JP3196569B2 - Load control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load control device for controlling a load such as a lock motor for a door of an automobile.

[0002]

2. Description of the Related Art Conventionally, as a control device for controlling a door lock motor of an automobile, which is a load, Japanese Utility Model Laid-Open No. 5-40558.
There is one described in Japanese Patent Laid-Open Publication No. H10-210, which is configured as follows.

That is, as shown in FIG. 3, a communication circuit 1 serving as a slave station for multiplex communication is provided. This communication circuit 1 is connected to a control module serving as a master station for multiplex communication via a communication interface and a signal transmission line. The motor driver is controlled by the communication circuit 1 based on the information from the control module to drive the door lock motor, and turns off when the door is locked and turns on when the door is unlocked. A door detection switch 2 is provided, one end of the door detection switch 2 is grounded, and the other end of the door detection switch 2 is connected to a power supply VDD via a first pull-up resistor 3 and via an input protection resistor 4. It is connected to the input port Pi of the communication circuit 1.

Further, a Schmitt NAND circuit 6 having one input terminal connected to the power supply VDD and the other input terminal connected to the output port Po of the communication circuit 1 is provided, and is synchronized with the turning on and off of the ignition switch. The Schmitt NAND circuit 6 is turned on and off by the Lo and Hi signals output from the communication circuit 1, and the output of the Schmitt NAND circuit 6 controls the NPN transistor 7.

A second pull-up resistor 8 having a resistance smaller than that of the first pull-up resistor 3 is provided in parallel with the first pull-up resistor 3.
The current path between the power supply VDD and the power supply VDD is interrupted by a PNP transistor 9, and the PNP transistor 9 is controlled by an NPN transistor 7.

Therefore, when the ignition switch is on, a signal of Lo is output from the output port Po of the communication circuit 1, the Schmitt NAND circuit 6 is turned on, and both the transistors 7, 9 are turned on. 2
Is turned on, a current flows through the door detection switch 2 through the pull-up resistors 3 and 8, respectively.

On the other hand, when the ignition switch is off, the communication circuit 1 is in the sleep mode, a Hi signal is output from the output port Po of the communication circuit 1, the Schmitt NAND circuit 6 is turned off, and both the transistors 7, 9 are turned off. If the door detection switch 2 is turned on at this time, only the current via the first pull-up resistor 3 flows through the door detection switch 2 as a dark current, and thus the communication circuit 1 operates in the sleep mode. Sometimes, a necessary minimum current smaller than that in the normal mode slightly flows.

For example, when the ignition switch is turned off and the communication circuit 1 shifts to the sleep mode while the door is unlocked and the door detection switch 2 is turned on, the on state of the door detection switch 2 is changed to the communication circuit. 1
Is transmitted to the control module via the communication module, and the door lock command information from the control module is transmitted to the communication circuit 1.
And the communication circuit 1 controls the motor driver to drive the door lock motor, and the door is automatically locked.

[0009]

However, in the conventional case described above, the communication circuit does not return from the sleep mode to the normal mode unless the ignition switch is turned on.
For example, the communication circuit 1 remains in the sleep mode even when the driver leaves the vehicle with the ignition switch turned off and the door is locked, unlocks the door when the driver returns, and unlocks the door. The communication circuit 1 does not function until the switch is turned on.

Further, since the contacts of the door detection switch 2 are placed under extremely severe environmental conditions such as temperature, humidity, vibration, aging, etc. of an automobile, there is a problem that the contacts are constantly polluted and the contact resistance of the switch is increased. Is likely to occur, the sensitivity of the door detection switch 2 is reduced, and the communication circuit 1 may not be able to accurately detect the state of the door detection switch 2.

That is, there is a contact resistance in the door detection switch 2, which is represented by a broken line in FIG. 3, and the potential Vi of the input port Pi of the communication circuit 1 in the sleep mode is expressed by the following equation (1). , First pull-up resistor 3
It is determined by the voltage division ratio between the resistance (referred to as resistance R1) and the contact resistance (referred to as resistance rs) of the door detection switch 2. However,
The voltage of the power supply VDD is assumed to be Vd.

[0012]

(Equation 1)

By the way, in order to avoid contamination of the contacts,
While it is better to set R1 to be small and increase the dark current Is, it is necessary to increase R1 in order to reduce the dark current Is as much as possible and to suppress the consumption of the battery, and to increase the resistance of the first pull-up resistor 3. The value R1 is set to an appropriate value from both viewpoints.

