Electricity: power supply or regulation systems – Output level responsive – Using a three or more terminal semiconductive device as the...
Patent
1981-03-02
1982-12-28
Pellinen, A. D.
Electricity: power supply or regulation systems
Output level responsive
Using a three or more terminal semiconductive device as the...
340661, 363127, G05F 164
Patent
active
043664334
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to an output voltage-drop detecting apparatus for a stabilized DC power source, and more particularly to an output voltage-drop detecting apparatus which is well-suited for use in a stabilized DC power source device of the type whose output voltage is capable of being varied.
BACKGROUND ART
A variety of electronic devices, such as electronic computers and numerical control devices, incorporate a stabilized DC power source device for supplying a stabilized voltage to the instruments and components which they contain. Though various stabilized DC power source devices of the above type are available, they are generally provided with a rectifying and smoothing circuit for converting alternating current to direct current, a power control circuit for regulating the output voltage to a constant value, a reference voltage source, and an error amplifier, the alternating current being converted to direct current by the rectifying and smoothing circuit, after which the direct current is applied to the power control circuit. The latter circuit holds the output voltage at a set voltage by executing control in the following manner. Specifically, the output voltage delivered by the power control circuit and the reference voltage of the reference voltage power source are compared constantly by the error amplifier. If the output voltage attempts to drop, this is detected by the error amplifier which sends a signal to the power control circuit, the latter responding by raising the output voltage. If the output voltage attempts to rise, this is detected by the error amplifier which sends a signal to the power control circuit that responds by lowering the output voltage. Hence, the operation is such that the output is held constant at all times.
When it is desired to vary the output voltage in a stabilized DC power source device of the foregoing type, it suffices to divide the voltage of the reference voltage power source by a rheostat, thereby to change the reference voltage which is applied to the error amplifier.
There are cases where it is desired to monitor the output voltage of the abovesaid stabilized DC power source device to determine whether it is constantly within tolerance. There are times, for instance, when the output voltage of the stabilized DC power source is observed to determine whether it has surpassed a specified value, as when the power supply of a numerical control device is turned on, or to determine whether it has dropped below the specified value, as when the power supply of the numerical control device is cut off. In such cases a voltage-drop detecting circuit is provided, the circuit having a reference voltage source, a rheostat for dividing the reference voltage delivered by the reference voltage source, and a comparator, the arrangement being such that the DC output voltage and a detection level voltage set by the rheostat are compared by way of the comparator which issues a detection signal when the DC output voltage exceeds the detection level, this allowing the DC output voltage to be monitored. There are instances when the DC output voltage is varied for testing or other purposes, in the stabilized DC power source employing the voltage-drop detecting circuit of the above type. In such cases it is necessary to subject also the detection level of the voltage to a follow-up change by readjusting also the rheostat of the voltage-drop detecting circuit. This is a very troublesome operation. Furthermore, when the DC output voltage and the detection level of the voltage are close to one another, as when the detection level is greater than 95% of the DC output voltage, accurate detection of the voltage drop cannot be accomplished unless the reference voltage source provided in the voltage-drop detecting circuit is stabilized to a fairly high level of precision. This would raise the cost of manufacturing the stabilized DC power source circuit.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an output vo
REFERENCES:
patent: 3214700 (1965-10-01), Hook
patent: 3813666 (1974-05-01), Gately
Hattori Masayuki
Imazeki Ryoji
Fujitsu Fanuc Limited
Pellinen A. D.
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