Optical information recording with preformatted synchronization signals and information recording and reproducing method

Each information recording track has pre-formatted fore and rear header sections containing address information identifying the track, which permit each of the recording tracks to be accessed from either of the header sections. A predetermined synchronization signal is pre-formatted in a storing area for each frame having a predetermined data size, so that information can be non-rewritably recorded onto the storing area for a predetermined frame by referring to the pre-formatted synchronization signal. With this arrangement, data can be recorded onto a selected information recording track in either of the directions of relative reciprocating movement of the recording medium to a recording/reproducing head, and thus the recording speed can be increased. The arrangement also allows data to be recorded even when one of the header sections has become unreadable due to some defect of the recording medium, and prevents occurrence of jitters in reproduced signals by allowing data to be recorded accurately at predetermined locations for each of the frames.

BACKGROUND OF THE INVENTION 
The present invention relates generally to properly pre-formatted 
information recording media and methods of recording and reproducing 
information onto and from such pre-formatted information recording media. 
More particularly, the present invention is concerned with a technique 
which is applicable to write-once information recording media to improve 
the data storing efficiency, recording accuracy and burst-error correcting 
capability of the media. 
In recording data onto an information recording medium such as an optical 
card, it is usually desirable to maximize the recording density from the 
economical point of view. However, as the recording density is increased, 
there would occur more errors in reproduced data due to various defects of 
the recording medium. 
As an approach to reduce such reproduced data errors, it has been proposed 
to add error correction codes to data to be recorded so that the 
reproduced data errors can be corrected by reference to the added error 
correction codes. The reproduced data errors generally include "random 
errors" occurring randomly, and "burst errors" occurring in successive 
groups. While the random errors can be corrected relatively easily by use 
of the error correction codes, the burst errors can often not be corrected 
by the proposed approach because of their successive nature. 
In order to permit correction of the burst errors, it has been conventional 
to perform recording based on an interleave technique in such a manner 
that a series of data is divided into individual data pieces and 
scatteringly recorded onto the information recording medium. By recording 
the data scatteringly, successive errors on the recording medium in effect 
appear randomly and hence can be corrected in virtually the manner as the 
random errors. 
Where an optical card is used as a recording medium, a plurality of 
information units (sectors) are usually recorded onto a data track. But, 
as the number of sectors on the data track is increased, the length of the 
individual sectors would become shorter and the number of interleaves 
(i.e., the amount of information that can be mixedly contained within each 
sector) would decrease. This results in reduced scattering of the recorded 
data and hence in reduced error correction capability. 
Such inconveniences may be eliminated and error correction capability may 
be increased by increasing the number of interleaves while maintaining 
long-enough sector lengths. However, when relatively short data are to be 
recorded and if the number of interleaves is small in the data to be 
actually recorded, the conventional interleave technique would record the 
short data from the beginning of a sector in a packed condition, 
wastefully leaving a considerable amount of unrecorded area in the rear 
end portion of the sector, and this undesirably lowers the data storing 
efficiency. If new data is to be recorded onto the unrecorded area left in 
the rear end portion, the new data would unavoidably be interleaved in a 
different manner from the data recorded in the fore end portion of the 
sector. 
To provide a solution to the above-mentioned problem, Japanese Patent 
Application No. HEI 6-44032 proposes the following recording format. 
According to the proposed recording format, as shown in FIG. 7, a series 
of information to be recorded is reorganized as 40 packets or rows (packet 
1 to packet 40) each having a size of 272 bits: 190-bit data denoted in 
FIG. 7 as by "a1, a2, a3, . . . a190"; and 82-bit error correction codes 
denoted in FIG. 7 as by "a191, . . . a272". Then, as shown in FIG. 8, an 
48-bit frame is created which comprises an 8-bit synchronization signal F 
and 40 first-bit data of the individual packets and is serially arranged 
in the order of "F, a1, b1, c1, . . . n1". Similarly, another 48-bit frame 
is created which comprises an 8-bit synchronization signal F and 40 
second-bit data of the individual packets and is serially arranged in the 
order of "F, a2, b2, c2, . . . n2", another 48-bit frame is created which 
comprises an 8-bit synchronization signal F and 40 third-bit data of the 
individual packets and is serially arranged in the order of "F, a3, b3, 
c3, . . . n3", and so on. In this manner, a total of 272 frames are 
created and serially connected to ultimately form a data train of 13,056 
(48.times.272) bits, which is recorded onto a single data track of the 
optical card. 
