JP5373519B2 - Ionizer discharge needle contamination detection circuit and ionizer discharge needle contamination detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dirt detecting circuit of an ionizer discharge needle and a dirt detection method of an ionizer discharge needle, capable of capturing very small change due to existence of corona discharge of a discharge needle, with a small effect due to environmental changes such as difference of an installation place or change of power source voltage, and capable of preventing incorrect detection. <P>SOLUTION: The dirt detecting circuit 100 of an ionizer discharge needle generating ions by corona discharge is provided with a piezoelectric transformer 120 outputting high voltage to a discharge needle 130, a voltage control oscillation part 110 receiving feedback of the output voltage of the piezoelectric transformer 120 and controlling input voltage to the piezoelectric transformer 120, a phase comparing part 160 outputting waveforms corresponding to a phase difference between the input voltage and the output voltage to the piezoelectric transformer 120, and a voltage comparing part 190 comparing an integrated value of the output of the phase comparing part 160 and a reference voltage. When the integrated value is lower than the reference value, the circuit 100 detects dirt of the discharge needle 130. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an ionizer discharge needle contamination detection circuit and an ionizer discharge needle contamination detection method for generating ions by corona discharge.

  Conventionally, corona discharge ionizers are known (see, for example, Patent Document 1). The positive ions or the negative ions generated by the corona discharge of the discharge needle are sprayed so as to reach, for example, an object to be discharged, and are sprayed on the electronic device being manufactured. Then, the sprayed ions combine the charges charged in the electronic device with ions of different polarity, thereby eliminating static electricity and preventing the occurrence of static electricity failure.

  However, when fine particles adhere to the tip of the discharge needle and the discharge needle deteriorates, the amount of ions generated by the discharge needle decreases, and the amount of ions that actually contribute to static elimination also decreases. On the other hand, the corona discharge ionizer inspection apparatus described in Patent Document 1 detects only the true current generated by the ions generated from the emitter of the corona discharge ionizer, and eliminates static electricity that actually contributes to the charge removal of the object to be removed. Detect current. As a result, it is possible to confirm the contamination and deterioration degree of the emitter, the static elimination performance, and the like. As described above, there has been proposed a technique for detecting the contamination of the discharge needle using the change in the output voltage.

JP 2008-196952 A

  However, in actual operation, the change in the impedance of the discharge needle due to the presence or absence of corona discharge of the discharge needle is slight, and the change in the output voltage associated therewith is also slight. Also, the influence of environmental changes such as differences in ionizer installation location and power supply voltage has a greater effect on the output voltage, and the change in the output voltage accompanying the change in the impedance of the discharge needle is small. .

  The present invention has been made in view of such circumstances, and can detect a slight change due to the presence or absence of corona discharge of the discharge needle, and is affected by environmental changes such as differences in installation location and changes in power supply voltage. It is an object of the present invention to provide a small ionizer discharge needle contamination detection circuit and ionizer discharge needle contamination detection method that can prevent erroneous detection.

  (1) In order to achieve the above object, a stain detection circuit for an ionizer discharge needle according to the present invention is a stain detection circuit for an ionizer discharge needle that generates ions by corona discharge, and outputs a high voltage to the discharge needle. Piezoelectric transformer, voltage-controlled oscillation unit that receives feedback of the output voltage of the piezoelectric transformer and controls the input voltage to the piezoelectric transformer, and a waveform corresponding to the phase difference between the input voltage and the output voltage to the piezoelectric transformer And a voltage comparison unit that compares an integrated value of the output of the phase comparison unit with a reference voltage, and detects contamination of the discharge needle when the integration value is lower than the reference voltage. It is characterized by that.

  Thus, the presence or absence of corona discharge can be detected based on the magnitude of the input impedance of the discharge needle by utilizing the fact that the output of the piezoelectric transformer is easily affected by the load impedance and the phase between the input and output changes. As a result, a slight change in impedance of the discharge needle due to the presence or absence of corona discharge of the discharge needle can be captured. Moreover, the influence by environmental changes, such as a difference in an installation place and a change of a power supply voltage, is small, and a misdetection can be prevented.

