Optical card recording/reproducing apparatus with compensation for displacement deviation between data area of optical card and laser beam

An optical card recording/reproducing apparatus comprises a fixed optical head for scanning the surface of the card with a light beam, a shuttle for holding an optical card, and a motor for moving the shuttle with respect to the optical head. The moving position of the shuttle is detected by a rotary encoder coupled to the motor. The detection output of the encoder provides data which represents the relative positional relationship between the shuttle and the optical head and is used to control the moving speed of the shuttle in such a way that a data area on the optical card is scanned by the light beam at a constant speed. The state in which the optical card is loaded in the shuttle can also be detected, and this detection output is used to compensate for the detection result of the rotary encoder. As a result, the moving speed of the shuttle can be controlled in accordance with the relative positional relationship between the optical head and the optical card.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an optical card recording/reproducing 
apparatus which accesses an optical card having an optical data recording 
section, for data recording into and/or data readout from the card. 
2. Description of the Related Art 
Although, like an optical disk, such an optical card is not rewritable, it 
has as a large memory capacity as, for example, 1 to 2 MB, which is 
several thousands to a million times greater than that of a magnetic card. 
Therefore, optical cards have wide applications, such as for bankbooks, 
portable maps and prepaid cards for use in shopping. 
A recording/reproducing apparatus for accessing such optical cards is 
disclosed in Japanese Patent Application No. 61-178876 (corresponding to 
Japanese Patent Disclosure No. 63-37876), assigned to the same assignee as 
the present invention. 
FIG. 1 is a plan view illustrating an optical card for use in the above 
apparatus. An optical card 11 has its one surface provided with an optical 
data recording section 13, which is divided into a plurality of parallel 
tracks 12 in the lengthwise direction of the card. Movement of optical 
card 11 with respect to a fixed optical head or movement of a movable 
optical head with respect to optical card 11 when it is of a fixed type 
causes tracks 12 to be scanned with a laser beam for data 
recording/reproducing. 
Each track 12 has its center portion serving as a data section 15, and two 
identifier (ID) sections 14a and 14b, on which the address of the track is 
recorded, are provided adjacent to both ends of the data section 15, 
respectively. These ID sections 14a and 14b permit address readout in both 
lateral movements of card 11 with respect to the optical head. In order to 
prevent an error in data readout due to a scratch, stain or the like at 
the edge portions of optical card 11 and sufficiently stabilize the moving 
speed of the card 11 with respect to the optical head, ID sections 14a and 
14b are located at a given distance from the card's edge portions. 
FIG. 2 is a block diagram of an apparatus for recording/reproducing data 
using the optical card disclosed in the aforementioned Japanese Patent 
Disclosure No. 63-37876. According to this apparatus, a fixed optical head 
21 scans a track with a laser beam while moving optical card 11 in the 
track direction so as to access data section 15 for data 
recording/reproducing. When the recording/reproducing of one track is 
completed, optical head 21 moves in the direction perpendicular to the 
tracks to be ready for recording/reproducing of the next track. 
A shuttle 24 is provided at a predetermined location on an endless conveyor 
belt 23 stretched over pulleys 22a and 22b. Optical card 11 is loaded in 
shuttle 24 with the card's lengthwise direction coinciding with the moving 
direction of the shuttle 24. 
Accordingly, when conveyor belt 23 is driven, optical card 11 is moved in 
its lengthwise direction. The belt 23 is driven by a motor 26 coupled to 
pulley 22a. When shuttle 24 is conveyed by a distance corresponding to the 
length of the card, motor 26 is rotated in the reverse direction. 
Motor 26 is provided with a rotary encoder 27 for detecting the amount and 
direction of its rotation, and the detection signal from this rotary 
encoder 27 is fed back to a motor-servo circuit 26. 
Optical head 21, which is located at a predetermined location above the 
path of shuttle 24 conveyed by belt 23, comprises a laser diode 21a, a 
half prism 21b, a detector 21c, an objective 21d and a lens actuator 21e. 
A laser beam from laser diode 21a is irradiated onto optical card 11 
loaded in shuttle 24, through half prism 21b and objective 21d. Therefore, 
optical card 11 loaded in shuttle 24 is reciprocated about the laser beam 
irradiation point. The laser beam reflected at optical card 11 has the 
direction of its optical path changed 90.degree. by half prism 21b and 
enters detector 21c. 
The output of detector 21c is supplied through a demodulator 29 to a 
controller 28 as reproduction data. Recorded data is modulated in a 
predetermined system using a self clock, and the demodulation system of 
demodulator 29 is associated with the modulation system. 
