Electrical transmission or interconnection systems – Nonlinear reactor systems – Parametrons
Patent
1987-09-25
1989-06-13
Miller, Stanley D.
Electrical transmission or interconnection systems
Nonlinear reactor systems
Parametrons
307355, 307358, 307362, 307602, 307603, 307606, 340661, 36457101, G06G 714, H03K 513, G08B 2100, G01C 2500
Patent
active
048396052
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to signal compensation circuits for example for compensating the output signals from detection devices and in particular for compensating the output from door detection devices in lift or elevator doors.
In a previously proposed system in its simplest form a pair of sensors are mounted in spaced apart relationship along the leading edge of a sliding door. The output of the sensors is monitored and when a difference in levels of the two outputs is detected, this indicates an irregular shaped obstruction (for example the human form) in the doorway. The system is intended to operate on the principle that the sensors which are mounted on the leading edge of the door, monitor the door space as the door closes. When the sensors sense the presence of the slam post as the door closes the sensors respond equally and so that there is no difference in the level of the two output signals produced. When the human form moves into the door space the shape is irregular and so the two sensors respond differently producing output signals having different levels. A control circuit can be used to respond to this difference to retract the door as a safety measure.
With such systems the operation is never ideal and the two sensors may produce different output levels even when no human form intervenes into the doorway. For example, the slam post may not be parallel to the sensors and dust may gather on one of the sensors and not the other. One sensors may have components which prematurely age.
In order to avoid responding to such differences, it has been proposed to compare the difference between the two outputs at different times during the closure of the door in order to distinguish between variations produced by static components such as a non-parallel door post and variations produced by moving objects such as the human form. An appropriate control signal is then produced by comparing an actual difference signal with a delayed different signal.
According to the present invention there is provided an error compensation system comprising an input and an output terminal interconnected by a signal modifying circuit having a control input, comparison means connected to the output terminal to compare the signal at the output terminal with a reference signal to produce an error signal, first and second delay circuits having substantially different time constants and each connectable to delay and feed the error signal to the control input of the signal modifying circuit, and switch means operable in response to a predetermined condition to cause a selected one of the delay circuits to feed the error signal to said control input.
According to the present invention there is further provided an error compensation system comprising first and second terminals, a comparator having two inputs respectively connected to the first and second terminals and having an output, an integrator comprising resistance means and capacitance means connected to the output of the comparator, control means responsive to a predetermined condition to alter the value of at least one of said resistance and capacitance means to change the time constant of the integrating means, and modifying means for receiving an input signal and supplying it to the first terminal, the modifying means being responsive to the output of the integrator to modify the input signal in a sense to maintain the signal at the first terminal substantially constant.
According to the present invention there is yet further provided a signal compensation system comprising first and second sensors each providing an output in response to a monitored condition, means responsive to the output of the first sensor to provide a quasi reference signal, a comparator for comparing the output of the second sensor with the quasi reference signal to produce an error signal, feedback means responsive to the error signal to modify the output of the second sensor in a sense to equalise it with the quasi reference signal, a first time delay circuit having a first time constant co
REFERENCES:
patent: 3214700 (1965-10-01), Hook
patent: 3463939 (1969-08-01), Sturman
patent: 4017742 (1977-04-01), James
patent: 4349858 (1982-09-01), Torenius et al.
Bradbeer Peter F.
Trett John
Formula Systems Limited
Miller Stanley D.
Phan Trong Quang
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