JPH10250471A - Load operation control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent falling into a condition that a power load is continued to operate regardless of an on/off condition of a switch, without providing an element impeding a reverse flow of a current on wiring. SOLUTION: A connection point P1 between an oblique switch 46 and an oblique lamp 48 is connected to an ECU44 through a resistor 56, and to a power source 90 through resistors 54, 58. The resistor 58 is connected to the ECU44 through transistors 60, 62. A branch point Po is grounded through a diode 74 and resistor 80, a connection point P2 between the diode 74 and the resistor 80 is connected to the ECU44 through a resistor 82. In the ECU44, based on a potential of the connection point P2 in a condition turning off the transistors 60, 62, whether supply of power from a power source 88 is provided or not is judged, based on a potential of the connection point P1 in a condition turning on the transistors 60, 62 and shorting the resistor 58, whether the switch 46 is on or off is judged, to control lighting/extinguishing of a dome lamp 62 by a MOSFET 68.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load operation control device, and more particularly, to a load operation control device that determines the on / off state of a switch and controls the operation of a power load.

[0002]

2. Description of the Related Art A vehicle is provided with various switches such as a courtesy switch which is turned on / off in response to opening / closing of a door of the vehicle. The operation of various power loads is controlled in conjunction with the on / off of the various switches. (For example, a dome lamp that illuminates the interior of the vehicle in conjunction with the on / off operation of the courtesy switch, a door courtesy lamp provided on the door of the vehicle that illuminates the foot of the occupant, an ignition key lamp that illuminates the ignition key cylinder, etc. Etc.). Among various power loads whose operation is controlled in conjunction with the on / off of the switch, the on / off state of the switch is detected by an electronic control unit (hereinafter referred to as ECU), and the on / off state of the switch is detected by the ECU. Some are controlled based on the results.

FIG. 5 shows an example of a courtesy switch 10.
An example of a control device that controls turning on and off of the courtesy lamp 102 and the dome lamp 104 as an operation control device of an electric load whose operation is controlled in conjunction with turning on and off of 0 is shown. In FIG. 5, a courtesy switch 100 has one end grounded and the other end provided with a courtesy lamp 102 and a diode 1.
20, connected to the battery via the fuse 106. The dome lamp 104 has a fuse 106 at one end.
, And the other end is grounded via a transistor 108. Transistor 108
Is connected via a resistor 112 to an output port of an ECU 114 mounted on the board 110. Further, one end of the resistor 116 and the resistor 118 is connected between the courtesy switch 100 and the courtesy lamp 102, and the other end of the resistor 116 is connected to an input port of the ECU 114. The other end of the resistor 118 is connected to a battery via a power supply circuit (not shown).

In the above control device, the courtesy switch 1
The courtesy lamp 10 is directly linked to the turning on and off of 00.
2 is turned on and off. The change of the on / off state of the courtesy switch 100 is determined by the ECU 1 via the resistor 116.
The ECU 114 detects the change in the voltage input to the ECU 14. The ECU 114 turns on / off the transistor 108 in response to the detected change in the on / off state of the courtesy switch 100, and
The turning on and off of the dome lamp 104 is controlled so as to be linked to the turning on and off of the dome lamp 104. Therefore, the dome lamp 104 is turned on and off indirectly in conjunction with turning on and off the courtesy switch 100.

[0005]

In the above-described control device, the fuse 106 is blown due to a short circuit of the courtesy lamp 102, or the fuse 106 is blown (when the vehicle is transported, the fuse is blown). Even when the vehicle door is opened and the courtesy switch 100 is turned on, the ECU 11
4, the transistor 108 is turned on and the dome lamp 104 is turned on.

However, if the diode 120 is not present, then, when the door of the vehicle is closed and the courtesy switch 100 is turned off, a current flows backward from the resistor 118 to the courtesy lamp 102, and passes through the dome lamp 104 and the transistor 108. A so-called current wraparound, in which a current flows to the ground end, occurs. As a result, there has been a problem that the ECU 114 cannot detect that the courtesy switch 100 has been turned off, and the dome lamp 104 is continuously lit to cause a dead battery or the like.

[0007] In order to prevent the above-mentioned sneak current,
In the control device shown in FIG. 5, between the fuse 106 and the courtesy lamp 102 (the courtesy lamp 102 and the connection point P ₁
), A diode 1 for preventing reverse current flow
20 are provided. As described above, providing a diode at a place where a current may flow backward, for example, as shown in FIG. 3 of JP-A-56-112335,
Generally done widely.

