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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to an apparatus for recording a
master disc such as a LBR (Laser Beam Recorder), which is used for forming
optical discs for sale as replica discs by copying the master disc in a
factory. The present invention also relates to a device for changing the
transfer rate of the data to be recorded on the master disc, which is used
in such a master disc recording apparatus.
2. Description of the Related Art
A factory for manufacturing such optical discs is required to adapt various
types of optical discs such as CD, CD-ROM, LD, DVD, HVD and so on. In the
factory, a master disc is recorded or formed before it is copied to form
optical discs. The master disc has the physical shape same as the copied
optical disc and is recorded with the same information as the copied
optical disc. Accordingly, the master disc is recorded or formed for each
type of the optical disc as the object for copying.
As one type of optical disc, the CD (Compact Disc) is recorded mainly with
audio data. As another type, the CD-ROM (CD-Read Only Memory) is recorded
with a large volume of data for computers. As another type, the LD (Laser
Disc) is recorded with video data as well as the audio data. As another
type, the DVD (Digital Versatile Disc) is recorded with various control
data in addition to the video and audio data to allow various presentation
of the video and audio data. As another type, the HVD (High Vision disc)
is recorded with high vision data.
In those various types of optical discs, the standard record density is
different from type to type. Thus, the density of the record track in the
radial direction of the disc (i.e. track density) is also different from
type to type. For example, the DVD, which is based on the video data
compressing and encoding technique, has the same radius of recordable area
as the CD, but has the recordable time of 135 minutes, which is about
twice that of the CD (which has the recordable time of 74 minutes). Thus,
in the case of recording the master disc for the DVD, it takes about
double the recording time for the master disc recording apparatus to move
the optical pickup and record the information over the same radius, in
comparison with the master disc for the CD. That is to say, the record
time required for the optical pickup of the master disc recording
apparatus to move each radial distance on the DVD as the master disc is
about half of that of the CD as the master disc.
Therefore, in factories of manufacturing optical discs, each time the type
of optical disc to be manufactured is changed, the moving distance per
each unit time in the radial direction of the optical pickup of the master
disc recording apparatus is also changed or re-adjusted in accordance with
the new type. Further, in order to omit the re-adjustment of the moving
distance per each unit time, each factory is provided with a plurality of
master disc recording apparatuses which have moving distance per each unit
time in the radial direction of the optical pickups that are different
from each other to deal with the various types of the optical discs.
In this manner, the linear speed for recording (which is proportional to
the rotation number of the master disc) and the moving distance per each
unit time in the radial direction of the optical pickup in the master disc
recording apparatus are different from disc type to disc type. Thus, it
becomes necessary to re-adjust the moving distance per each unit time in
the radial direction of the optical pickup when the type of master disc is
changed.
However, since the master disc is used as the origin for manufacturing a
large number of optical discs for sale, the recording and forming
operation of the master disc requires high accuracy. In order to obtain
and keep such high accuracy, the adjustment of the moving distance per
each unit time in the radial direction of the optical pickup is a rather
difficult and time consuming operation.
Consequently, each time the type of optical disc is changed, the difficult
and time consuming adjustment of the master disc recording apparatus is
performed in accordance with the new type of optical disc to be
manufactured. Especially, when the moving distance per each unit time
speed in the radial direction is to be changed in large degrees, the
re-adjustment may not be possible.
Further, since high accuracy is required of the master disc recording
apparatus as explained above, each master disc recording apparatus is
rather expensive. Accordingly, if the number of master disc recording
apparatuses in one factory is increased as the number of types of optical
discs is increased so as not to perform such a re-adjustment, it is not
economically sound or quick in adapting the new type of optical disc.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a master disc
recording apparatus, which does not require re-adjustment even if the type
of master disc to be recorded is changed, and a transfer rate changing
apparatus suitable for the same.
