Title: Motor control circuit for mirror device
Abstract: The present invention provides a mirror device motor control circuit that can reliably stop a mirror at predetermined positions with a simple configuration. In the control circuit of the invention, part of a lock current flowing to the motor flows to a base terminal of a transistor. Thus, as long as a voltage corresponding to the lock current is equal to or greater than a specific value, this voltage is applied to the base terminal of the transistor, whereby between a collector terminal and an emitter terminal becomes conductive, and the current flowing to a gate of a MOSFET is grounded via the collector terminal and the emitter terminal of the transistor. For this reason, when the lock current flows, conduction between a drain terminal and a base terminal of the MOSFET is released and a drive current of the motor is cut off.
Patent Number: 6,900,605 Issued on 05/31/2005 to Nakaho
| Inventors:
|
Nakaho; Junichi (Aichi-ken, JP)
|
| Assignee:
|
Kabushiki Kaisha Tokai-Rika-Denki-Seisakusho (Aichi-ken, JP)
|
| Appl. No.:
|
648809 |
| Filed:
|
August 27, 2003 |
Foreign Application Priority Data
| Aug 27, 2002[JP] | 2002-246622 |
| Jul 22, 2003[JP] | 2003-277621 |
| Current U.S. Class: |
318/280; 318/434; 318/445; 318/504 |
| Intern'l Class: |
H02P 001/00 |
| Field of Search: |
363/132
318/280,445,434,504
|
References Cited [Referenced By]
U.S. Patent Documents
| 4374348 | Feb., 1983 | Shimura et al.
| |
| 2003/0076148 | Apr., 2003 | Tamiya et al.
| |
| 2003/0081440 | May., 2003 | Komatsu et al.
| |
| Foreign Patent Documents |
| 08-142756 | Jun., 1996 | JP.
| |
| 8-207663 | Aug., 1996 | JP.
| |
| 9-107691 | Apr., 1997 | JP.
| |
| 10-278675 | Oct., 1998 | JP.
| |
Other References
European Search Report dated Nov. 3, 2004 in corresponding European Application
No. EP 03 25 5282.
|
Primary Examiner: Masih; Karen
Attorney, Agent or Firm: Nixon Peabody, LLP
Claims
1. A control circuit that is used in a mirror device, where the position of a
mirror attached to a vehicle is changed in a predetermined direction by the driving
force of a motor, and controls electrical power supplied to the motor, the control
circuit comprising:
a drive current controlling transistor where, when a first terminal is connected
to a power source, a second terminal is connected to the motor and a voltage equal
to or greater than a predetermined value is applied to a third terminal that is
different from both the first and second terminals, a current flows from the first
terminal to the second terminal and application of the voltage is released, whereby
the current is blocked; and
a switching transistor where a fourth terminal is connected between the power
source and the third terminal, a fifth terminal is grounded, and which includes
a sixth terminal connected to the motor at an opposite side from the second terminal,
and a voltage equal to or greater than a specific value corresponding to a lock
current flowing through the motor is applied to the sixth terminal, whereby the
fourth terminal and the fifth terminal are switched to a conductive state and the
voltage applied to the third terminal is made less than the predetermined value.
2. The control circuit of claim 1, wherein the drive current controlling transistor
is a field-effect transistor.
3. The control circuit of claim 1, wherein the control circuit is symmetrically
configured via the motor.
4. The control circuit of claim 1, further comprising a waveform conversion component
that converts the waveform of the voltage applied to the sixth terminal, lowers
a maximum value of an output voltage lower than a maximum value of a substantially
pulse-like voltage equal to or greater than the inputted specific value, and inputs
the maximum value to the sixth terminal.
5. The control circuit of claim 4, wherein the waveform conversion component
is configured by a capacitor and a resistor.
6. The control circuit of claim 1, further comprising a compensation component
that lowers, in accompaniment with the elapse of time, the voltage equal to or
greater than the predetermined value on the basis of a current corresponding to
the pulse-like voltage in a state where the pulse-like voltage equal to or greater
than the specific value is applied to the sixth terminal.
7. The control circuit of claim 6, wherein the compensation component is configured
by a resistor and a capacitor.
8. The control circuit of claim 1, further comprising a bypass component where
a voltage corresponding to the pulse-like current equal to or greater than the
specific value is lowered in accompaniment with the elapse of time and applied,
is switched to an ON state and grounds the pulse-like current proceeding to the
third terminal before transmitting the pulse-like current to the third terminal.
9. The control circuit of claim 8, wherein the bypass component is configured
by a transistor, a resistor and a capacitor.
10. The control circuit of claim 1, further comprising a storage element, wherein
the storage element stores a charge due to the current flowing to the third terminal
and reduces the current flowing to the third terminal in accordance with the amount
of the stored charge.
11. The control circuit of claim 10, wherein the storage element is a capacitor.
Description
CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority under 35USC 119 from Japanese Patent Application
Nos. 2002-246622 and 2003-277621, the disclosures of which are incorporated by
reference herein.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a motor control circuit for a mirror device
used in an electric door mirror device or the like for a vehicle.
2. Description of the Related Art
Among rearview door mirrors disposed at the side of a door panel in correspondence
with a driver seat or a passenger seat in a vehicle, there is an electric door
mirror device where the door mirror can be folded and stored by the driving force
of a motor so that the mirror faces a substantial vehicle width-direction interior.