However, in a vehicle, a large number of wires between fuses, power loads provided in various parts of the vehicle, and switches are integrated as a wire harness. It is difficult to provide a diode in the middle of the wiring from to the switch. It is also conceivable to provide a diode in close proximity to the power load. is there.

Further, it is conceivable to provide a diode in the vicinity of the fuse. However, since a large number of fuses for a vehicle are housed in a dense state in a fuse box,
It is not preferable to provide a diode in the fuse box afterwards and connect the diode to a specific fuse in terms of wiring reliability and the like. Further, redesigning the fuse box on the assumption that the diode is incorporated leads to an increase in design cost and manufacturing cost.

The present invention has been made in view of the above facts, and prevents a state in which a power load continues to operate irrespective of the on / off state of a switch. It is an object to obtain a load actuation control device that can be prevented without providing an element.

[0011]

[MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
The load operation control device according to the invention described in claim 1 has an example
As shown in FIG. 1A, the feeding point (P₀)
The load power supply (10) to be supplied and the power supply point (P₀) And ground end
And a switch (12) provided between the power supply point (P
₀) Via the load power supply (10).
Load (14), the switch (12) and the feed point (P
₀) And the first detection point (P₁) Differs from the load power supply (10).
A detection power supply (16) for supplying electric power at a given voltage;
Detection point (P₁) Based on the potential of the switch (12).
ON / OFF state of the switch (12)
Control for controlling the operation of the power load (14) according to the state
Means (18) and the first detection point (P₁) And power load (14)
The second detection point (P_Two) Detection to detect the potential of
Means (20), detected by the detecting means (20)
The second detection point (P_Two) Based on the potential of the load
From (10), the feed point (P₀To determine if power is supplied to
The power supply point (P) from the load power supply (10). ₀) To power
When it is determined that power is not supplied,
Limiting means (22) for limiting the operation of (14).
Has formed.

According to the first aspect of the present invention, a switch is provided between a power supply point to which power is supplied from a load power supply and a ground terminal, and the detection power supply is a first power supply between the switch and the power supply point.
Power is supplied to the detection point, and the control means determines the on / off state of the switch based on the potential of the first detection point. As described above, when the switch is turned on, the potential at the first detection point is decreased, and when the switch is turned off, the potential at the first detection point is increased. Therefore, the control means controls the switch based on the potential at the first detection point. The on / off state can be determined, and the operation of the power load is controlled according to the determined state of the switch (for example, the power load is operated when the switch is on).

In the above-described load operation control device, for example, a contact failure occurs between the load power supply and the power supply point, the wiring between the load power supply and the power supply point is cut, or the load power supply and the power supply point are disconnected. The power supply from the load power supply to the power supply point may be caused by the overcurrent cutoff means such as a fuse or breaker placed between the load power supply and the power supply point. The switch changes from the on state to the off state while the supply of
Further, assuming that the power load has been operated before the switch is turned off, a current flows backward from the detection power supply to the power supply point via the first detection point (see the arrow A in FIG. 1A), and the power is further supplied. A so-called current sneak occurs in which a current flows from the point to the power load.

Due to the current sneaking, even if the switch changes to the off state, a large change does not occur in the potential at the first detection point, and the control means changes the on / off state of the switch from the potential at the first detection point. May not be determined.

On the other hand, according to the first aspect of the present invention, the detection power supply supplies power to the first detection point between the switch and the power supply point at a voltage different from that of the load power supply. Further, detection means for detecting the potential of the second detection point on the wiring between the first detection point and the power load is provided, and the limiting means detects the potential of the second detection point based on the potential of the second detection point detected by the detection means. To determine whether power is supplied from the load power supply to the power supply point. Thus, when the supply of power from the load power supply to the power supply point is stopped, the potential of the second detection point detected by the detection means changes. It can be reliably determined that the supply has been stopped.

The limiting means limits the operation of the power load when it is determined that power is not being supplied from the load power supply to the power supply point, so that the power load continues to operate regardless of the on / off state of the switch. Can be prevented. Further, it is not necessary to provide an element such as a diode for preventing the reverse flow of the current on the wiring through which the reverse current flows, that is, on the wiring between the feeding point and the first detection point.

The invention according to claim 2 is, as an example, shown in FIG.
As shown in (B), the detecting means (20) includes a first resistance means (24) having a first electric resistance provided between the second detection point (P ₂ ) and the ground end. Equipped with a detection power supply (1
6) a second resistance means (26) having a second electric resistance.
The power is supplied to the first detection point (P ₁ ) through the first detection point (P ₁ ).