On the other hand, the communication circuit 1 is usually constituted by a microcomputer (hereinafter referred to as a microcomputer). In a general microcomputer, for example, if the potential Vi of the input port is equal to or lower than VL (Vi ≦ VL), the level is Lo level and VH or higher. (Vi ≧ VH)
In this case, it is recognized as Hi level, and if VL <Vi <VH, it becomes indefinite. For example, NEC model number μPD78C
In the microcomputer No. 14, VL is 0.8 V, and when dark current Is is 0.1 mA, R1 is 50K when rs = 0.
Ω.

Using these values, the power supply voltage Vd
When the value of the contact resistance rs is obtained by performing the calculation of the expression 2 based on the expression 1 with the value of 5 V, rs ≦ 9.5 (KΩ),
That is, if the contact resistance of the door detection switch 2 is 9.5 KΩ or less, the communication circuit 1 operates normally, but if the contact resistance of the door detection switch 2 exceeds 9.5 KΩ, the communication circuit 1 does not operate normally. There is a risk.

[0016]

(Equation 2)

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems, and a detection switch for easily returning a communication circuit from a sleep mode to a normal mode and detecting a load state. It is an object of the present invention to be able to improve the sensitivity.

[0018]

According to the first aspect of the present invention,
Detected two different states such as an operation state and a non-operation state of the load, and transmitted the detected state of the load to a control unit via a communication line, and transmitted from the control unit to control the load to a desired state. A communication circuit for receiving the control signal, a load driving unit for outputting the received control signal from the communication circuit to control the load to a desired state, and an on / off state corresponding to two different states of the load. A normal mode in which a detection switch that is turned off and a first switching element that is turned on when a control signal is supplied to a control terminal when the detection switch is turned on, wherein the communication circuit performs communication with the control unit and the like; Besides having a sleep mode,
On the detection switch in the normal mode, input port OFF state is inputted, sensing port for sensing the on of the first switching element in the sleep mode in order to return from the sleep mode to the normal mode, the normal mode
Mode and sleep mode, respectively.
It has an output port to output the bell signal
It operates by the output of the output port of the communication circuit at the time of loading.
Current to prevent contact oxidation to the detection switch
Contact oxidation prevention comprising a second switching element to be supplied
And a current supply unit .

[0019]

Further, as set forth in claim 2 , the first type
It is effective if the switching element comprises a transistor, the control terminal is a base of the transistor, the ON control signal is a base current signal, and the base current signal is limited to a predetermined value by a base resistor.

[0021]

According to the first aspect of the present invention, when the ON / OFF state of the detection switch is input to the input port of the communication circuit in the normal mode, the state of the load corresponding to the ON / OFF state of the detection switch is controlled by the control unit. Is transmitted from the control unit to the communication circuit as a control signal, the load is controlled to a required state by the load driving unit, and when the ON of the first switching element is detected by the detection port of the communication circuit in the sleep mode. Then, the communication circuit returns from the sleep mode to the normal mode. Output port of communication circuit in normal mode
Output activates the contact oxidation prevention current supply and turns on.
A current for preventing contact oxidation is supplied to the status detection switch
Therefore, oxidation of the contact of the detection switch is prevented.

[0022]

Further, as in the second aspect of the present invention, the first switching element is constituted by a transistor, and a base current signal as an on-control signal is supplied to a base of the transistor as a control terminal. Is limited to a predetermined value by the base resistance, the sensitivity of the detection switch can be improved by appropriately setting the resistance value of the base resistance.

[0024]

FIG. 1 is a connection diagram of an embodiment of the present invention, and FIG. 2 is an explanatory diagram of the operation.

FIG. 1 shows an example in which the load is an automobile door lock motor. As shown in FIG. 1, a communication circuit 11 is provided, and the communication circuit 11 is connected to a control unit (not shown) via a communication line 12 or the like. The information is exchanged between the motor driver 13 and the communication circuit 11 based on the information from the control unit.
Is controlled, and the door lock motor 14 is driven.

A detection switch 1 which is turned off when the door of the vehicle is locked and turned on when the door is unlocked.
6, one end of the detection switch 16 is grounded, and the other end of the detection switch 16 is connected to a reverse current blocking diode 17
Resistance 18 which is the cathode, anode and base resistance of
Is connected to the base of a PNP transistor 19, which is the first switching element, and the emitter of the transistor 19 is connected to the power supply + B and the transistor 1
A second resistor 20 as a base resistor is provided between the emitter and the base of the transistor 9, and the collector of the transistor 19 is grounded via a third resistor 21.