The above object of the present invention can be achieved by a transfer
rate changing apparatus, to which a data block of digital data, which are
divided into a plurality of data blocks, is inputted from a data
transferring device by a first transfer rate each time when a transfer
instruction signal is supplied to the data transferring device. The
transfer rate changing apparatus is provided with: a memory device for
storing the data block by the first transfer rate, which is transferred
from the data transferring device, and outputting the stored data block by
a second transfer rate, which is different from the first transfer rate;
and a controlling device for supplying the transfer instruction signal,
which instructs the data transferring device to transfer one data block to
the memory device, to the data transferring device when the memory device
finishes outputting another data block which has been transferred from the
data transferring device prior to the one data block.
According to the transfer rate changing apparatus of the present invention,
the digital data (e.g. video data compressed and encoded by MPEG) are
divided into data blocks, each of which may have digital data of
predetermined data volume (e.g. 2.5M bytes). When the memory device
finishes outputting another data block which has been transferred from the
data transferring device prior to one data block, the transfer instruction
signal is supplied to the data transferring device from the controlling
device, so that one data block is transferred from the data transferring
device to the memory device according to the transfer instruction signal.
In those successive operations, the data block is transferred from the
data transferring device (e.g. a WORM type optical disc reader) and is
stored into the memory device (e.g. a RAW having a large memory capacity)
at a first transfer rate (e.g. 20M BPS) while the stored data block is
outputted from the memory device at a second transfer rate (e.g. 5M BPS).
Accordingly, the digital data are transferred in the form of data blocks
which are intermittently or continuously transferred from the data
transferring device, and are outputted in the form of data blocks which
are continuously outputted from the memory device. Namely, the change of
the transfer rate is performed by the transfer rate changing apparatus of
the present invention.
In the above described present invention, if the first transfer rate is
higher than the second transfer rate, the data transferring device
intermittently transfers the data block so to perform the change of the
transfer rate. However, even if the first transfer rate is lower than the
second transfer rate, the change of transfer rate is still possible.
Namely, in the latter case, the controlling device supplies the transfer
instruction signal such that the data transferring device transfers the
data block continuously (i.e. without any time interval between two
successive data blocks). Then, after the data blocks are accumulated in
the memory device, the memory device outputs the stored data blocks
continuously by the second transfer rate.
In the above described construction of the present invention, a data
transferring device may be the WORM type optical disc reader, but may be
any kind of data transferring device as long as it can be controlled by
the controlling device to perform the above described operation.
Further, a memory device may be the RAM having a large memory capacity, but
may be any kind of memory device as long as it can store a large volume of
digital data by a relatively high transfer rate such as a hard disc
device. The present invention still functions well as long as the digital
data can be controlled in the form of a plurality of data blocks by the
controlling device even if the memory capacity of the memory device is
rather small.
In one aspect of the transfer rate changing apparatus of the present
invention, the memory device comprises a plurality of memories (e.g. a
group of RAMs) each for storing the transferred data block by the first
transfer rate and outputting the stored data block by the second transfer
rate, and that the controlling device selects one of the memories on the
basis of a data volume of the data block and the first transfer rate, as a
memory to store the transferred data block by the first transfer rate, and
further selects another of the memories on the basis of the data volume of
the data block and the second transfer rate as a memory to output the
stored data block by the second transfer rate.
In this aspect, one of the memories is selected by the controlling device
on the basis of the data volume of the data block and the first transfer
rate. Then, the transferred data block is stored into the selected one of
the memories by the first transfer rate. Another of the memories is
selected by the controlling device on the basis of the data volume of the
data block and the second transfer rate. Then, the stored data block is
outputted from the selected another of the memories by the second transfer
rate. The selection may be performed such that two memories are
alternatively selected. The selection may be performed per each data block
such that each data block be stored in one of the memories. Alternatively,
the selection may be performed in the middle of transferring one data
block such that the digital data in one data block is stored separately
into two memories. In any event, the digital data are output in the form
of data blocks which are continuously output from the memories. Namely,
the change of transfer rate can be performed by use of a plurality of
memories which can easily accomplish a large memory capacity.
