Device for sensing the operative status of electrical equipment

• US 4,045,732 A
• Filed: 02/04/1976
• Issued: 08/30/1977
• Est. Priority Date: 09/02/1975
• Status: Expired due to Term

• Current Assignee: Pioneer Electronics (USA) Incorporated (Pioneer Corporation)
• Original Assignee: Pioneer Electronics (USA) Incorporated (Pioneer Corporation)
• Inventors: Yashiro, Kenji, Saeki, Yoshifumi
• Primary Examiner(s): Strecker, Gerard R.
• Application Number:
  US05/655,157
• Time in Patent Office: 573 Days
• Field of Search: 324/103 P, 324/132, 324/127, 324/133, 324/140 R, 324/140 D, 307/235 A, 307/235 J, 328/148, 328/163
• US Class Current: 324/133
• CPC Class Codes: G01R 29/04 Measuring form factor, i.e. quotient of root-mean-square value and arithmetic mean of instantaneous value; Measuring peak factor, i.e. quotient of maximum value and root-mean-square value

Abstract

The operative status of an electrical apparatus unit such as a television receiver, incorporating an AC-DC converter, and drawing a substantial amount of current is sensed while differentiating from the usage of a lower amount of current, as when operating in a standby mode. The sensor distinguishes between the standby current waveform and a distinctly different current waveform generated when the AC-DC converter draws current in the mode in which full power is on. The sensor incorporates a reference current detector responsive to the mean of the absolute value of alternating current flowing through a power line to the electrical unit, and a peak value current detector responsive to the peak value of the periodic signal on the power line. A comparator circuit receives outputs from both detectors, and provides an output signal when the ratio therebetween is in excess of a predetermined value, this condition only applying when the AC-DC converter is operative. The comparator may comprise a differential amplifier which periodically triggers a pulse generator to maintain a selected signal level and activate a relay as long as the selected proportionality exists between the peak and mean values of the AC power signal.

Claims

1. A device for sensing the energization condition of an electrical apparatus including an AC-DC converter circuit from at least one power line for the apparatus, comprising:

first amplitude detector means responsive to the current in the power line for generating a mean value signal indicative of the mean value of said current;

second amplitude detector means responsive to the current in the power line for generating a peak value signal indicative of the peak value of said current, the peak value signal being substantially greater in a first mode when the AC-DC converter is utilized than in a second mode when the converter is not utilized; and

comparator means responsive to the mean value signal and peak value signal for indicating the existence of an energized condition for the electrical apparatus when there is greater than a selected ratio between the peak value and mean value signals.

2. The invention as set forth in claim 1 above, wherein said device further comprises means in series circuit with the power line for the electrical apparatus for detecting the current waveform, wherein said first amplitude detector means provides an integrated signal and said second amplitude detector means provides a signal varying with the absolute value of the current waveform, and wherein said device further comprises means responsive to said comparator means for providing a steady state indication of the energization condition of the electrical apparatus.

3. A device for sensing the energization condition of an electrical apparatus including an AC-DC converter circuit from at least one power line to the apparatus, comprising:

means in series circuit with the power line for the electrical apparatus for detecting the current waveform of current therein;

first amplitude detector means responsive to the detected current waveform, the first amplitude detector means including a first terminal, rectifier means, capacitor means and first voltage divider means coupled to provide to the first terminal an integrated mean absolute value signal varying with the integrated mean absolute value of the detected current waveform;

a second amplitude detector means responsive to the detected current waveform, the second amplitude detector means including a second terminal, rectifier means, and second voltage divider means coupled to provide to the second terminal a peak value signal varying with the peak absolute value of the detected current waveform;

comparator means responsive to the mean value signal and peak value signal for indicating the existence of an energized condition for the electrical apparatus when there is greater than a selected ratio between the peak value and mean value signals, the comparator means including differential amplifier means coupled to receive signals from the first and second terminals and to provide an output signal when the voltage at the second terminal is greater than that at the first terminal, the ratio of voltages at the second and first terminals being selected to provide an output signal from said differential amplifier means only when an impulse peak signal arising from operation of the AC-DC converter is superposed on the power line signals; and

means responsive to said comparator means for providing a steady state indication of the energization condition of the electrical apparatus.

4. The invention as set forth in claim 3 above, including in addition pulse generator means responsive to the output from said differential comparator means, integrating means coupled to integrate the output signal from the pulse generator means, and switching signal means responsive to the output level of the integrating means for providing an output signal when the output level of the integrating means is in excess of a selected threshold level.

5. The invention as set forth in claim 3 above, wherein said first and second voltage divider means each comprise a pair of resistor means having a midpoint output terminal therebetween, and wherein said differential amplifier means has first and second inputs coupled to said midpoint terminals of said first and second voltage divider means respectively, and wherein said differential amplifier means includes an output transistor which is arranged to be conductive when the selected ratio between the peak absolute value signal and the mean absolute value signal exists.

6. A system for distinguishing the full energization condition of an electrical unit including an AC-DC converter from a standby condition in which alternating current is drawn without activation of the AC-DC converter to superpose a pulse peak on the alternating current waveform, comprising:

means coupled in circuit with the electrical unit for sensing the current waveform thereat;

means responsive to the ratio between the peak level of the absolute value of the sensed current and the mean level of the absolute value of the sensed current for providing a pulse output for each half-cycle in which greater than a selected ratio exists;

means responsive to the pulse outputs from the ratio responsive means for generating a control voltage whose amplitude is responsive to the number of pulse outputs received in a predetermined time; and

means responsive to the control voltage for generating a steady state output signal when the control voltage is in excess of a predetermined level.

7. The invention as set forth in claim 6 above, wherein said ratio responsive means comprises a unistable multivibrator coupled to charge an integrating capacitor to provide the control voltage.

8. The invention as set forth in claim 7 above, wherein said means for generating a control voltage comprises switch means coupled to be conductive in response to a selected level of control voltage, and relay means responsive to conduction of said switch means.