Electrical computers and digital processing systems: support – Computer power control – Having power source monitoring
Reexamination Certificate
1999-03-15
2001-07-31
Auve, Glenn A. (Department: 2181)
Electrical computers and digital processing systems: support
Computer power control
Having power source monitoring
C714S022000
Reexamination Certificate
active
06269450
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a computer monitoring device for monitoring whether a normal operation is being carried out by a computer applied to control upward and downward movements of a window in a power window system for a vehicle, and detection of nipping of foreign matter by the window, or the like.
2. Description of the Related Art
Conventionally, in a system using a microcomputer, a power window system for a vehicle or the like, the microcomputer is operated by a stabilized power supply, which is controlled to have a constant voltage on the basis of a voltage energized from a battery (about 5 V). At this point, in order to prevent the microcomputer from malfunctioning (for example, an operation that causes a power window to operate contrary to the purpose of a switching operation due to a latch-up or the like of an active signal, or the like), when the microcomputer is in an abnormal state, an operational state of the microcomputer is monitored by a microcomputer monitoring circuit (i.e., a so-called watchdog timer circuit).
Specifically, when the microcomputer is operating normally, it outputs a pulse signal to the microcomputer monitoring circuit in a predetermined cycle. While this pulse signal is being detected by the microcomputer monitoring circuit, the microcomputer is thereby judged to be operating normally. When the microcomputer monitoring circuit cannot detect the pulse signal for a predetermined period of time or more, the microcomputer monitoring circuit assesses that the microcomputer is in an abnormal state. Then, the microcomputer monitoring circuit outputs a signal for prohibiting signal processing circuit from communicating with the microcomputer to the signal processing circuit, which outputs a signal for operating a power window, so as to prevent the power window from malfunctioning. Then, the microcomputer monitoring circuit outputs a reset signal to the microcomputer so as to restart the microcomputer.
In this way, it is ensured that the microcomputer operates safely when the microcomputer is in an abnormal state. However, if the power source supplied to the microcomputer monitoring circuit is also employed for the power source supplied to the microcomputer, when the power supply voltage supplied to the microcomputer decreases, the power supply voltage supplied to the microcomputer monitoring circuit also decreases. As a result, there arises a problem in that it is no longer possible to ensure safe operation for preventing the power window from malfunctioning or the like when the microcomputer is in an abnormal state.
SUMMARY OF THE INVENTION
In view of the aforementioned facts, it is an object of the present invention to provide a computer monitoring device in which safe operation can be ensured even when the power supply voltage supplied to a microcomputer decreases and the microcomputer thereby enters an abnormal state.
In order to accomplish the aforementioned object, a first aspect of the present invention is a computer monitoring device provided at a controller which operates a device to be controlled in accordance with a program built into a computer, comprising: a power supply circuit that supplies power to the computer; a monitoring circuit that is operated by the power supplied from the power supply circuit and monitors an operational state of the computer; an abnormality processing circuit that is operated by the power supplied from the power supply circuit and performs processing when the computer is operating abnormally; an auxiliary power supply that can supply power to at least one of the monitoring circuit and the abnormality processing circuit; and switching means that switches from the power supply circuit to the auxiliary power supply when a voltage value of the power supplied from the power supply circuit decreases to a value lower than a predetermined voltage value.
Alternatively, instead of the switching means, the present aspect may comprise voltage detecting means that detects the voltage of the power supply circuit, and switching control means which, on a basis of detection results of the voltage detecting means, switches from the power supply circuit to the auxiliary power supply when the voltage decreases to a value lower than a predetermined value.
In the first aspect of the present invention, the auxiliary power supply is provided for cases in which the power supply voltage supplied from the power supply circuit decreases. When the power supply voltage supplied from the power supply circuit decreases and the computer enters an abnormal state, the switching means switches from the power supply circuit to the auxiliary power supply. Alternatively, instead of the switching means, the present first aspect may comprise voltage detecting means that detects the voltage of the power supply circuit, and switching control means which, on a basis of detection results of the voltage detecting means, when the voltage decreases to a value lower than a predetermined value, switches from the power supply circuit to the auxiliary power supply. In this case, on the basis of the detection results of the voltage detecting means, the switching control means switches from the power supply circuit to the auxiliary power supply.
Then, power is supplied to the monitoring circuit and the abnormality processing circuit. For this reason, since the monitoring circuit and the abnormality processing circuit can continue to operate, processing for ensuring safe operation can be thereby performed.
A second aspect of the present invention is a computer monitoring device according to the first aspect of the present invention, wherein the switching means or the switching control means is a pair of diodes whose anode sides are respectively connected to an output end of the power supply circuit and an output end of the-auxiliary power supply, and whose cathode sides are connected to each other.
In accordance with the second aspect of the present invention, there is provided a computer monitoring device according to the first aspect of the present invention, the switching means or the switching control means is a pair of diodes whose anode sides are respectively connected to an output end of the power supply circuit and an output end of the auxiliary power supply, and whose cathode sides are connected to each other. Accordingly, the power supply circuit can be switched to the auxiliary power supply through a simple structure, and the power supply circuit and the auxiliary power supply are prevented from interfering with each other.
A third aspect of the present invention is a computer monitoring device provided at a controller which operates a device to be controlled in accordance with a program built into a computer, comprising: a power supply circuit controlling a voltage supplied from the power supply to be a constant voltage, and supplying power to the computer; a monitoring circuit that is operated by the power supplied from the power supply circuit and monitors an operational state of the computer; an abnormality processing circuit that is operated by the power supplied from the power supply circuit and performs processing when the computer is operating abnormally; an auxiliary power supply that can supply power to at least one of the monitoring circuit and the abnormality processing circuit; an overcurrent detecting circuit that detects an overcurrent supplied to the power supply circuit; and switching control means that, on a basis of a signal output from the overcurrent detecting circuit, switches from the power supply circuit to the auxiliary power supply.
In the third aspect of the present invention, the auxiliary power supply is provided for cases where the power supply voltage supplied from the power supply circuit decreases. When an overcurrent being supplied to the power supply circuit is detected by the overcurrent detecting circuit, the switching control means switches from the power supply circuit to the auxiliary power supply. Accordingly, power is supplied from the auxiliary powe
Iwata Hitoshi
Kawarazaki Yoshiharu
Nishibe Yasushi
Auve Glenn A.
Cole Thomas W.
Kabushiki Kaisha Tokai-Rika-Denki-Seisakusho
Nixon & Peabody LLP
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