Loading drive system

Details Loading drive system Loading drive system

2000-11-02

2002-09-10

Ro, Bentsu (Department: 2837)

Electricity: motor control systems

Open loop speed control system for dc motor with commutator

Analog armature control

C318S500000

Reexamination Certificate

active

06449427

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to a loading drive system for loading or unloading a disk such as a CD on a disk player.
BACKGROUND OF THE INVENTION
A loading drive system for a disk driver for CDs, CD-ROMs, and MDs uses a loading motor driven by a loading driver, which is adapted to receive:
a logic control signal for switching the operation of the motor from one mode to another among forward, reverse, and stop modes;
and a reference voltage for setting an output voltage of the loading driver.
FIG. 1
shows such a conventional loading drive system. A controller
11
shown in
FIG. 1
has a microcomputer to generate, at the output terminals PC
1
-PC
3
thereof, logic control signals L
1
and L
2
, to generate a forward, a reverse and a stop signals, and a reference voltage signal Vi for setting the output voltages to be supplied to a loading motor. A loading driver
12
receives, at the input terminals PL
1
-PL
3
thereof, the logic control signals L
1
and L
2
, and the reference voltage signal Vi, to generate at the output terminals PL
4
and PL
5
thereof, drive voltages Vo
1
and Vo
2
for the loading motor
13
, based on the logic control signals L
1
and L
2
and the reference voltage signal Vi.
In this example, the reference voltage Vi is supplied from the output terminal PC
1
of the controller
11
to the input terminal PL
1
of the loading driver
12
. At the same time, the logic control signals L
1
and L
2
are supplied from the output terminals PC
2
and PC
3
of the controller
11
to the input terminals PL
2
and PL
3
of the loading driver
12
. The logic control signals L
1
and L
2
together define a forward, a reverse, and a stop signal for the loading motor
3
, in terms of combinations of their HIGH and LOW levels of the logic control signals, which are for example HIGH-LOW, LOW-HIGH, and LOW-LOW.
The loading driver
12
determines, from the logical status of the logic control signals L
1
and L
2
and the level of the reference voltage signal Vi, the value and the polarity of the output voltage to be supplied to the loading motor
13
and generates appropriate output voltages Vo
1
and Vo
2
at the output terminals PL
4
and PL
5
thereof, based on the value and the polarity. The loading motor
13
is driven by the output voltages Vo
1
and Vo
2
of the loading driver.
Thus, a conventional loading drive system requires two signal lines for supplying the loading driver
12
with logic control signals L
1
and L
2
for establishing a forward, a reverse, and a stop mode signal, and another line for supplying a reference voltage signal Vi, hence requiring three lines in total for setting up the output voltage for the motor. The loading drive system also requires a corresponding number of input and output terminals.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a loading drive system having a fewer signal lines, and hence a fewer output and input terminals, or pins, for supplying logic control signals along with a reference voltage signal from a controller to a loading driver.
A loading drive system according to the invention comprises:
a control section
21
which converts a given reference voltage signal Vi and a multiplicity of logic control signals (e.g. two logic signals L
1
and L
2
) to a first control voltage Vi
1
and a second control voltage Vi
2
such that the difference between said first and second control voltages Vi
1
and Vi
2
, respectively, represents said reference voltage Vi and the polarity (including nullity) of said difference represents combinations of said logic control signals;
a loading driver
23
for performing, upon receipt of said first and second control voltage Vi
1
and Vi
2
, respectively, from said control section
21
, operations to generate a first output voltage Vo
1
by subtracting said second control voltage Vi
2
from said first control voltage Vi
1
and a second output voltage Vo
2
by subtracting said first control voltage Vi
1
from said second control voltage Vi
2
;
said loading drive system outputting said first and second output voltages Vo
1
and Vo
2
, respectively, of said loading driver as the outputs of the loading drive system.
Thus, the invention may reduce not only the number of signal lines required for supplying the loading driver with logic control signals and a reference voltage signal, but also the corresponding number of input and output terminals or pins, thereby adding a further freedom in the design, and hence facilitating easier design, of a loading driver, under a given limitation on the number of pins.
The loading driver may have a muting circuit which converts the first control voltage Vi
1
and/or the second control voltage Vi
2
received from the control section
21
to zero volt when the first control voltage Vi
1
and/or the second control voltage Vi
2
are (is) below a predetermined level.
Thus, when the first and/or the second control voltages Vi
1
and Vi
2
, respectively, are (is) lower than the predetermined level, the muting circuit mutes. That is, the muting circuit converts the first and/or the second voltages to zero volt prior to the operations as described above. This enables canceling out the offset voltages in the first and second control voltages Vi
1
and Vi
2
, i.e. output saturation voltages that remain in the first and second control voltages Vi
1
and Vi
2
, thereby improving the input-output characteristics of the loading drive system and the range of control voltages available to the loading driver.
The loading driver is provided with:
first voltage-current conversion means for converting the first control voltage Vi
1
received from the control section
21
into a first current I
1
′;
second voltage-current conversion means for converting the second control voltage Vi
2
received from the control section
21
into a second current I
2
′;
first current-voltage conversion means for converting current I
1
, which is the first current I
1
′ minus the second current I
2
′, into a first voltage; and
second current-voltage conversion means for converting current
12
, which is the second current I
2
′ minus the first current I
1
′, into a second voltage, to thereby perform the aforementioned operations in terms of the converted currents I
1
and I
2
.
In this arrangement, the aforementioned operations to obtain output voltages Vo
1
and Vo
2
from the first and the second control voltages Vi
1
and Vi
2
, respectively, received from the control section
21
, may be performed easily and correctly.
In another aspect of the invention, a loading drive system comprises:
a control section
21
which converts a reference voltage signal and a multiplicity of logic control signals (e.g. two logic signals L
1
and L
2
) to a first control voltage Vi
1
and a second control voltage Vi
2
such that the difference between said first and second voltages Vi
1
and Vi
2
, respectively, represents said reference voltage Vi and the polarity (including nullity) of said difference represents combinations of said logic control signals:
a loading driver
23
for performing, upon receipt of said first and second voltages from said control section, operations to generate an output voltage by subtracting said first voltage from said second voltage or by subtracting said second voltage from said first voltage;
said loading drive system outputting said first and second output voltages of said loading driver as the outputs of the loading drive system.
This loading drive system may also incorporate therein muting circuits, voltage-current conversion means and current-voltage conversion means similar to those described above in connection with the preceding example.
Thus, although the level of the drive output voltage is somewhat reduced, the system advantageously has a simple structure in carrying out the aforementioned operations, and a simple output structure requiring a minimum number of output buffers and output terminals.


REFERENCES:
patent: 3742328 (1973-06-01), Ohta
patent: 5977755 (1999-11-01), Miki et al.
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