Active ionization device for dissipating electrostatic charges with a device for optical indication of an operating state

Abstract

The invention relates to an active ionization device for dissipating electrostatic charges, which can be connected to at least one high-voltage source and is designed as at least one electrode, preferably freestanding in space. The ionization device includes a device for optically indicating the operating state of the at least one electrode, which is configured to optically indicate the operating state of the at least one electrode, provided that the high voltage applied to the at least one electrode is not controlled and without an associated control system. According to the invention, it is particularly provided that the device for optically indicating the operating state comprises only a converter device, which is configured to convert a high voltage supplied by the high-voltage source of the at least one electrode into an operating voltage necessary for operating the device for optically indicating the operating state.

Description

[0001] The present invention lies generally in the field of high-voltage electrode arrangements, which are used as discharge electrodes in a wide variety of applications. Specifically, the invention relates in particular to a device for monitoring the operational reliability of at least one active ionization device for neutralizing surface charges, especially charges on railway materials.

[0002] High-voltage electrodes for neutralizing surface charges are known in a wide variety of designs and configurations. In particular, such high-voltage electrodes are used as active ionization devices for dissipating electrostatic charges.

[0003] A high-voltage electrode arrangement of the type considered herein is known, for example, from German patent application DE 37 25 142 A1, where it is referred to as a high-voltage electrode comprising at least two individual electrodes. The high-voltage electrode arrangement known from this prior art is spatially separated from a voltage supply and current measuring device and connected via electrical conductors.

[0004] German patent application DE 10 2006 005 670 A1 relates to an air ionization device with pointed electrodes connected via electrical coupling elements to a high-voltage supply line, the latter being connectable to a high-voltage source, and with a signaling device coupled to the high-voltage supply line. To further develop the air ionization device such that the signaling device has low energy consumption yet provides an intense signal, it is proposed that the signaling device include a pulse circuit and at least one signal generator that outputs a pulsed signal when a proper high voltage is applied to the high-voltage supply line.

[0005] Publication EP 0 212 931 A1 concerns another air ionization device.

[0006] The processing of a wide variety of materials, including (but not limited to) web-based materials such as paper or plastic webs, requires web areas that are largely free of static electricity, particularly static charges resting on the surface of the web materials. In many cases, such charge-free conditions are generally desirable to prevent, for example, unwanted adhesion between layers of the material, whether layered or intended to be layered.

[0007] In other applications, it can be advantageous to first create a charge-free web surface in order to then selectively apply a very specific amount of charge. This approach is particularly useful when a controlled attenuation force of the different web layers is desired, determined by the amount of surface charge, or when the web surfaces of, for example, a paper web need to be prepared for an electrostatically assisted printing process.

[0008] However, the field of application of the present invention is not limited to the electrostatic discharge of materials in web form, but also relates to so-called "one-piece flow" applications, in which in particular individual parts or assemblies, such as printed circuit boards, plastic parts, glasses, etc., are to be electrostatically discharged.

[0009] It is known to use active discharge electrodes for such discharge processes. These electrodes are based on the principle of targeted ionization of the air molecules located between the active discharge electrode (positioned close to the surface) and the surface, sufficient to dissipate all surface charges within a given time. However, the high voltage required to apply to these electrodes for sufficient ionization is a disadvantage, particularly when such active discharge systems or electrodes are to be used in potentially explosive atmospheres. Under certain conditions, this can easily lead to an unwanted, ignitable spark.

[0010] Furthermore, the high voltages required by these active discharge electrodes are a disadvantage if effective protection against personal contact cannot be guaranteed in a given application. Nevertheless, such active discharge electrodes are predominantly used in modern technology because monitoring the ionization current they conduct is relatively straightforward. Such a current flowing through the intentionally created ionization path serves as an indicator that the active discharge electrode is functioning correctly. If no current flow is detected, the ionization path, which is essential for dissipating surface charges, is not formed, thus indicating that the active discharge electrode is not functioning correctly.

[0011] To circumvent the aforementioned disadvantages of active discharge systems or active discharge electrodes, it is also known to use so-called passive discharge electrodes, which are not based on the operating principle of an actively and artificially created ionization zone. Such passive discharge electrodes are mostly cord- or wire-like structures, for example, cords with carbon fibers, grounding tongues, brushes, or so-called "tinsle bars." These passive discharge electrodes are arranged at a short distance from the surface of the material web or material to be discharged and are connected to a reference or ground potential.Due to their mostly pointed shape, the electric field lines emanating from the surface charges concentrate at the ends of the individual elements extending towards the surface to be discharged, so that the resulting high electric field strength ensures that these surface charges flow away across the small gap between the electrode elements and the surface even if this gap is not additionally ionized by actively applying an ionization voltage.

[0012] However, such passive discharge electrodes have the disadvantage that simple functional monitoring, i.e., monitoring to ensure that the electrode can dissipate charges, is not guaranteed.

[0013] Furthermore, such passive discharge elements lack current-limiting components, which means that under certain conditions, an ignitable spark can occur between the surface to be discharged and a single protruding fiber. This can even happen within such a passive discharge electrode (discharge cord, grounding tongue, brush, "tinsle bars," etc.), since surface charges on a surface are rarely homogeneous, but rather exhibit a multitude of charge regions with varying charge levels and polarities.

[0014] Because of these disadvantages, active discharge systems or active discharge electrodes for neutralizing surface charges are preferred in many applications instead of passive discharge electrodes.

[0015] For a specific design of such a high-voltage electrode arrangement, reference is made to publication EP 0 384 022 B1. In such an arrangement, the high-voltage electrode is connected to a high-voltage power supply via a high-voltage cable (a high-voltage supply line).

[0016] With such an arrangement, the operator cannot see at the electrode itself whether high voltage is present or not. Therefore, high-voltage power supplies are generally equipped with indicator lights that inform the operator about the operating status of the high-voltage electrode. Such information is important not only for safety reasons, but also for ensuring smooth workflows.

[0017] However, the function indicator of the high-voltage power supply is often not visible from the location of the high-voltage electrode.

[0018] It is also possible that the power supply indicates high voltage is switched on, but this voltage is not present at the electrode due to a break in the high-voltage cable. In applications with multiple high-voltage electrodes operating on multiple high-voltage power supplies, it can be difficult to determine the operating status of a specific electrode.

[0019] For these reasons, the operator and owner of such a system has an interest in an operating and function indicator directly at the electrode.

[0020] The technical problems of an operating indicator at the electrode are, firstly, the high operating voltage of the electrode, amounting to several kV, and secondly, the lack of a counter-potential when electrodes are operated unipolar and the operating current flows from the electrode via a corona discharge.

[0021] Therefore, to this day no operating indicator for high-voltage electrodes is available that meets practical requirements.

[0022] The invention is therefore based on the objective of providing a high-voltage electrode arrangement serving as an active ionization device, which includes a simple and cost-effective operating state detection system, which in turn enables the realization of an easily perceptible display of the operating state for the operating personnel under practically all operating conditions.

[0023] This problem is solved by the subject matter of independent claim 1, wherein advantageous further developments of the active ionization device are specified in the dependent claims.

[0024] Accordingly, the invention relates to an active ionization device for dissipating electrostatic charges, which can be connected to at least one high-voltage source and is designed as at least one electrode, in particular free-standing in space, especially in the form of a single electrode. In particular, the at least one electrode can have a free end pointing in a principal direction.

[0025] According to the invention, in this context, it is provided that the active ionization device has a device for optically indicating an operating state of the at least one electrode of the active ionization device.

[0026] The device for optically indicating the operating state of the electrode is designed to optically indicate the operating state of the at least one electrode, to which at least one high voltage may be applied, without control and without any control associated with the device for optically indicating the operating state of the electrode.

[0027] The advantages achievable with the solution according to the invention are obvious: Firstly, the active ionization device itself has a corresponding function indicator, preferably directly on the at least one electrode. This provides the operator with an easily perceptible indication of the operating status in a simple yet effective manner.

[0028] To enable the active ionization device to be manufactured as simply and cost-effectively as possible despite the operating state monitoring, the invention provides that the device for optically indicating the operating state is designed without a corresponding control system. In other words, the device for optically indicating the operating state is preferably directly galvanically connected to the at least one electrode of the active ionization device and is operated via the high voltage applied to the at least one electrode.

[0029] Thus, according to the invention, the active ionization device does not have a control device associated with the device for optically indicating the operating state for controlling the device for optically indicating the operating state.

[0030] According to the invention, it is further provided that the active ionization device has a converter device associated with the device for optical indication of the operating state, which is configured to convert a high voltage provided by the high voltage source of the at least one electrode, in particular one standing freely in space, into an operating voltage necessary for the operation of the device for optical indication of the operating state.

[0031] According to one possible implementation of the active ionization device according to the invention, the inverter device comprises a series circuit consisting of at least one ohmic resistor and at least one light source, in particular in the form of an LED.

[0032] The device for visually indicating the operating status preferably includes at least one light-emitting diode (LED). Of course, it is also conceivable that another light source is used.

[0033] In possible embodiments of the active ionization device, the optical indication of the operating state could be configured to output a different optical signal depending on the magnitude of the high voltage applied to the at least one electrode via the high-voltage source. For example, depending on the magnitude of the high voltage applied to the at least one electrode via the high-voltage source, a light source, in particular a light-emitting diode, could imitate light of a different color for the optical indication of the operating state.

Claims

[1] Active ionization device for dissipating electrostatic charges, which can be connected to at least one high-voltage source and is designed as at least one electrode, in particular free-standing in space, in particular in the form of a single electrode, wherein the active ionization device has a device for optically indicating an operating state of the at least one electrode of the active ionization device, wherein the device for optically indicating the operating state of the at least one electrode of the active ionization device is designed to which the at least one electrode may be connected.The applied high voltage is to optically indicate the operating state of the at least one electrode of the active ionization device without control and without a control device associated with the device for optically indicating the operating state of the at least one electrode of the active ionization device, wherein the device for optically indicating the operating state only has a converter device which is configured to convert a high voltage provided by the high voltage source of the at least one electrode, in particular one standing freely in space, into an operating voltage necessary for operating the device for optically indicating the operating state. [2] Active ionization device according to claim 1, wherein the active ionization device does not have a control device associated with the device for optical indication of the operating state for controlling the device for optical indication of the operating state. [3] Active ionization device according to claim 1 or 2, wherein the converter device comprises a series circuit of at least one ohmic resistor and at least one light source, preferably in the form of an LED. [4] Active ionization device according to one of claims 1 to 3, wherein the device for optical indication of the operating state is designed to output a different optical signal and in particular an optical signal different with respect to a flashing frequency, with respect to a wavelength or color and / or with respect to an intensity, depending on the amount of a high voltage connected to the at least one electrode by means of the high voltage source.