Optical card processing apparatus with means for determining a relative position between head and card

An information processing apparatus according to the present invention includes a head for performing recording of information on and/or reproduction of information from a recording medium, a carriage on which the recording medium is loaded and being adapted to be movable relative to the head, a first detector for detecting a loading position of the recording medium with respect to the carriage, a second detector for detecting a position of the carriage in a moving direction and a circuit for outputting a signal representing that the medium is loaded at predetermined position with respect to the head on the basis of outputs from the first and second detectors.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an information processing apparatus for 
moving a recording medium mounted on a carriage with respect to a head to 
record information on the medium and/or reproduce the information from the 
medium. 
2. Description of the Related Art 
Disk, card-like, and tape-like information recording media are known as 
conventional information recording media. Some information recording media 
can record and reproduce information, and some can only reproduce 
information. In a recordable information recording medium, information 
tracks are scanned with a light beam spot having a small diameter and 
modulated in accordance with given recording information to record the 
information as an optically detectable information bit array. 
In order to reproduce information of a recording medium, a given 
information track is scanned with a light beam having a power low enough 
not to record information on the recording medium, and a beam reflected by 
the surface of the medium or transmitted through the medium is detected. 
Therefore, information can be read from an information bit array of an 
information track. 
In an optical information processing apparatus for recording or reproducing 
information on or from an information recording medium, a so-called 
"optical head" must be used to irradiate the recording medium with a light 
beam spot and detect a beam reflected by or transmitted through the 
medium. The optical head is movable in an information tracking direction 
and a direction perpendicular to the information tracking direction with 
respect to the recording medium. A relative displacement allows scanning 
of the information track with a light beam spot. In the optical head, part 
of the optical system, e.g., an objective lens is held to be movable 
independently in a direction along its optical axis (focusing direction) 
and a direction (tracking direction) perpendicular to the optical axis and 
in the information tracking direction of the recording medium. The 
objective lens is generally held through an elastic member. Movement of 
the objective lens in the above focusing and tracking directions is 
generally performed by an actuator utilizing an electromagnetic 
interaction. 
Recording and reproduction of a card-like optical information recording 
medium (optical card) shown in FIG. 1 will be described below. 
Referring to FIG. 1, a large number of parallel information tracks 2 extend 
on an information recording surface of an optical card 1 in the D.sub.1 
-D.sub.2 direction. A home position 3 is defined on the information 
recording surface and serves as a reference position for access of the 
information tracks 2. The information tracks 2 are arranged in an order of 
2-1, 2-2, 2-3, . . . from the side near the home position 3. Tracking 
tracks (e.g., 4-1, 4-2, 4-3, . . . ) are formed adjacent to the 
information tracks 2 (e.g., 2-1, 2-2, 2-3, . . . ) on the information 
recording surface. The tracking tracks are utilized as a guide for 
auto-tracking (AT) a light beam spot in the recording and reproduction 
modes so as to accurately trace a predetermined information track with the 
light beam spot. In an optical information recording/reproducing 
apparatus, AT servo control is performed for AT. According to AT servo 
control, when a deviation of the light beam spot from the information 
track is detected (i.e., an AT error), a detection signal is negatively 
fed back to the tracking actuator to move the objective lens relative to 
the optical head so as to adjust the position of the objective lens in the 
tracking direction. Therefore, the light beam spot can trace the 
information tracks. 
When the information tracks are scanned with the light beam spot in the 
information recording/reproduction mode, the light beam must be focused to 
form a spot having an optimal size (i.e., the light beam must be set in an 
in-focus state) on the information recording surface of the optical card. 
For this purpose, auto focusing (AF) servo is performed in the optical 
information recording/reproducing apparatus. In AF servo control, a 
deviation of the light beam spot from an in-focus state (i.e., an AF 
error) is detected, and the detection signal is negatively fed back to the 
focusing actuator, thereby moving the objective lens with respect to the 
optical head such that the objective lens is aligned with the focusing 
direction. Therefore, the light beam spot can be set in an in-focus state 
on the surface of the optical card. 
