Dynamic magnetic information storage or retrieval – Recording on or reproducing from an element of diverse utility – Card
Reexamination Certificate
2000-07-14
2002-06-04
Neal, Regina Y. (Department: 2651)
Dynamic magnetic information storage or retrieval
Recording on or reproducing from an element of diverse utility
Card
C360S046000, C360S051000, C235S449000, C235S436000
Reexamination Certificate
active
06400517
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a magnetic media processing device for reading magnetic data magnetically recorded on a magnetic media such as a magnetic card to be processed thereby.
2. Description of the Related Art
A conventional magnetic card processing device provided with a function for reading and writing magnetic data on a magnetic card employs a conveyance monitoring method for performing the reading-and-writing process with a high accuracy even though the conveyance speed of the magnetic card varies.
The conventional magnetic card processing device employing the conveyance monitoring method is shown in FIG.
1
. Upper and lower pair of rollers
11
and
12
conveying a magnetic card
10
are arranged in a direction of conveyance, and rotated in a predetermined conveyance direction by pulleys
13
fixed on ends of shafts of the rollers which are driven by a motor
14
through a worm, a worm wheel and a belt
15
. The motor
14
is controlled to drive the conveyance rollers
11
and
12
and convey the magnetic card
10
in a predetermined direction.
A magnetic head
16
for executing a magnetic process of reading and writing magnetic data is disposed in a middle position of the pair of conveyance rollers
11
to correspond to a magnetic stripe
17
of the magnetic card
10
.
Beside the head
16
there are disposed a detection roller
19
of a rotary encoder
18
and the magnetic head
16
on the same line in a width direction of the conveyance direction. The detection roller
19
is pushed by a pusher roller
20
to catch the conveyed magnetic card
10
, whereby the roller
19
is rotated by the conveyance of the magnetic card
10
.
The detection roller
19
is connected with a slit disc
21
having slits formed on a circumference thereof at predetermined equal intervals each of which is detected by a light projector
22
and a light receiver
23
, whereby a pulse signal is generated for each predetermined distance corresponding to a conveyance travel of the magnetic card
10
.
A conventional write circuit of the conventional magnetic card processing device is shown in
FIG. 2
, wherein a signal “a” from the light receiver
23
of the rotary encoder
18
is processed by an encoder waveform processing circuit (encoder processor)
24
to form a pulse signal “b” of a square wave which is applied to a write circuit
25
which generates an output signal “c” of writing data synchronized with the pulse signal “b” to be written into the magnetic stripe
17
by the magnetic head
16
.
A conventional magnetic data reading circuit of the magnetic card processing device is shown in FIG.
3
. The signal “a” from the light receiver
23
of the rotary encoder
18
is converted to the pulse signal “b” of square waves by the encoder waveform processing circuit
24
to be outputted to a CPU (central processing unit)
26
. A signal read by the magnetic head
16
is amplified by an amplifier
27
to generate an amplified signal “d” which is differentiated by a differentiator
28
to detect its peaks. A signal “e” of the detected peaks is compared with a slice level by a comparator
29
, and the read signal “f” is applied to the CPU
26
. The magnetic head
16
, the amplifier
27
, the differentiator
28
, and the comparator
29
provide a read circuit means of this device.
In the CPU
26
the time lapse of each time “tc” of rise and fall of the read signal “f” is timed to be stored, the lapse of time “td” of rise of the pulse signal “b” from the rotary encoder
18
is timed to be stored, and the movement travel A of the magnetic card
10
between pulses of the pulse signal “b” is previously obtained and known, whereby data of distance is made from time components of the data lengths.
In
FIG. 3
, for instance, a distance (data length) P corresponding to data “O” of the read signal “f” is computed out by the lapse time tc
1
and tc
2
of rise and fall of signals before and after the data and lapse time td
1
, td
2
, td
3
and td
4
of the pulse signal “b” before and after each time based on the equation (1) below;
P=A×(td
2
−tc
1
)/(td
2
−td
1
)+A+A×(tc
2
−td
3
)/(td
4
−td
3
) (1)
According to this equation, a time length of the read signal corresponding to data “0” and “1” may be converted to a distance. This is a conveyance monitoring method, wherein data of “0” and “1” is judged after such conversion to the distance, thereby reading data even if the conveyance speed is changed.
This conventional method, however, has the disadvantages below.
When a proper circuit for improving a reading ability about a low output card is installed into the read circuit means (
16
,
27
,
28
and
29
), particularly the differential circuit
22
, a processing delay of waveforms happens on reading.
As a rapid speed change happens between several bits of the pulse signal “b” based on deformation of the card or dirt adhered to the same, an error of the above-described distance conversion becomes enlarged, resulting into reading error at worst.
In
FIG. 4
, for instance, as a speed change happens in the magnetic card
10
at a point “×”, a time length T
2
of the pulse signal “b” of the rotary encoder
18
is expressed by the following equation;
T
2
=td
4
−td
3
wherein an elapse time tc
2
of fall of the read signal “f” is located in the time length T
2
.
Accordingly, when the read signal “f” before and after of the point “×” is converted into distance, the time length T
1
of the pulse signal “b” in the distance P
1
is represented by the following equation;
T
1
=td
2
−td
1
Since an elapse time tc
1
of the rise of the read signal “f” is located in the time length T
1
, the above described distance P
1
is computed out by these elapse data according to the above-mentioned equation (1).
During the time lengths T
1
and T
2
of the pulse signal “b” of the rotary encoder
18
, the magnetic card
10
is conveyed by same distance A, and the average speeds of A/T
1
an A/T
2
are different, whereby the distance by the time “t” of the average speed of A/T
1
is different from the distance by the time “t” of the average speed of A/T
2
, thereby causing an error in the distance.
When the peaks or the signal “d”, viz., the peaks of the signal “d” produced from the amplifier
27
are converted into a distance in
FIG. 4
, the error may be absorbed because it is small. As described above, however, a process delay time “ta” for processing waveforms exists in the differentiator
28
, and is regarded as time for conveying the magnetic card
10
whereby error of the above-mentioned distance is enlarged.
For instance, in
FIG. 4
, when the distance conversion is executed by peaks of the signal “d”, the error is so small that the distance P
1
and P
2
are converted as distances corresponding to two pulses (line “g”). When the distance conversion is executed by the read signal “f”, the above-mentioned process delay time “ta” is treated as the time for conveying the magnetic card
10
, whereby the error of the distance is enlarged. The distance P
1
is converted as a distance for 1.8 pulses (line “h”) and the distance P
2
is converted as a distance for 2.2 pulses, so that error of the distance conversion is large resulting into reading error at worst.
To avoid the process delay of waveforms of the differentiator
28
, there may be proposed a read circuit means for correcting the phase into complete 90 degrees by differential, in which an output reduction portion “y” appears in processed waveforms of a signal “j” of FIG.
5
which is a exact differentiated output, thereby providing a status that a low output card seems to be accessed. When the output decrease portion “y” becomes large, one pulse is regarded as two pulses in the succeeding atop, viz. the comparator
29
, resulting in wrong reading.
As a result, when the waveform process delay by the read circuit means is tried to be resolved by a circuit, the reading function is lowered and such resolution cannot be performed b
Neal Regina Y.
Omron Corporation
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