Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – Analysis of complex waves
Reexamination Certificate
2000-05-15
2001-07-24
Karlsen, Ernest (Department: 2858)
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
Analysis of complex waves
Reexamination Certificate
active
06265860
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a waveform sampling apparatus for A/D converting a fixed repeat-cycle analog input voltage.
2. Description of the Prior Art
FIG. 1
shows an example of a conventional waveform measuring system comprising a integrator circuit and an A/D converter.
In
FIG. 1
, the waveform measuring system consists of an integrator circuit
101
, a digitizing circuit
102
and a gate controller
103
which are connected to a CPU
104
via a CPU bus. A memory
105
and a display device
106
and such like are also connected via the CPU bus to the CPU
104
.
The integrator circuit
101
is a well known integrator circuit in which an analog voltage is integrated by controlling the ON/OFF state of a integrator gate. In the integrator circuit
101
, integrator gate ON/OFF control; integration is performed while the integrator gate is ON and the integral is outputted while the gate is OFF. The digitizing circuit
102
digitizes the integral outputted from the integrator circuit
101
. The gate controller
103
controls the ON/OFF state of the integrator gate in the integrator circuit
101
by outputting a gate control signal to the integrator circuit
101
.
The CPU
104
uses software processing to data-process the value digitized by the digitizing circuit
102
, displays the processed result on the display screen
106
and stores it in the memory
105
. Data processing performed here is for instance processing to determine the average value of multiple waveform measurements of an analog input voltage.
In the above-mentioned waveform, measuring system, for an analog input signal with a repeat-cycle T′ as shown in
FIG. 2
, integration is carried out during integration time T1 during which the integrator gate is ON; the integral is output and the integrator is reset during reset time T2 in which the integrator gate is OFF.
The waveform measuring system described above has the following disadvantages.
It is desirable to be able to set the integration period T, which consists of integration time T1 and reset time T2, to a value (e.g. 500 ms, 1.0 s, 10 s or such like) in accordance with the cycle of the analog output voltage of the device being measured. In a conventional waveform measuring system the circuit configuration of the gate controller and integrator circuit required in order to vary the integrator period T to a discretionary value has been complex.
In addition, problems such as leaks in the integrator circuit and overflow in the digitizing circuit have occurred when the integrator time T1 has been set to a long time, and these elements are unfortunately included in the data outputted after A/D conversion.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a waveform measuring apparatus and a waveform obtaining method that solve the problems described above, and which can discretionally set the integration period T to a value in accordance with the cycle of the analog output voltage of the device being measured without increasing the complexity, and moreover without problems such as leakage and overflow.
In order to achieve the above objective, a first a waveform measuring apparatus of the present invention is a waveform measuring apparatus comprising:
an integrator circuit having a gate for switching, which integrates a fixed repeat-cycle analog input voltage during a period when the gate is ON;
control means for controlling the ON/OFF of the gate based on a unit integration time set discretionally; and
an A/D converter for A/D converting the analog input voltage based on the integrated output of the integrator circuit;
wherein said control means take the first cycle of a period covering 2 cycles of the analog input voltage to be a fist integration period, take the second cycle thereof to be a second integration period, control the gate ON/OFF with a control signal which alternates repeatedly between ON/OFF at each unit cycle corresponding to the unit integration time during the first integration period and control the gate ON/OFF with the control signal inverted in phase during the second integration period.
A second waveform measuring apparatus of the present invention is a waveform measuring apparatus comprising:
first and second integrator circuits each having a gate for switching, which integrate a fixed repeat-cycle analog input voltage during a period when the gate is ON;
a gate controller for outputting a gate control signal which alternates repeatedly ON/OFF at each unit cycle which corresponds to a unit integration time set discretionally;
a phase inverter for inverting the phase of a gate control signal inputted to the second integrator circuit; and
a A/D converter for A/D converting the analog input voltage based on the integrated output of the integrator circuits.
A first waveform obtaining method of the present invention is a waveform obtaining method which integrates a fixed repeat-cycle analog input voltage, comprising the steps of:
taking the first cycle of a period covering 2 cycles of the analog input voltage to be a first integration period and taking the second cycle thereof to be a second integration period; and
integrating the analog input voltage with first gate control signal which alternates repeatedly between ON/OFF at each unit cycle corresponding to a unit integration time set discretionally during the first integration period and integrating the analog input voltage with second gate control signal inverted the phase of the first gate control signal, thereby obtaining the integral of the analog input voltage.
A second waveform obtaining method of the present invention is a waveform obtaining method which integrates a fixed repeat-cycle analog input voltage, comprising the steps of:
integrating the analog input voltage with a gate control signal which is repeated ON/OFF at each unit cycle corresponding to a unit integration time set discretionally and integrating the analog input voltage with the gate control signal which has been inverted, thereby obtaining an integral of the analog input voltage.
According to the present invention described above, since an integrator circuit integrates an analog input voltage based on a gate control signal which is repeated ON/OFF at each unit cycle which corresponds to a unit integration time set beforehand, when the unit integration time is shortened, integration time can be set to a value in accordance with the analog input voltage cycle. Furthermore, since an analog input voltage is integrated at each unit integration time, even if the integration time is set to a long time, there is no integrator circuit leakage, digitizing circuit overflow or other such problems as a conventional system.
According to an aspect of the present invention, the first cycle of a period containing 2 cycles of an analog input voltage is deemed to be a first integration period and the second cycle thereof is deemed to be a second integration period; during the first integration period the gate ON/OFF is controlled with a control signal which alternates repeatedly between ON/OFF at each unit cycle which corresponds to unit integration time and during the second integration period the gate ON/OFF is controlled with the phase inverted control signal; therefore the portion not integrated in the first integration period is integrated in the second integration period with the result that the analog input voltage is integrated at each unit integration time over 1 cycle.
According to another aspect of the present invention in which an analog input voltage is A/D converted based on the output of first and second integrator circuits, the first integrator circuit is controlled based on a gate control signal which is repeated ON/OFF at each unit cycle which corresponds to unit integration time set beforehand, and the second integrator circuit is controlled by means of the phase inverted control signal; therefore a portion not integrated in the first integrator circuit is integrated in the second integrator circuit with the result as above that th
Eguchi Hiroshi
Sakamoto Kazuo
Yada Eiichi
Advantest Corporation
Karlsen Ernest
Knobbe Martens Olson & Bear LLP
Kobert Russell M.
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