This type of electric door mirror device is ordinarily disposed with a folding/deploying
switch disposed near the driver seat in the vehicle. Power is supplied from the
battery of the vehicle to a folding/deploying motor via the switch and a control
circuit of the motor (see Japanese Patent Application Laid-Open (JP-A) No. 8-142756).
In the electric door mirror device, the control circuit is configured to stop
the motor when the mirror has been rotated to a fixed deployed position and a fixed
folded position. As an example of such a control circuit, there is a configuration
that detects a load applied to the motor and cuts off current flowing to the motor
when a load of a predetermined value or greater has been applied to the motor.
That is, the mirror is rotated to the deployed position or the folded position
and further rotation thereof is restricted. Thus, when the motor is locked, a lock
current that is larger than an ordinary activation current flows to the motor.
The control circuit has a configuration that cuts off the current flowing to the
motor when the lock current has flowed to the motor.
Although a relay circuit is used for the control circuit of the configuration
that detects the lock current and cuts off the current flowing to the motor, a
relay circuit usually has drawbacks in that the circuit scale is large and the
circuit configuration is complicated.
SUMMARY OF THE INVENTION
In light of the above-described facts, it is an object of the present invention
to obtain a mirror device motor control circuit that can reliably stop a mirror
at predetermined positions with a simple configuration.
The present invention is a control circuit that is used in a mirror device, where
the position of a mirror attached to a vehicle is changed in a predetermined direction
by the driving force of a motor, and controls electrical power supplied to the
motor, the control circuit comprising: a drive current controlling transistor where,
when a first terminal is connected to a power source, a second terminal is connected
to the motor and a voltage equal to or greater than a predetermined value is applied
to a third terminal that is different from both the first and second terminals,
a current flows from the first terminal to the second terminal and application
of the voltage is released, whereby the current is blocked; and a switching transistor
where a fourth terminal is connected between the power source and the third terminal,
a fifth terminal is grounded, and which includes a sixth terminal connected to
the motor at an opposite side from the second terminal, and a voltage equal to
or greater than a specific value corresponding to a lock current flowing through
the motor is applied to the sixth terminal, whereby the fourth terminal and the
fifth terminal are switched to a conductive state and the voltage applied to the
third terminal is made less than the predetermined value.
In the mirror device mirror control circuit of the above-described configuration,
the drive current controlling transistor is intervened between the motor and the
power source. The voltage equal to or greater than the predetermined value is applied
to the third terminal of the drive current controlling transistor, whereby between
the first terminal and the second terminal is placed in a conductive state, the
current flows to the motor, and the motor is driven. The position of the mirror
is changed by the driving force of the motor. For example, if the motor is a motor
for storing and deploying the mirror, the position of the mirror is changed by
the driving force of the motor from a storage position to a deployed position or
from the deployed position to the storage position.
Also, as described above, the motor is driven and the position of the mirror
is changed to the deployed position or the storage position so that, when further
change in the position of the mirror is regulated by a stopper or the like, an
output shaft of the motor is not rotated even if the drive current flows to the
motor. Thus, the lock current flows to the motor and the value of the current flowing
to the motor rises.
The sixth terminal of the switching transistor is connected at the opposite side
from the second terminal of the motor, and the voltage corresponding to the current
flowing through the motor is applied to the sixth terminal. Here, as described
above, when the lock current flows and the voltage applied to the sixth terminal
becomes equal to or greater than the predetermined value, the fourth terminal and
the fifth terminal of the switching transistor are placed in a conductive state.
The fourth terminal of the switching terminal is connected between the power
source and the third terminal of the drive current controlling transistor, and
the fifth terminal is grounded. For this reason, when the fourth terminal and the
fifth terminal of the switching transistor are placed in a conductive state, part
or all of the current that had flowed to the third terminal is grounded via the
fourth terminal and the fifth terminal of the switching transistor, and the voltage
applied to the third terminal becomes less than the predetermined value. Thus,
the drive current controlling transistor is switched to an OFF state and the current
with respect to the motor is cut off.
In this manner, the present invention has a configuration that stops the motor
on the basis of the lock current flowing to the motor. For this reason, miniaturization
becomes possible with a simple configuration and costs are also lowered in comparison
with a configuration that uses a relay circuit to cut off the current flowing to
the motor at a position at which the motor is locked.
Moreover, the invention has a configuration that stops the motor on the
basis of the lock current flowing to the motor. For this reason, when the invention
is used to control a motor that stores and deploys a mirror, the invention can
be applied to mirrors whose amount of displacement from the storage position to
the deployed position differs, without having to fundamentally change the design
of the circuit.
It should be noted that, in the present invention, the drive current controlling
transistor and the switching transistor may be transistors of any configuration,
including field-effect transistors. Also, in the present invention, the respective
terminals in the drive current controlling transistor and the switching transistor
are called first to sixth terminals. This is because, whereas the terminals are
called base terminals, collector terminals and emitter terminals in common transistors,
the terminals are called drain terminals, gate terminals and source terminals in
field-effect transistors. In the present invention, the first to sixth terminals
are not limited to terminals having such specific names.
The invention may also be disposed with a waveform conversion component that
converts the waveform of the voltage applied to the sixth terminal, lowers a maximum
value of an output voltage lower than a maximum value of a substantially pulse-like
voltage equal to or greater than the inputted specific value, and inputs the maximum
value to the sixth terminal.
In the mirror device motor control circuit of the above-described configuration,
when the extemporaneous substantially pulse-like current such as an inrush current
flows to the circuit immediately after activation of the motor has started, the
voltage resulting from this current is applied to the sixth terminal of the switching
transistor. However, in the present invention, this voltage is not directly applied
to the sixth terminal; rather, the waveform of the voltage is converted by the
waveform conversion component before it is applied to the sixth terminal.
