JP2012032153A - Non-contact dc voltage detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-contact DC voltage detector capable of highly efficiently measuring a potential being applied under the state where no current flows, in spite of simple configuration.SOLUTION: A non-contact DC voltage detector includes: a liquid crystal element 2 in which light transmissivity is changed by a potential difference between two electrodes 2A and 2B; a measuring electrode panel 3 which is electrically connected to the electrode 2A and receives an electric field; a comparison electrode 4 electrically connected to the electrode 2B; a reflector plate 5 disposed at a side of the electrode 2A; a light-emitting element 6 and a light-receiving element 7 disposed at a side of the electrode 2B; and a measuring circuit 8 for measuring electric field strength from an intensity signal of light measured by the light-receiving element 7.

Description

  The present invention relates to a non-contact type DC voltage detector that detects a DC voltage by non-contact.

  Conventionally, as a method for detecting a DC voltage, a potential difference is measured by bringing a probe into contact with a measurement object and a reference point. Moreover, it is possible to measure the magnitude | size of the applied alternating voltage by detecting the electromagnetic wave generated from now in the part to which the alternating voltage was applied. However, an electromagnetic wave is not generated from a DC voltage source in which no current flows, and there is a problem that measurement using this electromagnetic wave cannot be performed.

  In particular, when high voltage is applied, it is preferable to perform non-contact voltage measurement to prevent danger, but when only DC voltage is applied, voltage measurement using electromagnetic waves cannot be performed. Is being used. For example, in order to inspect and maintain a high-voltage feeder line in a railway, work is performed with the power supply to the feeder line stopped, but a contact-type voltage is used to confirm that the power supply is stopped reliably. The use of a meter is carried out.

  On the other hand, in the liquid crystal electric field sensor of Patent Document 1, it is considered to measure the electric field strength using a liquid crystal cell arranged in equilibrium with the electric field in the vicinity of the measurement target. As described above, since the liquid crystal cell changes the light transmittance by the potential difference applied with high insulation, the electric field can be measured using this.

JP-A-8-86815

  However, in the configuration such as the liquid crystal electric field sensor of Patent Document 1, the electric field strength is measured by directly exposing the liquid crystal cell to an electric field. Did not go. In addition, it is difficult to distinguish between the electric field generated from a feeder line to which voltage is applied without current flowing and the electric field generated by static electricity. There is a problem that occurs.

  The present invention has been made in consideration of the above-mentioned matters, and is a non-contact type DC voltage capable of measuring a potential applied in a state in which no current is flowing with high efficiency while having a simple configuration. An object is to provide a detector.

  In order to solve the above-described problems, the present invention provides a liquid crystal element whose light transmittance varies depending on a potential difference between two electrodes, and a measurement electrode panel that is electrically connected to one electrode of the liquid crystal element and receives an electric field. A reference electrode electrically connected to the other electrode of the liquid crystal element, a reflector disposed on the one electrode side, a light emitting element disposed on the other electrode side, and the other electrode side A non-contact type DC voltage detection comprising: a light receiving element disposed so that light is not directly incident on the light emitting element; and a measurement circuit that measures an electric field intensity by an intensity signal of the light measured by the light receiving element. Provide a bowl. (Claim 1)

  Since the measurement electrode panel that receives the electric field is attached to one electrode of the liquid crystal element, the electric field generated from the measurement object can be efficiently received at a position away from the liquid crystal element, and the liquid crystal electrically connected to the measurement electrode panel An amount of electric charge corresponding to the magnitude of the electric field can be stored in one electrode of the element, and an electric field is generated between both electrodes of the liquid crystal element. Therefore, the liquid crystal element disposed in the electric field matches the electric field strength. The light transmittance changes. The measurement electrode panel is preferably formed of a metal having excellent conductivity, such as aluminum, and the area thereof is preferably large in order to receive the electric field more efficiently, for example, a non-contact type DC voltage detector It is large enough to cover almost the entire measurement end.

  The liquid crystal element includes a pair of glass materials having the light-transmitting electrodes (transparent electrodes) transferred to the inner surface, a pair of alignment films sandwiched by these glass materials and having deflection characteristics different from each other by 90 °, And a sealing material that encloses the liquid crystal layer in a state in which a spacer and a liquid crystal layer made of liquid crystal are disposed between the alignment films. Therefore, the said reflecting plate is arrange | positioned at the one electrode side by contact | abutting to the outer surface of one electrode glass base material. The light emitting element and the light receiving element are disposed on the other electrode side by being disposed so as to face the outer surface of the other electrode glass substrate.

  Note that the reference electrode is electrically connected to the other electrode of the liquid crystal element, which serves as a reference potential. Therefore, it is preferable that the potential of the comparison electrode is stable. For example, the reference electrode is connected to a negative electrode power supply line or a negative electrode power supply line provided with, for example, the light emitting element, the light receiving element, and the measurement circuit as a reference voltage supply source. It is a plate.