With the proposed recording format, because each frame is fixed at a 
predetermined data size, a maximal number of interleaves can be set and 
maintained. Further, because even short data are recorded scatteringly in 
each of the frames and new data can be non-rewritably interleaved onto 
unrecorded areas of the individual frames (i.e., even when packets 1-3 
have been recorded, packet 4 and following packets are left in a 
scattering state so as to be interleaved), the recording efficiency can be 
significantly enhanced while maximizing the error correction capability. 
The data recording area in one track has a size of 48.times.373=13,056 
bits, and a header section is pre-formatted at the fore end of each track, 
which, as shown in FIG. 9, includes a lead-in section for bit 
synchronization and a BOS (Beginning of Sector) section storing address 
information etc. A similar lead-in section is also pre-formatted at the 
rear end of the track. That is, the lead-in sections are pre-recorded or 
pre-formatted on both sides of the data recording area of each track, with 
the BOS section being interposed between one of the lead-in sections and 
recording area. 
However, because the known optical card format has the BOS section 
pre-formatted next to only one end portion thereof, data can be recorded 
only when the optical card is moved relative to the head just in one 
particular direction although the optical card reciprocates in two 
directions, and this results in poor efficiency. When the information 
recorded on the BOS section can not be read due to some defect such as 
dust, stain or scar on or in the optical card surface, desired data 
recording can not be effected at all. 
Further, according to the interleave technique proposed in the Japanese 
patent application, no frame-by-frame synchronization signals F are 
pre-formatted; instead, they are written when desired data are recorded 
onto the data recording area. Thus, due to ununiform speed of the optical 
card's relative reciprocating movement or the like, the frame-by-frame 
synchronization signals F could not be recorded accurately at 
predetermined locations, so that there would occur undesirable jitters in 
the reproduced signals. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide an 
information recording medium which allows data to be recorded thereon in 
either of directions of the medium's relative reciprocating movement to a 
recording/reproducing head and even when a header section (BOS section) 
has become unreadable due to a defect of the recording medium. 
It is another object of the present invention to provide an information 
recording medium which allows a synchronization signal for each frame to 
be recorded accurately at a predetermined location thereof to thereby 
prevent occurrence of undesirable jitters in reproduced signals. 
It is still another object of the present invention to provide a method for 
efficiently recording or reproducing information onto or from an 
information recording medium. 
In order to accomplish the above-mentioned objects, the present invention 
according to a first aspect provides an information recording medium which 
comprises a plurality of information recording tracks, and a pair of 
header sections pre-formatted at fore and rear ends of each of the 
recording tracks, each of the header sections of each of the tracks 
containing at least address information identifying the track, whereby, 
when information is to be recorded or reproduced onto or from desired one 
of the tracks, the desired track can be accessed from either the fore end 
or the rear end by referring to either of the header sections thereof. 
According to the above-mentioned first aspect of the invention, each 
information recording track has pre-formatted fore and rear header 
sections containing at least address information identifying the track, 
and reference to either of the header sections permits the information 
recording track to be accessed from either the fore end or the rear end of 
the track. Thus, when data are to be recorded, either of the fore and rear 
header sections can be accessed first irrespective of the direction of 
relative movement of the recording medium to the head (i.e., irrespective 
of whether the relative movement is in the fore-to-rear or rear-to-fore 
direction), and thus the data recording can be performed on the track 
after it has been ascertained, from the information contained in the 
header section, that the track is a desired track. With this arrangement 
to allow data to be recorded onto the recording medium in either of the 
directions, the recording speed can be substantially increased. Further, 
even when the information contained in one of the header sections has 
become unreadable due to a partial defect of the recording surface of the 
medium, desired data recording can nevertheless be effected during the 
relative movement of the medium as long as the information in the other 
header section is readable. This is very advantageous. 