In the above described one aspect, the apparatus may be further provided
with: a writing selector switch for switching to selectively connect the
selected one of the memories with the data transferring device; and a
reading selector switch for switching to selectively connect the selected
another of the memories with an output of the apparatus.
In this aspect, on one hand, the selected one of the memories is connected
by the writing selector switch with the data transferring device. On the
other hand, the selected another of the memories is connected by the
reading selector switch with an output of the apparatus. In this
construction, the switching of the selector switches may be performed per
each block data. Alternatively, the switching of the selector switches may
be promptly performed in the middle of the data block in accordance with
the memory capacity of each memories.
In the above described one aspect, each of the memories may be a buffer
memory having writing and reading clocks different in frequency from each
other. Thus, the writing and reading operations can be separately
performed on the basis of the writing and reading clocks respectively.
In another aspect of the transfer rate changing apparatus the present
invention, the controlling device supplies a writing clock corresponding
to the first transfer rate and a reading clock corresponding to the second
transfer rate, to the memory device. Thus, on the basis of the writing
clock, the storing operation can be reliably performed at by the first
transfer rate, while the outputting operation can be reliably performed at
the second transfer rate.
The above object of the present invention can be also achieved by a master
disc recording apparatus provided with: a data transferring device for
transferring a data block of digital data, which are divided into a
plurality of data blocks, at a first transfer rate each time when a
transfer instruction signal is supplied thereto; a memory device for
storing the data block at the first transfer rate, which is transferred
from the data transferring device, and outputting the stored data block at
a second transfer rate, which is different from the first transfer rate; a
controlling device for supplying the transfer instruction signal, which
instructs the data transferring device to transfer one data block to the
memory device, to the data transferring device when the memory device
finishes outputting another data block which has been transferred from the
data transferring device prior to the one data block; and a recording
device for recording the data block outputted from the memory device onto
a data track of a master disc by the second transfer rate such that a
recording point where the data block is recorded on the data track is
moved in a radial direction of the master disc by a moving distance per
each unit time which is constant regardless of the type of master disc.
According to the transfer rate changing apparatus of the present invention,
the digital data (e.g. video data compressed and encoded by MPEG) are
divided into the data blocks, each of which may have digital data of
predetermined data volume (e.g. 2.8M bytes). When the memory device
finishes outputting another data block which has been transferred from the
data transferring device prior to one data block, the transfer instruction
signal is supplied to the data transferring device from the controlling
device, so that one data block is transferred from the data transferring
device to the memory device according to the transfer instruction signal.
In those successive operations, the data block is transferred from the
data transferring device (e.g. a WORM type optical disc reader) and stored
into the memory device (e.g. a RAM having a large memory capacity) at the
first transfer rate (e.g. 20M BPS) while the stored data block is
outputted from the memory device at the second transfer rate (e.g. 5M
BPS). Accordingly, the digital data are outputted in the form of data
blocks which are continuously outputted from the memory device. Then, the
data block outputted from the memory device is recorded by the recording
device onto the data track of the master disc at the second transfer rate.
The recording point (e.g. a laser beam spot formed on the master disc) is
moved in the radial direction of the master disc. At this time of
recording, the moving distance per each unit time is constant regardless
of the type of the master disc (e.g. the CD, the CD-ROM, the DVD, the
HVD). For example, the movement for the radial range of 25 mm to 58 mm on
the master disc is performed in 74 minutes regardless of the type of the
master disc. Accordingly, once the moving distance per each unit time of
the recording point is set to the recording device, it is not necessary to
change it in the moving distance per each unit time, so that the
re-adjustment of the recording device is not necessary when the type of
the master disc to be recorded is changed.
In one aspect of the master disc recording apparatus of the present
invention, the data transferring device intermittently reproduces a record
medium, on which the digital data are recorded, to generate the data block
one after another. Thus, the data block can be easily generated one after
another by the data transferring device.
