control operation.
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