Wake-up circuit

Details Wake-up circuit Wake-up circuit

2001-09-19

2003-01-21

Wells, Kenneth B. (Department: 2816)

Miscellaneous active electrical nonlinear devices, circuits, and

Signal converting, shaping, or generating

Synchronizing

C327S198000

Reexamination Certificate

active

06509767

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a wake-up circuit, more particularly to a wake-up circuit preferred for such external switch input circuits as power-driven window switches, door modules, power-driven seat modules, etc. installed on vehicles.
2. Description of the Prior Art
Each of the external switch input circuits such as power-driven window switches, power-driven mirror switches, door modules, power-driven seat modules, etc. installed on vehicles is required to work even after the ignition key is turned off. This is why power is kept supplied to the external switch input circuit. When this circuit is kept set in a state ready to work any time, however, the power consumption increases over the capacity of the on-vehicle battery, thereby the engine of the vehicle often cannot be started.
In order to prevent such a problem, there have been proposed various types of wake-up circuits, each of which drives the subject vehicle into a low power consumption mode (sleep mode) automatically in a predetermined time after the ignition switch is turned off, thereby suppressing the power consumption, and when any one of the switches of the wake-up circuit is operated, the normal operation (wake-up) mode is restored.
Each of such the conventional wake-up circuits, as shown in the circuit diagram in
FIG. 3
, is configured by a controller (hereinafter, to be described as “CPU”)
31
; a switch unit
32
; pull-up means
33
; and wake-up trigger signal generating means
34
.
The CPU
31
is provided with a plurality of input terminals (IN
1
, IN
2
, and IN
3
) and a trigger signal input terminal (INT) used to receive a voltage for waking up itself from the sleep state. When a voltage entered to one of the input terminals (IN
1
to IN
3
) drops, the CPU
31
outputs a plurality of control signals for controlling the external device (not shown). The CPU
31
goes into a predetermined state, for example, into the sleep mode, a few minutes after the ignition key is turned off. The CPU
31
is woken up by a voltage applied to the trigger signal input terminal (INT).
The switch unit
32
is provided with a plurality of switches (
32
a
,
32
b
, and
32
c
), each of which is grounded at its one end. The other end of each of those switches (
32
a
,
32
b
, and
32
c
) is connected to its corresponding input terminal (IN
1
/IN
2
/IN
3
) of the CPU
31
via a resistor (R
35
/R
36
/R
37
)
The pull-up means
33
connects a power supply terminal
35
to the other end of each of the switches (
32
a
to
32
c
) of the switch unit
32
via pull-up resistors (R
31
/R
32
/R
33
) respectively so as to pull up the other end of each of the switches (
32
a
to
32
c
).
The wake-up trigger signal generating means
34
is configured by a PNP switch transistor TR
1
and an OR circuit (ground:
1
, not ground:
0
) consisting of diodes (D
31
, D
32
, and D
33
). The base of the transistor TR
1
is connected to the anode side of the OR circuit and the emitter of the TR
1
is connected to a power supply terminal
36
, and the collector of the TR
1
is connected to the trigger signal input terminal (INT) of the CPU
31
. The cathode of the OR circuit (consisting of diodes D
31
, D
32
, and D
33
) is connected to the other end of each of the switches (
32
a
to
32
c
) of the switch unit
32
.
Because the conventional wake-up circuit is configured as described above, when any one of the switches (
32
a
to
32
c
) of the switch unit
32
is operated, the switch (
32
a
to
32
c
) is grounded at its one end. The voltage applied to the corresponding input terminal (IN
1
to IN
3
) corresponding to the operated switch (
32
a
to
32
c
) of the CPU
31
goes into the low level. On the other hand, the CPU
31
monitors the voltage at this input terminal (IN
1
to IN
3
) and decides the operated switch (
32
a
to
32
c
) and outputs a control signal via the output terminal (not shown) in accordance with the operated switch (
32
a
to
32
c
) so as to control the subject external device installed in a vehicle.
In the case where any one of the switches (
32
a
to
32
c
) of the switch unit
32
is operated while the CPU
31
is in a predetermined state, for example, in the sleep mode to be set a few minutes after the ignition key is turned off, one end of the switch (
32
a
to
32
c
) is grounded. As a result, the anode side of the OR circuit composed of the diodes (D
31
to D
33
) also takes the ground voltage, thereby the transistor TR
1
is turned on. The power supply
36
thus applies a voltage to the trigger signal input terminal (INT) of the CPU
31
and the terminal (INT) is driven into the high level. At this high level of the voltage entered to the terminal (INT), the CPU
31
is restored to the normal mode and outputs control signals for controlling the subject external device installed on a vehicle, in accordance with the operated switch (
32
a
to
32
c
).
Because of the configuration and the operation as described above, the CPU
31
controls the target device in accordance with the operated switch (
32
a
to
32
c
) When no operation is required, the CPU
31
goes into the sleep mode so as to suppress the power consumption. When any one of the switches (
32
a
to
32
c
) is operated in the sleep mode, the CPU
31
is woken up.
However, such a wake-up circuit, in which the switches (
32
a
to
32
c
) of the switch unit
32
are disposed in parallel with respect to the CPU
31
, is required so as to provide the same number of connection lines and the same number of input terminals (IN
1
to IN
3
) of the CPU
31
as the number of switches (
32
a
,
32
b
, and
32
c
) respectively. In addition, connection lines are also needed for the diodes (D
31
to D
33
) so as to connect the wake-up trigger signal generating means
34
. Consequently, the conventional wake-up circuit requires many parts and many connection lines, so that the circuit is complicated in structure.
Furthermore, because the configuration of the start-up circuit is decided by the number of switches (
32
a
to
32
c
) of the switch unit
32
, the wake-up circuit is not compatible with other circuits when the number of switches of the switch unit
32
differs among them. This has been an obstacle for reducing the manufacturing cost of the start-up circuit.
Furthermore, it has been difficult to increase the number of switches in the switch unit
32
without modification of the circuit configuration; for example, when another switch
32
d
is to be added to the switch unit
32
, another connection line, another input terminal IN
4
, another diode D
34
, etc. denoted by broken lines in
FIG. 3
are needed for the CPU
31
. Once the start-up circuit is designed, therefore, it is very difficult to expand the circuit.
SUMMARY OF THE INVENTION
Under such circumstances, it is an object of the present invention to solve the above conventional problems and provide a wake-up circuit to be simplified in configuration, to require less parts and less connection lines, and to be configured regardless of the number of switches, thereby to be easy to increase the number of switches later.
In order to solve the above conventional problems, the wake-up circuit of the present invention comprises a controller provided with an analog voltage input terminal and a trigger signal input terminal so as to output a plurality of control signals corresponding to a value of an analog voltage entered to the analog voltage input terminal; and resistance value changing means provided with a plurality of switches and a plurality of resistors, one end of which is grounded and the other end of which is connected to the analog voltage input terminal as well as to a power source by pull-up means provided with at least a pull-up resistor, so as to change, by the switches, the resistance value between the one end and the other end, wherein a wake-up trigger signal generating means is provided between the resistance value changing means and the trigger signal input terminal, thereby the wake-up trigger signal generating means outputs a trigger s

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