In another aspect of the master disc recording apparatus of the present
invention, the recording device records the data block onto the data track
such that a linear velocity of the recording point along the data track is
increased relative to the linear velocity corresponding to a standard
transfer rate of the master disc by an amount based on a ratio of the
standard transfer rate and the second transfer rate if the standard
transfer rate is lower than the second transfer rate.
In this aspect of the present invention, if the standard transfer rate is
lower than the second transfer rate, the linear velocity of the recording
point along the data track is increased by the amount based on the ratio
of the standard transfer rate and the second transfer rate. Thus, the
recording density per each unit length obtained by the recording device
can be substantially equal to the recording density corresponding to the
standard transfer rate.
In another aspect of the master disc recording apparatus of the present
invention, the recording device records the data block onto the data track
such that a linear velocity of the recording point along the data track is
reduced relative to the linear velocity corresponding to a standard
transfer rate of the master disc by an amount based on a ratio of the
standard transfer rate and the second transfer rate if the standard
transfer rate is higher than the second transfer rate.
In this aspect of the present invention, if the standard transfer rate is
higher than the second transfer rate, the linear velocity of the recording
point along the data track is decreased by the amount based on the ratio
of the standard transfer rate and the second transfer rate. Thus, the
recording density per each unit length obtained by the recording device
can be substantially equal to the recording density corresponding to the
standard transfer rate.
In another aspect of the master disc recording apparatus of the present
invention, the memory device comprises a plurality of memories each for
storing the transferred data block by the first transfer rate and
outputting the stored data block by the second transfer rate, and that the
controlling device selects one of the memories on the basis of a data
volume of the data block and the first transfer rate, as a memory to store
the transferred data block at the first transfer rate, and further selects
another of the memories on the basis of the data volume of the data block
and the second transfer rate as a memory to output the stored data block
at the second transfer rate.
In this aspect, the digital data are outputted in the form of data blocks
which are continuously outputted from the memories. Thus, the
re-adjustment of the recording device is not necessary when the type of
master disc to be recorded is changed.
The nature, utility, and further features of this invention will be more
clearly apparent from the following detailed description with respect to
preferred embodiments of the invention when read in conjunction with the
accompanying drawings briefly described below.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a master disc recording apparatus as a first
embodiment of the present invention;
FIG. 2 is a block diagram of a transfer rate changing device in the master
disc recording apparatus of FIG. 1;
FIG. 3 is a block diagram of a recording device in the master disc
recording apparatus of FIG. 1;
FIG. 4 is a timing chart of a transfer rate in one operation of the
transfer rate changing device of FIG. 2; and
FIG. 5 is a timing chart of a transfer rate in another operation of the
transfer rate changing device of FIG. 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the accompanying drawings, an embodiment of the present
invention will be now explained.
(I) First Embodiment
A master disc recording apparatus as a first embodiment of the present
invention is shown in FIG. 1.
In FIG. 1, a master disc recording apparatus 100 is provided with: editing
units EU1 to EUn for integrating (storing) the information from a
plurality of record media such as a VTR (Video Tape Recorder) to
intermediate record media RM1 to RMn respectively; reproducing units RU1
to RUn for reproducing the information integrated (stored) in the editing
units EU1 to EUn respectively; a modulator 4 for outputting a laser
modulation signal S1m in accordance with the digital data reproduced by
the reproducing unit RUi (i=1, 2, . . . , n); a recording device 5 having
an optical pickup including a laser unit, for recording the reproduced
information by irradiating a master disc 6 with a modulated laser beam LB
from the laser unit, which is modulated by the laser modulation signal S1m
outputted from the modulator 4; and an inspecting device 7 for inspecting
the quality of the digital data after the modulator 4 i.e. the laser
modulation signal S1m. The master disc 6 is used for electrically molding
a stamper to copy and produce optical discs (e.g. DVDs, HVDs) for sale.