Light beam spots S.sub.1 and S.sub.3 in FIG. 2 are used for tracking, and 
light beam spot S.sub.2 is used for performing focusing control, forming 
an information pit in the recording mode, and detecting the information 
pit in the reproduction mode. Address portions 6-1, 6-2, 6-3, . . . are 
preformatted on the information tracks 2-1, 2-2, 2-3, . . . to 
discriminate the respective information tracks. Data portions 5-1, 5-2, 
5-3, . . . follow the address portions 6-1, 6-2, 6-3, . . . . When an 
information track is scanned with the light beam spot S.sub.2, a track 
number is read out from the address portion, and information is recorded 
in the data portion or read out therefrom to perform reproduction. 
When the optical card having the above arrangement is used in an optical 
information processing apparatus, the following card feeding mechanism 
must be used. The card feeding mechanism has an arrangement shown in FIG. 
3. The optical card 1 is fixed on a carriage 44 through card holders 8. 
Each of the card holders 8 has a groove-like shape. When the optical card 
1 is slid along the upper surface of the carriage 44 from the backward 
direction, and abuts against a card abutment plate 7, the card holders 8 
hold the optical card 1. The carriage 44 has slide bearings 46 on both its 
sides, and parallel slide shafts 47 extend through the corresponding slide 
bearings, so that the carriage 44 can be moved along the slide shafts 47 
in a direction D.sub.1 (or a direction D.sub.2 opposite to the direction 
D.sub.1). A coil core is arranged below the carriage 44. A coil 43 is 
wound around the coil core. Yokes 48 and 49 fixed on the main body of the 
apparatus extend above and below the coil 43 along the moving direction of 
the carriage 44. The yokes 48 and 49 are coupled together with a yoke 51 
extending through the center of the core of the coil 43, and both ends of 
the yokes 48, 49, and 51 are connected to iron pieces 52, thereby 
constituting a magnetic circuit. For this reason, permanent magnets 53 and 
54 are arranged in the yokes 48 and 49 such that their N poles oppose each 
other and S poles oppose each other. With this arrangement, when current 
flows through the coil 43, a drive force for driving the carriage 44 in 
the direction D.sub.1 or D.sub.2 is obtained in accordance with the 
direction of the current. 
A linear encoder 31 is arranged on one side of the carriage 44. The linear 
encoder comprises a belt having parallel slits extending in the direction 
D.sub.1 /D.sub.2 and a pulse detector such as a photodiode moved together 
with the carriage 44 to count the slits of the belt. Therefore, a 
displacement of the optical card upon movement of the carriage 44 can be 
indirectly detected. 
A light-shielding plate 35 is also disposed on one side of the carriage 44 
to extend parallel to the direction D.sub.1 /D.sub.2. A position sensor 32 
(left sensor 33 and right sensor 34 each consisting of a light-emitting 
element and a light-receiving element) for detecting the position of the 
carriage 44 upon shielding of light by the light-shielding plate 35 is 
fixed on the apparatus main body. These sensors are so-called 
photointerrupters. The mounting position of the position sensor 32 is set 
such that the light-shielding plate 35 shields light incident on the left 
sensor 33 when the carriage 44 is accelerated from the right end in the 
direction D.sub.1 and reaches a constant speed, and that the shielding 
plate 35 shields light incident on the right sensor 34 when the carriage 
44 is accelerated from the left end in the direction D.sub.2 and reaches a 
constant speed. The sensors 33 and 34 of the position sensor 32 are set at 
high level when light is not shielded by the light-shielding plate 35. 
However, when light is shielded by the light-shielding plate 35, the 
sensors 33 and 34 are set at low level. 
In the optical information processing apparatus having the card feeding 
mechanism described above, after the optical card 1 is loaded on the 
carriage 44, the carriage 44 is accelerated in the direction D.sub.1 from 
the right end. When the carriage 44 reaches a constant speed, addressing 
is performed from a time when the left sensor 33 goes low to a time when 
the right sensor 34 goes high. Data write/read access is performed. When 
the right sensor 34 goes high, a predetermined number of pulses are 
counted by the linear encoder 31. When the count of the linear encoder 31 
reaches the predetermined number, a reverse command is output to reverse 
the drive direction of the carriage 44 (i.e., the direction of the current 
supplied to the coil 43 is reversed). After the reverse operation, the 
carriage 44 is accelerated in a direction D.sub.2. When the right sensor 
34 goes low and then the left sensor 33 goes high after the carriage 44 
reaches a constant speed, a predetermined number of pulses are counted by 
the linear encoder 31. When the count of the linear encoder 31 reaches the 
predetermined number, a reverse command is output to reverse the drive 
direction of the carriage 44. 