Due to this conversion of the waveform, the voltage is lowered to less than the
specific value—i.e., less than the value of the current necessary to make
the fourth terminal and the fifth terminal conductive—and is outputted.
Thus, a voltage equal to or greater than the predetermined value—i.e., equal
to or greater than the value of the current necessary to make the first terminal
and the second terminal conductive—can be applied to the third terminal
of the drive current controlling transistor at the time, or immediately after,
driving of the motor is initiated.
The invention may also be disposed with a compensation component that lowers,
in accompaniment with the elapse of time, the voltage equal to or greater than
the predetermined value on the basis of a current corresponding to the pulse-like
voltage in a state where the pulse-like voltage equal to or greater than the specific
value is applied to the sixth terminal.
In the mirror device motor control circuit of the above-described configuration,
when the extemporaneous substantially pulse-like current such as an inrush current
flows to the circuit immediately after activation of the motor has started, the
voltage resulting from this current is applied to the sixth terminal of the switching transistor.
Thus, as long as this voltage is equal to or greater than the specific value,
the fourth terminal and the fifth terminal of the switching transistor become conductive
and the value of the current applied to the third terminal of the drive current
controlling transistor falls below the predetermined value.
Here, in the present invention, as described above, when the extemporaneous
substantially pulse-like current flows to the circuit, the compensation component
applies the voltage corresponding to this substantially pulse-like current to the
third terminal of the drive current controlling transistor. For this reason, the
extemporaneous substantially pulse-like current flows to the circuit and conduction
between the first terminal and the second terminal of the drive current controlling
transistor during the time when the fourth terminal and the fifth terminal of the
switching transistor are conductive can be secured. Thus, the motor can be reliably driven.
Because the compensation component applies the voltage to the third terminal
while lowering the voltage in accompaniment with the elapse of time, the voltage
that the compensation component applied to the third terminal falls below the predetermined
value after a set period of time has elapsed, even if application of the voltage
corresponding to the third terminal by the compensation component is initiated.
For this reason, a voltage equal to or greater than the predetermined value can
be prevented from being applied to the third terminal over a long period of time
in a state where the fourth terminal and the fifth terminal of the switching transistor
are conductive.
The invention may also be disposed with a bypass component where a voltage corresponding
to the pulse-like current equal to or greater than the specific value is lowered
in accompaniment with the elapse of time and applied, is switched to an ON state
and grounds the pulse-like current proceeding to the third terminal before transmitting
the pulse-like current to the third terminal.
In the mirror device motor control circuit of the above-described configuration,
when the extemporaneous substantially pulse-like current such as an inrush current
flows to the circuit immediately after activation of the motor has started, the
voltage resulting from this current is applied to the sixth terminal of the switching transistor.
Thus, as long as this voltage is equal to or greater than the specific value,
the fourth terminal and the fifth terminal of the switching transistor become conductive
and the value of the current applied to the third terminal of the drive current
controlling transistor falls below the predetermined value.
Here, in the present invention, as described above, when the extemporaneous
substantially pulse-like current flows to the circuit, the voltage corresponding
to this current is applied to the bypass component, whereby the bypass component
is switched to the ON state. In the ON state of the bypass component, the current
proceeding to the sixth terminal of the switching transistor is grounded before
it reaches the sixth terminal. For this reason, even if the extemporaneous substantially
pulse-like current flows, the motor can be reliably started without the fourth
terminal and the fifth terminal of the switching transistor becoming conductive.
Moreover, because the voltage applied to the bypass component is lowered
in accompaniment with the elapse of time, the bypass component is switched to the
OFF state after the set period of time has elapsed. Thus, the voltage corresponding
to the lock current can be applied to the sixth terminal.
The invention may also be disposed with a storage element that stores a charge
due to the current flowing to the third terminal and reduces the current flowing
to the third terminal in accordance with the amount of the stored charge.
In the mirror device motor control circuit of the above-described configuration,
when the current equal to or greater than the predetermined value flows to the
third terminal of the drive current controlling transistor, a charge is stored
in the storage element connected to the third terminal. Moreover, when the charge
stored in the storage element increases due to the current continuing to flow to
the third terminal, the current flowing to the third terminal is reduced in accordance
with the amount of the charge that the storage element has stored. Thus, eventually
the voltage applied to the third terminal falls below the predetermined value,
conduction between the first terminal and the second terminal is released, the
drive current flowing to the motor is cut off, and the motor is stopped.
Here, the amount of the charge that the storage element stores during the period
of time from when between the first terminal and the second terminal is placed
in a conductive state to until the conduction is released is dependent on the time
when the third terminal is placed in a conductive state. For this reason, the motor
is fundamentally driven only for a set period of time from when the first terminal
and the second terminal have been placed in a conductive state, and the position
of the mirror is changed only by a set amount.
In this manner, in the present invention, because the motor is not driven for
a period of time equal to or greater than the set period of time, the motor can
be reliably stopped, even if the voltage equal to or greater than the specific
value is not applied to the sixth terminal of the switching transistor in the event
that an amount of time equal to or greater than the set period of time has elapsed.
