JPS6318936Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a high-frequency noise simulator that quantitatively measures the influence of impulsive noise that enters the power supply section of electronic equipment, particularly digital electronic equipment, on the operation of the electronic equipment. .

Conventional high-frequency noise simulators are configured to manually change switches and coaxial cable connections depending on the pulse voltage, time width, phase, polarity, injection phase, etc. The operation and reconnection of the coaxial cable require a relatively large amount of time and effort and are inefficient.

This invention is configured to automatically change the switch corresponding to the pulse voltage, time width, phase, polarity, injection phase, etc. and change the connection of the coaxial cable. The purpose of the present invention is to realize a high-frequency noise simulator that can efficiently and accurately perform connection changes and perform noise tests quickly.

FIG. 1 is a diagram showing an embodiment of the present invention.
1 is AC power supply connection terminal, AVR is voltage regulator, T
Reference numeral 1 denotes a step-up transformer, which is, for example, an autotransformer that can change the secondary voltage by sliding a sliding contact piece SC. PM is a drive motor for the sliding contact piece SC, and is composed of, for example, a pulse motor. EDP
is its drive circuit, which is composed of, for example, a DC power supply and a high-speed electronic switch, and sends out a number of pulse signals to the pulse motor PM in accordance with a control signal from a central processing unit of a computer, which will be described later. T2 is a power transformer, D is a rectifying diode, F1 is a ripple removal filter, and SW1 is a polarity changeover switch, such as a self-restoring electromagnetic switch. EDS
Reference numeral 1 denotes the drive circuit, which is composed of, for example, a DC power supply and an on/off switch, and supplies an excitation current to the drive coil COL1 of the switch SW1 in response to a control signal from the central processing unit of the computer. R is input high resistance, CC1 or CCn is coaxial cable, CR1 or CR (n-1) is coaxial relay, EDC1 or
EDC (n-1) is the drive circuit for each coaxial relay,
It has the same configuration as EDS1. MSW is an opening/closing switch, for example, a mercury switch (Mercury Wetted Contact), which is opened and closed by displacement and restoration of a movable contact corresponding to excitation and demagnetization of the drive coil COL2. The EDM's driving circuit consists of, for example, a frequency multiplier, a preset counter, a monostable multivibrator, a high-speed open/close switch, and a DC power supply. SW2 is a self-recovering electromagnetic changeover switch, COL3 is its drive coil,
EDS2 is its drive circuit and has the same configuration as EDS1. CCC1 and CCC2 are coaxial cables for connection, AC2 is an AC power supply connection terminal, F2 is a noise elimination filter, and HS is a high frequency elimination circuit, which is made of, for example, a conductive wire provided with a high frequency loss material on the outer periphery. C1
and C2 are pulse signal coupling capacitors, TO1 and TO2 are output terminals, and coaxial cables CCO1 and
It is connected to the power terminal of the electronic device under test via each internal conductor of CCO2. CPU is the central processing unit of the computer, KBV is the pulse voltage setting circuit,
KBP is pulse polarity setting circuit, KBW is pulse width setting circuit, KBF is pulse frequency setting circuit, KBPH
is a pulse phase setting circuit, KBM is a pulse injection phase setting circuit, and each setting circuit consists of, for example, a keyboard. PB1 to PBn are signal detection probes,
EDD is a malfunction indicator, for example consisting of a cathode ray tube.

FIG. 2 is a sectional view showing an example of the configuration of the probes PB1 to PBn, and FIGS. 3 and 4 are wiring diagrams showing their electrical connections.
is an insulating holder on the detection end side, 2 is a ring-shaped protrusion, 3 is
is a metal needle, 4 is an insulating support tube, 5 is a collar-like projection, 6
7 is a spring, 7 is a detection element such as a field effect transistor, 8 is a lead wire of the source electrode of field effect transistor 7, 9 is a light source such as a light emitting diode, 10 is a power source, 11 is a power switch, 12
13 is an optical fiber, 13 is a holder on the light receiving side, 14 is a photodetector, 15 is a leader line for taking out the output thereof, 16 is a power source, 17 is a power switch, and the leader line 15 for taking out the output of the photodetector 14 is centrally processed. Connect it to the device CPU, close the power switch 17, connect the lead wire 8 of the source electrode of the field effect transistor 7 to the common line (earth) of the logic circuit in the electronic device under test, and resist the elasticity of the spring 6. Insulating support tube 4
is moved back and the inside of the bent tip of the metal needle 3 is brought into contact with the pin at the output end of the logic circuit, and then the insulating support tube 4 is restored and moved forward to connect the inside of the bent tip of the metal needle 3 and the tip of the insulating support tube 4. When the power switch 11 is closed with a pin in between, the light emitting diode 9 emits light according to the magnitude of the output of the field effect transistor 7 corresponding to the signal or noise level at this pin, and this light is transmitted to the optical fiber 12. The light enters the photodetector 14 via the lead line 15, and its output is introduced and stored in the central processing unit CPU via the leader line 15. In this probe, since the input and output are electrically isolated by the optical fiber 12, there is no risk that the circuit constants of the central processing unit CPU will affect the circuit under test through the probe. It has the advantage that there is no risk of high frequency noise entering the circuit under test.