The communication circuit 11 has a sleep mode in addition to the normal mode for performing communication with the control unit and the like.
An input port Pi to which an OFF state is input, a detection port PINT for detecting the on state of the transistor 19 in the sleep mode to return from the sleep mode to the normal mode,
H in normal mode and sleep mode
It has an output port Po for outputting i-level and Lo-level signals.

The collector of the transistor 19 and the detection port PINT of the communication circuit 11 are connected via the fourth resistor 22. When the detection switch 16 is turned on during the sleep mode of the communication circuit 11, the base of the transistor 19 is turned on. When the signal is supplied, the transistor 19 is turned on,
As a result, the potential of the detection port PINT of the communication circuit 11 becomes Lo.
The communication circuit 11 returns from the sleep mode to the normal mode by inverting the level from the Hi level to the Hi level.

Further, the second switching element N
The base of the PN transistor 24 is connected to the output port Po of the communication circuit 11 via the fifth resistor 25, and the transistor 24 is turned on by the Hi output from the output port Po, so that the contact oxidation preventing current from the power supply + B becomes the sixth. The current flows to the detection switch 16 via the resistor 26 and the collector and the emitter of the transistor 24.
7 are configured.

Further, the input port Pi of the communication circuit 11 is connected to the detection switch 16 via the seventh resistor 29 and the transistor 24.
That is, when the communication circuit 11 is in the normal mode, the detection switch 1
The potential of the input port Pi corresponding to the on / off state of the switch 6 is input to the communication circuit 11 and the state of the detection switch 16 is detected.

Therefore, as shown in the timing chart of FIG. 2, when the detection switch 16 is turned on when the communication circuit 11 is in the normal mode, the transistor 19 is turned on,
At the same time as the current from the power supply + B flows through the detection switch 16 via the second and first resistors 20 and 18 and the diode 17, the sixth resistor 26 and the Hi of the output port Pi of the communication circuit 11 are Hi.
A contact oxidation preventing current flows from the power supply + B via the transistor 24 which is turned on by the output. Here, as shown in FIG. 2, the input port Pi of the communication circuit 11 is inverted to the Lo level and the detection port PINT is inverted to the Hi level in synchronization with the ON of the detection switch 16.

On the other hand, as shown in FIG. 2, when the communication circuit 11 enters the sleep mode, the output port Po of the communication circuit 11 is output.
When the detection switch 16 is turned on in this state, the transistor 19 is turned on. When the transistor 19 is turned on, the detection port PINT of the communication circuit 11 is inverted to the Hi level, and the communication circuit 11 is switched from the sleep mode to the normal mode. , The output port Po is inverted to Hi level, the transistor 24 is turned on, and the sixth resistor 26
Also, the contact oxidation preventing current from the power supply + B flows to the detection switch 16 via the transistor 24 in the ON state, and when returning from the sleep mode to the normal mode, a larger current flows to the detection switch 16 than in the sleep mode and the contact oxide layer is formed. Is destroyed, and the operation of the detection switch 16 by the communication circuit 11 is reliably detected.

When the communication circuit 11 is in the sleep mode, the transistor 24 is off regardless of whether the detection switch 16 is on or off. 2, only the current flowing through the first resistors 20, 18 and the diode 17 flows to the detection switch 16, and a dark current smaller than that in the normal mode flows.

Considering the sensitivity of the detection switch 16, when the communication circuit 11 is in the sleep mode, the dark current Is flowing through the detection switch 16 is set to 0.1 mA similarly to the case of FIG. Assume that the transistor 19 is designed to be turned on at a base current IB of / 10.

Assuming that the base-emitter voltage VBE of the transistor 19 and the voltage drop VDI of the diode 17 are both 0.7 V, the resistance value RA of the first resistor 18 and the resistance value RB of the second resistor 20 are respectively By calculation of Expressions 3 and 4, they are 36 KΩ and 7.8 KΩ.

[0036]

(Equation 3)

[0037]

(Equation 4)

Further, under this condition, the detection switch 16 which does not hinder the turning on of the transistor 19 is performed.
When the resistance value rs of the contact resistance (indicated by a broken line in FIG. 1) is derived, the current Is ′ flowing through the first resistor 18 at this time becomes
Since the operation of the transistor 19 does not hinder until Is' = 2 ・ IB, the resistance rs of the contact resistance of the detection switch 16 is calculated to be about 144 KΩ by the calculation of Expression 5.
And the allowable width of the resistance value rs is 9.
As a result, the sensitivity of the detection switch 16 is greatly improved as compared with the conventional one, and the resistances RA and RB of the first and second resistors 18 and 20 are appropriately set to make the transistor 19 By adjusting the base current, the sensitivity of the detection switch 16 can be set to a better state than before.

