Dynamic magnetic information storage or retrieval – General recording or reproducing
Reexamination Certificate
2000-11-16
2002-12-17
Faber, Alan T. (Department: 2651)
Dynamic magnetic information storage or retrieval
General recording or reproducing
C360S132000
Reexamination Certificate
active
06496314
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a recording/playback apparatus.
2. Description of the Related Art
There is a system which is provided with an in-cassette memory for recording information regarding recording contents or the like and a cassette-side antenna and in which access is gained to the in-cassette memory while keeping the recording/playback apparatus side in a non-contact state.
When reducing the size of a recording/playback apparatus, it is necessary, from the viewpoint of strength, to form the cassette holding member, which holds the recording medium cassette and which moves between the recording/playback position where recording and/or playback is effected to and from the recording medium cassette and the cassette passing position where the passing of the recording medium cassette is effected between the interior and the exterior of the apparatus, must be formed of a metal.
FIG. 14
shows an example of a coil pattern formed on a printed circuit board. As shown in
FIG. 14
, the coil formed on the printed circuit board is realized by spirally developing the pattern on the printed circuit board from a terminal (input terminal) al on one side of the coil connected to a tap
211
toward the inner periphery side.
Here, when an attempt is made to connect a terminal (output terminal) b
1
on the opposite side of the terminal al to a tap
213
, it is impossible to lead out the pattern from the side (side A) where the pattern forming the coil is developed (In the same plane, it is impossible for one pattern to jump over the other pattern so that the two patterns may not come into contact with each other), so that it is necessary to lead out the pattern from a terminal a
2
of the coil of the side A to the opposite side (side B) through a through-hole, and to form on the side B a pattern indicated by a dashed line, connecting the pattern to the terminal b
1
through the through-hole. That is, it is necessary to form the printed circuit board
1
as a two-layer (double-sided) substrate. Further, in this case, by connecting terminals c
2
and c
1
in the intermediate portion of the coil by utilizing the side B, it is possible to prepare a tap
212
.
To keep the substrate area small while improving the inductance of this coil, a spiral pattern is formed on either of the sides A and B of the double-layer substrate as in the case of a printed circuit board
220
shown in
FIG. 15
(That is, the number of turns of the coil is increased). However, in the case of
FIG. 15
, while taps
221
and
22
connected to both ends of the coil can be easily formed, it is impossible, due to the fact that it is a pattern on a substrate, to form an intermediate tap unless air wiring (for example, wiring using a jumper line).
Thus, if an improvement in inductance is to be achieved with a small substrate area, and further, if an intermediate tap is to be provided, another layer is added to form a three-layer structure to form a pattern for the intermediate tap on the printed circuit board, whereby, as in the case of a printed circuit board
230
shown in
FIG. 16
, it is possible to mount taps
231
through
233
without performing air wiring. In the case of the example shown in
FIG. 16
, an intermediate terminal a
2
is formed between the input terminal a
1
connected to the tap
231
and the output terminal b
1
connected to the tap
233
, and this intermediate terminal a
2
is connected to the tap
232
through the terminal c
1
.
When a coil formed on a substrate is used, for example, in a circuit of an antenna used in radio communication, electromagnetic coupling non-contact communication or the like, the power last step circuit on the transmission side is in many cases formed as a push-pull circuit, and, to supply transmission power to the coil, it is more advantageous that an intermediate tap be formed in the coil.
FIG. 17
shows an example of a coil of a transmission apparatus using a coil having no intermediate tap (the printed circuit board
220
described with reference to
FIG. 15
) in electromagnetic coupling non-contact communication.
Drive signals of normal and reverse phases are emitted by signal sources V
1
and V
2
in FIG.