As the resistance means, any means can be used as long as it causes a voltage drop when a current flows, and for example, a resistor or another element having electric resistance can be used. According to the second aspect of the present invention, since the detection power supply supplies power to the first detection point via the second resistance means having the second electric resistance, for example, the voltage of the load power supply and the voltage of the detection power supply are the same. In this case, the detection power supply can supply power to the first detection point at a voltage different from that of the load power supply.

According to the second aspect of the present invention, when power is not supplied from the load power supply to the power supply point, the second resistance means, the first detection point, the second detection point, and the first resistance means of the detection power supply. Since the current flows through the second detection point, the potential at the second detection point becomes a value obtained by dividing the voltage of the detection power supply by the first resistance means and the second resistance means (from the second resistance means to the feeding point). If an element or a power load that causes a voltage drop is provided in the middle of the wiring, the electric potential of the second detection point further decreases due to the electric resistance of the element or the power load.) Then, power is supplied from the load power supply to the feeding point. Since the value is clearly different from the case where the power supply point is not supplied, the limiter can more reliably determine the state where power is not supplied from the load power supply to the power supply point.

The first resistance means and the second resistance means need not be provided on the wiring between the feeding point and the first detection point, but can be provided close to the control means. In the case where the means is constituted by a microcomputer, the microcomputer may be a one-chip microcomputer including the first resistance means and the second resistance means, or may be provided on a substrate on which the microcomputer is mounted. Therefore, the provision of the first resistance means and the second resistance means does not cause a problem such as a deterioration in the appearance of the vehicle interior or an increase in design cost and manufacturing cost.

By the way, in the invention of claim 2, the first
Is provided between the second detection point and the ground end.
Therefore, a dark current flows through the first resistance means.
Is the first resistance R of the first resistance means.₁Increase the value of
Can reduce dark current and reduce power consumption
be able to. On the other hand, make sure that the switch is
To detect the change in the on / off state of the switch
It is desirable to increase the change in the potential of the first detection point due to
And this is the second electrical resistance R of the second resistance means. _TwoThe value of the
Can be achieved by lowering

However, assuming that R ₁ ≫R ₂ , a case where power is supplied from the load power supply to the power supply point, a case where power is not supplied from the load power supply to the power supply point and a current sneak occurs, Therefore, even if the change in the potential at the second detection point is small and the power is not supplied from the load power supply to the power supply point, the limiter may not be able to detect the change due to, for example, a change in the voltage of the detection power supply. is there.

In view of the above, the invention according to claim 3 is, as an example, as shown in FIG.
The first detection point (via the second resistance means (26) and the third resistance means (28) having a third electrical resistance connected in series to the second resistance means (26). P ₁ ) is supplied with electric power, and on / off is controlled by the control means (18).
The switching means (30) for short-circuiting both ends of the third resistance means (28) when turned on is configured. The limiting means (22) turns off the switching means (30) of the detection power supply (16). In this state, it is determined whether power is supplied from the load power supply (10) to the power supply point (P ₀ ), and the control means (18)
Is characterized in that the on / off state of the switch (12) is determined while the switching means (30) is on.

According to the third aspect of the present invention, it is determined whether or not power is supplied from the load power supply to the power supply point in a state where the switching means is off (a state where both ends of the third resistance means are not short-circuited). Therefore, assuming that a current sneak occurs, when the sneak current flows through the third resistance means, the limit means determines whether power is supplied from the load power supply to the power supply point. Will be judged.

Therefore, if the value of the third electric resistance R ₃ of the third resistance means is increased (for example, if R ₃ ≫R ₂ ),
Even a higher first value of the electrical resistance R ₁ of the first resistor means in order to reduce power consumption, and if power to the feeding point from the load power is being supplied, the power to the feeding point from the load power supply Is not supplied, and the change in potential at the second detection point when the current sneak occurs can be increased,
The limiter can reliably determine that the power is not being supplied from the load power supply to the power supply point based on the potential at the second detection point.

The control means determines the on / off state of the switch in a state where the switching means is on (a state where both ends of the third resistance means are short-circuited). if the lower value of the electrical resistance R _2, independently of the third value of the electrical resistance R ₃ of the third resistor means, the change in potential of the first detection point associated with the change in state of the switch on-off is large Become. Therefore, the control unit can reliably determine the on / off state of the switch based on the potential at the first detection point.

