EP0000136B1 - Device for measuring the toner concentration in a development mixture - Google Patents

Device for measuring the toner concentration in a development mixture Download PDF

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Publication number
EP0000136B1
EP0000136B1 EP78100137A EP78100137A EP0000136B1 EP 0000136 B1 EP0000136 B1 EP 0000136B1 EP 78100137 A EP78100137 A EP 78100137A EP 78100137 A EP78100137 A EP 78100137A EP 0000136 B1 EP0000136 B1 EP 0000136B1
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EP
European Patent Office
Prior art keywords
plate
coil
shaped coils
coils
measuring
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EP78100137A
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German (de)
French (fr)
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EP0000136A1 (en
Inventor
Peter Prohaska
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Hoechst AG
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Hoechst AG
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G03G15/08—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer
    • G03G15/0822—Arrangements for preparing, mixing, supplying or dispensing developer
    • G03G15/0848—Arrangements for testing or measuring developer properties or quality, e.g. charge, size, flowability
    • G03G15/0849—Detection or control means for the developer concentration
    • G03G15/0853—Detection or control means for the developer concentration the concentration being measured by magnetic means
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S222/00—Dispensing
    • Y10S222/01—Xerography

Definitions

  • the invention relates to a device for measuring the toner concentration of a developer mixture of toner and ferromagnetic carrier material in an electrophotographic developing device with a tangential and inclined to a cylinder for applying the developer mixture to the photoconductive surface of a drum-running baffle for the non-applied developer mixture, on which one of a component-supported coil is arranged, the latter being part of a measuring oscillator.
  • the monitoring system for the toner concentration in a developer described in DE-QS 25 25 952 has all the features mentioned above.
  • a tubular component is wound with a helical coil and inserted into the deflector plate with the axis vertical.
  • the tube diameter is small, relative to the width of the baffle, so that only a small portion of the developer mixture trickling down over the baffle passes through the tubular coil carrier.
  • the measuring coil is connected to measuring devices for measuring the changes in inductance of the measuring coil as a measure of the change in the toner concentration in the developer.
  • a device for monitoring and regulating the concentration of a toner in a developer mixture in which samples of the developer mixture are guided past the turns of a coil which is arranged in an alternating voltage circuit, the output signals of which Inductance of the coil and thus the toner concentration in the samples of the developer mixture depend and in which an arrangement coupled to the AC voltage and responsive to the output signals is provided for determining the toner concentration.
  • the arrangement for guiding the samples of the developer mixture past the turns of the coil is a sample tube made of non-magnetic material passing through the coil.
  • DE-OS 19 36 815 relates to a device for measuring the toner concentration of a developer mixture, which consists of a coil with a ferromagnetic core, which forms a magnetic circuit of the coil together with part of the developer mixture.
  • the coil and its magnetic circuit form an inductance, the change of which influences the output frequency of an oscillating circuit, so that any change in the permeability of the developer mixture results in a change in frequency.
  • the core of the coil lies against the outside of the wall of the developer container, which at least in this area must consist of a non-magnetic material so that the magnetic field can penetrate through the wall into the developer container and the magnetic circuit of the coil extends over that part the developer mix that reads towards the core.
  • US Pat. No. 3,094,049 relates to a measuring device in which two layers of an electrically conductive film are applied to a transparent measuring plate made of insulating material and are connected to a voltage source whose output voltage is variable. A partial flow of the developer flows from this measuring plate, from which toner in an arrangement and strength corresponding to the applied voltage and the toner concentration in the developer mixture is deposited on the measuring plate. The measuring plate is then irradiated with light, the light transmittance of the plate is measured and compared with a reference pattern, and a difference signal is obtained therefrom, which regulates the supply of toner to the developer mixture.
  • no measuring coil is used, but rather an essentially optically working measuring device with the measuring plate, the light transmittance of which determines the regulation of the toner supply after the toner is deposited on the measuring plate.
  • the above-mentioned known electromagnetic devices for measuring the The toner concentration has in common that only too small subsets of the developer mixture are detected, which are not representative of the mean value of the toner concentration in the developer mixture.
  • Another disadvantage is that the coils used have a certain height, which allows installation only at certain points of the copying machine and that the small inner diameter of the coils or the tubes are a cause of blockages with developer mixture, which requires frequent cleaning .
  • the object of the invention is to improve a device according to the preamble of claim 1 so that a coil system is created which is adapted to the tightest space in the copier and which determines a representative average of the toner concentration of the photoconductive layer in the developer container backflowing developer mixture with great accuracy.
  • the advantages are achieved that the flat measuring coils used in the measuring device have a very low overall height, which means that there are no difficulties when installing them in a copier, in which generally little space is available, and that the developer flow through the measuring coils remains largely undisturbed, e.g. does not experience a narrowing, and is largely covered.
  • the developer mixture 7 is removed from a developer supply 8 in a developer tank 14 by means of a so-called magnetic brush and applied to the surface of the drum 2.
  • the magnetic brush consists of a cylinder 3 which can be rotated about its longitudinal axis 37 in the direction of arrow A.
  • a plurality of magnets 15, 16, 17, 18 are arranged radially in the interior of the cylinder 3, of which the magnets 16, 17 serve to convey the developer mixture 7 and the magnet 15 to apply the developer mixture 7 to the drum 2.
  • the cylinder 3 is about half immersed in the developer supply 8 and the developer mixture of toner and carrier particles is drawn to the surface of the cylinder 3 adjacent to the magnets 16, 17 and to develop the latent image on the surface of the drum 2 by the rotation of the Cylinder 3 promoted.
  • the ferromagnetic carrier particles align themselves in the direction of the lines of force of the magnetic field and, together with the toner, form a brush-like coating made of developer mixture on the surface of the cylinder 3.
  • a doctor blade 35 is used to limit the thickness of this coating attached to the right end edge of the developer tank 14 at a predetermined distance from the surface of the cylinder 3.
  • the magnets 15 to 18 are preferably bar magnets, the poles of which lie near the inside of the cylinder jacket have alternating polarity. The magnet 18 serves to keep the developer mixture 7 aligned after the contact between the cylinder 3 and the drum 2 like a magnetic brush.
  • the developing device 1 is fastened on a support frame 9 which is arranged on a console 36.
  • a cover 12 closes the developing device 1 upwards.
  • a mixer shaft 10, which rotates about its longitudinal axis 38, is provided near the bottom of the developer tub 14 and ensures appropriate mixing of the developer supply 8 in the developer tub 14.
  • a suction housing 13 of a suction 11 is connected in an integrated construction, which adjoins the developer tub 14 and ensures that free-floating developer mixture is sucked outside the developer tub 14.
  • the deflector plate 4 is attached to a fastening support 19 and can be designed, for example, over its width, ie perpendicular to the plane of the drawing, in a sawtooth manner, wherein the tips of the saw teeth 4 'can be bent up.
  • the developer mixture 7 trickles through the baffle 4 into the developer tank 14 back to the developer supply 8.
  • circuit board 21 which extends across the width of the deflector plate 4 and which carries a plurality of flat coils 6, 6 ', 6 "with its conductor tracks in the plane of the circuit board.
  • the lower end of the deflector plate 4 bears against a further fastening support 20, on which lateral limits of the deflector plate 4 are attached, which are not shown.
  • the coil system 6, 6 ', 6 is part of a circuit for determining changes in the inductance of the coil system 6, 6', 6" as a function of changes in the concentration of the toner in the developer mixture 7, the circuit also not actuating signals shown toner supply device generated.
  • the embodiment of a coil system shown in FIG. 2a has a plurality of flat coils 6, 6 ', 6 ",... With their conductor tracks in the plane of the circuit board, which are electrically connected to one another in series.
  • These flat coils 6, 6', 6" extend almost over the entire length of the circuit board 21 and thus also over the entire width of the diverter plate 4.
  • the conductor tracks 22 of these coils have the shape of non-closed rectangles, the individual conductor tracks each having a central part 23 of each coil 6, 6 'or . 6 ", ... go out and have side edges 24, 25 that become longer towards the outside.
  • the connection of the individual coils 6, 6 ', 6" from the via point, not shown, of the central part 23 of the individual coil to the splicing coil is partial shown in dashed lines.
  • the conductor tracks 22 of the coils 6, 6 ', 6 are obtained by etching the surface of an electrically conductive plate. This can be done, for example, in a known manner by coating the plate with a light-sensitive layer onto which a negative of the coil is copied The result is an overetch, ie the coil appears raised.
  • a metal foil, thin metal sheet or the like can also be used to produce the coil system, which is then connected to the board 21.
  • FIG. 2b shows a further embodiment of the coil system with a number of flat coils 6, 6 ', 6 "... With their conductor tracks in the plane of the circuit board, the conductor tracks 26 of which run spirally from the inside to the outside. These coils are likewise electrical in series with one another connected.
  • the conductor tracks of the individual coils can also be guided differently from the preferred exemplary embodiments, and that the manufacture of the individual coils can also be carried out by other etching processes or other methods, such as, for example, galvanizing the conductor tracks onto the circuit board. can be done.
  • FIG 2c shows a further embodiment of the coil system, which carries an inductance from a number of flat coils 6, 6 ', 6 ", ..., which are shown schematically in the drawing.
  • the shape of an individual flat coil corresponds to one of those shown in FIG 2a or 2b described coil forms.
  • the flat coils are arranged geometrically next to one another on both sides of a strip 39 and on each side. To avoid an electrically conductive contact between the developer mixture 7 and the coils, these are surrounded by a layer of electrically insulating, transparent material 27.
  • the strip 39 consists, for example, of a plastic film which is coated on both sides with copper.
  • the individual flat coils are etched out of the copper layer on each side of the strip 39.
  • the central part 23 of one of the flat coils 6, 6 ', 6 ", ... is electrically connected via a via point 40 to the corresponding, opposite flat coil 6, 6', 6", ... on the other side of the strip 39. As indicated schematically in FIG. 2c, the coils 6, 6 ', 6 ", ...
  • Matrix 41 are connected together in a matrix 41 in such a way that the coils in a single row 42 of the matrix 41 are electrically connected to one another in series Matrix 41, on the other hand, are electrically connected in parallel. If, for example, it is a square matrix, the total inductance of the matrix is equal to the inductance of the individual coils 6, 6 'or 6 "etc. In practice, there is a matrix of 25 coils , which are arranged in 5 rows of 5 coils, have proven their worth. Of course, you can also choose a matrix that is not square but rectangular. In addition, the most varied combinations of series and parallel connections are conceivable within the matrix.
  • the geometrical arrangement of the coils next to each other on each side of the strip 39 does not mean that coils lying next to one another must also be electrically connected to one another, since the coils can be interconnected to form a specific matrix.
  • Fig. 3 shows a block diagram of the device for measuring the toner concentration of the developer mixture 7.
  • the flat coils on the circuit board are components of a measuring oscillator 34 which is connected to a reference oscillator 28.
  • the two oscillators are controlled by a timer 30, which either switches the measuring oscillator 34 or the reference oscillator 28, so that only the output frequency of one of the two oscillators is applied to a frequency / voltage converter 29.
  • the output voltage of the converter 29 is amplified accordingly in an amplifier 31 and controls a Schmitt trigger stage 32. This is set such that a motor 33 connected to it is switched on when it is necessary to replenish the developer mixture with toner to be replenished, and is switched off when the developer mixture has the desired toner concentration.
  • the motor 33 actuates a toner supply device, not shown.
  • the circuit structure of the measuring oscillator 34 is known per se and comprises an oscillating circuit, formed from a capacitor and the inductance of the coils of the circuit board 21.
  • This oscillating circuit is arranged in the collector path of a transistor, the base of which is connected to a voltage source.
  • the transistor is part of an oscillator circuit which has a further transistor.
  • the emitters of the two transistors are connected to the collector of a further transistor which works as a switching transistor and is opened or closed by the timer 30.
  • any change in the leakage inductance of the combination of coils 6, 6 ', 6 ", ... on the board 21 changes the frequency of the measuring oscillator 34.
  • the output frequency of the measuring oscillator 34 is compared with the fixed output frequency of the reference oscillator 28.
  • the setting is such that as the toner concentration in the developer mixture decreases, the resonance frequency of the measuring oscillator 34 increases and the deviation of this frequency from the fixed reference frequency of the reference oscillator 28 increases upwards.
  • the motor 33 is put into operation. As long as the output frequency of the measuring oscillator 34 is below the value of the fixed frequency of the reference oscillator 28, the Schmitt trigger stage 32 does not respond and motor 33 stands still, so that no toner is supplied to the developer mixture.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Dry Development In Electrophotography (AREA)
  • Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
  • Magnetic Brush Developing In Electrophotography (AREA)

Description

Die Erfindung betrifft eine Vorrichtung zur Messung der Tonerkonzentration eines Entwicklergemisches aus Toner und ferromagnetischem Trägermaterial in einer elektrofotografischen Entwicklungsvorrichtung mit einem tangential und geneigt zu einem Zylinder zum Antragen des Entwicklergemisches an die fotoleitende Oberfläche einer Trommel verlaufenden Ableitblech für das nicht angetragene Entwicklergemisch, auf welchem eine von einem Bauteil getragene Spule angeordnet ist, welche letztere Bestandteil eines Meßoszillators ist.The invention relates to a device for measuring the toner concentration of a developer mixture of toner and ferromagnetic carrier material in an electrophotographic developing device with a tangential and inclined to a cylinder for applying the developer mixture to the photoconductive surface of a drum-running baffle for the non-applied developer mixture, on which one of a component-supported coil is arranged, the latter being part of a measuring oscillator.

Bei den bekannten Kopiergeräten, bei denen die latenten elektrostatischen Bilder auf der Oberfläche einer fotoleitfähigen Schicht mit Hilfe eines Entwicklergemisches aus Toner und ferromagnetischem Trägermaterial entwickelt werden, verbrauchen sich nur die Tonerpartikeln, während das ferromagnetische Trägermaterial zurückbleibt und wiederverwendet werden kann. Es Ist daher eforderlich, das Entwicklergemisch periodisch oder kontinuierlich durch die Ergänzung des verbrauchten Toners aufzufrischen, um die Konzentration des Toners in dem Entwicklergemisch zum Erzielen einer gewünschten Dichte der entwickelten Kopien auf einem vorgegebenen Wert innerhalb enger Grenzen zu halten. Wenn die Tonerkonzentration in dem Entwicklergemisch kleiner als die optimale Konzentration ist, wird die Schwärzung der entwickelten Kopie zu gering, und wenn andererseits die Tonerkonzentration zu groß ist, ergeben sich Kopien mit einem unerwünschten Untergrund.In the known copying machines, in which the latent electrostatic images on the surface of a photoconductive layer are developed with the aid of a developer mixture of toner and ferromagnetic carrier material, only the toner particles are consumed, while the ferromagnetic carrier material remains behind and can be reused. It is therefore necessary to periodically or continuously replenish the developer mixture by replenishing the used toner in order to keep the concentration of the toner in the developer mixture to a predetermined value within narrow limits in order to achieve a desired density of the developed copies. If the toner concentration in the developer mixture is less than the optimal concentration, the density of the developed copy becomes too low, and if the toner concentration is too high, copies with an undesirable background result.

Das in der DE-QS 25 25 952 beschriebene Überwachungssystem für die Tonerkonzentration in einem Entwickler weist sämtliche zuvor angeführten Merkmale auf.The monitoring system for the toner concentration in a developer described in DE-QS 25 25 952 has all the features mentioned above.

Ein rohrförmiges Bauteil ist mit einer schraubenförmigen Spule bewickelt und mit senkrecht stehender Achse in das Ableitblech eingesetzt. Der Rohrdurchmesser ist klein, relativ zur Breite des Ableitbleches, so daß nur eine kleine Teilmenge des über das Ableitblech herabrieselnden Entwicklergemisches den rohrförmigen Spulenträger durchsetzt. Die Meßspule ist mit Meßeinrichtungen zum Messen der Induktivitätsänderungen der Meßspule als Maß für die Änderung der Tonerkonzentration in dem Entwickler verbunden.A tubular component is wound with a helical coil and inserted into the deflector plate with the axis vertical. The tube diameter is small, relative to the width of the baffle, so that only a small portion of the developer mixture trickling down over the baffle passes through the tubular coil carrier. The measuring coil is connected to measuring devices for measuring the changes in inductance of the measuring coil as a measure of the change in the toner concentration in the developer.

Aus der DE-QS 20 14 430 ist eine Vorrichtung zur Überwachung und Regelung der Konzentration eines Toners in einer Entwicklermischung bekannt, bei der Proben der Entwicklermischung an den Windungen einer Spule vorbeigeführt werden, die in einem Wechselspannung führenden Kreis angeordnet ist, dessen Ausgangssignale von der Induktivität der Spule und damit der Tonerkonzentration in den Proben der Entwicklermischung abhängen und bei der eine mit dem Wechselspannung führenden Kreis gekoppelte, auf die Ausgangssignale ansprechende Anordnung zur Bestimmung der Tonerkonzentration vorgesehen ist. Die Anordnung zum vorbeiführen der Proben der Entwicklermischung an den Windungen der Spule ist eine durch die Spule führende Probenröhre aus unmagnetischem Material.From DE-QS 20 14 430 a device for monitoring and regulating the concentration of a toner in a developer mixture is known, in which samples of the developer mixture are guided past the turns of a coil which is arranged in an alternating voltage circuit, the output signals of which Inductance of the coil and thus the toner concentration in the samples of the developer mixture depend and in which an arrangement coupled to the AC voltage and responsive to the output signals is provided for determining the toner concentration. The arrangement for guiding the samples of the developer mixture past the turns of the coil is a sample tube made of non-magnetic material passing through the coil.

Die DE-OS 19 36 815 betrifft eine Vorrichtung zum Messen der Tonerkonzentration einer Entwicklermischung, die aus einer Spule mit einem ferromagnetischen Kern besteht, der zusammen mit einem Teil der Entwicklermischung einen magnetischen Kreis der Spule bildet. Die Spule und ihr magnetischer Kreis bilden eine Induktivität, deren Änderung die Ausgangsfrequenz eines Schwingkreises beeinflußt, so daß jede Änderung der Permeabilität der Entwicklermischung eine Frequenzänderung zur Folge hat. Die Spule liegt mit ihrem Kern an der Außenseite der Wandung des Entwicklerbehälters an, der zumindest in diesem Bereich aus einem unmagnetischen Material bestehen muß, damit das magnetische Feld durch die Wandung hindurch in den Entwicklerbehälter eindringen kann und der magnetische Kreis der Spule sich über denjenigen Teil der Entwicklermischung schließt, der dem Kern gegenüber liest.DE-OS 19 36 815 relates to a device for measuring the toner concentration of a developer mixture, which consists of a coil with a ferromagnetic core, which forms a magnetic circuit of the coil together with part of the developer mixture. The coil and its magnetic circuit form an inductance, the change of which influences the output frequency of an oscillating circuit, so that any change in the permeability of the developer mixture results in a change in frequency. The core of the coil lies against the outside of the wall of the developer container, which at least in this area must consist of a non-magnetic material so that the magnetic field can penetrate through the wall into the developer container and the magnetic circuit of the coil extends over that part the developer mix that reads towards the core.

Die US-PS 3,094,049 betrifft eine Meßeinrichtung, bei der zwei Schichten aus einem elektrisch leitenden Film auf einer transparenten Meßplatte aus isolierendem Material aufgebracht und mit einer Spannungsquelle verbunden sind, deren Ausgangsspannung variabel ist. Über diese Meßplatte fließt ein Teilstrom des Entwicklers, aus dem Toner in einer Anordnung und Stärke entsprechend der angelegten Spannung und der Tonerkonzentration im Entwicklergemisch an die Meßplatte abgeschieden wird. Danach wird die Meßplatte mit Licht durchstrahlt, die Lichtdurchlässigkeit der Platte gemessen und mit einem Bezugsmuster verglichen und daraus ein Differenzsignal gewonnen, das die Tonerzufuhr zu dem Entwicklergemisch regelt. In dieser bekannten Meßvorrichtung wird keine Meßspule sondern eine Im wesentlichen optisch arbeitende Meßvorrichtung mit der Meßplatte, deren Lichtdurchlässigkeit nach der Tonerabscheidung auf der Meßplatte die Regelung der Tonerzufuhr bestimmt, verwendet.US Pat. No. 3,094,049 relates to a measuring device in which two layers of an electrically conductive film are applied to a transparent measuring plate made of insulating material and are connected to a voltage source whose output voltage is variable. A partial flow of the developer flows from this measuring plate, from which toner in an arrangement and strength corresponding to the applied voltage and the toner concentration in the developer mixture is deposited on the measuring plate. The measuring plate is then irradiated with light, the light transmittance of the plate is measured and compared with a reference pattern, and a difference signal is obtained therefrom, which regulates the supply of toner to the developer mixture. In this known measuring device no measuring coil is used, but rather an essentially optically working measuring device with the measuring plate, the light transmittance of which determines the regulation of the toner supply after the toner is deposited on the measuring plate.

Aus der US-PS 3,504,276 sind gedruckte Flachspulen für die Anwendung in Schaltungen. zur Ermittlung von Rissen in Rohrleitungen über eine Messung des magnetischen Flusses bekannt, Die Spulen und die Rohrleitungen werden relativ zueinander bewegt. Bei dem Meßgut handelt es sich also nicht um Entwicklergemisch, dessen Tonerkonzentration bestimmt werden soll.From US-PS 3,504,276 are printed flat coils for use in circuits. Known for determining cracks in pipelines by measuring the magnetic flux. The coils and the pipelines are moved relative to one another. The material to be measured is therefore not a developer mixture whose toner concentration is to be determined.

Den oben genannten bekannten elektromagnetischen Vorrichtungen zur Messung der Tonerkonzentration ist gemeinsam, daß nur zu kleine Teilmengen der Entwicklermischung erfaßt werden, die nicht repräsentativ für den Mittelwert der Tonerkonzentration in dem Entwicklergemisch sind. Des weiteren ist von Nachteil, daß die verwendeten Spulen eine bestimmte Bauhöhe haben, die den Einbau nur an bestimmten Stellen des Kopiergerätes zuläßt und daß der geringe innere Durchmesser der Spulen bzw. der Rohre Anlaß zu Verstopfungen mit Entwicklergemisch sind, wodurch ein häufiges Reinigen erforderlich wird.The above-mentioned known electromagnetic devices for measuring the The toner concentration has in common that only too small subsets of the developer mixture are detected, which are not representative of the mean value of the toner concentration in the developer mixture. Another disadvantage is that the coils used have a certain height, which allows installation only at certain points of the copying machine and that the small inner diameter of the coils or the tubes are a cause of blockages with developer mixture, which requires frequent cleaning .

Aufgabe der Erfindung ist es, eine Vorrichtung nach dem Oberbegriff des Patentanspruchs 1 so zu verbessern, daß ein Spulensystem geschaffen wird, das an engste Raumverhältnisse in dem Kopiergerät angepaßt ist und das die Bestimmung eines repräsentativen Mittelwertes der Tonerkonzentration des von der fotoleitfähigen Schicht in den Entwicklerbehälter zurückströmenden Entwicklergemisches mit großer Genauigkeit ermöglicht.The object of the invention is to improve a device according to the preamble of claim 1 so that a coil system is created which is adapted to the tightest space in the copier and which determines a representative average of the toner concentration of the photoconductive layer in the developer container backflowing developer mixture with great accuracy.

Diese Aufgabe wird gemäß der Erfindung dadurch gelöst,

  • a) daß das Bauteil als eine auf dem Ableitblech aufliegende, sich über die gesamte Breite des Ableitbleches erstreckende Platine ausgebildet ist,
  • b) daß die Spule aus mehreren, durch ihre Nebeneinanderanordnung die gesamte Breite der Platine erfassenden, mit ihren Leiterbahnen in der Platinenebene liegenden und elektrisch miteinander verbundenen Flachspulen besteht und.
  • c) daß die Platine mit einem elektrisch isolierenden transparenten Material vergossen ist.
According to the invention, this object is achieved by
  • a) that the component is designed as a board lying on the deflector plate and extending over the entire width of the deflector plate,
  • b) that the coil consists of a plurality of flat coils which, due to their side-by-side arrangement, cover the entire width of the circuit board, lie with their conductor tracks in the plane of the circuit board and are electrically connected to one another.
  • c) that the circuit board is cast with an electrically insulating, transparent material.

Die Ausgestaltung der Erfindung ist aus den Kennzeichnenden Merkmalen der Patentansprüche 2 bis 8 ersichtlich.The embodiment of the invention can be seen from the characterizing features of claims 2 to 8.

Mit der Erfindung werden die Vorteile erzielt, daß die in der Meßvorrichtung verwendeten flachen Meßspulen eine sehr geringe Bauhöhe bestizen, wodurch es keine Schwierigkeiten beim Einbau in ein Kopiergerät gibt, in welchem im allgemeinen wenig Platz zur Verfügung steht, und daß der Entwicklerstrom durch die Meßspulen weitgehend ungestört bleibt, z.B. keine Einengung erfährt, und zum größten Teil erfaßt wird.With the invention, the advantages are achieved that the flat measuring coils used in the measuring device have a very low overall height, which means that there are no difficulties when installing them in a copier, in which generally little space is available, and that the developer flow through the measuring coils remains largely undisturbed, e.g. does not experience a narrowing, and is largely covered.

Die Erfindung wird im folgenden anhand von zeichnerisch dargestellten Ausführungsbeispielen näher beschrieben.The invention is described in more detail below with reference to exemplary embodiments illustrated in the drawings.

In den Zeichnungen zeigen:

  • Fig. 1 eine schematische Ansicht eines Teils eines Kopiergeräts, das eine Ausführungsform der Erfindung enthält,
  • Fig. 2a bis 2c Ausführungsformen von Spulensystemen, die Bestandteil der Vorrichtung zur Messung der Tonerkonzentration im Entwicklergemisch sind, und
  • Fig. 3 ein Blockschaltbild der Vorrichtung zur Messung der Tonerkonzentration des Entwicklergemisches.
  • Fig. 1 der Zeichnung zeigt in schematischer Ansicht eine Entwicklungsvorrichtung 1 und eine Trommel 2 eines Kopiergerätes. Die Trommel 2 ist mit einer fotoleitenden Oberfläche versehen und dreht sich beispielsweise in Richtung des Pfeils B. Auf der fotoleitenden Oberfläche der Trommel 2 befindet sich ein elektrostatisches latentes Bild, das in der Entwicklungsvorrichtung 1 mit dem Entwicklergemisch in Berührung gebracht wird, um es in ein sichtbares Tonerbild zu entwickeln.
The drawings show:
  • 1 is a schematic view of part of a copying machine incorporating an embodiment of the invention;
  • 2a to 2c embodiments of coil systems that are part of the device for measuring the toner concentration in the developer mixture, and
  • Fig. 3 is a block diagram of the device for measuring the toner concentration of the developer mixture.
  • Fig. 1 of the drawing shows a schematic view of a developing device 1 and a drum 2 of a copying machine. The drum 2 is provided with a photoconductive surface and rotates, for example, in the direction of the arrow B. On the photoconductive surface of the drum 2 there is an electrostatic latent image which is brought into contact with the developer mixture in the developing device 1 in order to bring it into contact develop visible toner image.