As described above, the mirror device motor control circuit pertaining to the
invention can miniaturize a configuration with a simple configuration and can reliably
stop a mirror at predetermined positions.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a circuit diagram of a mirror device motor control circuit pertaining
to a first embodiment of the present invention;
FIG. 2 is a circuit diagram corresponding to FIG. 1 in a state where a lock
current is flowing;
FIG. 3 is a time chart showing waveforms of voltages applied to each of a third
terminal of a drive current controlling transistor and a sixth terminal of a switching transistor;
FIG. 4 is a perspective view of a mirror device;
FIG. 5 is a circuit diagram of a mirror device motor control circuit pertaining
to a second embodiment of the present invention;
FIG. 6 is a time chart showing waveforms of voltages applied to each of a third
terminal of a drive current controlling transistor and a sixth terminal of a switching transistor;
FIG. 7 is a circuit diagram of a mirror device motor control circuit pertaining
to a third embodiment of the present invention;
FIG. 8 is a time chart showing waveforms of voltages applied to each of a third
terminal of a drive current controlling transistor and a sixth terminal of a switching transistor;
FIG. 9 is a circuit diagram of a mirror device motor control circuit pertaining
to a fourth embodiment of the present invention;
FIG. 10 is a circuit diagram of a mirror device motor control circuit pertaining
to a fifth embodiment of the present invention;
FIG. 11 is a time chart showing waveforms of voltages applied to each of a third
terminal of a drive current controlling transistor and a sixth terminal of a switching
transistor; and
FIG. 12 is a circuit diagram of a mirror device motor control circuit pertaining
to a sixth embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Configuration of First Embodiment
In FIG. 1, the configuration of a mirror device motor control circuit
10
(referred to below simply as "the control circuit
10") pertaining to a first
embodiment of the invention is illustrated by a circuit diagram.
As illustrated in this diagram, the present control circuit
10 is disposed
with a switch section
12 and a drive control section
14. The switch
section
12 is disposed with a pair of switches
16 and
18.
The switch
16 is disposed with three terminals
16A,
16B and
16C, and is configured so that one of between the terminal
16A and
the terminal
16B and between the terminal
16A and the terminal
16C
is placed in a conductive state and the other is placed in a disconnected state.
The switch
18 is similarly disposed with three terminals
18A,
18B
and
18C, and is configured so that one of between the terminal
18A
and the terminal
18B and between the terminal
18A and the terminal
18C is placed in a conductive state and the other is placed in a disconnected
state. However, whereas the terminal
16A of the switch
16 is connected
to the positive terminal of a battery installed in the vehicle, the terminal
18A
of the switch
18 is grounded. Also, in the switches
16 and
18,
the terminal
16B is connected to the terminal
18C and the terminal
16C is connected to the terminal
18B.
Moreover, the switches
16 and
18 are set so as mutually interwork.
When the terminal
16A and the terminal
16B are connected by the switch
16, the terminal
18A and the terminal
18B are connected by
the switch
18, and when the terminal
16A and the terminal
16C
are connected by the switch
16, the terminal
18A and the terminal
18C are connected by the switch
18.
The drive control section
14 is disposed with a motor
20 and a
pair of n-channel field-effect transistors
22 and
24 (referred to
below simply as "the MOSFETs
22 and
24") respectively serving as
drive current controlling transistors. The motor
20 is housed at an inner
side of a door mirror
26 serving as the mirror shown in FIG.
4. An
output shaft is directly or indirectly and mechanically connected to a support
shaft
27 that rotatably supports, using the substantial vertical direction
of the vehicle as an axial direction, the door mirror
26 around this axis.
Due to the output shaft rotating, the door mirror
26 is rotated in a deployment
direction (the direction of arrow Y
1 in FIG. 4) or a storage direction (the
direction of arrow Y
2 in FIG.
4).
One terminal of the motor
20 is connected to a drain terminal serving
as a second terminal of the MOSFET
22. In the MOSFET
22, a source
terminal serving as a first terminal is connected to the terminal
16B of
the switch
16 and to the terminal
18C of the switch
18. With
respect thereto, the other terminal of the motor
20 is connected to a drain
terminal serving as a second terminal of the MOSFET
24. In the MOSFET
24,
a source terminal serving as a first terminal is connected to the terminal
16C
of the switch
16 and to the terminal
18B of the switch
18.
The drive control section
14 is also disposed with a resistor
28.
One end of the resistor
28 is connected to a contact point
30 between
the terminal
16B of the switch
16 and the terminal
18C of
the switch
18 and the source terminal of the MOSFET
22. The other
end of the resistor
28 is connected to an end of a resistor
34. Moreover,
the other end of the resistor
34 is connected to a contact point
36
between the source terminal of the MOSFET
24 and the terminal
18B
of the switch
18 and the terminal
16C of the switch
16.
The other end of the resistor
28 is also connected to a terminal of a
resistor
38. The other end of the resistor
38 is connected to a gate
terminal serving as a third terminal of the MOSFET
22. Moreover, the other
end of the resistor
28 is connected to an end of a resistor
40 between
the other end of the resistor
28 and the end of the resistor
34.
The other end of the resistor
40 is connected to a gate terminal serving
as a third terminal of the MOSFET
24.
Moreover, the drive control section
14 is disposed with a pair of
NPN transistors
42 and
44 respectively serving as switching transistors.
In the transistor
42, an emitter terminal serving as a fifth terminal is
connected to a contact point
46 between the contact point
30 and
the source terminal of the MOSFET
22, and a collector terminal serving as
a fourth terminal is connected to a contact point
48 between the resistor
38 and the gate terminal of the MOSFET
22. In the transistor
44,
an emitter terminal serving as a fifth terminal is connected to a contact point
50 between the contact point
36 and the source terminal of the MOSFET
24, and a collector terminal serving as a fourth terminal is connected to
a contact point
52 between the resistor
40 and the gate terminal
of the MOSFET
24.
An end of a capacitor
56 configuring a waveform conversion component is
connected to a contact point
54 between the contact point
46 and
the source terminal of the MOSFET
22. The other end of the capacitor
56
is connected to a terminal of the motor
20 via a resistor
58 configuring
a waveform conversion component together with the capacitor
56, and a base
terminal serving as a sixth terminal of the transistor
42 is connected to
a contact point
60 between the capacitor
56 and the resistor
58.
With respect thereto, an end of a capacitor
64 configuring a waveform
conversion component is connected to a contact point
62 between the contact
point
50 and the source terminal of the MOSFET
24. The other end
of the capacitor
64 is connected to the other terminal of the motor
20
via a resistor
66 configuring a waveform conversion component together with
the capacitor
64, and a base terminal serving as a sixth terminal of the
transistor
44 is connected to a contact point
68 between the capacitor
64 and the resistor
66.
The drive control section
14 is also disposed with zener diodes
70
and
72. One end of the zener diode
70 is connected to a contact point
74 between the contact point
54 and the source terminal of the MOSFET
22, and the other end of the zener diode
70 is connected to a contact
point
76 between the contact point
48 and the gate terminal of the
MOSFET
22.
In the zener diode
70, a current can ordinarily flow from one end to the
other end, but the current cannot flow in the opposite direction. However, a large
current flows from the other end to the one end by a zener effect only when a voltage
of a predetermined size or greater is applied to the other end of the zener diode
70.
One end of the zener diode
72 is connected to a contact point
78
between the contact point
62 and the source terminal of the MOSFET
24,
and the other end of the zener diode
72 is connected to a contact point
80 between the contact point
52 and the gate terminal of the MOSFET
24. In the zener diode
72 also, similar to the zener diode
70,
a current can ordinarily flow from one end to the other end, but the current cannot
flow in the opposite direction. However, a large current flows from the other end
to the one end by a zener effect only when a voltage of a predetermined size or
greater is applied to the other end of the zener diode
72.
Action and Effects of the First Embodiment
Next, the action and effects of the present embodiment will be described.
As shown in FIG. 1, in the present control circuit
10, when the terminal
16A and the terminal
16B of the switch
16 are connected, the
terminal
18A and the terminal
18B of the switch
18 are connected
in conjunction therewith, whereby a current A
1 flows from the terminal
16A
to the terminal
18B via the resistors
28 and
34.
Moreover, a current A
2 corresponding to the voltage of both ends
of the resistor
34 at this time flows to the resistor
40, and a voltage
Vg corresponding to the voltage of both ends of the resistor
34 is applied
to the gate terminal of the MOSFET
24. When the voltage Vg is greater than
a predetermined value Vg1, between the drain terminal and the source terminal of
the MOSFET
24 is switched to an ON state, and it becomes possible for current
to flow from the drain terminal to the source terminal.
At this time, a current A
3 flows from the resistor
28 to the resistor
38, and a voltage corresponding to the voltage of both ends of the resistor
28 is applied to the gate terminal of the MOSFET
22. Thus, although
between the drain terminal and the source terminal of the MOSFET
22 is switched
to an ON state and it becomes possible for the current to flow from the drain terminal
to the source terminal, in the MOSFET
22, it is possible for the current
to flow from the source terminal to the drain terminal by a parasitic diode effect.
Thus, a drive current A
4 flows to the motor
20, the motor
20
is driven, and the door mirror
26 is rotated in the storage direction (the
direction of arrow Y
2 in FIG. 4) by this driving force.
In this state, the door mirror
26 reaches the storage position and rotation
of the door mirror
26 is restricted by a stopper member and the vehicle
body, whereby rotation of the door mirror
26 is forcibly stopped. In this
manner, when the motor
20 is energized in a state where the rotation of
the door mirror
26 has been forcibly stopped, the motor
20 becomes
locked and the lock current flows. As shown in the time chart of FIG. 3, when the
motor
20 is locked after a predetermined period of time T
3 has elapsed
from an activation starting time T
0 of the motor
20, the lock current
gradually increases and the voltage applied to the motor
20 rises in accompaniment therewith.
As shown in FIG. 2, part of the current A
4 flowing through the motor
20
becomes a current A
5 and flows to the resistor
66, and a voltage
Vb corresponding to the current A
5 is applied to the base terminal of the
transistor
44. Thus, the lock current also similarly flows to the resistor
66, and the voltage Vb corresponding to the lock current is applied to the
base terminal of the transistor
44.
As described above, because the lock current gradually increases, as shown in
the time chart of FIG. 3, a predetermined period of time T
4 elapses and
the voltage Vb also increases in accompaniment with the increase in a voltage Vr.
Moreover, when the lock current reaches a specific size so that the voltage Vr
reaches a voltage Vrm corresponding to this, the voltage Vb reaches a specific
value Vbm, whereby between the collector terminal and the emitter terminal of the
transistor
44 becomes conductive.