Each of the editing units EU1 to EUn is provided with: a VTR for
reproducing the video signal of the cinema video image which has been
taken by a telecine camera etc.; an encoder for encoding and compressing
the output of the VTR by high efficiency (e.g. by the MPEG1 or MPEG2
standard); and an adding device for adding an audio signal, a character
information signal, etc. to the video signal. Each of the editing unit EU1
to EUn performs formatting of the intermediate record media RM1 to RMn
respectively in correspondence with the type of the master disc 6 (i.e.
the type of the copied optical discs for sale) and records the information
on the formatted intermediate record media RM1 to RMn. Here, it is to be
noted that the information recorded on the intermediate record media RM1
to RMn is the same as that to be recorded on the master disc 6.
The intermediate record medium RMi (i=1, 2, . . . , n) may be an optical
disc of WORM (Write Once Read Many) type, an optical disc of re-writable
type such as a MO (Magneto Optical) disc, etc. The reason why the
information is once integrated (stored) to the intermediate record medium
RMi is to unite the information supplied via different routes on the
intermediate record medium RMi and to perform the quality check of the
united information on the intermediate record medium. The intermediate
record medium RMi is reproduced by a maximum transferring rate of 20 to
30M BPS (Mega Bit Per Second), for example.
Each of the reproduction units RU1 to RUn reproduces the intermediate
record media RM1 to RMn respectively, and outputs the reproduced digital
data according to a predetermined transferring rate (e.g. 20M BPS).
The modulator 4 outputs the laser modulation signal S1m for modulating the
laser beam LB in accordance with the digital data supplied from the
reproducing unit RUi.
The recording device 5 has an optical pickup including a laser unit for
emitting a laser beam LB such as an Argon laser beam in correspondence
with the digital data reproduced by the reproducing unit RUi, i.e., the
laser beam LB modulated by the laser modulation signal S1m. The recording
device 5 performs cutting (light exposing) of the glass original disc i.e.
the master disc pre-form which is composed of glass material, by real time
by use of the laser beam LB which is modulated by the modulator 4. The
optical pickup of the recording device 5 is adjusted to proceed in a
radial direction of the disc by a constant moving distance per each unit
time in the radial direction (i.e. the moving speed in the radial
direction at each radial position), regardless of the type of disc used as
the recording object. For example, the adjustment of various constants in
the servo circuit for driving the optical pickup of the record device 5 is
performed such that the optical pickup be moved on the disc for the record
radius of 25 mm to 58 mm in 74 minutes with respect to, as the standard,
the moving distance per each unit time in the standard reproduction of the
CD.
The master disc 6 consists of a glass original disc made of glass material.
The external shape of the glass original disc is shaped in accordance with
the type of optical disc as the copy object (such as a DVD, HVD, CD,
etc.). The glass original disc is finely surface-polished, is washed by
the ultra sound wave, and is coated with (photo-resist) the
photo-sensitive agent.
The recording device 5 rotates the master disc 6 while irradiating the
photo-resist coated on the master disc 6 with the laser beam LB which is
modulated by the modulator 4. By this, the light exposed portion (i.e. the
pit) is formed on the glass original disc to be the master disc 6.
The inspecting device 7 inspects the quality of the digital data after
modulation by the modulator 4.
In FIG. 1, each of the reproducing units RU1 to RUn is provided with: a
data transferring device 1; a transfer rate changing device 2; and a
personal computer 3.
The data transferring device 1 reproduces the intermediate record medium
RMi by a predetermined transfer rate (e.g. 20M BPS). At the time of
reproducing, the data transferring device 1 reproduces the intermediate
record medium RMi intermittently on the basis of a transfer instruction
signal St, which is supplied from the transfer rate changing device 2.
This intermittent reproduction forms "block data" one after another, which
is the reproduced digital data in each block prescribed by the
intermittent reproduction.
The transfer rate changing device 2 changes the transfer rate (20M BPS) of
the digital data, which is transferred from the data transferring device
1, to a different transfer rate (10 M BPS), and outputs the data by this
different transfer rate (10 M BPS).
The personal computer 3 controls the overall operation of each of the
reproducing units RU1 to RUn.