When an AC voltage is applied to terminal AC1 in FIG. 1, the voltage is kept constant by the constant voltage device AVR.
After the voltage is increased to the required high voltage by the autotransformer T1, it is applied to the diode D via the power transformer T2, and the rectified output is passed through the filter F1 and the changeover switch.
The output current of the driving circuit EDM is applied to the driving coil CC1 via SW1 and a high resistance R.
When current flows intermittently through COL2 and the mercury switch MSW opens and closes, the rectified voltage E of the diode D charges the distributed capacitance of the coaxial cable CC1 via the high resistance R when the mercury switch MSW is open.
If the composite impedance (hereinafter referred to as the termination impedance) of the circuit connected to the output side of the mercury switch MSW is formed equal to the characteristic impedance of the coaxial cable CC1,
The moment the MSW is closed, the termination impedance is reduced to 1/2
A voltage E is generated, and a step voltage -1/2E, which drops from voltage E to 1/2E, is generated on the input side of the mercury switch MSW. This voltage propagates through the coaxial cable CC1 and is specularly reflected at the tip. This specularly reflected voltage -1/2 is combined with the voltage 1/2E of the terminating impedance via the mercury switch MSW, and the voltage of the terminating impedance becomes zero. Therefore, a square test pulse signal is generated in the terminating impedance.
The time width is determined by the voltage propagation time in the coaxial cable CC1, i.e., the axial length of the coaxial cable CC1.

Next, when an alternating current voltage is applied to the terminal AC2, it is applied to the power supply section of the electronic device under test via the filter F2, the high frequency blocking circuit HS, the output terminals TO1 and TO2, and the internal conductors of the coaxial cables CCO1 and CCO2. When the movable contact of the changeover switch SW2 is switched to the contact a side, a test pulse signal is applied to the output terminal TO1 via the coupling capacitor C1, and is applied to the electronic device under test via the internal conductor and external conductor of the coaxial cable CCO1. added to. When the movable contact of the changeover switch SW2 is switched to the contact b side, the test pulse signal is applied to the electronic device under test via the coupling capacitor C2, the output terminal TO2, and the inner and outer conductors of the coaxial cable CCO2. Therefore, the test pulse signal is superimposed on the alternating current voltage applied to the terminal AC2 and is applied to the electronic device under test.

In the proposed noise simulator, when a setting value corresponding to the required voltage value is set in the pulse voltage setting circuit KBV, an output signal from the central processing unit CPU of the computer corresponding to this setting value is used to output the signal through the drive circuit EDP. The pulse motor PM is rotated step by step in the forward and reverse directions, and the autotransformer T1
When the sliding contact piece SC slides to make the output voltage correspond to the set value, and the pulse polarity setting circuit KBP is set to the set value corresponding to the desired pulse polarity, the central processing unit CPU corresponding to this set value is set. The output signal drives the drive coil COL through the drive circuit EDS1.
The excitation or demagnetization of 1 is controlled by the changeover switch SW1.
is switched or restored, and the pulse width setting circuit
When you set a setting value corresponding to the required pulse width in KBW, the central processing unit corresponding to this setting value
Drive circuit EDC1 or
Coaxial relay CR1 or
Are all CR(n-1) kept open?
Only CR1 closes, CR1 and CR2, or CR
1 to CR3, ... or CR1 to CR(n-
All of 1) are closed and only the coaxial cable CC1 is connected to the input high resistance R and mercury switch MSW connection line, or the cascade connection circuit of coaxial cable CC1, coaxial relay CR1 and coaxial cable CC2 is connected to R and MSW. , or connect the cascaded circuits of CC1 to CC3 to the connection line of R and MSW, ...or connect the cascaded circuits of CC1 to CCn to the connection line of R and MSW. .
(Of course, the configuration must be such that sudden changes in impedance do not occur between the cascade-connected coaxial circuits.
This is the connection point of coaxial cables CC1 and CCC1,
The same applies to the connection point between CCC1 and MSW and the connection point between MSW and CCC2. ) Furthermore, when a setting value corresponding to the required pulse frequency is set in the pulse frequency setting circuit KBF, the high-speed opening/closing switch of the drive circuit EDM is activated by the output signal of the central processing unit CPU corresponding to this setting value, and the high-speed opening/closing switch of the drive circuit EDM is activated. Excitation and demagnetization are repeated, and the mercury switch MSW opens and closes according to the set value, and the pulse phase setting circuit
When a setting value corresponding to the required pulse phase is set in KBPH, the central processing unit corresponding to this setting value
The output signal of the CPU presets the preset counter of the drive circuit EDM to a value corresponding to the set phase, and the frequency of the AC voltage applied to terminal AC2 is multiplied in the frequency multiplier circuit, and this multiplied frequency is counted by the preset counter. The output signal when the count value reaches the preset value causes the monostable multivibrator to oscillate, instantaneously closing the high-speed open/close switch, and instantaneously energizing the drive coil COL2, thereby opening/closing the mercury switch MSW. The phase of the test pulse signal generated by this corresponds to the preset value of the preset counter.
When the setting value corresponding to the required injection phase is set in the pulse injection phase setting circuit KBM, the drive circuit is activated by the output signal of the central processing unit CPU corresponding to this setting value.
Excitation or demagnetization of the drive coil COL3 is controlled via the EDS2, and the movable contact piece of the changeover switch SW2 is brought into switching contact with either contact a or b.