In this manner, because between the collector terminal and the emitter terminal
of the transistor
44 becomes conductive, as shown in FIG. 2, the current
A
2 that had flowed to the gate terminal of the MOSFET
24 until then
becomes a current A
6 and is grounded via the collector terminal and the
emitter terminal of the transistor
44. Thus, the current A
2 flowing
to the gate terminal of the MOSFET
24 is reduced or eliminated, and the
voltage Vg applied to the gate terminal of the MOSFET
24 becomes lower than
the predetermined value Vg1. For this reason, between the drain terminal and the
source terminal of the MOSFET
24 is cut off and the supply of current to
the motor
20 is cut off.
As described above, in the present control circuit
10, the voltage Vbm
corresponding to the lock current of a predetermined value or greater flowing to
the motor
20 is applied to the base terminal of the transistor
44,
whereby the supply of current to the motor
20 can be cut off. Moreover,
because the transistor
44 can be disposed on the same circuit board as the
circuit board disposed with the MOSFET
24 and the like, overall miniaturization
can be accomplished and costs also become lower in comparison with a configuration
disposed with a relay circuit.
Immediately after the terminal
16A and the terminal
16B
of the switch
16 and the terminal
18A and the terminal
18B
of the switch
18 are connected, a pulse-like inrush current that is larger
than the ordinary drive current of the motor
20 flows. Thus, as shown in
the time chart of FIG. 3, the voltage Vr applied to the motor
20 also becomes
larger than that of the ordinary drive time (i.e., after the predetermined period
of time T
1 elapses) until the predetermined period of time T
1 elapses
from the drive starting time T
0 of the motor
20.
Naturally, after the inrush current has flowed through the motor
20,
the inrush current flows through the resistor
66 and proceeds to the capacitor
64 and the base terminal of the transistor
44, and the voltage Vb
of a size corresponding to the inrush current is applied to the base terminal of
the transistor
44.
As long as the size of the voltage Vb corresponding to the inrush current is
equal
to or greater than the specific value Vbm, there is conduction between the collector
terminal and the emitter terminal of the transistor
44. Thus, in this state,
the voltage Vg applied to the gate terminal of the MOSFET
24 does not become
equal to or greater than the predetermined value Vg1, and between the drain terminal
and the source terminal of the MOSFET
24 is cut off.
In the present control circuit
10, the resistor
66 and the capacitor
64 configure an "integration circuit (delay circuit)". For this reason,
the waveform of the voltage Vb applied to the base terminal of the transistor
44
is converted when the substantially pulse-like inrush current flows. That is, the
waveform of the voltage Vb is changed from a pulse to a waveform that gradually
increases in accompaniment with the elapse of time.
Thus, even if the inrush current flows to the present control circuit
10,
a maximum value Vb
1 of the voltage Vb applied to the base terminal of the
transistor
44 does not reach the specific value Vbm. Moreover, because the
current value is rapidly reduced after the inrush current reaches a peak as a substantial
pulse, the maximum value Vb1 of the voltage Vb resulting from the inrush current
does not reach the specific value Vbm during the period of time from after the
inrush current flows to until the predetermined period of time T
1 elapses.
Thus, in the present control circuit
10, the voltage Vb applied to the
base terminal of the transistor
44 is not conducted between the collector
terminal and the emitter terminal of the transistor
44 at the time driving
of the motor is started and immediately thereafter, even if the inrush current
flows. For this reason, the current A
2 can be reliably oriented to the gate
terminal of the MOSFET
24 and the voltage Vg corresponding to the current
A
2 can be reliably applied to the gate terminal of the MOSFET
24,
and conduction can be reliably achieved between the drain terminal and the source
terminal of the MOSFET
24 so that the motor
20 can be driven.
As shown in FIG. 1, in the present control circuit
10, the circuit configuration
between the switch
16 side (upper half of FIG. 1 with the motor
20
as a boundary) and the switch
18 side (lower half of FIG. 1 with the motor
20 as a boundary) is symmetrical via the motor
20. Thus, when the
terminal
16A and the terminal
16C of the switch
16 are connected
and the terminal
18A and the terminal
18C of the switch
18
are connected, the transistor
42, the resistor
58 and the capacitor
56 provide the same action as the transistor
44, the resistor
66
and the capacitor
64. For this reason, the same effect can be obtained even
when the door mirror
26 is deployed from the storage position.
Second Embodiment
Next, other embodiments of the invention will be described. It should be noted
that, for the purpose of describing the embodiments below, the same reference numerals
will be given to parts that are fundamentally the same as those in embodiments
preceding the embodiment being described, including the first embodiment, and that
description of those parts will be omitted.
In FIG. 5, a circuit diagram of a mirror device motor control circuit
90
(referred to below simply as "the control circuit
90") pertaining to a second
embodiment of the invention is illustrated.
As illustrated in this diagram, a drive control section
91 of the present
control circuit
90 is disposed with a capacitor
92 serving as a storage
terminal. An end of the capacitor
92 is connected between the resistor
28
and the resistor
38, and the other end of the capacitor
92 is connected
between the resistor
34 and the resistor
40.
Because the present control circuit
90 disposed with the capacitor
92 in this manner is the same as the control circuit
10 pertaining
to the first embodiment excluding the capacitor
92, the control circuit
90 fundamentally provides the same action as that of the first embodiment,
and the same effects can be obtained.
However, by disposing the capacitor
92 in the present control circuit
90, a charge is stored in the capacitor
92 when the current A
1
flows due to the terminal
18A and the terminal
18B of the switch
18 being connected when the terminal
16A and the terminal
16B
of the switch
16 are connected.
As shown in FIG. 5, the gate terminal of the MOSFET
24 is connected to
the capacitor
92 via the resistor
40, whereby the current value of
the current gradually flowing to the gate terminal of the MOSFET
24 is reduced
in accordance with the charge that the capacitor
92 has stored. Thus, as
shown in the time chart of FIG. 6, the voltage Vg acting on the gate terminal of
the MOSFET
24 gradually drops in accompaniment with the elapse of time.
For this reason, when the predetermined period of time—i.e., the period
of time that the door mirror
26 is rotated until the storage position-elapses
and the voltage Vg becomes equal to or less than the predetermined value Vg1, conduction
between the drain terminal and the source terminal of the MOSFET
24 is released.
Thus, in this state, conduction to the motor
20 is forcibly cut off, the
driving of the motor
20 is stopped, and the door mirror
26 stops
rotating at the storage position.
In this manner, in the present control circuit
90, because the motor
20
is forcibly stopped not only when the lock current has reached the predetermined
value or greater but also due to the predetermined period of time elapsing, drawbacks
arising due to the lock current acting for a long period of time on the motor
20
and the MOSFETs
22 and
24 can be prevented.
Configuration of Third Embodiment
Next, a third embodiment of the invention will be described.
In FIG. 7, the configuration of a mirror device motor control circuit
100
(referred to below simply as "the control circuit
100") pertaining to the
present embodiment of the invention is illustrated by a circuit diagram.
As illustrated in this diagram, in the present control circuit
100, in
contrast to the control circuit
10 pertaining to the first embodiment, a
resistor
102 is disposed between the contact point
74 and the drain
terminal of the MOSFET
22, and a resistor
104 is disposed between
the contact point
78 and the drain terminal of the MOSFET
24.
Also, the resistors
38 and
40 are not disposed in the control
circuit
100, the other end of the resistor
28 and the contact point
48 are directly connected, and the other end of the resistor
34 and
the contact point
52 are directly connected.
Moreover, a diode
106 is disposed between the contact point
48
and the contact point
76, and the orientation of the current between the
contact point
48 and the contact point
76 is restricted to an orientation
from the contact point
48 to the contact point
76. Similarly, a diode
108 is disposed between the contact point
52 and the contact point
80, and the orientation of the current between the contact point
52
and
80 is restricted to an orientation from the contact point
52
to the contact point
80.
Also, in the present control circuit
100, the capacitor
56 is
not disposed between the contact point
54 and the contact point
60,
and the contact point
54 and the contact point
60 are not connected.
Thus, the other end of the resistor
58 is connected only to the base terminal
of the transistor
42. However, an end of a resistor
110 configuring
a compensation component is connected to the contact point
54. The other
end of the resistor
110 is connected to a contact point
112 between
the diode
106 and the contact point
76. Moreover, a resistor
113
is disposed between the contact point
76 and the contact point
112.
The capacitor
64 is not disposed between the contact point
62 and
the contact point
68, and the contact point
62 and the contact point
68 are not connected. Thus, the other end of the resistor
66 is connected
only to the base terminal of the transistor
44. However, an end of a resistor
114 configuring a compensation component is connected to the contact point
62. The other end of the resistor
114 is connected to a contact point
116 between the diode
108 and the contact point
80. Moreover,
a resistor
117 is disposed between the contact point
80 and the contact
point
116.
Moreover, an end of a capacitor
118 configuring a compensation component
is connected to the contact point
112, and the other end of the capacitor
118 is connected to the contact point
116.
Action and Effects of the Third Embodiment
In the present control circuit
100 of the above configuration, when the
terminal
16A and the terminal
16B of the switch
16 are connected
and the terminal
18A and the terminal
18B of the switch
18
are connected, the current A
2 separated from the current A
1 flows
to the diode
108 and proceeds to the gate terminal of the MOSFET
24.
Also, in this state, a current A
7 proceeding to the resistor
110
via the contact points
30,
46 and
54 flows. After the current
A
7 has flowed from the resistor
110 to the capacitor
118,
it is separated into a current A
8, which proceeds to the gate terminal of
the MOSFET
24, and a current A
9, which proceeds to the resistor
114.
Thus, in this state, the voltage Vg based on the current A
2 and the
current A
8 is applied to the gate terminal of the MOSFET
24 and the
voltage Vg exceeds the predetermined value Vgm, whereby between the drain terminal
and the source terminal of the MOSFET
24 becomes conductive and the drive
current flows to the motor
20. Thus, the driving of the motor
20 starts.
The lock current of a specific size or greater flows to the motor
20,
and when the voltage Vb corresponding to the lock current becomes the specific
value Vbm or greater and is applied to the base terminal of the transistor
44,
between the collector terminal and the emitter terminal of the transistor
44
becomes conductive, and part or all of the current A
2 passes through the
collector terminal and the emitter terminal of the transistor
44 and is
grounded. Thus, because the voltage Vg that had been applied to the gate terminal
of the MOSFET
24 until then drops or is eliminated, conduction between the
drain terminal and the source terminal of the MOSFET
24 is released and
conduction with respect to the motor
20 is cut off.
In this manner, in the present control circuit
100, the voltage Vb corresponding
to the lock current applied to the base terminal of the transistor
44 becomes
equal to or greater than the specific value Vbm, whereby conduction with respect
to the motor
20 is cut off. Thus, the same effects as those of the first
embodiment can be obtained.
Incidentally, as described earlier, the substantially pulse-like inrush
current flows immediately after driving of the motor
20 is initiated. Here,
in the present control circuit
100, part of the inrush current proceeds
to the base terminal of the transistor
44 via the resistor
66, and
the voltage Vb resulting from this inrush current is applied to the base terminal.
However, as shown in the time chart of FIG. 8, in contrast to the first
embodiment, because the capacitor
64 is not disposed, the waveform of the
voltage Vb resulting from the inrush current applied to the base terminal of the
transistor
44 becomes a substantial pulse, and does not become a waveform
that gradually rises as in the first embodiment. For this reason, the voltage Vb
is applied to the base terminal of the transistor
44, whereby between the
collector terminal and the emitter terminal of the transistor
44 becomes
conductive, and part or all of the current A
2 is grounded.
The inrush current proceeds to the resistor
114 via the zener diode
70
and the resistor
113. A voltage Ve between both ends of the resistor
114
at the time the inrush current has flowed rises extemporaneously to a maximum value
Vem. Here, because the contact point
116 between the capacitor
118
and the resistor
114 is connected to the gate terminal of the MOSFET
24,
the current flows for a set period of time and the voltage between both ends of
the resistor
114 becomes equal to or greater than a set value. Thus, regardless
of the state of the transistor
44, the voltage Vg corresponding to the voltage
Vem is applied to the gate terminal of the MOSFET
24. Because the voltage
Vg corresponding to the voltage Vem exceeds the predetermined value Vgm, between
the drain terminal and the source terminal of the MOSFET
24 becomes conductive.
Also, because the inrush current is substantially pulse-like and the integration
circuit is configured by the resistor
110 and the capacitor
118,
the voltage Ve between both ends of the resistor
114 gradually drops after
it reaches the maximum value Vem. However, because the voltage Vg corresponding
to the maximum value Vem exceeds the predetermined value Vgm, a predetermined period
of time T
5 (less than T
1) is necessary during the period of time
until the voltage Vg corresponding to the dropping voltage Ve becomes equal to
the predetermined value Vgm.
As described above, because the inrush current is substantially pulse-like, the
voltage Vb corresponding to the inrush current applied to the base terminal of
the transistor
44 rapidly drops after reaching the maximum value Vbm, and
falls below the voltage Vb
1 necessary for conduction between the collector
terminal and the emitter terminal of the transistor
44. Thus, until the
voltage Vb resulting from the inrush current becomes less than the specific value
Vb1, the voltage Vg corresponding to the voltage Ve is applied to the gate terminal
of the MOSFET
24 and conduction is allowed between the drain terminal and
the source terminal, whereby conduction is continuously allowed between the drain
terminal and the source terminal of the MOSFET
24 during the period of time
until the predetermined time T
1 from the drive starting time T
0 of
the motor
20 to until the inrush current stops flowing elapses.
That is, even in the present control circuit
100, the driving of the
motor
20 can be reliably started similar to the first embodiment.
It should be noted that, as shown in FIG. 7, even in the present control circuit
100, the circuit configuration is symmetrical between the switch
16
side and the switch
18 side via the motor
20. Thus, when the terminal
16A and the terminal
16C of the switch
16 are connected and
the terminal
18A and the terminal
18C of the switch
18 are
connected, the transistor
42 and the resistor
58 provide the same
action as the transistor
44 and the resistor
66. For this reason,
the same effects can be obtained even when the door mirror
26 is deployed
from the storage position.
Fourth Embodiment
Next, a fourth embodiment of the invention will be described.
In FIG. 9, a circuit diagram of a mirror device motor control circuit
120
(referred to below simply as "the control circuit
120") pertaining to the
fourth embodiment of the invention is illustrated.
As will be understood by comparing this diagram with FIG. 7, in a drive control
section
122 of the present control circuit
120, the other end of
the resistor
28 (end portion opposite from the contact point
30)
and the other end of the resistor
34 (end portion opposite from the contact
point
36) are not connected in comparison to the third embodiment; rather,
the other end of the resistor
28 is connected to the contact point
52,
and the other end of the resistor
34 is connected to the contact point
48.
However, although there is a difference in configuration with respect to the above
point, the operation of the circuit is the same as that of the configuration where
the other end of the resistor
28 and the other end of the resistor
34
are connected.
Also, in the present control circuit
120, a resistor
124 is disposed
in place of the diode
106, and a resistor
126 is disposed in place
of the diode
108. Moreover, in the present control circuit
120, the
resistors
110 and
114 are not disposed, the contact points
54
and
112 at both ends of the resistor
110 in the third embodiment
are not connected and, similarly, the contact points
62 and
116 at
both ends of the resistor
114 are not connected (in FIG. 9, the contact
points
58 and
62 are omitted because the resistors
110 and
114 are not present).
As described above, the diodes
106 and
108 are disposed in the
control
circuit
100 of the third embodiment so that, when the transistors
42
and
44 are switched to the ON state, the currents that are supposed to proceed
to the gate terminals of the MOSFETs
22 and
24 are prevented from
being grounded via the collector terminals and emitter terminals of the transistors
42 and
44.
With respect thereto, although the diodes
106 and
108 are not
disposed in the present control circuit
120, the resistors
124 and
126 are disposed so that, even when the transistors
42 and
44
are switched to the ON state, set currents can be applied to the gate terminals
of the MOSFETs
22 and
24. That is, although there is a difference
in configuration with respect to the above point, the present control circuit
120
fundamentally provides the same action as the control circuit
100 of the
third embodiment, and the same effects can be obtained.
Moreover, as described above, although the resistors
124 and
126
are disposed in the present control circuit
120, the resistors
110
and
114 and the diodes
106 and
108<