The output of detector 21c is also supplied to focus/track-servo circuit 
30, which drives lens actuator 21e in accordance with a command from 
controller 28 to control the focusing and tracking of objective 21d so 
that a laser beam is irradiated on the optical card always in a focused 
state. 
Controller 28 controls laser diode 21a through a laser driver 31 to emit a 
laser beam whose intensity is modulated according to the level, "0" or 
"1," of recording data at the time of data recording and emit a laser beam 
with a constant level (normally, "0" level in the data recording) at the 
time of data reproducing. Controller 28 also controls motor-servo circuit 
25, demodulator 29 and focus/track-servo circuit 30 to seek a desired 
track based on the track data demodulated by demodulator 29. 
In response to a command from controller 28, motor servo circuit 25 
controls motor 26 based on the detection signal from rotary encoder 27 so 
that ID sections 14a and 14b and data section 15 of optical card 11 pass 
the beam irradiation point at a constant speed. This constant speed with 
respect to the laser beam at the time of data recording/reproducing is 
required due to the employment of the modulation system using the self 
clock. 
FIG. 3 is a block diagram illustrating the arrangement of a motor-servo 
circuit 25. This motor-servo circuit 25 comprises a read only memory (ROM) 
25a, a digital to analog (D/A) converter 25b a power amplifier 25c, a 
direction discriminator 25d, an up/down counter 25e, a frequency to 
voltage (F/V) converter 25f and a subtractor 25g. 
ROM 25a has addresses which correspond to the individual points within the 
reciprocating range of card 11, and has target data of the conveying speed 
of shuttle 24 at those points stored at the respective addresses. Shuttle 
24, before the start of the operation, is secured to its initial position, 
for example, one edge of shuttle 24 is at the beam irradiation point. 
Therefore, ROM 25a contains data which gradually accelerates shuttle 24 as 
the shuttle moves, sets shuttle 24 at a constant speed when the head of ID 
section 14a reaches the beam irradiation point, and gradually decelerates 
shuttle 24 when the end of ID section 14b passes the beam irradiation 
point. 
When control signals, such as a drive direction signal DIRC and drive 
signal DRIV, from controller 28 are supplied to ROM 25a, the address 
corresponding to the aforementioned initial position is set in ROM 25a. 
The speed target data read out from ROM 25a is supplied to motor 26 through 
D/A converter 25b, subtractor 25g and power amplifier 25c. Subtractor 25g 
is also supplied with a signal from rotary encoder 27 in order to provide 
a feedback control to set the rotational speed of motor 26 at the target 
level. 
The output of D/A converter 25b is supplied to a +terminal of subtractor 
25g. Rotary encoder 27, which is coupled directly to the shaft of motor 
26, outputs a phase A pulse signal and a phase B pulse signal, the order 
in which these pulses are generated is reversed depending on the 
rotational directions of motor 26 and which are supplied to direction 
discriminator 25d. Based on which one of the phases of the phase A and 
phase B signals is leading, direction discriminator 25d discriminates the 
moving direction of shuttle 24. 
Direction discriminator 25d affixes a plus or minus signal in accordance 
with the discriminated shuttle moving direction to either one of the phase 
A and B signals, and sends the resultant signal to F/V converter 25f where 
it is converted to a voltage signal corresponding to the conveying speed 
with the direction considered. This voltage signal is then supplied to - 
terminal of subtractor 25g. 
Direction discriminator sends the above-mentioned one of the phase A and B 
signals to an up count terminal or a down count terminal of up/down 
counter 25e in accordance with the discriminated shuttle moving direction. 
Consequently, the count value of up/down counter 25e is increased or 
decreased by the amount corresponding to the amount of rotation of motor 
26. Accordingly, the address of ROM 25a is updated to be always correspond 
to the current position of shuttle 24 as measured from the initial 
position. 
With the above design, shuttle 24 is gradually accelerated from the initial 
position, and is moved at a constant speed from the point where the head 
of ID section 14a reaches the beam irradiation point to a point where the 
end of ID section 14b passes the beam irradiation point, and is thereafter 
gradually decelerated to stop moving when it reaches pulley 22b. 
In the above recording/reproducing apparatus, when the modulation system at 
the time of recording uses a self clock, for example, in the case of the 
modified frequency modulation (MFM) system or 2-7 modulation system, the 
relative moving speed of the optical card and the laser beam should be 
constant between ID sections 14a and 14b. 