As described above, according to the third aspect of the present invention, the value of the first electric resistance of the first resistance means is increased for the purpose of reducing power consumption, and the on / off state of the switch is reliably detected. Even when the value of the second electric resistance of the second resistance means is reduced for the purpose, it is possible to reliably determine whether or not power is supplied from the load power supply to the power supply point.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 2 shows, as a load operation control device according to the present invention, a lamp on / off control device 40 for controlling the turning on and off of a lamp provided in a vehicle. The lamp on / off control device 40 includes an ECU (Electronic Control Unit) 44 mounted on a board 42. Although not shown, the ECU 44 includes a CPU,
It has a ROM for storing programs and the like executed by the CPU, a RAM for storing various data and the like, an input port, and an output port, which are connected to each other via a bus. The ECU 44 corresponds to the control means and the restriction means of the present invention.

The lamp turning on / off control device 40 includes a courtesy switch 46 provided near the hinge of the vehicle door and turned on when the vehicle door is opened and turned off when the vehicle door is closed. ing. Courtesy switch 46
Has one end grounded and the other end connected to one end of a courtesy lamp 48 disposed on the inner side surface of the vehicle door. The other end of the courtesy lamp 48 is connected to one end of a fuse 50 via a branch point P ₀ (corresponding to a power supply point of the present invention). The other end of the fuse 50 is directly connected to a battery (not shown), and a voltage V (for example, V = 12
V). This battery corresponds to the load power supply of the present invention, and is hereinafter referred to as “first power supply 88”.

Although not shown, the courtesy switches 46 and the courtesy lamps 48 are provided in the same number as the number of doors of the vehicle, and are provided at each door of the vehicle.
The courtesy lamps 48 of each door have the same fuse 50 respectively.
It is connected to the.

The courtesy switch 46 and the courtesy lamp 4
8, a connection point P ₁ (corresponding to a first detection point of the present invention) is located at the connection point P ₁ via a terminal 52 formed on the substrate 42 and a resistor 54. One end of a resistor 56 (corresponding to a second resistance means according to claim 2) and one end of the resistor 56 are connected. The other end of the resistor 56 is connected to the input port B of the ECU 44. Therefore, the input port B of the ECU44 potential V ₁ of the connection point P ₁ is input as the voltage V _B.

The other end of the resistor 54 is connected to one end of the resistor 58 and PN
It is connected to the collector of P transistor 60. resistance
The other end of the battery 58 is connected to a power supply circuit (not shown).
And a voltage V equal to that of the first power supply 88.
Is supplied with power. Below, the power supply circuit and battery
Are collectively referred to as “second power supply 90”. Note that the voltage of the resistor 54 is
Air resistance (second electric resistance) R_TwoAnd the electrical resistance of the resistor 58
(Third electrical resistance) R _ThreeIs R_Two≪R_ThreeIt has been.

The other end of the resistor 58 is also connected to the emitter of the PNP transistor 60, and the base of the PNP transistor 60 is connected to the collector of the NPN transistor 62. Therefore, the PNP transistor 60
Is turned on, both ends of the resistor 58 are short-circuited. NP
The emitter of the N transistor 62 is grounded.
The base of the N transistor 62 is connected to the output port C of the ECU 44.

The PNP transistor 60 and the NPN
The transistor 62 corresponds to the switching means of the present invention, and is turned on / off by a signal output from the output port C of the ECU 44. Also, the second power supply 9
0, resistor 54, resistor 58, PNP transistor 60, N
The PN transistor 62 corresponds to the detection power supply of the present invention.

One end of a dome lamp 64 disposed on the ceiling of the interior of the vehicle is connected to the branch point P ₀ . The other end of the dome lamp 64 is connected to the terminal 6 formed on the substrate 42.
6 is connected to the drain of the MOSFET 68 mounted on the substrate 42. The gate of the MOSFET 68 is connected to the output port D of the ECU 44 via the resistor 70, and the source of the MOSFET 68 is grounded.

The branch point P ₀ is connected to the anodes of a diode 74 and a diode 76 mounted on the substrate 42 via a terminal 72 formed on the substrate 42. The cathode of the diode 76 is connected to the power supply circuit 78. The cathode of the diode 74 is respectively connected to one end of the (first corresponds to the resistance means according to claim 2) and the resistor 82 resistor 80 via the node P _2, the resistance 8
The other end of 0 is grounded. The other end of the resistor 82 is EC
It is connected to input port A of U44.