Therefore, by appropriately changing the setting values of each setting circuit and changing the peak value, polarity, frequency or phase, and injection phase of the test pulse signal, it is possible to find the lowest pulse voltage that causes malfunction in the electronic device under test. It is possible to effectively take countermeasures against common mode noise that enters from the power supply line to the electronic device under test through the ground air and either side of the power supply line.

In addition, the movable contact piece of changeover switch SW2 is connected to contact a.
(or b) side and output terminal TO1
Coaxial cable CCO1 connected to (or TO2)
(or CCO2) outer conductor of coaxial cable CCO2
(or CCO1), the test pulse signal will be applied to the electronic device under test via the two power supply lines, making it suitable for examining normal mode noise mixed into the power supply line. It is.

In the proposed noise simulator, if the electronic device under test includes a logic circuit, probe PB1 or
The metal needle 3 of one of the probes of PBn is crimped and held, the detection signal of each probe when no test pulse signal is applied is stored in the central processing unit CPU, and the detection signal of each probe when a test pulse signal is applied is stored. By comparing it with the detection signal and displaying the comparison result on the display EDD, the lowest pulse voltage that causes a malfunction in the electronic device under test can be determined very easily and reliably.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIGS. 2 to 4 are diagrams showing an example of the configuration of a signal detection probe in the noise simulator of the present invention.
AC1 and AC2: AC power supply connection terminals, AVR: Constant voltage device, T1: Step-up transformer, SC: Sliding contact piece, PM: Drive motor, EDP, EDS1, EDC1 to EDC (n-1), EDM and EDS2: Drive Circuit, T2: Power transformer, D: Rectifier diode, F1 and F2: Filter, SW1 and SW
2: Selector switch, COL1 to COL3: Drive coil, R: Input high resistance, CC1 to CCn,
CCC1, CCC2, CCO1 and CCO2: Coaxial cable, CR1 or CR (n-1): Coaxial relay,
MSW: Open/close switch, HS: Frequency blocking circuit,
C1 and C2: coupling capacitors, TO1 and TO
2: Output terminal, CPU: Computer central processing unit, KBV, KBP, KBW, KBF, KBPH and
KBM: Setting circuit, PB1 or PBn: Probe,
EDD: Malfunction indicator, 1 and 13: Holder, 2
and 5: protrusion, 3: metal needle, 4: support tube, 6: spring, 7: field effect transistor, 8 and 1
5: Leader line, 9: Light source, 10 and 16: Power supply, 1
1 and 17: power switch, 12: optical fiber, 1
4: It is a photodetector.

Claims (1)

[Scope of utility model registration request] A drive motor for a sliding contact piece in a step-up transformer and its drive circuit, a rectifier circuit for the secondary output of the step-up transformer, an electromagnetic changeover switch for changing the polarity of the output of the rectifier circuit and its drive circuit, and the polarity changer. An electromagnetic on-off switch connected to the electromagnetic changeover switch and its drive circuit, and a plurality of coaxial cables branched from the connection line between the electromagnetic changeover switch for polarity change and the electromagnetic on-off switch, and a coaxial relay. A drive circuit provided for each of the plurality of coaxial relays and a switching contact are connected to the electromagnetic switch, and one fixed contact is connected via a first coupling capacitor. An electromagnetic type for pulse injection phase switching, in which the fixed contact is connected to one line of the power supply line to the electronic device under test, and the other fixed contact is connected to the other line of the power supply line via a second coupling capacitor. The control signals according to the respective settings of the changeover switch and its drive circuit, pulse voltage setting circuit, pulse polarity setting circuit, pulse width setting circuit, pulse frequency setting circuit, pulse phase setting circuit, and pulse injection phase setting circuit are transmitted as described above. A drive circuit for the drive motor, a drive circuit for the electromagnetic changeover switch for polarity change, a drive circuit for each of the plurality of coaxial relays, a drive circuit for the electromagnetic open/close switch, and a drive circuit for the electromagnetic changeover switch for pulse injection phase change. A central processing unit of the computer that sends signals to each drive circuit separately, a probe that detects signals from the logic circuit in the electronic device under test, and a central processing unit of the computer that detects signals from the logic circuit in the electronic device under test, which are detected by the probe when the test pulse signal is applied and not applied. A noise simulator comprising: a display for comparing results of signals stored in the device; and a coaxial cable connected to each output end of the power supply line.