With the above arrangement, however, optical card 11 reciprocates in a 
state loaded in shuttle 24 secured to conveyor belt 23, so that rotary 
encoder 27 detects the positional relationship between shuttle 24 and 
optical head 21, not the positional relationship between optical card 11 
and optical head 21. 
Since motor 26 is controlled based on the position of shuttle 24, if the 
position of optical card 11, when loaded in shuttle 24, is shifted in the 
track direction, or the position of ID sections 14a and 14b in card 11 is 
shifted due to the error in manufacturing, parts of ID sections 14a and 
14b, and data section 15 at the worst, become the acceleration and 
deceleration regions, thus resulting in inaccurate data 
recording/reproducing/ 
A conventional solution to this problem is to provide a greater constant 
moving range (distance) for shuttle 24 in order to allow for the deviation 
of optical card 11 which may be caused when it is loaded in the shuttle or 
when it is manufactured. 
However, this measure needs a longer time for reciprocating the shuttle 24, 
thus lengthening the access time. 
SUMMARY OF THE INVENTION 
It is an object of this invention to provide an accurate and high speed 
data recording/reproducing in an optical card recording/reproducing 
apparatus, which moves a shuttle in which an optical card is loaded and an 
optical head for emitting a laser beam in relative to each other to scan 
tracks on the card with the laser beam for data recording on or data 
readout from a target track. 
The optical card recording/reproducing apparatus according to this 
invention comprises a holding section for receiving an optical card, an 
optical head for emitting a light beam, a motor for moving the holding 
section and the optical head in relative to each other, a data-area 
detector for detecting a positional relationship between the data area of 
the optical card and the holding section, and a motor-servo circuit for 
controlling driving of the motor based on a detection result attained by 
the data-area detector to thereby control a relative moving speed of the 
holding section and the optical head.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
An optical card recording/reproducing apparatus according to one embodiment 
of this invention will be explained below referring to the accompanying 
drawings. Since this embodiment has the same general arrangement as that 
of the conventional apparatus shown in FIG. 2, the arrangement of this 
embodiment will thus be omitted from the explanation. This embodiment is 
characterized in its motor-servo circuit shown in a block diagram of FIG. 
4. The numerals designating the components in FIG. 4 are the same as those 
number which designate corresponding or identical components shown in fIG. 
3, thus, the detailed explanation thereof is omitted. 
Motor-servo circuit 25 of this embodiment only differs from the one shown 
in FIG. 3 in that it is further provided with a data-area detector 41 and 
a preset-data memory 42. 
Preset-data memory 42 sotes an address data of ROM 25a corresponding to the 
position of the head of identifier section 14a or 14b measured from the 
initial position. The present data corresponds to the length necessary for 
accelerating the shuttle to the desired speed. 
Binary data corresponding to the reflection light of optical card 11 is 
supplied from controller 28 (FIG. 2) to data-area detector 41, which in 
turn determines from which section within the laser-beam irradiated region 
of optical card 11 the light is reflected: ID section 14a, ID section 14b, 
or data section 15. Upon detecting which one of the sections 14a, 14b, or 
15 of the beam irradiated region the light is reflected from, data-area 
detector 41 sends its detection signal to a preset terminal of up/down 
counter 25e. In response to the leading edge of the detection signal, 
up/down counter 25e fetches the data of preset-data memory 42 as a preset 
value. 
Accordingly, even if card 11 is erroneously loaded in shuttle 24 or the 
position of ID sections 14a, 14b in card 11 are shifted in manufacturing, 
the count value of up/down counter 25e will be corrected at the time the 
data area is detected, thus representing the accurate position of optical 
card 11 with respect to the light beam. Controlling motor 26, based on the 
data read out from ROM 25a in accordance with the count value, may permit 
ID section 14a data section 15 and ID section 14b of optical card 11 to 
pass the irradiation point of the laser beam from optical head 21 at an 
accurate constant speed. Thus, it is not necessary that the card access 
time be lengthened and the recording/reproducing speed be reduced. 
FIG. 5 gives a detailed illustration of data-area detector 41. This 
detector 41 mainly comprises re-triggerable one-shot multivibrators 51 and 
52 and a NAND gate 53. The binary data from controller 28 is supplied to 
an input terminal B of multivibrator 51, and the Q output of multivibrator 
51 is supplied to an input terminal B of multivibrator 52. The Q output of 
multi-vibrator 51 and the QQ output of multivibrator 52 are supplied 
through NAND gate 53 to up/down counter 25e. Here, the Q output of 
multivibrator 51 is supplied to NAND gate 53 through an integration 
circuit constituted by a resistor R2 and a capacitor C2. For example, 
74LS123, products of Texas Instruments, may serve as these multivibrators 
51 and 52. 