[0039]

(Equation 5)

As described above, according to the above embodiment, when the detection switch 16 is turned on when the communication circuit 11 is in the sleep mode, the transistor 19 is turned on. This is detected by the detection port PINT of the communication circuit 11 and the communication circuit 11 is turned on. Returns from sleep mode to normal mode,
As in the prior art, for example, when the driver leaves the vehicle with the ignition switch turned off and the door is locked, and unlocks when the driver returns, the communication circuit 1 is in the sleep mode even if the door is unlocked. The communication circuit 11 can be reliably returned to the normal mode until the ignition switch is turned on without any occurrence of such a situation.

In the normal mode, the current supply unit 2 for preventing contact oxidation is provided by the output of the output port Po of the communication circuit 11.
7 is turned on, and a contact oxidation preventing current larger than that in the sleep mode is supplied to the detection switch 16 in the ON state, so that the contact oxidation of the detection switch 16 can be prevented.

Further, by appropriately adjusting the base current of the transistor 19 by using the first and second resistors 18 and 20, the sensitivity of the detection switch 16 can be improved as compared with the prior art.

In the above-described embodiment, a case has been described in which the load is the door lock motor 14 of the vehicle, and two states of the door lock and the door unlock are detected by the communication circuit 11 as the load states. The load is not particularly limited to the door lock motor 14, but may be any load that can take two different states such as an operating state and a non-operating state.

[0044]

As described above, according to the first aspect of the present invention, when the detection switch is turned on during the sleep mode of the communication circuit, this is detected by the detection port of the communication circuit, and the communication circuit is switched from the sleep mode to the normal mode. Therefore, the communication circuit can be reliably and easily returned to the normal mode. Also, the output of the communication circuit in the normal mode
The current supply for contact oxidation prevention is activated by the output of the power port
The ON state detection switch is
Since a large contact oxidation prevention current is supplied, the detection switch
Contact oxidation of the switch can be prevented.

[0045]

Further, according to the second aspect of the present invention, the first switching element is constituted by a transistor, and a base current signal as an ON control signal is supplied to a base as a control terminal. By limiting to a predetermined value by the resistance, the sensitivity of the detection switch can be improved as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a connection diagram of an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of one embodiment.

FIG. 3 is a connection diagram of a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 communication circuit 13 motor driver 14 door lock motor 16 detection switch 18, 20 first and second resistor 19 transistor (switching element) 27 current supply unit for preventing contact oxidation Po output port Pi input port PINT detection port

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02J 1/00-1/16 H02J 13/00-13/00 311 B60R 25/00 605 E05B 65/20 H04Q 9/00-9/16

Claims (3)

(57) [Claims] 1. A method for detecting two different states of a load, such as an operation state and a non-operation state, and communicating the detected state of the load to a control unit via a communication line to control the load to a desired state. A communication circuit that receives a control signal transmitted from a control unit; a load driving unit that outputs the received control signal from the communication circuit to control the load to a desired state; and that the load has two different states. A detection switch that is turned on and off correspondingly; and a first switching element that is turned on by supplying an on control signal to a control terminal when the detection switch is turned on, wherein the communication circuit communicates with the control unit and the like. And a sleep mode in addition to the normal mode in which the detection switch is turned on and off in the normal mode. Sensing port for sensing the on of the first switching element in the sleep mode in order to return to de, the normal mode, the sleep mode
Output ports that output signals of different levels
And the output of the output port of the communication circuit in the normal mode.
Operates the detection switch in the ON state to prevent contact oxidation
Contact acid comprising a second switching element for supplying current
An apparatus for controlling a load, further comprising a current supply unit for preventing current generation . 2. The method according to claim 1, wherein the first switching element is a transistor.
And the control terminal is the transistor base of the transistor.
The ON control signal is a base current signal.
Source current signal is limited to a predetermined value by the base resistor.
Load of the control device according to claim 1, wherein the that. 3. The vehicle according to claim 2, wherein the load is a door lock motor of an automobile.
There are door locks and door unlocks as load conditions.
3. The load control device according to claim 1, wherein two states of the load are detected by the communication circuit .