The diode 74 and the resistor 80 correspond to the detecting means of the present invention. The potential V ₂ of the connection point P ₂ is input to the input port A of the ECU 44 as the voltage _VA . The potential V ₂ at the connection point P ₂ is substantially equal to the value of the branch point P _0, the potential of the branch point P ₀ by a voltage V _A is indirectly ECU
44 is detected. Thus, the branch point P ₀ also corresponds to the second detection point of the present invention.

When power is supplied from the first power supply 88 to the branch point P ₀ , regardless of the on / off state of the courtesy switch 46, a current (dark current) always flows through the resistor 80 to the ground terminal. Flows. Therefore, the electric resistance (first electric resistance) R ₁ of the resistor 80 is set to a relatively high value (R ₁ ≫R) in order to suppress dark current and reduce power consumption.
₂ ).

On the other hand, the cathode of a diode 84 is connected to the power supply circuit 78, and the anode of the diode 84 is connected to a power supply different from the battery. The power supply circuit 78 is connected to a power supply terminal POW of the ECU 44 and converts the power supplied via the diode 76 or the diode 84 into a voltage (for example, 5
V) to supply to ECU44. Since power is supplied to the power supply circuit 78 via the diode 76 or the diode 84, the ECU 44 operates by being supplied with power from the power supply circuit 78 even when the fuse 50 is blown, for example.

[0040] Note that in the lamp point off controller 40, the wiring outside the substrate 42 (e.g. by connecting the branching point P ₀ and courtesy lamp 48 lines and has a wiring that is connected to the courtesy lamp 48 connection points P ₁ ) Are integrated as a wire harness with a number of other wires provided in the vehicle.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG. 3 showing the dome lamp turning on / off control processing executed by the ECU 44. Step 150
Then, a signal for turning off the NPN transistor 62 is output from the output port C, and the NPN transistor 62 is turned off. As a result, the PNP transistor 60 is also turned off, and the connection point P ₁ is connected to the second power supply 90 via the resistors 54 and 58.
Connected to. In step 152, reads the voltage V _A input to the input port A, the value of the voltage V _A at the next step 154 determines whether more than a predetermined value.

Here, assuming that conduction is established between the branch point P ₀ and the first power supply 88 and power is supplied from the first power supply 88 to the branch point P ₀ , the on / off of the courtesy switch 46 is assumed. , The potential V _{2 at the} connection point P ₂ (≒ potential V _{0 at the} branch point P ₀ ) is substantially equal to the voltage V (for example, 12 V) of the first power supply 88. On the other hand, there is no conduction between the branch point P ₀ and the first power supply 88, and the first power supply 8
When power is not supplied to the branch point P ₀ from FIG.
As will be described later in detail, if the transistor 60 and 62 if turned off, the potential V ₂ at the connection point P ₂ voltage V of the first power supply 88
Clearly lower than

In step 154, taking into account that the voltage V of the first power supply 88 (ie, the battery of the vehicle) fluctuates due to fluctuations in the load, etc.
It uses a slightly lower voltage value than the voltage V of the power source 88, between the first power source 88 in step 154 and the branch point P ₀ is determined whether or not conducting.

The first power source 88 is rendered conductive during the branch point P _0, if power is supplied to the branch point P ₀ from the first power supply 88, the determination at Step 154 is negative, at step 156 After the abnormality flag is set to 0, in step 162, the process waits until a predetermined time t _OFF (see FIG. 4) has elapsed since the transistors 60 and 62 were turned off in the previous step 150. When a predetermined time t _OFF has elapsed after the transistors 60 and 62 have been turned _off , the process proceeds to step 164, where a signal for turning on the NPN transistor 62 is output from the output port C, and the NPN transistor 62 is turned on. As a result, the PNP transistor 60 is also turned on, the resistor 58 is short-circuited, and the connection point P ₁ is connected to the second power supply 90 via the resistor 54.

[0045] In the next step 166 reads the voltage V _B that is input to the input port B, the value of the voltage V _B at the next step 168 determines whether more than a predetermined value. In addition, EC
The voltage V _B input to the input port B of U44 is the connection point P
Approximately equal to ₁ potential V _1, also As the predetermined value, higher than the potential V ₁ of the connection point P ₁ when the courtesy switch 46 is on, and the connection point when the courtesy switch 46 is turned off P _A value lower than the potential V1 of ₁ is set. Therefore, in step 168, it is determined whether or not the courtesy switch 46 is on.