The reverse operation, addressing, data write/read access are performed 
with reference to the carriage position in the optical information 
processing apparatus described above. Unless the optical card 1 is 
accurately loaded, operation errors such as an addressing timing error 
occur. In order to solve this problem, a card position detector 9 shown in 
FIG. 3 is arranged in the conventional optical information processing 
apparatus. A reflection photoswitch is often used as the card position 
detector 9. When the optical card 1 abuts against the card abutment plate 
7 and is accurately loaded on the carriage 44 while the carriage 44 is 
located at a given position, light reflected by an end of the optical card 
1 returns to the card position detector 9. For this reason, when the 
optical card 1 is loaded in front of the card abutment plate 7, no light 
reflection from the end of the optical card 1 is detected. Therefore, an 
inaccurate card position is discriminated. 
An apparatus for detecting a loading state of a card by using an optical 
head in place of the above card position detector is described in Japanese 
Patent Laid-Open (Kokai) No. 61-280073. 
In either conventional apparatus, the card loading state is detected. When 
the card loading position on the carriage is inaccurate, re-loading is 
time-consuming. If the carriage 44 is fed without re-loading the optical 
card 1, recording/reproduction is performed on the information tracks in a 
region where the moving speed of the carriage is unstable. Thus, accurate 
recording/reproduction cannot be performed. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to solve the conventional problems 
described above and to provide an information processing apparatus capable 
of performing accurate recording and/or reproduction without re-loading a 
recording medium even if the recording medium is not accurately loaded on 
a carriage. 
In order to achieve the above object of the present invention, there is 
provided an information processing apparatus comprising: 
a head for performing recording and/or reproduction of information on 
and/or from a recording medium; 
a carriage loaded with the recording medium thereon and movable with 
respect to the head; 
a first detector for detecting a loading position of the recording medium 
with respect to the carriage; 
a second detector for detecting a position of the carriage in a moving 
direction; and 
a circuit for outputting a signal representing that the medium is located 
at a predetermined position with respect to the head, on the basis of 
outputs from the first and second detectors.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 4 is a schematic view showing an information processing apparatus 
according to an embodiment of the present invention. A card feeding 
mechanism of this embodiment is obtained by omitting the card position 
detector 9 from the card feeding mechanism shown in FIG. 3. A description 
of an arrangement and a function of the card feeding mechanism will be 
omitted. Referring to FIG. 4, an optical information recording/reproducing 
apparatus 19 is connected to a central processing unit (CPU) 50 serving as 
a host controller. In the recording/reproducing apparatus of this 
embodiment, an external optical card 1 on a carriage 44 can be loaded 
inside the apparatus through a convey mechanism (i.e., a linear motor 
including the coil 43). When recording/reproduction is completed, the 
optical card 1 can be ejected from the apparatus. In the 
recording/reproducing apparatus, a phase-locked loop (PLL) control circuit 
is arranged to control the carriage 44 to be driven at a constant speed. 
More specifically, a reference frequency signal for linear motor constant 
speed control is input from a reference frequency oscillator 36 to a large 
scale integrated circuit (LSI) 37 for driving a motor. A feedback pulse 
signal from a linear encoder 31 is also input to the LSI 37. A speed 
control output j and a phase control output k are output to an adder 38 in 
accordance with control signals from a microprocessing unit (MPU) 10 
arranged in the recording/reproducing apparatus 19. The adder 38 adds the 
outputs j and k, and an output from the adder 38 is amplified by an 
amplifier 39. The amplified signal is filtered by a loop filter 40, and 
the filtered output is supplied to a driver 41. The driver 41 receives an 
output signal for driving the linear motor and outputs it to a coil 43 
through a direction switching device 42. The direction switching device 42 
switches the direction of the current in response to a D.sub.1 /D.sub.2 
switch signal from the MPU 10. Therefore, the D.sub.1 /D.sub.2 direction 
of the carriage 44 can be switched. 
When the operation of the carriage 44 progresses, a position detection 
signal from a position sensor 32 consisting of a light-shielding plate 35 
mounted on the carriage and right and left sensors 34 and 33 is input to 
the MPU 10. This input signal is used to control the reverse operation of 
the carriage and also serves as a gate signal for a demodulation circuit 
45 for information reproduction. The MPU 10 detects the position of the 
carriage on the basis of an output signal from the position sensor 32 and 
an output pulse from the linear encoder 31. At the same time, the MPU 10 
detects a position (i.e., an information track position along the 
longitudinal direction) of the optical card 1, i.e., a position of an 
address portion, upon reception of the reproduction signal for the address 
portion in the information track of the optical card 1 after demodulation 
of the reproduction signal by demodulation circuits. 
A light beam radiation optical system 17 including a light source for 
writing or reading information in or from the optical card is prepared to 
form light beam spots (three light beam spots S.sub.1, S.sub.2, and 
S.sub.3 in this embodiment as previously described) on the optical card 1 
in the information recording mode and/or the information reproduction 
mode. In order to receive reflected beams of the three light beam spots, 
photodetectors 22, 23, and 24 are arranged in this embodiment. Output 
signals from the photodetectors 22, 23, and 24 serve to supply a 
reproduction signal from an information track to the demodulation circuit 
45 and a detection signal to an AT/AF control circuit 11. The AT/AF 
control circuit 11 drives an AF actuator 15 in accordance with the 
detection signal and control timing signals from the MPU 10 to move the 
objective lens of the light beam radiation optical system 17 in a 
direction (Z direction) perpendicular to the surface of the optical card 1 
and to perform a focusing (in-focus) operation of the light beam spots. 
The AT/AF control circuit 11 also drives an AT actuator 16 in accordance 
with the detection signal and control timing signals from the MPU 10 to 
move, e.g., the objective lens and hence the light beam spot on the 
surface of the optical card 1 in a direction Y (i.e., a direction 
perpendicular to the directions R and Z), thereby achieving AT control. A 
motor 13 is driven in accordance with a control signal from the MPU 10 to 
move an optical head 18 in the tracking direction. The optical head 18 
includes the light beam radiation optical system 17, the photodetectors 
22, 23, and 24, the AF actuator 15, and the AT actuator 16. A modulation 
circuit 12 drives the light beam radiation optical system 17 to record the 
information signal from the MPU 10 or outputs a light beam for reading out 
the information Go obtain a reproduction signal. 
FIG. 5 is a perspective view showing a detailed arrangement of the optical 
head 18. The optical head 18 includes a collimator lens 28, a beam shaping 
prism 29, a beam splitting diffraction grating 30, a beam splitter 20, a 
reflection prism 25, an objective lens 26, and a focus aberration 
converging lens system 21. 
A laser beam emitted from a semiconductor laser 27 is incident as a 
divergent beam on the collimator lens 28. The divergent beam is collimated 
by the collimator lens 28. This collimated beam is shaped by the beam 
shaping prism 29 to have a predetermined light intensity distribution. The 
shaped beam is incident on the diffraction grating 30 and is split into 
three effective beams (i.e., 0th-order diffracted beam and .+-.1st-order 
diffracted beams). These three beams are incident on the beam splitter 20 
and are transmitted straight. The beams are then reflected by the 
reflection prism 25 and are incident on the objective lens 26. The beams 
are thus focused through the objective lens 26, thereby forming three beam 
spots, i.e., a beam spot S.sub.1 (corresponding to the +1st-order 
diffracted beam), a beam spot S.sub.2 (corresponding to the 0th-order 
diffracted beam), and a beam spot S.sub.3 (corresponding to the -1st-order 
diffracted beam) on the optical card 1. The positional relationship 
between the three beams on the optical card 1 has been described with 
reference to FIG. 2. Reflected beams of the three beam spots formed on the 
optical card 1 are almost collimated through the objective lens 26. The 
collimated beams are reflected by the reflection prism 25 and are further 
reflected by the beam splitter 20. The reflected beams are converged by 
the converging lens system 21. The converged beams are respectively 
incident on the photodetectors 22, 23, and 24. FIG. 6 schematically 
illustrates the respective photodetectors, and the photodetector 23 is a 
four-split beam splitter. 
A method of detecting a loading state of the optical card on the carriage 
44 in this embodiment will be described with reference to FIGS. 7A to 7L. 
FIGS. 7A to 7H show relationships among the card feeding speed, beam spot 
positions on the card, detection signals from the respective sensors, and 
control signals in the reading mode. In this case, a state representing an 
appropriate loading state of the optical card 1 on the carriage 44 is 
exemplified. More specifically, the optical card 1 is accelerated in a 
direction D.sub.1 from a point A and reaches a constant speed as a 
reproduction speed at a point B.sub.1. A left sensor output a goes low at 
a point C. A predetermined number of encoder pulses are counted from the 
point C. An address reproduction control signal c falls at a point I and 
is kept low during a predetermined interval (IJ). Meanwhile, the address 
portion 6-1 is reproduced to output an address reproduction signal d. The 
address reproduction signal d is a binary signal obtained by performing 
appropriate processing suitable for frequency and amplitude 
characteristics of the reproduction signal of the address portion. In this 
case, the address reproduction signal is used as a window for card 
position detection. Edges Q.sub.1 and Q.sub.2 of the address reproduction 
signal are detected. If the edges Q.sub.1 and Q.sub.2 fall within the 
interval IJ, the card is loaded on the carriage 44 within an allowable 
range, i.e., within an allowable range for correcting the reverse position 
of the carriage 44. If one or both of the edges Q.sub.1 and Q.sub.2 does 
not fall within the interval IJ, improper loading of the optical card on 
the carriage 44 is determined and re-loading of the optical card is 
determined to be required. 
Thereafter, a predetermined number of linear encoder pulses are counted 
from, e.g., the leading edge Q.sub.1 of the address reproduction signal. A 
data reproduction control signal e falls at a point K and is kept low 
within a predetermined interval. The data reproduction control signal e is 
a timing signal representing reproduction of a data portion. For example, 
the signal e is used when reproduction characteristics of the address and 
data portions are different from each other and reproduction processing is 
switched to match with reproduction of the data portion or when timings 
with other signals are matched. 
FIGS. 7I to 7L show a case wherein an error of loading of the optical card 
on the carriage 44 falls within the allowable range. In this case, an 
address reproduction control signal c' is output at the same timing as in 
FIG. 7E. However, like the address reproduction signal d', the address 
reproduction control signal is shifted by an amount corresponding to a 
difference between a distance between the point c and the edge Q.sub.1 ' 
and a distance between the point c and the edge Q.sub.1 or CQ.sub.1 
'-CQ.sub.1 as compared with the reference interval of an amount 
corresponding to a distance between the point c and the edge Q.sub.1 or 
CQ.sub.1 of FIG. 7D in the direction D.sub.2. The optical card is 
accelerated in the direction D.sub.1 from the point A and reaches an 
almost constant speed at the point B. However, the speed is unstable in an 
interval BB.sub.1. It is thus preferable to start the reproduction 
operation of the recording area from a point B.sub.1. Similarly, the speed 
is stabilized from a point G.sub.1 during scanning in the direction 
D.sub.2. At the position of the optical card shown in FIG. 7I, it is 
difficult to perform accurate reproduction since the speed unstable region 
between the intervals GG.sub.1 reaches the right end of the data area 
during scanning of the carriage 44 in the direction D.sub.2. According to 
the present invention, the scanning reverse position of the carriage 44 is 
shifted by the amount CQ.sub.1 '-CQ.sub.1 which is a shift from the 
reference position. In other words, during carriage feeding in the 
direction D.sub.1 in FIG. 7D, deceleration is started with a delay of an 
amount DE from a point D. However, as shown in FIG. 7L, compensation is 
conducted so that deceleration is started with a delay of DC'=DE+(CQ.sub.1 
'-CQ.sub.1). Although deceleration is basically started with a delay of an 
amount CH from a point C in carriage feeding in the direction D.sub.2, 
compensation is performed to start deceleration with a delay of 
CH'=CH-(CQ.sub.1 '-CQ.sub.1). In this manner, the loading position errors 
of the optical card 1 can be compensated to always scan the same area of 
the optical card 1 with the light beam spot and to achieve recording and 
reproduction. 
This compensation may be performed for every carriage feeding. However, the 
compensation may be performed for every appropriate interval. 
Alternatively, the compensation may be performed once upon insertion of 
the card, and the compensation value may be replaced with a representative 
value in the subsequent operations. 
In the above embodiment, the address portion which is preformatted in each 
track is used to detect a card position. However, a preformatted recording 
portion (e.g., a home position 3 in FIG. 1) may be used for detecting a 
card position. 
In the above embodiment, while the leading and trailing edges Q.sub.1 and 
Q.sub.2 of the address reproduction signal fall within the low-level 
interval of the address reproduction control signal c, loading of the card 
falls within the allowable range of the reverse position of the carriage 
possible to be compensated. However, even if one of the edges Q.sub.1 and 
Q.sub.2 falls within the low-level interval of the address reproduction 
control signal c, loading may fall within the reverse enable range of the 
carriage. In the above embodiment, a low level of the address reproduction 
control signal is used as a window for card detection. However, a window 
signal obtained in a similar technique may be used to detect the card 
position. The window signal is generated by using an output from the 
position detector and the pulses from the linear encoder. However, a 
window signal may be directly generated by using another position sensor. 
In the above embodiment, the detected loading position information of the 
optical card is also used to compensate for the carriage reverse timing. 
However, when a medium in which address and data signals are recorded by 
different schemes is used, the detected information described above may be 
used for a switching scheme of a reproduction signal processing circuit. 
This will be described below. 
FIG. 8 is a block diagram showing a demodulation circuit 45 used in the 
second embodiment of the present invention. The demodulation circuit is 
incorporated in the apparatus, as shown in FIG. 4. 
FIG. 9A is an enlarged view showing a recording surface of an optical card 
used in this embodiment, FIG. 9B shows a scanning speed during feeding of 
the optical card in the reading mode and a moving state of the optical 
card, and FIGS. 9C to 9M show relationships between radiated positions of 
the light beam spots on the optical card and the respective control 
signals. FIGS. 10A to 10M are views showing relationships among the 
scanning speed of the card 1, the radiated positions of a light spot on 
the card, and the respective control signals in a write/verify mode. FIGS. 
10A to 10M correspond to FIGS. 9A to 9M, respectively. 
Switching of the address/data reproduction in the reading mode will be 
described with reference to FIGS. 8 and 9A to 9M will be described below. 
When an optical card 1 is moved in a direction D.sub.1, a switch SW1 is 
switched to a left sensor 33 side in response to a D.sub.1 /D.sub.2 
direction signal. An output a from the left sensor 33 is input to a 
switching signal generating circuit 55. The optical card 1 is gradually 
moved in the direction D.sub.1 from a point A (FIG. 9B) and is accelerated 
to reach a constant reproduction speed from a point B. When the output a 
from the left sensor goes low at a point C (FIG. 9C), linear encoder 
pulses g are counted. When a predetermined number of linear encoder pulses 
are counted, an address reproduction control signal c falls from a point I 
(FIG. 9E) and is kept low during a predetermined interval (the I-J 
interval). The address reproduction control signal c is input to an 
address/data switching circuit 56. 
A reproduction signal read from an information track 2-1 is input to a 
processing circuit 57 for a data portion and a processing circuit 58 for 
an address portion. The processing circuit 58 processes the address 
reproduction signal d of the address portion 6-1 (FIG. 9A) of the 
reproduction signal in accordance with its frequency and amplitude 
characteristics to output a binary signal. The binary signal is input to 
the address/data switching circuit 56 and a detecting circuit 59 for the 
address portion. 
The address/data switching circuit 56 outputs the address reproduction 
signal d input from the processing circuit 58 during the low-level 
interval (i.e., the I-J interval) of the address reproduction control 
signal c. The detecting circuit 59 supplies a detection signal of the edge 
Q (leading or trailing edge) of the address reproduction signal d to the 
switching signal generating circuit 55 through a switch SW2. 
The switching signal generating circuit 55 counts a predetermined number 
(.alpha.) of linear encoder pulses g from the edge Q of the address 
reproduction signal d. The data reproduction control signal e falls at a 
point K and is kept low during a predetermined interval (i.e., K-L 
interval which is an interval ".beta."). The data reproduction control 
signal e is input to the address/data switching circuit 56. 
During the low-level interval of the data reproduction control signal e, a 
data reproduction signal f of the data portion 5-1 input from the 
processing circuit 57 is output from the address/data switching circuit 
56. 
Meanwhile, when the address portion detection signal which is transmitted 
through the detecting circuit 59 is input to a counter A60 and a counter 
B61, counting of linear encoder pulses g is started. The counter A60 
continuously counts the pulses (.gamma.) until a right sensor output b 
goes high. The counter B61 continuously counts pulses (.delta.) until a 
point J where the address reproduction control signal c goes high. 
The optical card 1 is decelerated at a point E and its drive direction is 
reversed in the direction F. The optical card 1 is then accelerated and 
reaches a predetermined reproduction speed from a point G. In this case, a 
track jump occurs at the normal reverse position point F, and the 
information track 2-2 is irradiated with the beam spot S2. At this point 
F, the switch SW1 is switched so that the right sensor output b is passed. 
A count .gamma. counted by the counter A60 is used to perform a 
calculation .epsilon.=.gamma.-.alpha.-.beta. by an arithmetic logic unit 
62. Values .alpha. and .beta. are eigenvalues, and the respective value 
.gamma. is changed when the optical card 1 is inclined relative to the 
carriage 44. When the right sensor output b goes low at the point D, the 
calculated number .epsilon. (FIG. 9I) of linear encoder pulses are 
counted. A data reproduction control signal e" falls at a point R (FIG. 
9I) and is kept low during a predetermined interval (an R-S interval, 
.beta. pulses ) . The data reproduction control signal e" is input to the 
address/data switching circuit 56. 
Meanwhile, the reproduction signal reproduced from the information track 
2-2 is input to the processing circuits 57 and 58 and is converted into a 
binary signal, so that a data reproduction signal f" of the data portion 
5-2 is output first. During the low-level interval of the data 
reproduction control signal e", the data reproduction signal f" of the 
data portion 5-2 input from the processing circuit 57 is output from the 
address/data switching circuit 56. 
The arithmetic logic circuit 62 performs a calculation 
.zeta.=.gamma.-.delta.. After linear encoder pulses g corresponding to the 
".zeta." are counted from the point D, the address reproduction control 
signal c" falls at a point T and is kept low during a predetermined 
interval (i.e., a T-U interval). This signal is input to the address/data 
switching circuit 56. When an address portion reproduction Signal d" 
output from the processing circuit 58 is input to the address/data 
switching circuit 56, the address portion reproduction signal d" is output 
from the address/data switching circuit 56 during the low-level interval 
of the address reproduction control signal c". 
FIGS. 10A to 10M show relationships between the scanning speed of the 
optical card, the portions of the optical card 1 irradiated with the light 
beam spots, and the respective control signals in a write/verify mode. 
In the recording mode, the power of the light beam from a light beam 
radiation optical system 17 must be increased. For this purpose, the 
scanning speed of the light beam is lower than that in the reproduction 
mode. 
Information write access is performed in the forward path during optical 
card movement. The track in which the information is written in the 
forward path is scanned at a high speed to reproduce the information in 
the backward path so as to confirm the recorded state. 
This mode is called a write/verify mode. 
A difference between a data address switching operation in the write/verify 
mode and that in the reading mode is that a recording control signal h 
falls at a point K' and is kept low during a predetermined interval (a 
K'-L' interval, .beta.' count) when the linear encoder pulses are counted 
from the edge Q of the address portion reproduction signal d during a 
predetermined interval (corresponding to .alpha.' count). The recording 
control signal h is used as a control signal for sending out a modulated 
recording signal i for writing recording data. 
In the above embodiment, the linear encoder pulses are counted. However, if 
the moving distance of the carriage can be detected, a rotary encoder may 
be used. Alternatively, another drive technique may be utilized although 
the carriage is driven using a linear motor. 
The present invention is not limited to the particular embodiments 
described above, and various changes and modifications may be made within 
the spirit and scope of the invention. Each of the above embodiments 
exemplifies an optical information processing apparatus. However, the 
present invention is also applicable to a magnetic information processing 
apparatus using a magnetic head. In addition, the shape of the medium is 
not limited to a card-like shape. The present invention is also applicable 
to an apparatus using a disk-like or tape-like medium. Other various 
applications may be incorporated in the present invention without 
departing from the scope of the appended claims.