  (2) Also, the ionizer discharge needle contamination detection method according to the present invention is a method for detecting ionizer discharge needle contamination in which ions are generated by corona discharge, and is an input voltage to a piezoelectric transformer controlled by output voltage feedback. Detecting the output voltage of the piezoelectric transformer, outputting the waveform according to the phase difference between the detected input voltage and the output voltage, and integrating the output according to the phase difference Comparing the value with a reference voltage, and detecting contamination of the discharge needle when the integrated value is lower than the reference voltage. Thereby, the presence or absence of corona discharge by the discharge needle can be detected. Moreover, the influence by environmental changes, such as a difference in an installation place and a change of a power supply voltage, is small, and a misdetection can be prevented.

  According to the present invention, the presence / absence of corona discharge by the discharge needle can be detected, the influence of environmental changes is small, and erroneous detection can be prevented.

It is a block diagram which shows the structure of the contamination detection circuit of the ionizer discharge needle concerning this invention. It is the schematic which shows the equivalent circuit of a piezoelectric transformer and a discharge needle. It is a graph which shows the frequency characteristic of a piezoelectric transformer. It is a figure which shows the example of the operation | movement waveform of a phase comparison part. It is a figure which shows the example of the operation | movement waveform of a phase comparison part. It is a table | surface which shows the equivalent circuit constant of a discharge needle. It is a figure which shows the operation | movement waveform at the time of normal. It is a figure which shows the operation | movement waveform at the time of dirt.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, in order to facilitate understanding of the description, the same reference numerals are given to the same components in the respective drawings, and duplicate descriptions are omitted.

(Configuration of ionizer discharge needle contamination detection circuit)
FIG. 1 is a block diagram showing a configuration of an ionizer discharge needle contamination detection circuit 100. In the ionizer discharge needle contamination detection circuit 100, a function for detecting contamination of the ionizer discharge needle is added to the ionizer AC high-voltage power supply circuit. As shown in FIG. 1, the ionizer discharge needle contamination detection circuit 100 includes a voltage-controlled oscillation unit 110, a drive unit 115, a piezoelectric transformer 120, a discharge needle 130, a voltage dividing resistor 140, a rectification unit 150, a phase comparison unit 160, An integration circuit 170, a reference voltage generation unit 180, a voltage comparison unit 190, and an output unit 195 are provided.

  The voltage controlled oscillator 110 receives feedback of the output voltage of the piezoelectric transformer 120, generates an oscillation signal, and controls the input voltage to the piezoelectric transformer 120. The drive unit 115 receives an oscillation signal from the voltage controlled oscillation unit 110, generates an alternating voltage, and applies it to the piezoelectric transformer 120. The piezoelectric transformer 120 boosts the input voltage and outputs it. The piezoelectric transformer 120 has a characteristic that the output voltage changes according to the frequency of the input AC voltage. The high output voltage is output to the discharge needle 130. The piezoelectric transformer 120 is, for example, a single plate or a laminated Rosen-type piezoelectric transformer.

  When an AC high voltage output from the piezoelectric transformer 120 is applied in a normal state, the discharge needle 130 emits corona discharge at the tip of the discharge needle 130 to release ions. The voltage dividing resistor 140 is a resistor for taking out the output voltage of the piezoelectric transformer 120 by voltage division. The rectifying unit 150 rectifies the output voltage of the extracted piezoelectric transformer 120.

  Thus, the output voltage of the piezoelectric transformer 120 is dropped by the voltage dividing resistor 140 and input to the voltage controlled oscillator 110 via the rectifier 150. Then, the voltage controlled oscillation unit 110 controls the output voltage of the piezoelectric transformer 120 by changing the oscillation frequency. Thereby, the contamination detection circuit 100 of the ionizer discharge needle has a function of keeping the output voltage constant.