When the door of the vehicle is opened and the courtesy switch 46 is turned on, if power is supplied from the first power supply 88 to the branch point P ₀ , the fuse 50 and the branch A current flows to the ground terminal through the point P ₀ , the courtesy lamp 48, the connection point P ₁ , and the courtesy switch 46. As a result, the courtesy lamp 48 is turned on, and the feet of the occupant performing the boarding operation by opening the door of the vehicle are illuminated. The potential V ₁ of the connection point P ₁ is substantially 0V and the determination in step 168 is affirmative.

If the determination at step 168 is affirmative, the routine proceeds to step 170, where it is determined whether the abnormality flag is 1. If the determination in step 170 is negative, the process proceeds to step 172, where a signal for turning on the MOSFET 68 is output from the output port D to turn on the MOSFET 68. As a result, the first power supply 88 supplies the fuse 5
0, branch point P ₀ , dome lamp 64, MOSFET 68
Current flows through the dome lamp 64, and the dome lamp 64 is turned on. When the occupant opens the vehicle door and performs the getting on / off operation,
The vehicle interior is illuminated by the dome lamp 64.

When the door of the vehicle is closed and the courtesy switch 46 is off, the potential of the connection point P ₁ is supplied by the second power supply 90 connected to the connection point P ₁ via the resistor 54. V ₁ is pulled up. In this case, the resistor 58 is shorted by PNP transistor 60, the electric resistance R ₂ of the resistor 54 is the R ₂ «R _3, the potential V ₁ of the connection point P _1, when the courtesy switch 46 is turned on , And the determination in step 168 is denied.

If the determination at step 168 is negative (and the determination at step 170 is positive), the process proceeds to step 174, where a signal for turning off the MOSFET 68 is output from the output port D to turn off the MOSFET 68. As a result, the dome lamp 64 is turned off.

In the next step 176, the previous step 1
A predetermined time after the transistors 60 and 62 are turned on at 64
t_ON(See FIG. 4). And tiger
A predetermined time t since the transistors 60 and 62 are turned on._ONHas passed
Then, the process returns to step 150 and the above processing is repeated. Obedience
Therefore, the transistors 60 and 62 are turned on and off at regular intervals.
When the transistors 60 and 62 are off, the first
Power supply 88 and branch point P ₀It is determined whether the
When the transistors 60 and 62 are turned on.
The on / off state of the courtesy switch 46 is determined.
And

By the way, for example, the courtesy lamp 48 is short-circuited and an overcurrent flows through the fuse 50, so that the fuse 50 is blown, the fuse 50 is pulled out for transporting the vehicle, or the first power supply 88 is connected to the branch point P. ₀
When the connection failure between the wirings and the like occurs, if the courtesy switch 46 is on, the potential V of the connection point P _2
2 is approximately 0 V, but when the courtesy switch 46 is turned off, the current flows backward from the second power supply 90 to the branch point P ₀ through the connection point P ₁ and the courtesy lamp 48,
Diode 74 from the branch point P _0, the current flows into the through resistor 80 ground terminal, the potential V ₂ at the connection point P ₂ is clearly higher than 0V.

Here, when the courtesy switch 46 is on and the transistors 60 and 62 are on and both ends of the resistor 58 are short-circuited, the potential V _{2 at the} connection point P ₂ is generated due to the above-mentioned reverse current. Is

[0053]

(Equation 1)

(The electric resistance of the courtesy lamp 48 and the like is small and can be neglected.) The voltage V of the second power supply 90 is divided by the electric resistances of the resistors 54 and 80, and has a value corresponding to the divided voltage. The electrical resistance R ₂ of R ₂ ≪R ₁
Therefore, the actual potential V ₂ is substantially equal to the voltage V of the second power supply 90 (≒ the voltage V of the first power supply 88).

On the other hand, even when the courtesy switch 46 is on, if the transistors 60 and 62 are off and the resistor 54 is connected to the second power supply 90 via the reverse flow of current, the potential V ₂ at the connection point P ₂ is

[0056]

(Equation 2)

Is as follows. Here, the electric resistance R ₃ of the resistor 58
Since R ₃ ≫R ₂ , the potential V ₂ is clearly lower than the voltage V of the second power supply 90 (≒ the voltage V of the first power supply 88). When the courtesy switch 46 is off, as shown in FIG.
Despite the potential V ₂ to the state of the on-off of 62 becomes less than a predetermined value (low level).