Multivibrators 51 and 52 are each externally coupled with a resistor and a 
capacitor for setting their time constants. These multivibrators 51 and 52 
use the same capacitor C1 but use different resistors; R1 for the former 
multivibrator 51 and 8R1 for the latter whose resistance is eight times 
greater than that of R1. The time constant determined by C1 and R1 is set 
to correspond to time tw which is slightly greater than the data period of 
one binary data bit. 
Multivibrator 51 outputs a single pulse (positive pulse) with a pulse width 
tw from the output terminal Q when the level at its input terminal B 
changes to "1" from a "0" level, and multivibrator 52 outputs a single 
pulse (negative pulse) with a pulse width 8tw from the inverted output 
terminal QQ when the level at its input terminal B changes to "1" from a 
"0" level. 
With reference to the timing charts shown in FIGS. 6A to 6E, the operation 
of this embodiment will now be described. When drive direction signal DIRC 
and drive signal DRIV from controller 28 are supplied to ROM 25a, data is 
read out from ROM 25a at the address corresponding to the initial position 
of the shuttle and motor 26 is driven. This causes shuttle 24 to be set in 
an accelerated motion. 
When ID section 14a or 14b of optical card 11 comes to a point whereat the 
laser beam from optical head 21 is irradiated, data area detector 41 
detects the head of ID section 14a or 14b based on a readout signal 
(binary data). According to this embodiment, to prevent erroneous 
detection of the ID section due to reading a signal generated by dust or 
the like, the detected area is not considered to be holding data therein 
unless more than one byte of sequential data is output therefrom. 
When binary data as shown in FIG. 6A is supplied to multivibrator 51, the Q 
output of multivibrator 51 is set at a "1" level (see FIG. 6B) to be in 
synchronous with the rising of the first pulse. So as to be in synchronism 
with the rising of the QQ output of multivibrator 51, the inverted Q 
output of multivibrator 52 shifts to a "0" level as shown in FIG. 6C. 
When multivibrator 51 receives more than one byte (8 bits) of input data in 
succession, it remains in a triggered state so that the Q output remains 
at a "1" level. However, the inverted QQ output of multivibrator 52 
returns to a "1" level from a "0" level after time 8tw has elapsed, as 
shown in FIG. 6C. 
The output of the integration circuit to which the Q output of 
multivibrator 51 shown in FIG. 6B becomes "1" level with a slight delay 
after the Q output of multivibrator 51 becomes "1" level, as shown in FIG. 
6D. 
When the inverted QQ output of multivibrator 52 as shown in FIG. 6C becomes 
"1" level, i.e., at time 8tw after the rising of the first pulse of the 
binary data, the output of NAND gate 53 changes from "1" level to "0" 
level as shown in FIG. 6E to become a data-area detection signal. 
When no more binary data is received, multivibrator 51 has its Q output 
changed to "0" level from "1" level at time tw after the rising of the 
last pulse, as shown in FIG. 6A. As shown in FIG. 6D, the output of the 
integration circuit becomes "0" level with a slight delay from the 
occurrence of the above event, so that the output of NAND gate 53 becomes 
"1" level as shown in FIG. 6E, thus stopping the generation of the 
data-area detection signal. 
As should be obvious from the above, the Q output of multivibrator 52 is 
not changed to "1" level from "0" level unless more than one byte of 
continuous binary data appears. Without detection of more than one byte of 
continuous binary data, therefore, the data area is not detected, thus 
preventing erroneous detection of the data area even if binary data is 
singly outputted due to detection of dust or the like. 
As has been explained above, according to this embodiment, the positional 
relationship of the data area of an optical card with respect to the 
optical head can be detected and the data-readout address in ROM 25a, 
which controls motor speed 26 can be compensated according to the detected 
relationship. Even if the position of the optical card loaded in the 
shuttle is deviated or the data area of the card is shifted during 
manufacturing, data can be recorded/reproduced accurately and at a high 
speed. 
The data area may be detected by recording a pattern different from an 
address in advance in ID sections 14a and 14b and detecting the pattern. 
In this case, the data stored in the preset memory should represent the 
recording position of the pattern. The amount of rotation of the motor may 
be detected by a linear encoder instead of a rotary encoder. In addition, 
the ID sections need not be provided at both end portions of an optical 
card, and the optical head may be moved instead of the shuttle along the 
tracks on the optical card.