In FIG. 1, the master disc recording apparatus 100 simplifies the
adjustment of the servo control in the recording device 5, by employing a
plurality of editing units EU1 to EUn, each of which is exclusive for one
type of the record medium, and a plurality of reproducing units RU1 to
RUn, each of which is also exclusive for one type of the record medium,
respectively. However, the master disc recording apparatus 100 can
function by employing just one set of the editing unit and the reproducing
unit while adjusting the recording device 5 in accordance with the type of
record medium.
FIG. 2 shows a construction of the transfer rate changing device 2.
In FIG. 2, the transfer rate changing device 2 is provided with: a
controller 10, buffer memories BM1 to BMn, a writing switch SWw and a
reading switch SWr.
Each of the buffer memories BM1 to BMn may be a RAM (Random Access Memory)
for storing data of a predetermined volume (e.g. 2.5M bytes). The memory
capacity of each of the buffer memories BM1 to BMn may be enough to store
one block data (i.e. the reproduced digital data in each block)
transferred from the data transferring device 1, for example. However,
since the memory, such as a RAM is speedy in writing and reading the data,
this memory capacity of each of the buffer memories BM1 to BMn may be any
value while the buffer memories BM1 to BMn are switched over regardless of
transferring the digital data by the block unit. This is because it is
enough to store the transferred digital data without overflowing it.
Each of the buffer memories BM1 to BMn is a memory which can perform the
writing operation and the reading operation by different clocks and by
different frequencies (i.e. different transfer rates) from each other,
such as a dual port memory.
The writing switch SWw selects one buffer memory BMi among the buffer
memories BM1 to BMn on the basis of a writing selection signal Sw, and
supplies the transferred digital data to the selected buffer memory BMi.
The reading switch SWr selects one buffer memory BMj (which may be
coincident or not coincident with the buffer memory BMi) among the buffer
memories BMi to BMn on the basis of a reading selection signal Sr, and
supplies the stored digital data from the selected buffer memory BMj.
The controller 10 supplies the writing selection signal Sw to the writing
switch SWw to select one buffer memory BMi. The controller 10 also
supplies writing clocks W1 to Wn each having the same frequency as that of
the transfer rate of the block data (e.g. 20M BPS) transferred from the
data transferring device 1 to each of the buffer memories BM1 to BMn. The
controller 10 further supplies the reading clocks R1 to Rn each having the
same frequency as the recording frequency of the recording device 5. When
transferring the digital data to the buffer memory BMi is completed, the
controller 10 supplies the transfer instruction signal St to the data
transferring device 1, and also supplies a control signal Sc to indicate
the start of the transferring of the digital data from the buffer memory
BMi to the recording device 5.
FIG. 3 shows a construction of the recording device 5.
In FIG. 3, the recording device 5 is provided with a sliding device 11 and
an optical pickup 12. The sliding device 11 is constructed to move the
optical pickup 12 in the radial direction of the master disc 6 as
indicated by arrows 21 in the figure according to the control signal Sc,
which is supplied from the transfer rate changing device 2. The optical
pickup 12 is provided with a driving unit 13 and a laser unit 14. The
driving unit 13 is constructed to drive the laser unit 14 by supplying a
laser driving power thereto, which is modulated in accordance with the
laser modulation signal S1m supplied from the modulator 4. The laser unit
14 emits the laser beam LB modulated according the laser modulation signal
S1m. Accordingly, a recording point Prec at which the laser beam LB is
focused on a record track of the master disc 6 is moved in the radial
direction of the master disc 6 in accordance with the sliding motion of
the sliding device 11 as indicated by arrows 22 in the figure.
Next, the recording operation of the master disc recording apparatus 100
will be explained.
In the present embodiment, the digital data is supplied to the master disc
6, which is the origin of copying a DVD (which has a standard average data
rate of 5M BPS), by the data rate of 10 M BPS (i.e. by the double data
rate of the standard average data rate) so as to perform a high speed
recording operation.
When the personal computer 3 in the reproducing unit RUi instructs the
start of transferring to the reproducing unit RUi, the transfer
instruction signal St is sent to the data transfer device 1 from | | |