17
. These signals are increased in power by transistors Q
1
and Q
2
and resonated at a predetermined communication frequency by a capacitor C
3
. The values of capacitors C
1
and C
2
and resistors R
1
through R
7
are determined by the characteristics of the circuit. The DC voltage applied to the collectors of the transistors Q
1
and Q
2
is supplied through choke coils L
1
and L
2
, and the connection point of the choke coils L
1
and L
2
undergoes decoupling by a choke coil L
3
and a capacitor C
2
. The radiation of the output signal is maximum in a direction perpendicular to the printed circuit board
2
. Further, transistors Q
3
and Q
4
are used for the purpose of buffering.
There is a technique as shown in
FIG. 24
, in which signals are transmitted and received in a non-contact state between a communication apparatus
301
having an antenna
303
and a communication apparatus
302
having an antenna
304
by utilizing the electromagnetic coupling generated between the antennas
303
and
304
. When the antennas
303
and
304
of the communication apparatuses
301
and
302
consist of ordinary RCL circuits as shown in
FIG. 25
, the equivalent circuits of the antennas
303
and
304
are as shown in FIG.
26
. The communication conducted between the antennas
303
and
304
is effected by the mutual inductance M.
Impedances Z
1
through Z
5
in
FIG. 26
are as follows: Z
1
corresponds to the impedance 1/j&ohgr;C
1
of the capacitor C
1
of the antenna
303
; Z
2
corresponds to the synthetic impedance R
1
+j&ohgr;(L
1
−M) consisting of the resistance R
1
of the antenna
301
and the inductance L
1
−M obtained by subtracting the mutual inductance M from the inductance L
1
; Z
3
corresponds to the impedance j&ohgr;M corresponding to the mutual inductance M; Z
4
corresponds to the synthetic impedance R
2
+j&ohgr;(L
2
−M) consisting of the resistance of the antenna
2
and the inductance L
2
−M obtained by subtracting the mutual inductance M from the inductance L
2
; and Z
5
corresponds to the impedance 1/j&ohgr;C
2
of the capacitor C
2
of the antenna
302
.
In the circuit shown in
FIG. 26
, assuming that the current flowing through the impedance Z
2
is i
1
and that the current flowing through the impedance Z
5
is i
2
, the currents i
1
and i
2
can be expressed by the following formulas 1 and 2.
i
1
=−SEin×
Z
1
/{
Z
1
+
Z
2
+
Z
3
(
Z
4
+
Z
5
)/(
Z
3
+
Z
4
+
Z
5
)) (1)
i
2
=
i
1
×
Z
3
/(
Z
3
+
Z
4
+
Z
5
) (2)
Here, S indicates the mutual susceptance of the amplifier driving the antenna
301
. Thus, −SEin indicates the total current of the circuit.
And, the voltage E
2
applied to both ends of the antenna
302
is expressed by the following formula 3.
E
2
=
i
2
×
Z
5
=
i
1
×
Z
3
×
Z
5
/(
Z
3
+
Z
4
+
Z
5
) (3)
From formulas 1 through 3, the reciprocal of amplification degree D, which is the inverse number of the amplification degree G, is obtained as shown by the following formula 4.
D
=1
/G=Ein/E
2={−1/(
S×Z
1
×
Z
3
×
Z
5
)}×{(
Z
1
+
Z
2
+
Z
3
)(
Z
3
+
Z
4
+
Z
5
)−
Z
32
} (4)
Here, assuming that both the primary circuit and the secondary circuit are resonating, the resonance frequency &ohgr;O is expressed by the following formula 5.
&ohgr;
0
=1
/{square root over (L
1
C
1
)}
1
/{square root over (L
2
C
2
)}
(5)
And, assuming that the coupling coefficient is k, k is expressed by the following formula 6 from the values of the mutual inductance M and the inductance L
1
and the inductance L
2
of the antenna
301
and the antenna
302
.
k=M/{square root over (L
1
L
2
Kaneko Masayasu
Katoku Takashi
Ota Shuichi
Faber Alan T.
Kananen, Esquire Ronald P.
Rader & Fishman & Grauer, PLLC
Sony Corporation
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