  The phase comparison unit 160 outputs a waveform corresponding to the phase difference between the input voltage and the output voltage to the piezoelectric transformer 120. The waveform is output by comparing the phases of the rectangular wave output of the voltage controlled oscillator 110 and the sine wave output of the piezoelectric transformer 120. The phase comparison unit 160 outputs the phase difference as an ON / OFF duty ratio. The phase difference between the input and output of the piezoelectric transformer 120 is converted into an ON / OFF duty ratio by the phase comparison unit 160 and rectified through an integration circuit, and then compared with the reference voltage by the voltage comparison unit 190 to discharge needle. 130 is output as a dirt detection. The integration circuit 170 rectifies the output PCout of the phase comparison unit 160 to obtain an integral value.

  The reference voltage generator 180 generates a reference voltage used as a reference for comparison by the voltage comparator 190. For example, an integral value when the duty ratio of the output of the phase comparison unit 160 is 34% can be set in advance as the reference voltage. Accordingly, it is possible to detect that the corona discharge is not generated when the duty ratio is smaller than this with reference to the duty ratio of 34%, and to know the contamination of the discharge needle 130.

  Further, the integrated value of the output of the phase comparator 160 when the resistance value of the resistance component Rp of the discharge needle 130 is 91% of the initial value can be set in advance as a reference voltage. Thus, by detecting that the resistance component Rp of the discharge needle 130 has decreased to less than 91% of the initial value based on the change in the phase between the input and output of the piezoelectric transformer 120, the contamination of the discharge needle 130 can be known.

  The voltage comparison unit 190 compares the integrated value of the output of the phase comparison unit 160 with the reference voltage. The output unit 195 outputs that the contamination of the discharge needle is detected when the integrated value is lower than the reference voltage. The output can be performed by, for example, a display indicating that dirt is detected, but is not particularly limited. In this manner, the contamination state of the discharge needle 130 can be determined and output based on the result of comparison with the reference voltage by the voltage comparison unit 190.

(Operation of the ionizer discharge needle contamination detection circuit)
The operation of the ionizer discharge needle contamination detection circuit 100 configured as described above will now be described. First, the voltage controlled oscillator 110 applies a controlled input voltage to the piezoelectric transformer 120. The piezoelectric transformer 120 boosts the input voltage and applies the output voltage to the discharge needle 130. The voltage dividing resistor 140 and the rectifier 150 feed back the output voltage, and the voltage controlled oscillator 110 controls the input voltage of the piezoelectric transformer 120. The phase comparison unit 160 detects an input voltage to the piezoelectric transformer 120.

  On the other hand, the phase comparison unit 160 detects the output voltage of the piezoelectric transformer 120 and outputs a waveform corresponding to the phase difference between the detected input voltage and output voltage. Then, the voltage comparison unit 190 compares the integrated value of the output corresponding to the phase difference with the reference voltage, and the output unit 195 outputs the contamination detection of the discharge needle when the integrated value is lower than the reference voltage. The reference voltage is set in advance in consideration of the characteristics of the piezoelectric transformer 120 and the type of the discharge needle 130. Assuming that the resistance value of the resistance component of the discharge needle 130 is 91% of the normal value, the integrated value of the output of the phase comparison unit 160 may be calculated, and the integrated value may be set as the reference voltage. Further, an integral value when the duty ratio of the output of the phase comparison unit 160 is 34% may be set as the reference voltage.

  Thus, the presence or absence of corona discharge can be detected by the magnitude of the input impedance of the discharge needle 130 by utilizing the fact that the output of the piezoelectric transformer 120 is easily affected by the load impedance and the phase between the input and output changes. . As a result, a slight change in impedance due to the presence or absence of dirt on the discharge needle 130 can be captured. Further, since the contamination is detected based on the duty ratio rather than the magnitude of the output voltage of the piezoelectric transformer 120, the influence of environmental changes such as a difference in installation location and a change in power supply voltage is small, and erroneous detection can be prevented.