In this embodiment, as shown in FIGS. 4A and 4B, when the transistors 60 and 62 are off, the first power supply 88 and the branch point P ₀ conduct. dolphin whether, that is, power to the branch point P ₀ from the first power supply 88 is judged whether it is supplied (step 15
4) Therefore, for example, the fuse 50 is blown by an overcurrent flowing through the fuse 50, or the fuse 50 is removed for transporting the vehicle, or the first power supply 8
In the event that a wiring connection failure has occurred between the wiring 8 and the branch point P ₀ , the determination in step 154 is positively made regardless of the on / off state of the courtesy switch 46.

If the determination in step 154 is affirmative, in step 158, a signal for turning off the MOSFET 68 is output from the output port D to turn off the MOSFET 68. In the next step 160, the abnormality flag is set to 1 and then in step 162 Move to. The above, until the determination in step 154 is negative by the dome lamp 64 together with becomes off state, conduction between the branch point P ₀ and the first power source 88 is performed, for example, replacement of fuses 50 Since the abnormality flag does not become 0, the determination in step 170 is affirmed, the MOSFET 68 is continuously turned off, and the dome lamp 64 is continuously turned off (operation is restricted). Note that the determination in step 170 is made in steps 156 and 160 in which a value is set in the abnormality flag.
Together with the limiting means of the present invention.

As described above, the first power supply 88 supplies the branch point P
_Even when power is not supplied to ₀ , it is possible to prevent the dome lamp 64 from continuing to light regardless of the on / off state of the courtesy switch 46. Also, it is not necessary to provide a diode in the middle of the wire harness or the like in order to prevent the backflow of the current. Then, for example, the blown fuse 50 is replaced or the blown fuse 5 is removed.
When the continuity between the first power supply 88 and the branch point P ₀ is restored, for example, by resetting ₀ or by repairing a wiring contact failure, the determination in step 154 is affirmed, and the abnormality flag is set. 0, the courtesy switch 46
The MOSFET 68 is turned on and off in conjunction with turning on and off of the dome lamp, and the turning on and off of the dome lamp is controlled in conjunction with the turning on and off of the courtesy switch 46.

[0061] Further, not between the branch point P ₀ and the first power source 88 is turned on, when power to the branch point P ₀ from the first power supply 88 is not supplied, a MOSFET as described above
Since T68 is continuously turned off, the second power supply 90
From a current does not flow to the dome lamp 64, based on the value of the voltage V _B that is input to the input port B, it is possible to accurately determine the state of the on-off of the courtesy switch 46. Therefore, if power is supplied from a power source different from the first power source 88 and there is another power load whose operation is to be controlled in conjunction with the on / off of the courtesy switch 46, the voltage input to the input port B based on the value of V _B, it can be accurately controlled in conjunction with operation of the power load on and off of the courtesy switch 46.

In the above description, the first power supply 88 and the branch point P
_{Although the} example in which the fuse 50 is provided between ₀ and ₀ has been described, a circuit breaker or the like may be provided instead, or no overcurrent cutoff means such as a fuse or a circuit breaker is provided. You may.

In the above description, the case where the turning on and off of the dome lamp 64 is controlled in conjunction with the on / off of the courtesy switch 46 has been described as an example.
For example, the lamp for illuminating the key insertion opening of the ignition key cylinder and the lamp for illuminating the feet of the occupant in the vehicle cabin may be simultaneously turned on and off. In addition to the courtesy switch 46, for example, the operation of various switches such as a lamp that is turned on and off in response to opening and closing of the cover of the grab box and the operation of various power loads such as lamps in response to the on and off of a switch that is turned on and off according to the opening and closing of the luggage compartment outer panel. May be controlled.

In the above description, the switch provided in the vehicle as the switch according to the present invention is replaced with the power load (dome lamp 64) provided in the vehicle as the power load according to the present invention.
Has been described, but it is needless to say that the present invention is not limited to application to a vehicle, but can be applied to operation control of various electric / electronic devices.

Although the embodiments of the present invention have been described above, the above embodiments include the embodiments of the technical matters described below in addition to the embodiments of the technical matters described in the claims. I have.

(1) The control means periodically switches the ON / OFF state of the switching means, determines whether or not power is supplied from the load power supply to the power supply point by the limiting means, and is controlled by the control means. 3. The load operation control device according to claim 2, wherein the on / off state of the switch is determined alternately.

(2) The load operation control device according to claim 1, wherein a second power load is provided between the power supply point and the switch.