In one preferred embodiment, each of the header sections includes a section 
having a predetermined data group pre-formatted for bit synchronization 
(corresponding to the lead-in section), and a section having pre-formatted 
track address information (corresponding to the BOS section). 
The present invention according to a second aspect provides a write-once 
information recording medium which comprises a plurality of information 
recording tracks, each of the tracks being comprised of a plurality of 
storing areas for a plurality of frames each corresponding to a 
predetermined data size, a predetermined synchronization signal being 
pre-formatted in the storing area for each of the frames. This arrangement 
permits information to be non-rewritably recorded onto the storing area 
for selected one of the frames by referring to the pre-formatted 
synchronization signal. 
According to the above-mentioned second aspect of the present invention, a 
predetermined synchronization signal is pre-formatted in the storing area 
for each of the the frames in such a manner that information can be 
non-rewritably recorded onto the storing area for a desired frame by 
referring to the pre-formatted synchronization signal. With this 
arrangement, it is possible to eliminate the need for formatting a 
synchronization signal for each frame during data recording, and the 
frame-by-frame synchronization signals can be appropriately recorded at 
respective predetermined locations, without being influenced by ununiform 
speed of the relative reciprocating movement of the recording medium for 
recording operation in a recording/reproducing apparatus. This 
significantly simplifies the data recording operation and prevents 
occurrence of jitters in the reproduced signals. 
The information recording medium of the invention may be constructed to 
have the above-mentioned first and and second aspects. 
Further, the present invention provides a method for performing at least 
one of information recording and reproduction onto and from a write-once 
information recording medium, which comprises the steps of accessing 
desired one of the tracks at either of the fore and rear ends by referring 
to either of the header sections thereof when information is to be 
recorded or reproduced, moving the recording or reproducing head relative 
to the recording medium from one of the fore and rear ends to the other 
end of the accessed desired track, and recording or reproducing the 
information onto or from one of the storing areas for selected one of the 
frames, by referring to the pre-formatted synchronization signal during 
relative movement of the head to the recording medium. 
According to the method of the present invention, it is possible to access 
a desired track from either the fore end or the rear end by referring to 
either of the fore and rear header sections, and by moving the head 
relative the accessed track from one of the fore and rear ends to the 
other end, it is also possible record or reproduce information in either 
of the directions of the relative reciprocating movement. This increases 
the speed and efficiency of recording or reproduction. Also, because 
information can be accurately recorded onto or reproduced from a desired 
track by referring to the pre-formatted synchronization signal in the 
course of the relative movement, the recording and reproducing accuracy 
can be increased. 
As one preferred embodiment, in the step of recording the information, data 
of a series of information to be recorded may be scattered across the 
frames by interleaving in such a manner that pieces of the data are 
mixedly recorded within each of the frames. As another preferred 
embodiment, in the step of reproducing the information, reproduced data of 
the individual frames may be released from their interleaved state, so as 
to reproduce the series of the information. The series of information may 
include a data group of a plurality of bits and predetermined error 
correction codes.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 is a schematic plan view showing an optical card 1 as an embodiment 
of a write-once information recording medium according to the present 
invention. On one surface of the optical card 1, there is provided a 
rectangular information recording region 2 which occupies about 60% of the 
total area of the surface. The information recording region 2 includes a 
central write-once data recording section 3 and two pre-formatted or 
pre-recorded header sections 4a and 4b located at both ends of the data 
recording section 3. The information recording region 2 has a plurality of 
information recording tracks extending in "x" direction in the figure and 
arranged in parallel to each other in "y" direction. The "x" direction is 
where a recording/reproducing head H (FIG. 4) is moved relative to the 
card 1 along the recording region 2 in order to record or reproduce 
information onto or from a particular information recording track, while 
the "y" direction is where the recording/reproducing head H is moved 
relatively across the recording region 2 in order to be properly 
positioned over a particular information recording track. 
For convenience of description, one end (left side in FIG. 1) of the 
optical card 1 where the header section 4a is provided will be referred to 
as a fore end, while the other end (right side in FIG. 1) of the optical 
card 1 where the header section 4b is provided will be referred to as a 
rear end. Although not specifically shown, a plurality of servo-tracking 
guide tracks are also provided on the recording region 2, each interposed 
between adjacent information recording tracks, as well known in the art. 
A further description will be made about an exemplary storing format of the 
recording tracks 21 in the information recording region 2, with reference 
to FIG. 2. 
Each of the information recording tracks 21 includes a central write-once 
data recording area 31, and fore and rear header sections 4a1 and 4b1 
located on opposite sides of the data recording track section 31. Such 
data recording area 31 and fore and rear header sections 4a1 and 4b1 of 
the individual recording tracks 21 together constitute the data recording 
section 3 and fore and rear header sections 4a and 4b of FIG. 1, 
respectively. 
The fore header section 4a1 of each information recording track 21 is 
composed of a lead-in section 42a having a group of predetermined data 
pre-formatted for the purpose of bit synchronization, and a BOS (Beginning 
of Sector) section 43a having address information identifying that 
recording track 21. The lead-in section 42a is located adjacent to the 
extreme fore end of the recording track 21, and the BOS section 43a is 
located to the right of the lead-in section 42a, i.e., closer to the 
middle of the recording track 21. This arrangement is for the purpose of 
allowing the lead-in section 42a to be first read by the head H when the 
relative movement of the head H is in the backward (i.e., fore-to-rear) 
"x" direction. The lead-in section 42a contains 144-bit pre-formatted 
informational that is for example comprised of three sets or repetitions 
of 8-bit frame synchronization signal F and 40-bit synchronization signal 
S. The BOS section 43a contains 288-bit pre-formatted information that is 
for example comprised of six repetitions of 8-bit frame synchronization 
signal F, 14-bit track address information and other necessary 
information. For example, the frame synchronization signal F is a 
predetermined 8-bit coded signal, and the bit synchronization signal S 
comprises 40 information pits (40-bit data of logical "1"). 
The rear header section 4b1 of each of the information recording tracks 21 
contains pre-formatted information that has the same contents but is 
arranged oppositely to that of the fore header section 4a1. That is, in 
the rear header section 4b1, lead-in section 42b is located adjacent to 
the extreme rear end of the recording track 21, and BOS section 43b is 
located to the left of the lead-in section 42b, i.e., closer to the middle 
of the track 21. This arrangement is for the purpose of allowing the 
lead-in section 42b to be first read by the head H when the relative 
movement of the head H is in the forward (i.e., rear-to-fore) "x" 
direction. 
An 8-bit extreme-end frame synchronization signal F is added, at the 
extreme read end of the lead-in section 42b of the rear header section 
4b1, so as to be first read by the head H when the relative movement of 
the head is in the forward (i.e., rear-to-fore) "x" direction. However, it 
is not necessary to add such an extreme-end frame synchronization signal F 
to the fore header section 4a1 because the extreme-fore-end data is 
originally the 8-bit frame synchronization signal F. 
Referring next to the format of the data recording area 31 of each of the 
tracks 21, the track section 31 is comprised of storing areas for a 
plurality of frames, say, 272 frames, and each of the frames has a 
predetermined data size such as 48 bits. In each of the frame storing 
areas is pre-formatted a predetermined frame synchronizing signal F, so 
that information is non-rewritably recorded onto a desired frame storing 
area by referring to the pre-formatted synchronization signal F. As an 
example, one frame may have a size of 48 bits so that the synchronization 
signal F pre-formatted in the area has a size of 8 bits and the remaining 
40 bits form an available data recording segment D. Namely, at the time of 
fabrication of the optical card 1, a total of 272 frame synchronization 
signals F are pre-formatted at constant intervals in predetermined 
locations of the data recording area 31, with the data recording segment D 
for each frame being left blank for the user's subsequent writing. 
The term "pre-formatting" is used to mean pre-recording predetermined 
information such as bit synchronization signal S, frame synchronization 
signal F and header information A such as address information in 
accordance with predetermined standards at the time of fabrication of the 
optical card 1. Recording such pre-format information may be effected by 
use of any conventionally-known recording apparatus and method or 
technique, and hence will not be described here any further. 
Next, a description will be made about an exemplary apparatus and method 
for recording and/or reproducing information onto and/or from the optical 
card 1 pre-formatted in the above-mentioned manner. 
FIG. 4 is a block diagram showing an exemplary general hardware structure 
of the optical information recording/reproducing apparatus employed in the 
present invention. Input section 50 of the device includes various input 
means such as a keyboard, operation panel and other device for inputting 
data of information to be recorded onto the optical card 1 and various 
operational instructions to the apparatus. Output section 51 includes 
various output means such as for printing reproduced data and outputting 
video and audio data. Microcomputer COM which comprises CPU 52, ROM 53 and 
RAM 54 controls the recording and reproducing operations in the 
recording/reproducing apparatus. Under the control of the microcomputer 
COM, optical card drive 55, in which the optical card 1 is removably set 
in place, records and/or reproduces information onto and/or from the 
optical card 1. 
FIG. 5 is a flowchart of a program, to be executed by the CPU 52, for 
recording information onto the optical card 1 set in the optical card 
drive 55. 
First, at step S1, information to be recorded is introduced via the input 
section 50. At next step S2, the CPU 52 selects one of available (writable 
or blank) recording tracks 21 in the data recording region 3 of the card 1 
and creates a data map of the introduced information in correspondence 
with the selected track 21. In preparing the data map, the to-be-recorded 
information is classified into a plurality of packets each having a 
predetermined data size (e.g., 190 bits), and error correction codes 
having a predetermined number of bits (e.g., 85 bits) are added to each of 
the packets. Thus, for each of the packets, this procedure creates a data 
group of one or more packets each having 272 bits. 
Then, for the selected track 21, the information and error correction codes 
of each packet are stored into a predetermined recording/reproducing 
buffer memory in the form of a matrix data map having 40 rows and 272 
columns as shown in FIG. 3. At this time, if all the data recording areas 
D of the track 21 are available for recording, the to-be-recorded 
information will be temporarily stored into the buffer in correspondence 
with all the data map areas; however, if data has already been recorded on 
the recording areas corresponding to packets 1 and 2 with the remaining 
recording areas corresponding to packets 3 to 40 being available for 
recording, the to-be-recorded information will be temporarily stored into 
the buffer at its map locations c1-c272 to n1-n272 and not at its map 
locations a1-a272 to b1-b272. As will be described later, this permits 
efficient write-once recording even onto scattering empty recording areas. 
Preferably, RAM of the optical card drive 55 (not shown) is used as the 
above-mentioned recording/reproducing buffer memory, although the RAM 54 
of the microcomputer COM may be used. 
Next, at step S3, the recording/reproducing head H which is provided in 
association with the optical card drive 55 is caused to access the 
selected recording track 21. As the head H is moving relative to the track 
21, it is possible to ascertain whether or not the recording/reproducing 
head H is actually accessing the selected recording track 21, by referring 
to the header information A including the track address information 
pre-formatted in the BOS section of the header section 4a1 or 4b1. Because 
the two BOS sections 43a and 43b are provided at the opposite ends of the 
track 21, one of the sections 43a and 43b can always be referred to and 
hence recording of the information can be effected, irrespective of the 
direction of the relative oscillating movement of the 
recording/reproducing head (the forward or backward "x" direction) to the 
optical card 1. Further, even when some defect in the recording surface of 
the optical card 1 prevented the information of one of the BOS sections 
43a or 43b from being read out properly during the relative movement of 
the head H in the backward "x" direction, data recording can be effected 
as the head H is moved relative to the track 21 in the reversed "x" 
direction, as long as the other BOS section 43b or 43a is readable. 
Once it has been ascertained that the recording/reproducing head H is 
actually accessing the selected recording track 21, the optical card drive 
55 continues the forward or backward relative movement of the 
recording/reproducing head H along the track 21, during which time it 
performs the following recording process on the optical card 1. 
That is, at step S4, the data of the individual frames are read out from 
the data map (FIG. 3) stored in the recording/reproducing buffer memory 
and are sequentially recorded onto the corresponding recording areas D 
(FIG. 2) in an interleave fashion. More specifically, when the relative 
movement of the recording/reproducing head H is in the backward "x" 
direction arrowed in FIG. 2, 40-bit data comprising respective first bit 
data of packets 1-40 arranged in the order of "a1, b1, c1, . . . n1" are 
read out in a serial manner and stored into the recording segment D 
corresponding to frame 1. Next, 40-bit data comprising respective second 
bit data of packets 1-40 arranged in the order of "a2, b2, c2, . . . n2" 
are read out in a serial manner and stored into the recording segment D 
corresponding to frame 2. Thus, by reading out from the data map the 
respective row bits of the individual packets column by column, data 
trains of 272 frames (frame 1 to frame 272) are created and are recorded 
onto the corresponding recording areas D of the optical card 1. Because 
during this time the presence of the recording segment D for each frame 
can be confirmed by reference to the pre-formatted frame synchronization 
signal F, the data of each frame can be recorded onto accurate storing 
locations of the optical card 1 even when the relative movement speed of 
the recording/reproducing head has become ununiform. Of course, in this 
case, the frame-by-frame data recording is performed while jumping over 
such storing locations corresponding to already-recorded packets (e.g., if 
packets 1 and 2 have been already recorded, then the storing locations for 
data A1-a272 and b1-b272 are jumped over). 
In the case where the relative movement of the recording/reproducing head H 
is in the opposite direction to the arrowed "x" direction of FIG. 2, the 
data map is read in the opposite direction to the above-mentioned, i.e., 
in the order of n272, . . . b272, a272 and n1, . . . c1, b1, a1, so that 
all the data can be recorded in the same direction. Conversely, even where 
the relative movement of the recording/reproducing head H is in the 
opposite direction to the arrowed "x" direction of FIG. 2, the data map 
may be read in the above-mentioned direction so that the data recorded 
direction varies among the recording tracks 21. In such a case, a flag 
indicative of the direction of the recorded data may be recorded in the 
header sections 4a1 and 4b1 for each recording track 21 so that the data 
can be rearranged with reference to the flag during reproduction. 
Once the data recording has been completed for one track 21 in the 
above-mentioned manner, it is examined whether there is other information 
to be recorded. If so, the CPU 52 loops back to step S2 to repeat the 
above-mentioned operations. Namely, the CPU 52 selects any of the 
available recording tracks 21 in the data recording region 3 of the 
optical card 1, so that the data recording is performed on the selected 
track 21 in the above-mentioned manner. Because available recording tracks 
are often adjoining to each other in write-once information recording 
media, the recording track 21 adjoining the track 21 used in the last 
cycle may be selected and the other to-be-recorded information may be 
recorded on the selected adjoining recording track 21. 
Now, a description will be made about an exemplary program, to be executed 
by the CPU 52, for reproducing information from the optical card 1 set in 
the optical card drive 55. 
First, at step S10, the CPU 52 designates one or more tracks 21 from which 
to reproduce the recorded data. At next step S11, the 
recording/reproducing head H of the optical card drive 55 is caused to 
access the designated track 21. As mentioned earlier in connection with 
the recording process, it is possible to ascertain whether or not the 
recording/reproducing head H is actually accessing the designated track 
21, by referring to the header information A containing the track address 
information pre-formatted in the BOS section 43a or 43b of the header 
section 4a1 or 4b1 as the head H is moving relative to the track 21. 
Because the two BOS sections 43a and 43b are provided at the opposite ends 
of the track 21, one of the sections 43a and 43b can always be referred to 
and hence reproduction of the information can be effected, irrespective of 
the direction of the relative movement of the recording/reproducing head 
H. Even with the conventional optical cards having only one BOS section, 
the recording/reproducing head H is allowed to move relative to the card 
in either of the directions at the time of reproduction because no 
particular inconvenience would not arise from confirming the track address 
after reading out the recorded data on the track 21. However, if the BOS 
sections are provided at the opposite ends of the card as in the present 
invention, improper access to a wrong track 21 can be readily detected to 
immediately stop the reproducing operation on the track 21, which will 
significantly improve the reproducing efficiency. 
Once it has been ascertained that the recording/reproducing head H is 
accessing the designated track 21, the optical card drive 55 continues the 
forward or backward relative movement of the recording/reproducing head H 
along the track 21, during which time it performs the following 
reproduction process. 
At step S12, the data reproduced for each frame from the designated track 
21 are temporarily stored into the above-mentioned recording/reproducing 
buffer memory. Then, the data for each packet are read out from the buffer 
memory after the data has been released from the interleaved state, and 
the reproduced packet data (190 bits) are checked and corrected for any 
possible error by use of the error correction codes (82 bits). 
Then, at step S13, it is examined whether the data on all the designated 
tracks 21 have been reproduced. If not, i.e., if there is another track 21 
to be reproduced, the CPU 52 loops back to step S11 to repeat the 
above-mentioned operations for the unreproduced track. 
Because the reproduction is performed on the data of the individual frames 
which are, as mentioned earlier, recorded on accurate storing locations on 
the basis of the respective frame synchronization signals irrespective of 
whether the relative movement speed of the recording/reproducing head is 
uniform or not, it is possible to acquire good-quality reproduced signals 
with no jitters. In addition, by reproducing the data recorded 
scatteringly on the basis of the interleave technique, the present 
invention can correct error easily without being influenced by any defect 
of the data recording areas such as dust, stain or scar. 
It should be understood that various modifications are possible without 
departing from the basic features of the present invention. As an example, 
the present invention may be applied to any other write-once information 
recording media than the optical card, such as an optical disk where one 
circular track comprises a plurality of sectors and each of the sectors is 
an unit to be accessed. Namely, in rotary recording media such as the 
optical disk, each sector may be considered as one information recording 
track of the present invention. The pre-formatting of two header sections 
at the opposite ends of each track in the present invention, which allows 
the relative movement of the recording/reproducing head to be in either of 
the forward and backward "x" directions, may not have to be applied to the 
rotary recording media rotatable only in a single direction. However, the 
pre-formatting of frame-by-frame synchronization signals may be applied to 
the single-direction rotary recording media. 
The present invention may of course be applied to two-surface-recording 
optical cards as well as to single-surface-recording optical cards. It 
should be apparent that the present invention is also applicable to 
hybrid-type information recording media which for example have a function 
of an optical card and a function of another recording medium such as an 
IC or magnetic card. 
In summary, the present invention is characterized in that each information 
recording track has pre-formatted fore and rear header sections containing 
at least address information identifying the track and reference to one of 
the header sections permits the information recording track to be accessed 
in either of the forward and backward directions at the time of recording 
or reproduction. Thus, when recording data, one of the fore and rear 
header sections can be accessed first irrespective of the direction of the 
relative movement of the recording medium to the head, and thus the data 
recording can be performed on the track after it has been ascertained from 
the header section that the track is a desired track. With this 
arrangement to allow data to be recorded onto the recording medium in 
either of the directions, the recording speed can be increased to a 
substantial degree. Further, even when the information recorded on one of 
the header sections has become unreadable due to a partial defect of the 
recording surface of the medium, desired data recording can be effected by 
the relative movement of the medium as long as the information recorded on 
the other header section is readable. This is very advantageous. 
The present invention is also characterized by predetermined 
synchronization signals pre-formatted in the storing areas for the 
individual frames in such a manner that information can be recorded on the 
storing area for a given frame by referring to the pre-formatted 
synchronization signal. With this arrangement, it is possible to eliminate 
the need for formatting a synchronization signal for each frame at the 
time of recording and to always record the frame-by-frame synchronization 
signals accurately at respective predetermined locations, without being 
influenced by ununiform speed of the relative reciprocating movement of 
the recording medium for recording in a recording/reproducing apparatus. 
This significantly simplifies the data recording operation and prevents 
occurrence of jitters in the reproduced signals. 
Furthermore, with the method of the present invention, it is possible to 
access a desired track from either its fore end or its rear end by 
referring to either of the fore and rear header sections, and by moving 
the head relative the accessed track backwardly or forwardly, it is also 
possible record or reproduce information from either of the directions of 
the relative reciprocating movement. This can increase the speed and 
efficiency of recording and reproduction. Also, because information can be 
accurately recorded onto or reproduced from a desired track by referring 
to the pre-formatted synchronization signal during the relative movement, 
the recording and reproducing accuracy can be increased.