(Principle of dirt detection)
Next, the principle of detecting dirt on the discharge needle 130 using an equivalent circuit model will be described. FIG. 2 is a schematic diagram showing an equivalent circuit of the piezoelectric transformer 120 and the discharge needle 130. As shown in FIG. 2, in the equivalent circuit, the piezoelectric transformer 120 includes a first braking capacitor C ₀₁ connected in parallel to the primary side, an inductor L ₁ , a capacitor C ₁ and a resistor R connected in series to the primary side. ₁ and a second braking capacity C ₀₂ connected in parallel to the secondary side. Further, the discharge needle 130 can be represented by a capacitance component Cp and a resistance component Rp of the discharge needle 130. The piezoelectric transformer 120 outputs a voltage with a voltage conversion ratio φ.

  When an AC high voltage is applied in a normal state, the discharge needle 130 emits a corona discharge at its tip to release ions. However, when dust or the like adheres to the discharge needle 130 or corrodes with corona discharge and atmospheric corrosive gas, corona discharge does not occur and ions cannot be released. In the state of corona discharge, the resistance value of the resistance component Rp in the equivalent circuit is large, but when the corona discharge stops, the resistance value of the resistance component Rp decreases. Therefore, the state of the input impedance of the discharge needle 130 differs depending on whether or not corona discharge is performed. In addition, as the case where the discharge needle 130 is contaminated, it is conceivable that dust or the like adheres to the discharge needle 130 as described above or corroded by corona discharge and corrosive gas in the atmosphere. Including cases that do not occur.

On the other hand, the ionizer discharge needle contamination detection circuit 100 has a function of making the output constant. When the discharge needle 130 is contaminated, a change in the driving frequency to keep the output constant appears as a large change on the input side. That is, the phase delay of the output voltage with respect to the input voltage is reduced. FIG. 3 is a graph showing the frequency characteristics of the piezoelectric transformer 120. As shown in FIG. 3, the piezoelectric transformer 120 uses a frequency range with higher efficiency than the resonance frequency F ₀ as a usage range, and the boost ratio (voltage conversion ratio) is a decreasing function of the driving frequency in the usage range. When the discharge state of the discharge needle 130 is changed, the inductor L ₁ and the capacitor C ₁ connected in series to the primary side in the equivalent circuit are changed by the control for making the output voltage constant. As a result, the step-up ratio changes, and the admittance as viewed from the input side of the piezoelectric transformer 120 increases as shown in Equation 1 below. Then, the phase difference between the input voltage and the output voltage of the piezoelectric transformer 120 changes so that the phase delay of the output voltage of the piezoelectric transformer 120 becomes smaller.

  On the other hand, the piezoelectric transformer 120 is easily affected by a change in load impedance, as can be seen from its equivalent circuit, and when the discharge needle 130 enters a non-discharge state, the phase between the output voltage and the input / output changes. Such a phase change is also reflected in the phase difference. As described above, the phase difference between the input voltage and the output voltage changes due to the influence of frequency control and the influence of change in load impedance.

  4A and 4B are diagrams illustrating examples of operation waveforms of the phase comparison unit 160. FIG. As operation waveforms, input signals PCAin and PCBin and output signal PCout of the phase comparator 160 are shown. FIG. 4A shows an operation waveform when the discharge state is maintained by the normal discharge needle 130. FIG. 4B shows an operation waveform when the discharge needle 130 becomes dirty and becomes in a no-discharge state. As shown in FIGS. 4A and 4B, when the discharge needle 130 becomes dirty and becomes in a no-discharge state, the duty ratio of the output signal PCout of the phase comparison unit 160 becomes small. Then, the presence or absence of contamination can be detected by integrating the output signal PCout and comparing it with the reference voltage.

  Next, an experiment was conducted to measure the resistance component of the equivalent circuit when the discharge needle 130 was discharged normally and when it was dirty and did not discharge. FIG. 5 is a table showing equivalent circuit constants of the discharge needle 130. As shown in FIG. 5, when the discharge needle 130 is normal, the resistance value of the resistance component Rp is 54.8 kΩ, whereas when the discharge needle 130 is dirty, the resistance value of the resistance component Rp is 49. 0.4 kΩ, which was reduced to 90% of the original. Note that the capacitance component Cp of the discharge needle 130 did not change at 4.8 pF in any case. Thus, it was demonstrated that the discharge needle 130 was soiled when the resistance component of the discharge needle 130 decreased to less than 91% of the original. The present invention utilizes this change.

  In addition, an experiment was performed to compare the duty ratio when the discharge needle 130 is normal and dirty. FIG. 6A is a diagram illustrating operation waveforms obtained in a normal state. FIG. 6B is a diagram illustrating an operation waveform at the time of contamination. In the normal operation waveform, the phase of the output voltage PCBin of the piezoelectric transformer 120 is delayed by 68.91 ° from the phase of the input voltage PCAin. On the other hand, in the operation waveform at the time of contamination, the phase of the output voltage PCBin of the piezoelectric transformer 120 is delayed by 59.28 ° from the phase of the input voltage PCAin.

  Therefore, it was found that when the discharge needle 130 is normal, the duty ratio of the output of the phase comparison unit 160 is 39.50%. On the other hand, when the discharge needle 130 is dirty, the duty ratio of the output of the phase comparator 160 is found to be 33.64%. This proves that the discharge needle is soiled when the duty ratio of the output of the phase comparator 160 is less than 34%. Thus, it has been demonstrated that the contamination of the discharge needle 130 can be detected by utilizing the fact that the phase of the output voltage of the piezoelectric transformer 120 changes and the duty ratio becomes small.

100 Ionizer Discharge Needle Contamination Detection Circuit 110 Voltage Control Oscillator 115 Drive Unit 120 Piezoelectric Transformer 130 Discharge Needle 140 Voltage Dividing Resistor 150 Rectifier 160 Phase Comparator 170 Integration Circuit 180 Reference Voltage Generator 190 Voltage Comparator 195 Output C Capacitance C ₀₁ Braking capacity C ₀₂ Braking capacity C ₁ Capacity L ₁ Inductor R ₁ Resistance Cp Capacitance component Rp Resistance component F ₀ Resonance frequency L Inductor PCAin Input PCAin Input voltage PCBin Output voltage PCout Output φ Voltage conversion ratio

Claims (2)

A contamination detection circuit for an ionizer discharge needle that generates ions by corona discharge,
A piezoelectric transformer that outputs a high voltage to the discharge needle;
In response to feedback of the output voltage of the piezoelectric transformer, a voltage controlled oscillation unit that controls the input voltage to the piezoelectric transformer;
A phase comparator that outputs an ON / OFF rectangular wave in which a phase difference between an input voltage and an output voltage to the piezoelectric transformer is represented as ON ;
A voltage comparison unit that compares an integrated value of an output whose phase difference is expressed as ON and a reference voltage;
An ionizer discharge needle contamination detection circuit that detects contamination of the discharge needle when the integrated value is lower than the reference voltage. A method for detecting contamination of an ionizer discharge needle that generates ions by corona discharge,
Detecting an input voltage to the piezoelectric transformer controlled by output voltage feedback;
Detecting an output voltage of the piezoelectric transformer;
Outputting an ON / OFF rectangular wave in which the phase difference between the detected input voltage and output voltage is represented by ON ;
Comparing the integrated value of the output whose phase difference is represented by ON with a reference voltage,
A method for detecting contamination of an ionizer discharge needle, wherein the contamination of the discharge needle is detected when the integrated value is lower than the reference voltage.

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