  Since the reflector is disposed on one electrode side of the liquid crystal element, it reflects light transmitted from the light emitting element disposed on the other electrode side and transmitted through the liquid crystal element, and transmits the liquid crystal element again to the light receiving element. It can be made incident. The reflector is preferably a mirror body excellent in terms of light reflectivity, and more preferably light such as paper or polished glass between the mirror body and the electrode in order to cause light scattering. A diffusion layer is provided.

  Moreover, it is preferable that one electrode and the reflecting plate of the liquid crystal element are disposed in a state of physically floating from the constituent members other than the liquid crystal layer. Similarly, it is preferable that the measurement electrode panel electrically connected to the one electrode is also insulated to the extent that static electricity can be accumulated from other parts so as to obtain appropriate chargeability. It is preferable that a plate of acrylic resin (polymer of methacrylic acid resin) is in close contact with the surface of an insulating container made of a synthetic resin having appropriate insulating properties such as vinyl chloride.

  The light-emitting element emits a stable amount of light and is preferably a light-emitting diode (LED) that emits light efficiently, but an organic light-emitting diode (OLED) or a light-emitting polymer (LED) It may be a light emitting element using organic EL such as LEP (Light Emitting Polymer).

  The light receiving element may be any element as long as it can receive light emitted from the light emitting element and convert it into an electrical signal. For example, a photoresistor, a phototransistor, a photodiode, or the like can be used. It is preferable to provide a light shielding plate between the light emitting element and the light receiving element so that light from the light emitting element does not directly enter the light receiving element. For example, the light receiving element is inserted into a light shielding cylinder made of cylindrical silicon rubber. It is preferable to arrange.

  The measurement circuit measures the electric field strength using the light intensity signal measured by the light receiving element. When the electric field strength exceeds a predetermined threshold value, for example, a warning sound is output using a buzzer or the like. It is preferable that However, the measurement circuit may convert the electric field strength into an electric signal such as current or voltage and output it.

  In the case where an electric field shielding layer formed in a container shape covering at least the liquid crystal element, the light emitting element, and the light receiving element is provided (Claim 2), the liquid crystal element and its peripheral members are covered with the electric field shielding layer. Therefore, it does not cause malfunction due to the influence of disturbance. It becomes difficult to be affected by an electric field from a direction other than the measurement target of the electric field. In other words, the potential of the measurement target can be measured without being affected by static electricity generated by the operator's operation. The electric field shielding layer may be formed with the measurement electrode panel having a container shape, but a comparative electrode or a power supply line may be used as the electric field shielding layer.

  In addition to the liquid crystal element, the light emitting element, and the light receiving element, by forming a unitized sensor unit that includes the measurement electrode panel and the comparison electrode, the sensor unit can be made an independent structure. The influence can be reduced, and stable electric field measurement can be easily realized.

  A first sensor unit and a second sensor unit each including the liquid crystal element, a measurement electrode panel, a comparison electrode, a light emitting element, and a light receiving element are arranged side by side in the electric field detection direction, and the measurement circuit is a first sensor When a value obtained by subtracting the measured value of the electric field strength by the second sensor unit from the measured value of the electric field strength by the first sensor unit in a state where a negative bias voltage is applied only to the measuring electrode of the unit is less than a predetermined threshold value When a warning output unit for outputting a warning is provided (Claim 3), the measured value of the electric field can be distinguished from positive and negative, and the threshold value can be accurately set at a predetermined electric field strength.

  In other words, even if the sensor unit is positive or negative, a measured value of the electric field strength can be obtained when there is a potential difference with the reference electrode, but a negative bias voltage is applied to the first sensor unit. Therefore, by subtracting the measurement value of the second sensor unit from the measurement value of the first sensor unit, the measurement value corresponding to the bias voltage is always output when the potential of the measurement target is lower than the potential of the comparison electrode. As the potential of the measurement target becomes higher than the potential of the reference electrode, the value obtained by subtracting the measurement value of the second sensor unit from the measurement value of the first sensor unit becomes smaller.

  In addition, it is preferable that each sensor part is partitioned off with insulators, such as ABS resin. In addition, since both the sensor parts are arranged vertically with respect to the object to be measured, one electric field strength can be measured by the pair of front and rear sensor parts, so that highly accurate measurement can be performed.

  A bias applying unit having a contact that can contact the measurement electrode panel in a state where a predetermined bias voltage is applied, and the liquid crystal element and the measurement electrode panel are arranged at a distal end portion, and a reference potential electrode as a comparison electrode at a base end portion. In the case where a rod body in which a connecting portion is disposed and a warning output unit that outputs a warning when the measured value of the electric field intensity is equal to or greater than a predetermined threshold (Claim 4), the measurement is performed at the tip of the rod body. An electrode panel is provided, and by applying a bias voltage to the potential of the measurement electrode panel by the bias application unit, the sensitivity to the electric field to be measured can be adjusted, and fluctuations in measurement sensitivity can be prevented.

  FIG. 14 is a graph showing characteristics of the liquid crystal element, and shows that the relationship between the potential difference between both electrodes of the liquid crystal element and the light transmittance is not a linear proportional relationship. By applying a bias voltage of, for example, 1.2 V to the liquid crystal element having such characteristics and shifting the measurement start point, a minute voltage change can be made by utilizing the range in which the change in light transmittance with respect to the change in potential difference is large. Can be detected. In addition, since the reference potential electrode connecting portion is arranged as the comparison electrode, if a ground wire is connected to this connecting portion, for example, the ground potential becomes the reference potential, and therefore the influence of the generation of static electricity due to the operation of the operator is affected. It can be made not to receive. Since the rod is long, its upper end can be brought as close as possible to the feeder wire at a high position.

  According to a second aspect of the present invention, there is provided a liquid crystal element whose light transmittance is changed by a potential difference between two electrodes, a first measurement electrode panel electrically connected to one electrode of the liquid crystal element, and the other of the liquid crystal elements A second measurement electrode panel electrically connected to the electrodes, and a first dielectric and a first dielectric attached to both measurement electrode panels in a state where these measurement electrode panels are arranged substantially perpendicular to the electric field detection direction. 2 dielectrics, a comparison electrode in contact with and / or one of these dielectrics and connected to a reference voltage source, a reflector arranged on the one electrode side, and arranged on the other electrode side A light emitting element, a light receiving element arranged so that light is not directly incident on the other electrode side from the light emitting element, and a measurement circuit for measuring an electric field intensity by an intensity signal of light detected by the light receiving element. That features Providing a non-contact type DC voltage detector for (claim 5).

  By arranging the two measurement electrode panels substantially perpendicular to the electric field detection direction, the electric field can be efficiently received. Between the two measurement electrode panels, the dielectric constant, thickness, and measurement electrode of the dielectric facing the measurement electrode panel A potential difference is generated by the difference in the position of the panel in the electric field detection direction, which is applied to both electrodes of the liquid crystal element, and the light transmittance of the liquid crystal element changes according to the potential difference. That is, light emitted from the light emitting element is transmitted through the liquid crystal element, reflected by the reflecting plate, and incident on the light receiving element. The measurement circuit measures the potential of the measurement target using the intensity of light incident on the light receiving element. In addition, since the electric field from a direction different from the detection direction is absorbed by the comparison electrode, the influence can be reduced.

  The two measurement electrode panels are arranged side by side at the same distance via a dielectric having a different dielectric constant with respect to the comparison electrode, so that different amounts of charges can be accumulated in the electric field to be measured. However, the potentials of both measurement electrode panels may be made different by changing the positions of both measurement electrode panels in the electric field detection direction. Further, both measurement electrode panels may be arranged side by side in the electric field measurement direction. It is preferable that both the measurement electrode panels are appropriately insulated to such an extent that static electricity can be accumulated from other portions.

  The measurement electrode panel that receives an electric field is preferably formed of a metal having excellent conductivity, and its area is preferably large. The potential of the comparison electrode is preferably stable. For example, the negative electrode power line of the substrate or a plate connected to the negative electrode power line is preferable.

  The reflector is preferably a mirror body excellent in terms of light reflectance, and more preferably includes a mirror body and a light diffusion layer. As the light emitting element, not only a light emitting diode that emits a stable amount of light but also an organic EL such as an organic light emitting diode or a light emitting polymer can be used. For example, a photoresistor, a phototransistor, or a photodiode can be used as the light receiving element. For example, the light receiving element is preferably inserted in a light shielding cylinder made of cylindrical silicon rubber.

  The measurement circuit measures the electric field intensity using the light intensity signal measured by the light receiving element, and outputs a warning sound or the like using a buzzer or the like, for example, when the signal intensity exceeds a predetermined threshold value. The measurement circuit may convert the electric field strength into an electric signal and output it.

  In the case where an electric field shielding layer formed in a container shape that is electrically connected to the comparison electrode and covers the entire liquid crystal element except for the opening for the measurement electrode panel is provided (Claim 6), the electric field measurement direction The influence of the electric field from other directions can be blocked by the electric field shielding layer, and the electric field can be measured only at the portion where the opening is formed. Therefore, the fluctuation of the measured value due to disturbance can be suppressed.

  As described above, according to the present invention, the electric field can be effectively measured even at a position away from the measurement target. In addition, since the reference potential can be determined by the comparison electrode, the influence of ambient disturbance such as static electricity can be reduced.

  In addition, by providing the electric field shielding layer, it is possible to form a sensor unit that can suppress the influence of an unnecessary electric field as much as possible. By performing comparison using a plurality of measurement electrode panels, it is possible to perform more stable measurement.

It is a figure which shows the whole structure of the non-contact-type DC voltage detector which concerns on 1st Embodiment of this invention. It is a figure which shows the example which united the sensor part of the non-contact-type DC voltage detector. It is a figure which shows the structure of the sensor part of FIG. 2 as a circuit. It is a figure which shows the electrical property of the sensor part of FIG. It is a figure which shows the structure of the non-contact-type DC voltage detector of 2nd Embodiment. It is a figure which shows the structure of the said non-contact-type DC voltage detector as a circuit. It is a figure which shows the electrical property of the said non-contact-type DC voltage detector. It is a figure which shows the structure of the non-contact-type DC voltage detector of 3rd Embodiment. It is a figure which shows the structure of the said non-contact-type DC voltage detector as a circuit. It is a figure which shows the example of the alarm device using the non-contact-type DC voltage detector of this invention. It is a figure which shows the non-contact-type DC voltage detector of 4th Embodiment. It is a figure which shows the non-contact-type DC voltage detector of 5th Embodiment. It is a figure which shows the structure of the said non-contact-type DC voltage detector as a circuit. It is a figure which shows the characteristic of a liquid crystal element.

  Hereinafter, the configuration of the non-contact DC voltage detector 1 according to the first embodiment of the present invention will be described with reference to FIG. The non-contact type DC voltage detector 1 of the present invention is electrically connected to a liquid crystal element 2 whose light transmittance is changed by a potential difference between two electrodes 2A and 2B, and one electrode 2A of the liquid crystal element 2. A measurement electrode panel 3 that receives an electric field, a comparison electrode 4 that is electrically connected to the other electrode 2B of the liquid crystal element 2, a reflector 5 that is disposed on the one electrode 2A side, and the other electrode 2B The light-emitting element 6 arranged on the side, the light-receiving element 7 arranged so that light does not directly enter the light-emitting element 6 on the other electrode 2B side, and the electric field intensity by the intensity signal of the light measured by the light-receiving element 7 And a power source 9 for the measurement circuit 8.

  As shown in the enlarged view, the liquid crystal element 2 includes a pair of glass substrates 2A1, 2B1 having the light-transmitting electrodes (transparent electrodes) 2A, 2B transferred to the inner surface, and these glass substrates 2A1, 2B1. The liquid crystal layer 2E is sealed in a state where a pair of alignment films 2C and 2D having a deflection characteristic different from each other by 90 ° are sandwiched by the liquid crystal layer 2C and a liquid crystal layer 2E made of a spacer and liquid crystal is disposed between the alignment films 2C and 2D. And a sealing material 2F. The liquid crystal layer 2E is excellent in insulation, and the knitted wave surface can be twisted by a predetermined angle by the potential difference between the electrodes 2A and 2B. In addition, the thickness d of the liquid crystal layer 2E is formed as thin as possible so that a potential difference as low as possible can be detected.

  The measurement electrode panel 3 has a large area so that it can receive as much charge as possible when it is exposed to the electric field in a state of being arranged substantially perpendicular to the measurement direction X of the electric field generated from the measurement object. It is a plate-like body made of metal such as high-rate aluminum. The measurement electrode panel 3 is attached to a case 1A made of ABS, for example, which covers the entire contactless DC voltage detector 1 with a plate 3A made of acrylic resin in close contact with the back surface, and the electrode 2A is connected by a lead wire 3B. Are connected so as to have the same electric potential.

  The comparison electrode 4 of the present embodiment has substantially the same shape as the measurement electrode panel 3, and is a plate-like body made of a metal such as aluminum having a high area and high conductivity (hereinafter, the plate-like comparison electrode 4 is referred to as a comparison electrode panel). Construct). The back surface of the comparison electrode panel 4 is attached to the case 1A via a vinyl chloride plate 4A, for example, and is electrically connected to the electrode 2B by a lead wire 4B.

  Since the reflection plate 5 is arranged on the one electrode 2A side of the liquid crystal element 2, the light L1 generated from the light emitting element 6 arranged on the other electrode 2B side and transmitted through the liquid crystal element 2 is reflected, and again the liquid crystal element Can be transmitted and incident on the light receiving element 7. The reflector 5 is provided with a light diffusion layer 5B such as paper between the mirror body 5A which is excellent in the reflectance of the light L1 and the electrode.

  The light emitting element 6 is a light emitting diode excellent in energy conversion efficiency. The light receiving element 7 is a photo-resistor and is connected so as to be in close contact with the electrode 2B through a cylindrical rubber packing 7A so that light from the light emitting diode 6 does not directly enter the light receiving element 7.

  The control circuit 8 of the present embodiment includes a first base 8A to which the light emitting element 6 and the light receiving element 7 are attached, a second base 8B electrically connected to the first base 8A, and the circuits 8A and 8B. A detection circuit 8C that is attached and detects an electric field from a measurement value of the light receiving element 7, a bias voltage adjustment unit 8D that adjusts a bias voltage applied to the measurement electrode panel 3, and a bias that is adjusted by the bias voltage adjustment unit 8D A bias voltage application switch 8E for intermittently applying a voltage to the measurement electrode panel 3, a threshold value setting unit 8F for setting the measured electric field strength, a buzzer 8G for outputting a warning by sound or buzzer sound, and a power switch 8H Is provided. In the present embodiment, the measurement circuit 8 is divided into two substrates 8A and 8B. However, these may be formed as a single unit, and portions 8C, 8D, and 8F that perform signal processing. May be miniaturized by making an IC.

  The power source 9 is, for example, a battery, thereby reducing the size of the contactless DC voltage detector 1 and providing portability.

  When the measurement electrode panel 3 and the comparison electrode panel 4 are arranged perpendicular to the measurement direction X of the electric field and spaced apart from each other by a predetermined distance, the non-contact type DC voltage detector 1 Can be effectively received, and a potential difference is generated between them. At this time, since both the electrode panels 3 and 4 are configured to be in contact with the case 1A while maintaining an appropriate insulating property by the plates 3A and 4A, the charged charges can move and the chargeability is improved.

  Further, when both the electrode panels 3 and 4 are charged, an electric field in the direction of arrow Y is generated between the first and second electrodes 2A and 2B of the liquid crystal element 2 electrically connected thereto, and the liquid crystal layer 8C generates twisting of the knitting wave surface in accordance with the electric field strength in a state of being arranged perpendicular to the electric field in the direction of arrow Y, and by combining with the deflection characteristics of the electrodes 2A and 2B, the liquid crystal element 2 as a whole The light transmittance fluctuates according to the electric field strength of the measurement object. In particular, since the first electrode 2A is attached in a state where the portions other than the liquid crystal layer 2E are completely floated, high insulation can be maintained with respect to the second electrode 2B, and sufficient sensitivity can be obtained. .

  The measurement circuit 8 supplies stable power to the light emitting element 6 to emit light L1, and the light L1 transmitted through the liquid crystal element 2 is reflected by the reflecting plate 5, and the reflected light L2 is measured by the light receiving element 7. . Since the reflecting plate 5 includes the mirror body 5A and the light diffusion layer 5B, the light L1 can not only efficiently reflect but also generate diffused reflected light L2, and the light receiving element 7 can efficiently reflect the reflected light L2. It can be measured.

  The intensity of light measured by the light receiving element 7 is converted into electric field intensity by the detection circuit 8C, and when this reaches the set value by the threshold setting unit 8F, the buzzer 8G generates a warning sound to notify the user of the danger. Can do.

  Since the measurement electrode panel 3 is attached so as to keep insulation moderately, it is considered that unnecessary charges are accumulated in the measurement electrode panel 3 due to some disturbance. However, the measurement electrode panel is measured by the bias voltage application switch 8E. 3 can be applied with a bias voltage, so that preparation for electric field measurement using the measurement electrode panel 3 can be quickly made.

  2 and 3 are diagrams showing an example in which the configuration of the sensor unit Su of the non-contact type DC voltage detector 1 is unitized. The sensor unit Su houses the liquid crystal element 2, the light emitting element 6, and the light receiving element 7 in a container-shaped case 1 B made of a substantially sealed synthetic resin, and the surface of the case 1 B is covered with the measurement electrode panel 3. The electric field shielding layer S is formed by the measurement electrode panel 3. One electrode 2A of the liquid crystal element 2 is connected to the measurement electrode panel 3, and the other electrode 2B is connected to a common power line of the light emitting element 6 as a comparison electrode 4.

  In the container covered with the electric field shielding layer S, the influence of the external electric field is not exerted, so that the operation of the liquid crystal element 2 is stabilized. Further, since the common (negative electrode) power supply line Com is connected to the electrode 2B as the comparison electrode 4, the electric potential thereof is stabilized, and the electric field received by the measurement electrode panel 3 can be measured with high accuracy. Vcc is a positive power supply line, and Sig is a sensor signal output unit. 3 shows an example in which the simplest detection circuit 8C (see FIG. 1) is formed. This detection circuit 8C uses the output of the light receiving element 7 in the sensor unit Su to measure the electric field. Needless to say, a linearization calculation unit (linearizer) that obtains and outputs this as a sensor signal may be included.

  FIG. 4 is a diagram for explaining electrical characteristics of the non-contact type DC voltage detector 1 having the above-described configuration. As shown in FIG. 4, when the measurement electrode panel 3 becomes a positive potential compared to the comparison electrode 4 due to the influence of the electric field in accordance with the change in the potential P to be measured, as shown by the solid line f1, the electric field measurement signal F outputs a large value according to the magnitude of the potential P. However, even when the measurement electrode panel 3 has a negative potential with respect to the comparison electrode 4, the electric field measurement signal F outputs the same measurement signal F as when it is positive, as indicated by the broken line f2. That is, in the electric field measurement using the liquid crystal element 2, there is no distinction between positive and negative in the potential P to be measured, and an output can be obtained by the absolute value of the potential difference between the electrodes 2A and 2B.

  5 and 6 are diagrams showing the configuration of the non-contact type DC voltage detector 10 according to the second embodiment configured to make a positive / negative discrimination in the electric field measurement sensitivity. In this non-contact DC voltage detector 10, two sensor parts Su1, Su2 are arranged side by side in the electric field measurement direction X, and the sensor parts Su1, Su2 are separated by a plate-shaped sensor separator 11 made of ABS resin. I am letting.

  Reference numeral 12 denotes a measurement circuit of the non-contact DC voltage detector 10 according to the present embodiment. The measurement circuit 12 serves as a bias application unit that applies a bias voltage only to the front sensor unit Su1 with respect to the measurement target. A bias electrode 13 is attached. The electric field shielding layer S of the present embodiment is an aluminum film attached so as to cover the outer wall of the container 10A having an opening only on the surface facing the measurement object. The electric field shielding layer S is a common power source for the measurement circuit 12. Connected to the line. In addition, detailed description is abbreviate | omitted by attaching | subjecting the same code | symbol about the member which is the same as that of FIGS.

  As shown in FIG. 6, 14 is a voltage stabilization circuit that adjusts the power obtained from the battery 9 to a stable DC voltage, 15 is a voltage adjustment unit that generates a negative voltage to be applied to the bias electrode 13, and 16 is An arithmetic circuit for calculating the difference between the outputs of the two sensor units Su1 and Su2, 17 is a comparator for comparing the output of the arithmetic circuit with a predetermined threshold Th, and 18 is an alarm level when the output of the comparator 17 exceeds the threshold Th. A drive circuit for supplying electric power for driving the buzzer 8G when it is turned on, and a switch circuit 19 using a transistor or the like.

  The non-contact type DC voltage detector 10 having the above-described configuration brings the bias electrode 13 into contact with the measurement electrode panel 3 of the first sensor unit Su1 before measurement, and charges the negative voltage to the sensor electrode Su1, Su2. After resetting, by directing the opening of the non-contact type DC voltage detector 10 toward the measurement object, the potential of each sensor unit Su1, Su2 is changed in accordance with the potential P of the measurement object, and the potential P is a threshold value. A warning sound can be output when exceeding.

  FIGS. 7A and 7B are diagrams for explaining the electrical characteristics of the non-contact type DC voltage detector 10. When the potential P to be measured changes positively and negatively with respect to the reference potential. In addition, the measurement signals F1 and F2 measured by the sensor units Su1 and Su2 change as indicated by f3 and f4, respectively. Further, a warning is output when the value of the difference Sub obtained by subtracting the measured value of the electric field intensity by the second sensor unit Su2 from the measured value of the electric field intensity by the first sensor unit Su1 becomes smaller than the threshold values Th1 and Th2. Thus, a warning sound can be generated using the warning buzzer 8G only when the potential P to be measured is equal to or higher than the threshold values Pt1 and Pt2 corresponding to the threshold values Th1 and Th2.

  In addition, since the measurement is performed using the value of the difference Sub between the two sensor units Su1, Su2, even when the sensor unit Su1, Su2 includes noise N due to disturbance, the influence can be offset. More accurate detection can be performed.

  FIG. 8 and FIG. 9 are diagrams showing the configuration of the non-contact type DC voltage detector 20 according to the third embodiment, and the first measurement electrode panel 21 electrically connected to one electrode 2A of the liquid crystal element 2. A second measurement electrode panel 22 electrically connected to the other electrode 2B, and the two measurement electrode panels 21, 22 in a state where these measurement electrode panels 21 and 22 are arranged substantially perpendicular to the electric field detection direction X. 22, a first dielectric 23 and a second dielectric 24 having different relative dielectric constants, and a reference electrode 25 in contact with both of the dielectrics 23 and 24 and connected to a common power line, In addition to the liquid crystal element 2, the light emitting element 6, and the light receiving element 7, a sensor unit 26 that includes a linearization calculation unit, and a measurement circuit 27 that measures the electric field strength using an intensity signal of light detected by the light receiving element are provided. Other configurations are the same as or equivalent to those already described in detail with reference to FIGS.

  The measurement electrode panels 21 and 22 are both plate-like bodies made of a conductor such as aluminum, and are arranged perpendicular to the electric field measurement direction X at the measurement end. In addition, the measurement electrode panels 21 and 22 are arranged at intervals d1 and d2 with respect to the comparison electrode 25, and the dielectrics 23 and 22 having different dielectric constants between the measurement electrode panels 21 and 22 and the comparison electrode 25 are provided. It is filled with 24. Dielectrics 23 and 24 are interposed between the measurement electrode panels 21 and 22 and the comparison electrode 25, and the measurement electrode panels 21 and 22 are connected with insulation to such an extent that charges can be charged.

  In the present embodiment, the distances d1 and d2 are set to be approximately the same to prevent unevenness at the measurement end, and the dielectric constants of the dielectrics 23 and 24 are made different so that the charge charged to the measurement electrode panels 21 and 22 is different. Although the potential difference is generated as described above, the potential difference may be generated by making the distances d1 and d2 different. In this case, the dielectric constants of the dielectrics 23 and 24 may be the same. Further, the measurement electrode panels 21 and 22 may be arranged so as to overlap each other in the measurement direction X with a space therebetween.

  Since the comparison electrode 25 is connected to the common power supply line and connected to the electric field shielding layer S, the influence of the electric field from a direction different from the measurement direction X does not reach the sensor unit 26 and the measurement circuit 27. In addition, the measurement circuit 27 of the present embodiment includes a voltage stabilization circuit 27A, supplies stable power to the sensor unit 26, and outputs a measurement value from the sensor unit 26 as it is as an analog signal Sout.

  When the non-contact type DC voltage detector 20 is arranged in the electric field perpendicular to the electric field measurement direction X, a potential difference is generated between the measurement electrode panels 21 and 22 due to the difference in the dielectrics 23 and 24. Since the light transmittance of the liquid crystal element 2 is changed by this potential difference, the sensor unit 26 outputs a sensor signal Sig using the change of the light transmittance, and the measurement circuit 27 is an analog indicating the potential P to be measured. The signal Sout can be output.

  According to the above configuration, since all can perform stable measurement except for the measurement end with reference to the potential of the common power supply line, the influence of disturbance can be almost completely eliminated.

  FIG. 10 is a diagram showing an example of an alarm device 30 using any one of the non-contact type DC voltage detectors 1, 10, and 20. The alarm device 30 includes a helmet 31 that protects the operator's head and a non-contact type DC voltage detector 1 (10, 20) attached to the helmet 31. The non-contact type DC voltage detector. 1 (10, 20) includes a power switch Sw on an exposed portion such as a front surface thereof, and a measurement electrode panel 3 (21, 22) on an upper surface thereof.

  By performing the work with the alarm device 30 attached, when a portion where a high voltage is applied approaches the head, this is detected, and the buzzer 8G is provided in the non-contact type DC voltage detector 1 (10). If this is the case, this can be notified to the operator by a warning sound. Further, when the non-contact type DC voltage detector 20 does not include the buzzer 8G, the measurement potential P and the measurement electric field F are displayed on the display unit not shown, or when a high potential is detected, the voice or other methods are used. You may provide the alarm device which notifies an operator of danger.

  FIG. 11 is a diagram showing a non-contact DC voltage detector 40 according to the fourth embodiment. In the present embodiment, the measurement electrode panel 3 is attached to one end side of the rod body 41 and the comparison electrode panel 4 is attached to the multi-end side of the rod body 41 so as to cover both ends of the rod body 41. Further, a measuring circuit 42 including the liquid crystal element, the light emitting element, the light receiving element and its peripheral circuit is provided inside the rod body 41. Since other configurations are the same as those already described in detail, detailed description thereof is omitted.

  By providing between the electrode panels 3 and 4 at both ends of the bar 41 as in the present embodiment, the operator orients the bar 41 in the electric field measurement direction X, so that the potential difference between the electrode panels 3 and 4 is increased. Is generated, and the electric field strength (the potential to be measured) can be measured.

  12 and 13 are diagrams showing a non-contact type DC voltage detector 50 of the fifth embodiment. This non-contact DC voltage detector 50 includes the sensor unit Su at the tip of a bar 51 and a bias application unit 52 for applying a bias voltage to the measurement electrode panel of the sensor unit Su. Are provided with a measuring circuit 53, a power switch 54, a connecting portion 56 for connecting a ground wire 55 as a reference potential electrode as an example of the comparison electrode 4, and an amplification factor adjusting portion 57. Further, in this embodiment, the other components are the same or equivalent members as those already described in detail with reference to FIGS. 1 to 11, and thus detailed description thereof will be omitted by attaching the same reference numerals.

  The rod body 51 is made of, for example, vinyl chloride and has a length of about 1 m, and is preferably a cylindrical body in which a measurement circuit or the like can be formed. It may be a paper tube.

  The bias applying unit 52 includes an operation switch 52a, a relay coil 52b connected in series to the operation switch 52a, a relay contact 52c that is turned on when a current flows through the relay coil 52b, and a lead wire 52d. The bias voltage adjusted by the voltage adjusting unit 15 is applied to the measurement electrode panel 3 through the relay contact 52c and the lead wire 52d. The relay contact 52c (that is, including the relay coil 52b of the electromagnetic relay) and the lead wire 52d are preferably provided as close to the sensor unit Su as possible, and are preferably provided at the distal end portion of the rod body 51 as much as possible. It is preferable to be connected to the detector circuit 53 on the part side by power supply wiring.

  Moreover, the connection part 56 of this embodiment serves also as the sensor output confirmation terminal by the said sensor part Su. Further, the amplification factor adjusting unit 57 includes, for example, a changeover switch 57a, a variable resistor 57b that determines a basic amplification factor, and a plurality of resistors 57c that are selected by the changeover switch 57a and have different resistance values. The gain on the input side is determined.

  An operator operates the power switch 54 in a state where the ground wire 55 is brought into contact with the ground and the common power line of the measurement circuit 53 is stabilized at the ground potential, and the tip of the non-contact type DC voltage detector 50 is measured. The electric field from the measurement object is received by the sensor unit Su, and the potential P can be measured more accurately. Since the unit of the sensor unit Su has an independent structure as in the present embodiment, the influence of unnecessary charging can be reduced, and more stable measurement can be performed. Further, when the influence of unnecessary charging becomes large, the relay coil 52b is turned on via the relay contact 52c by pressing the operation switch 52a without turning the rod 51 toward the measurement object to turn it on. This state can be reset by applying a bias voltage to the measurement electrode panel 3.

  In an environment where the influence of static electricity generated by an operator's clothes or the like is large, sensitivity adjustment is performed by the changeover switch 57a, thereby making it possible to prevent unnecessary operations by adjusting the expression position due to environmental changes. In this embodiment, three levels of sensitivity adjustment are possible. Basically, after operating with the sensitivity of the second level and turning on the power, a reference point for the detection target, for example, the ground, rail, etc. Move the tip of the detector close to it and press the bias voltage application operation switch 52a, then bring the tip of the detector close to the feeder or trolley wire to be detected, and remotely pressurize the target voltage. Can be detected.

  In the present embodiment, an example in which the ground wire 55 is connected to the connection portion 56 is shown. However, since the connection portion 56 is provided at the proximal end portion of the rod 51, the ground wire 55 is omitted and the user is omitted. The body or the like may be used as a reference potential, and other comparison electrodes 4 may be connected. Further, in the above-described embodiment, the bias application unit 52 is a mechanical relay contact 52c, so that a bias voltage can be applied by the operation switch 52a at hand while avoiding leakage of charged charges, However, the bias application unit 52 may be formed by an electrode that can physically contact the measurement electrode panel 3.

1, 10, 20, 40, 50 Non-contact DC voltage detector 2 Liquid crystal element 2A, 2B Electrode 3, 21, 22 Measuring electrode panel 4 Reference electrode 5 Reflecting plate 6 Light emitting element 7 Light receiving element 8G Warning output unit 13, 52 Bias application part 52a Contact 23, 24 Dielectric S Electric field shielding layer Su1, Su2 Sensor part

Claims (6)

A liquid crystal element in which the light transmittance changes depending on the potential difference between the two electrodes;
A measurement electrode panel that is electrically connected to one electrode of the liquid crystal element and receives an electric field;
A reference electrode electrically connected to the other electrode of the liquid crystal element;
A reflector disposed on the one electrode side;
A light emitting device disposed on the other electrode side;
A light receiving element disposed so that light is not directly incident on the other electrode side from the light emitting element;
A non-contact type DC voltage detector, comprising: a measurement circuit that measures an electric field intensity based on an intensity signal of light measured by a light receiving element.   The non-contact type DC voltage detector according to claim 1, further comprising an electric field shielding layer formed in a container shape that covers at least the liquid crystal element, the light emitting element, and the light receiving element.   A first sensor unit and a second sensor unit each including the liquid crystal element, a measurement electrode panel, a comparison electrode, a light emitting element, and a light receiving element are arranged side by side in the electric field detection direction, and the measurement circuit is a first sensor When a value obtained by subtracting the measured value of the electric field strength by the second sensor unit from the measured value of the electric field strength by the first sensor unit in a state where a negative bias voltage is applied only to the measuring electrode of the unit is less than a predetermined threshold value The non-contact type DC voltage detector according to claim 1, further comprising a warning output unit that outputs a warning to the terminal.   A bias applying unit having a contact that can contact the measurement electrode panel in a state where a predetermined bias voltage is applied, and the liquid crystal element and the measurement electrode panel are arranged at a distal end portion, and a reference potential electrode as a comparison electrode at a base end portion. The non-contact type DC voltage detection according to claim 1 or 2, further comprising: a rod body in which a connecting portion is disposed; and a warning output unit that outputs a warning when the measured value of the electric field strength is equal to or greater than a predetermined threshold value. vessel. A liquid crystal element in which the light transmittance changes depending on the potential difference between the two electrodes;
A first measurement electrode panel electrically connected to one electrode of the liquid crystal element;
A second measurement electrode panel electrically connected to the other electrode of the liquid crystal element;
A first dielectric and a second dielectric attached to both measurement electrode panels in a state in which these measurement electrode panels are arranged substantially perpendicular to the electric field detection direction;
A reference electrode in contact with one or both of these dielectrics and connected to a reference voltage source;
A reflector disposed on the one electrode side;
A light emitting device disposed on the other electrode side;
A light receiving element disposed so that light is not directly incident on the other electrode side from the light emitting element;
A non-contact type DC voltage detector, comprising: a measurement circuit that measures an electric field intensity based on an intensity signal of light detected by a light receiving element.   The non-contact type DC voltage detector according to claim 5, further comprising an electric field shielding layer formed in a container shape that is electrically connected to the comparison electrode and covers the entire liquid crystal element except for the opening for the measurement electrode panel. .

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