[0068]

As described above, according to the first aspect of the present invention, there is provided a detection method for supplying power to a first detection point between a power supply point to which power is supplied from a load power supply and a switch at a voltage different from that of the load power supply. A power supply is provided, the on / off state of the switch is determined based on the potential of the first detection point, and the operation of the power load is controlled according to the state of the switch. The potential at the second detection point is detected, and the presence or absence of power supply from the load power supply to the power supply point is determined based on the potential at the second detection point, and it is determined that power is not supplied from the load power supply to the power supply point. In this case, the operation of the power load is limited, so that it is possible to reliably control the operation of the power load according to the on / off state of the switch without providing an element for preventing the backflow on the wiring through which the reverse current flows. Have an effect

According to a second aspect of the present invention, the detecting means comprises a second
A first resistance unit having a first electric resistance provided between the detection point and the ground end, wherein the detection power supply is connected to the first detection point via a second resistance unit having a second electric resistance; Since power is supplied to the power supply, it is possible to more reliably determine a state in which power is not supplied from the load power supply to the power supply point,
It has the effect of.

According to a third aspect of the present invention, in the second aspect of the present invention, the detection power supply is turned on while supplying power to the first detection point via the second resistance means and the third resistance means. And a switching means for short-circuiting both ends of the third resistance means. When the switching means is off, it is determined whether power is supplied from the load power supply to the power supply point, and the switching means is turned on. Since the on / off state of the switch is determined while the switch is on, the value of the first electric resistance of the first resistance means is increased for the purpose of reducing power consumption in addition to the above-mentioned effects, and the on / off state of the switch is changed. Even if the value of the second electric resistance of the second resistance means is reduced for the purpose of reliable detection, it is possible to reliably determine whether power is supplied from the load power supply to the power supply point. That With the results.

[Brief description of the drawings]

FIG. 1A is an example of the configuration of the invention according to claim 1, FIG. 1B is an example of the configuration of the invention according to claim 2, and FIG. It is the schematic which shows an example of a structure of the invention of 3 respectively.

FIG. 2 is a circuit diagram showing a schematic configuration of a lamp on / off control device according to the embodiment.

FIG. 3 is a flowchart showing a dome lamp turning on / off control process executed by the ECU shown in FIG. 2;

[4] (A) and (B) is a timing chart showing the timing of reading of the voltage V _A from off timing and input port A of the transistor as a switching means.

FIG. 5 is a circuit diagram showing an example of a schematic configuration of a conventional lamp on / off control device.

[Description of Signs] 40 Lamp on / off control device 44 ECU (control means, limiting means) 46 Courtesy switch (switch) 48 Courtesy lamp 54 Resistance (second resistance means, detection power supply) 58 Resistance (third resistance means, (Detection power supply) 60 PNP transistor (switching means, detection power supply) 62 NPN transistor (switching means, detection power supply) 64 Dome lamp (power load) 80 Resistance (first resistance means) 88 First power supply (load power supply) 90 No. 2 power supply (detection power supply)

Claims (3)

[Claims] 1. A load power supply for supplying power to a power supply point, a switch provided between the power supply point and a ground terminal, and a power load supplied with power from the load power supply via the power supply point. A detection power supply for supplying power to a first detection point between the switch and the power supply point at a voltage different from the load power supply; and determining an on / off state of the switch based on a potential of the first detection point. Control means for controlling the operation of the power load in accordance with the determined state of the switch; detection means for detecting a potential of a second detection point on a wiring between the first detection point and the power load; It is determined whether power is supplied from the load power supply to the power supply point based on the potential of the second detection point detected by the detection unit, and it is determined that power is not supplied from the load power supply to the power supply point. When the power A load operation control device comprising: a restriction means for restricting operation of the load. 2. The detection means includes first resistance means having a first electric resistance provided between the second detection point and a ground end, and the detection power supply includes a second resistance power supply. The load operation control device according to claim 1, wherein electric power is supplied to the first detection point via second resistance means having electric resistance. 3. The first power supply via the second resistance means and a third resistance means having a third electric resistance connected in series to the second resistance means. The control means is configured to supply power to the detection point, and to control on / off by the control means. When the power supply is turned on, the switching means short-circuits both ends of the third resistance means. Determining whether or not power is supplied from the load power supply to the power supply point in a state where the switching means is off, wherein the control means determines whether or not the switch is on and off while the switching means is on. 3. The load operation control device according to claim 2, wherein: