JP3786155B2 - controller - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a controller having a calculation processing unit that reads a switch terminal voltage as a signal and reads the operation state of the switch from this signal, and can improve the reliability of the input operation and reading determination of the signal. The present invention relates to a controller that can save power.
[0002]
[Prior art]
For example, an on-board controller inputs an ON / OFF signal (L level or H level) of a switch connected to the outside through a connector by an input circuit, and an arithmetic processing unit such as an internal CPU or other IC. A predetermined output is made to the controlled device by performing logic judgment and calculation.
FIG. 4 is a diagram showing an example of a conventional input circuit of such a controller.
Here, what is indicated by the symbol SW is a contact point of the switch, and this switch SW inputs some information as an ON / OFF signal to the controller. For example, an operation unit (button or the like) operated by the driver of the vehicle. ), Or a contact as an output unit of a sensor that detects some state in the vehicle.
[0003]
Also, what is denoted by reference numeral 1 is a CPU 1 that is an arithmetic processing unit. The CPU 1 includes a power input terminal 2, an output terminal 3 that outputs an input circuit control signal, a SW input terminal 4 to which a terminal voltage of the switch SW is input, and a ground terminal 5. In addition, the CPU 1 naturally includes, for example, an output terminal that outputs a control signal for controlling the device of the vehicle. However, since these are irrelevant to the present invention, description thereof is omitted.
[0004]
In this case, a power supply voltage stabilized by the power supply circuit 6 is input to the power supply input terminal 2 of the CPU 1, and the input side of the power supply circuit 6 includes a diode 7 for preventing a backflow of current and a connector 8. Via a power source 9 such as a battery.
The SW input terminal 4 of the CPU 1 is connected to one terminal of the switch SW via a signal input resistor 10, a current backflow prevention diode 11, and a connector 12.
The ground terminal 5 of the CPU 1 is connected to the ground together with the other terminal of the switch SW via the connector 13.
[0005]
An energization line 20 (first energization line) is provided between the output side of the power circuit 6 (power input terminal 2 of the CPU 1) and the SW input terminal 4 of the CPU 1 (more precisely, the anode side of the diode 11). Connected by.
A transistor TR1 (first switching element) and a pull-up resistor 21 are sequentially connected on the energization line 20 from the power supply side. In this case, the transistor TR1 is of the PNP type, and its emitter terminal is connected to the power supply side and its collector terminal is connected to the pull-up resistor 21. The base terminal of the transistor TR1 is connected to the emitter terminal via the resistor 22, and is connected to the output terminal 3 of the CPU 1 via the resistor 23. The voltage of the output terminal 3 of the CPU 1 is equal to that of the CPU 1. When turned off (L level) by the operation, the emitter terminal and the collector terminal become conductive by the switching operation of the transistor TR1.
[0006]
The energization line 20 is a line for applying a voltage to the switch SW in order to generate a terminal voltage of the switch SW, and its conduction state is switched by the control of the CPU 1 via the transistor TR1. In other words, the CPU 1 temporarily activates the transistor TR1 to turn on the energization line 20 at a timing (usually at regular intervals) when it is necessary to read the operation state of the switch SW in order to save power. The operation state of the switch SW is read from the voltage of the SW input terminal 4 (that is, input determination is performed).
Specifically, in this case, if the voltage of the SW input terminal 4 is ON (H level exceeding the threshold value), it can be determined that the switch SW is in the open state, and the voltage of the SW input terminal 4 is OFF ( (L level below the threshold value), it can be determined that the switch SW is in the closed state. This is because when the switch SW is closed, a current flows from the conduction line 20 to the ground side via the switch path (in this case, the path including the connector 12 and the switch SW). This is because the voltage of the SW input terminal 4 is almost at the ground level as long as is a constant low value.
[0007]
[Problems to be solved by the invention]
By the way, as for a switch (for example, the switch SW) connected to this type of controller and a connector (for example, the connector 12) for the connection, a component for a large current having an excessive rated current is used. The usage environment may be poor, such as being placed outdoors. In such a case, an oxide film (insulating film) is generated at the contact point of the switch and the contact reliability is likely to be lowered. To prevent this, it is necessary to pass a large current through the switch or the connector. is there. That is, with the configuration shown in FIG. 4, it is necessary to decrease the resistance value of the pull-up resistor 21 and increase the amount of current flowing through the switch path from the conduction line 20 when the switch SW is closed.
However, when the current in the switch path is simply increased in this way, there are the following problems.
[0008]
(1) The dark current increases, which hinders power saving. The dark current is the current that flows to the controller when the CPU is in the low power consumption mode when there is no change in the input signal from the switch and the controller does not need to operate. It is necessary to keep it as small as possible. The dark current varies depending on the number of ICs and input switches other than the CPU, but what flows through the switch path is a major factor in increasing the dark current.
[0009]
(2) The possibility of erroneous input (the above-mentioned input determination error) increases due to an increase in voltage drop of the switch or the like. That is, since the voltage drop is proportional to the current value, for example, when the current in the switch path in FIG. 4 is increased, the voltage drop in the switch SW, the connector 12 and the like increases accordingly, and the SW input when the switch SW is in the closed state Since the voltage at the terminal 4 becomes relatively high, an erroneous determination that the CPU 1 determines that the switch SW is in the open state in the input determination described above is likely to occur.
[0010]
In order to solve such a problem, for example, as shown in FIG. 5, a second energization line 30 having a separate pull-up resistor 31 (having a low resistance value for a large current) is provided. A configuration in which a voltage is applied to the switch SW via the second energization line 30 under a specific condition unrelated to the control (in the case of FIG. 5, the closing operation of the ignition switch IGSW) is conceivable.
With this configuration, when the specific condition is not satisfied, since a large current does not flow through the switch path, the dark current can be kept low, and if the specific condition is periodically satisfied, Contact activation (prevention of oxide film generation) of the switch SW and the connector 12 can be realized.
[0011]
However, when the specific condition is not satisfied for a long time, the contact activation of the switch SW or the like cannot be achieved, and an oxide film is generated. There is a risk that will not be made. Further, when the specific condition is satisfied and the switch SW is in a closed state, a large current always flows continuously through the switch path, and thus the above-described erroneous determination occurs due to a voltage drop of the switch SW or the like. There is a possibility, too, and the point of reliability is not enough.
Further, in this configuration, when the specific condition is satisfied and the switch SW is in a closed state, a large current always flows continuously through the switch path, so that there is a limit in terms of power saving. There is also a problem.
[0012]
Therefore, the present invention includes a calculation processing unit that receives a switch terminal voltage as a signal, and reads an operation state of the switch from the signal, and an input circuit for inputting the terminal voltage to an input terminal of the calculation processing unit. An object of the present invention is to provide a controller capable of highly realizing power saving including improvement of reliability of input operation and reading determination of the signal and reduction of dark current.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the controller according to claim 1 of the present invention is configured such that a terminal voltage of a switch is input as a signal, an operation processing unit that reads an operating state of the switch from the signal, and the terminal voltage is the operation process. In a controller having an input circuit for inputting to the input terminal of the unit,
The input circuit is
A first energization line for applying or energizing the switch with a voltage or current that generates a terminal voltage as the signal;
A second energization line for applying or energizing the switch with a voltage or current that activates the contact of the switch;
A first switching element provided in the first energization line and operated by the control of the arithmetic processing unit to bring the first energization line into a conductive state or a non-conductive state; and provided in the second energization line. And a second switching element that operates under the control of the arithmetic processing unit to bring the second energization line into a conductive state or a non-conductive state ,
A power supply circuit for supplying a stabilized power supply voltage to the arithmetic processing unit;
A ground side terminal of the switch is directly connected to the ground, a power source side terminal of the switch is connected to an input terminal of the arithmetic processing unit, and the voltage of the power source side terminal of the switch is the signal as the signal. And the configuration entered in
The first energization line and the second energization line are circuits that connect the output side of the power supply circuit and the power supply side terminal of the switch, respectively .
[0016]
According to a second aspect of the present invention, the controller operates the first switching element under the control of the arithmetic processing unit to bring the first energization line into a conductive state, and controls the second through the control of the arithmetic processing unit. The timing at which the second energization line is turned on by operating the switching element is made different.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, after describing a comparative example first, an example (embodiment) of an embodiment of the present invention will be described based on the drawings. In addition, about the component similar to the prior art shown in FIG.
( Comparative example )
As shown in FIG. 1, the input circuit of the controller of the comparative example includes an energization line 40 (second energization line) separate from the energization line 20 (first energization line), and this energization is controlled by the CPU 1a. A voltage for activating the contact is periodically applied to the switch SW via the line 40.
The CPU 1a of this example includes two terminals (first output terminal 3a and second output terminal 3b) as output terminals for outputting an input circuit control signal. Among these, the first output terminal 3a is the transistor TR1 (described above). The first switching element) is connected to the base terminal.
[0018]
The energization line 40 is a circuit that connects the input side of the power supply circuit 6 and the terminal of the switch SW (cathode side of the diode 11). On the energization line 40, the transistor TR2 (second circuit) is connected from the power supply side. Switching element) and the pull-up resistor 41 are sequentially connected. In this case, the transistor TR2 is of the PNP type, and has an emitter terminal connected to the power supply side and a collector terminal connected to the pull-up resistor 41. The base terminal of the transistor TR2 is connected to the emitter terminal via the resistor 42, and is connected to the second output terminal 3b of the CPU 1a via the resistor 43 and the inverter (NOT circuit) 43a. When the output voltage of 43a is turned off (L level) by the signal of the CPU 1a (the voltage of the second output terminal 3b), the emitter terminal and the collector terminal are brought into conduction by the switching operation of the transistor TR2.
Note that the resistance value of the pull-up resistor 41 of the energization line 40 is smaller than that of the pull-up resistor 21 of the energization line 20 so that a large current sufficient for contact activation can flow through the energization line 40. It has become.
[0019]
The CPU 1a of this example is programmed to output a control signal for the input circuit (drive signal for each transistor) at the timing shown in FIG. 3 from each output terminal.
That is, the CPU 1a temporarily turns off the voltage of the first output terminal 3a at a constant short period F1 (for example, about 10 msec to 20 msec) corresponding to the input signal read timing of the CPU 1a, and outputs the drive signal of the transistor TR1. To do. The ON time T1 per cycle of the drive signal (that is, the OFF time of the voltage at the terminal 3a) may be set to a sufficient time (for example, about 1 msec to 5 msec) required for reading the signal of the CPU 1a.
[0020]
Further, the CPU 1a temporarily turns on the voltage of the second output terminal 3b at a constant long period F2 necessary and sufficient for contact activation (for example, about 1 to 10 minutes), and outputs a drive signal for the transistor TR2. . The ON time T2 per cycle of the drive signal (that is, the ON time of the voltage of the terminal 3b) is a value necessary and sufficient for contact activation, and the OFF time per cycle of the drive signal of the transistor TR1 ( A value smaller than F1-T1) is set. Further, the timing for outputting the driving signal for the transistor TR2 (phase of the voltage waveform) is different from the timing for outputting the driving signal for the transistor TR1, so that the period during which the driving signal for each transistor is output does not overlap. It has become. That is, the drive signals of the transistors are not output simultaneously.
[0021]
In the controller described above, since the transistor TR1 of the energization line 20 operates during the input signal read timing period, if the switch SW is in an open state, an appropriate terminal voltage is generated in the switch SW, and the CPU 1a receives this input. It can be read from the signal that the switch SW is in the open state. If the switch SW is in the closed state, the terminal voltage is at the ground level (L level) as long as the contact reliability of the switch SW and the connector 12 is maintained, and the CPU 1a determines that the switch SW is in the closed state from this input signal. You can read something.
At this time, when the switch SW is in the closed state, a current flows in the switch path via the energization line 20, but since this current value is adjusted sufficiently low by the pull-up resistor 21, the switch SW or The value of the voltage drop of the connector 12 is also sufficiently low, and it is very unlikely that this voltage drop is so large that an error in reading determination by the CPU 1a occurs. In particular, in the case of this example, the timing at which the energization line 40 is turned on is set differently from that of the energization line 20 (that is, the input signal read timing) as described above. For this reason, when reading an input signal, it is reliably avoided that a large current flows in the switch path via the energization line 40, and a malfunction that causes an error in reading determination due to an increase in voltage drop of the switch SW or the like is avoided more reliably. Is done.
[0022]
In the above controller, the transistor TR2 of the energization line 40 is controlled independently of the transistor TR1 as described above, so that it is periodically controlled with a relatively long cycle of, for example, about 1 to 10 minutes regardless of the input signal reading timing. If a voltage is applied to the switch SW and the connector 12 and the switch SW is in the closed state, a large current adjusted by the pull-up resistor 41 flows to the switch SW and the connector 12, and the contacts are sufficiently activated. . For this reason, even if parts for large current are diverted to the switch SW and the connector 12 or the switch SW and the connector 12 are installed in a bad environment such as outside the vehicle compartment, the generation of oxide film at these contacts is prevented. Therefore, the contact reliability of these contacts can be maintained high.
[0023]
Therefore, according to the above controller, the current flowing through the switch path is kept low as a whole to reduce dark current and save power, while maintaining high contact reliability of the switch and the like, and increasing the voltage drop of the switch and the like. Therefore, it is possible to avoid the problem of erroneous input due to the above, and to improve the reliability of the signal input operation and reading determination from the switch.
FIG. 3 shows a change in current when the switch SW is in the closed state. In the case of this example, the current flowing in the switch path via the energization line 20 (transistor TR1) changes as shown in the uppermost stage of FIG. 3, and the current flowing in the switch path via the energization line 40 (transistor TR2). Changes as shown in the second stage of FIG. 3, and eventually the total current flowing through the switch path changes as shown in the third stage of FIG. Therefore, the average of the total current flowing through the switch path when the switch SW is in the closed state is as shown in the fourth stage of FIG. 3, and when the energization operation by the energization line 40 (transistor TR2) is not performed (the maximum in FIG. 3). A slight increase with respect to the bottom) is required.
[0024]
On the other hand, for example, when the reliability is improved by simply lowering the resistance value of the pull-up resistor 21, the current flowing through the switch path at every read timing via the energization line 20 (transistor TR1). Becomes a large current, so the average of the total current is greatly increased. In addition, as shown in FIG. 5, when a large current is caused to flow from another path under a specific condition such as when the ignition switch is turned on, the large current continues to flow if this condition continues to be established for a super-period. As a result, the average of the total current increases significantly.
[0025]
( Example )
Next, embodiments of the present invention will be described. As shown in FIG. 2, the input circuit of the controller of this example is characterized in that the energization line 40 is provided so as to connect the output side of the power supply circuit 6 and the terminal side of the switch SW. That is, in this case, the energization line 40 and the energization line 20 are provided in parallel. In this case, the inverter 43a is not provided, and the transistor TR2 is directly controlled by the voltage of the second output terminal 3b of the CPU 1a and operates at the same timing as in the comparative example .
In the case of this example, in addition to the same effect as the comparative example , the following effect can be obtained. That is, since the voltage and current values applied for contact activation via the energization line 40 are stable regardless of the output fluctuation of the power source 9, power saving including dark current can be achieved. Reliability can be improved more accurately.
[0026]
This is because, in the case of the above-described comparative example , the voltage and current values applied for contact activation via the energization line 40 depend on the fluctuation of the output voltage of the power supply 9. Therefore, in order to reliably activate the contacts, it is necessary to set the value of the pull-up resistor 41 so that, for example, a larger current than the fluctuation amount can be expected to flow. In this case, if the output voltage of the power source 9 is sufficiently high, more current than necessary flows. On the other hand, if such a high current setting is not performed, the current flowing for contact activation can be maintained to the minimum necessary, but when the output voltage of the power supply 9 decreases, the contact activation is not performed without flowing a sufficient current. The effect is slightly deteriorated.
On the other hand, in the case of this embodiment, the output voltage of the power supply circuit 6 is always kept at a substantially constant value. Therefore, there is no such inconvenience, and power saving including dark current and improvement in reliability are achieved. It can be realized more accurately.
[0027]
Note that the present invention is not limited to the embodiment described above, and may have various aspects. For example, in the above description, the CPU output voltage and the switch terminal voltage are in the L level state as “OFF” and the H level state is “ON”, but this is not determined.
[0028]
【The invention's effect】
In the controller of the present invention, by operating the first switching element of the first energization line at the input signal reading timing, an appropriate terminal voltage (H is applied to the switch by energization or voltage application through the first energization line. Level or L level), and the operation state of the switch can be read from the terminal voltage by the arithmetic processing unit.
At this time, when the switch is in a closed state, a current flows through the switch path via the first energization line, but this current value can be adjusted sufficiently low by setting the resistance value of the first energization line. Therefore, the value of the voltage drop of the switch and its connector is also sufficiently low, and there is little possibility that an error occurs in the reading determination in the arithmetic processing unit because this voltage drop is too large.
[0029]
In this controller, the second switching element of the second energization line is controlled independently of the first switching element, so that, for example, a relative time of about 1 minute to 10 minutes can be set regardless of the input signal reading timing. Apply a voltage to the switch and its connector periodically over a long period. If the switch is closed, a large current adjusted by the resistance value setting of the second energizing line is sent to the switch and its connector to activate the contacts. Can be fully accomplished. For this reason, even if parts for high current are diverted to the switch or its connector, or these parts are installed in a poor environment such as outside the passenger compartment, the generation of oxide film at these contacts is prevented, and these contacts are High contact reliability can be maintained.
[0030]
Therefore, according to this controller, the current flowing through the switch path is kept low as a whole to reduce dark current and save power, while maintaining high contact reliability of the switch and the like, and increasing the voltage drop of the switch and the like. Therefore, it is possible to avoid the problem of erroneous input due to the above, and to improve the reliability of the signal input operation and reading determination from the switch.
[0031]
In particular, as described in claim 2 , the timing at which the first switching element is actuated to bring the first energization line into the conducting state, and the second switching element is actuated to bring the second energizing line into the conducting state. If the timing is different, when reading an input signal, it is reliably avoided that a large current flows through the switch path via the second energization line, and an error occurs in the reading judgment due to an increase in voltage drop of the switch or the like. The trouble that occurs can be avoided more reliably.
[0032]
In the controller of the present invention , the first energization line and the second energization line are circuits for connecting the output side of the power supply circuit and the power supply side terminal of the switch, respectively. For this reason, the value of the voltage or current applied or energized for contact activation via the second energization line becomes stable regardless of fluctuations in the output of the power supply. Improved reliability can be achieved more accurately.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a comparative example of a controller.
FIG. 2 is a circuit diagram illustrating a configuration example of a controller.
FIG. 3 is a diagram illustrating an example of a waveform of a current flowing through a switch path of a controller.
FIG. 4 is a circuit diagram showing a conventional controller.
FIG. 5 is a circuit diagram showing an improved controller.
[Explanation of symbols]
1,1a CPU (arithmetic processing unit)
20 Energizing line (first energizing line)
40 Power line (second power line)
6 Power supply circuit 8, 12, 13 Connector 9 Power supply 21 Pull-up resistor 41 Pull-up resistor SW switch TR1 Transistor (first switching element)
TR2 transistor (second switching element)

Claims (2)

In a controller having an arithmetic processing unit that inputs a terminal voltage of a switch as a signal and reads an operating state of the switch from the signal, and an input circuit for inputting the terminal voltage to an input terminal of the arithmetic processing unit.
The input circuit is
A first energization line for applying or energizing the switch with a voltage or current that generates a terminal voltage as the signal;
A second energization line for applying or energizing the switch with a voltage or current that activates the contact of the switch;
A first switching element provided in the first energization line and operated by the control of the arithmetic processing unit to bring the first energization line into a conductive state or a non-conductive state; and provided in the second energization line. And a second switching element that operates under the control of the arithmetic processing unit to bring the second energization line into a conductive state or a non-conductive state ,
A power supply circuit for supplying a stabilized power supply voltage to the arithmetic processing unit;
A ground side terminal of the switch is directly connected to the ground, a power source side terminal of the switch is connected to an input terminal of the arithmetic processing unit, and the voltage of the power source side terminal of the switch is the signal as the signal. And the configuration entered in
The controller, wherein the first energization line and the second energization line are circuits that connect the output side of the power supply circuit and the power supply side terminal of the switch, respectively . The timing at which the first switching element is operated by the control of the arithmetic processing unit to bring the first energization line into a conductive state, and the second switching element is operated by the control of the arithmetic processing unit to operate the second switching element. The controller according to claim 1, wherein a timing at which the two energization lines are turned on is made different.

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