Das Entwicklergemisch 7 wird mittels einer sogenannten Magnetbürste einem Entwicklervorrat 8 in einer Entwicklerwanne 14 entnommen und an die Oberfläche der Trommel 2 angetragen. Die Magnetbürste besteht aus einem Zylinder 3, der um seine Längsachse 37 in Pfeilrichtung A drehbar ist. Im Inneren des Zylinders 3 sind mehrere Magnete 15, 16, 17, 18 radial angeordnet, von denen die Magnete 16, 17 zum Fördern des Entwicklergemisches 7 und der Magnet 15 zum Antragen des Entwicklergemisches 7 an die Trommel 2 dienen. Der Zylinder 3 taucht etwa zur Hälfte in den Entwicklervorrat 8 ein und das Entwicklergemisch aus Toner- und Trägerteilchen wird an die den Magneten 16, 17 benachbarte Oberfläche des Zylinders 3 gezogen und zur Entwicklung des latenten Bildes auf der Oberfläche der Trommel 2 durch die Drehung des Zylinders 3 gefördert. Unter dem Einfluß des Magnetfeldes der Magneten 15 bis 18 richten sich die ferromagnetischen Trägerteilchen in Richtung der Kraftlinien des Magnetfeldes aus und bilden zusammen mit dem Toner einen bürstenähnlichen Belag aus Entwicklergemisch auf der Oberfläche des Zylinders 3. Zur Begrenzung der Dicke dieses Belages ist eine Abstreifrakel 35 an der rechten Abschlußkante der Entwicklerwanne 14 in einem vorgegebenen Abstand von der Oberfläche des Zylinders 3 befestigt. Bei den Magneten 15 bis 18 handelt es sich bevorzugt um Stabmagnete, deren nahe der Innenseite des Zylindermantels liegenden Pole abwechselnde Polarität aufweisen. Der Magnet 18 dient dazu, das Entwicklergemisch 7 nach dem Kontakt zwischen dem Zylinder 3 und der Trommel 2 weiterhin magnetbürstenartig ausgerichtet zu halten.The developer mixture 7 is removed from a developer supply 8 in a developer tank 14 by means of a so-called magnetic brush and applied to the surface of the drum 2. The magnetic brush consists of a cylinder 3 which can be rotated about its longitudinal axis 37 in the direction of arrow A. A plurality of magnets 15, 16, 17, 18 are arranged radially in the interior of the cylinder 3, of which the magnets 16, 17 serve to convey the developer mixture 7 and the magnet 15 to apply the developer mixture 7 to the drum 2. The cylinder 3 is about half immersed in the developer supply 8 and the developer mixture of toner and carrier particles is drawn to the surface of the cylinder 3 adjacent to the magnets 16, 17 and to develop the latent image on the surface of the drum 2 by the rotation of the Cylinder 3 promoted. Under the influence of the magnetic field of the magnets 15 to 18, the ferromagnetic carrier particles align themselves in the direction of the lines of force of the magnetic field and, together with the toner, form a brush-like coating made of developer mixture on the surface of the cylinder 3. A doctor blade 35 is used to limit the thickness of this coating attached to the right end edge of the developer tank 14 at a predetermined distance from the surface of the cylinder 3. The magnets 15 to 18 are preferably bar magnets, the poles of which lie near the inside of the cylinder jacket have alternating polarity. The magnet 18 serves to keep the developer mixture 7 aligned after the contact between the cylinder 3 and the drum 2 like a magnetic brush.

Die Entwicklungsvorrichtung 1 ist auf einem Stützrahmen 9 befestigt, der auf einer Konsole 36 angeordnet ist. Eine Abdeckung 12 schließt die Entwicklungsvorrichtung 1 nach oben hin ab. Nahe dem Boden der Entwicklerwanne 14 ist eine sich um ihre Längsachse 38 drehende Mischerwelle 10 vorgesehen, die für eine entsprechende Durchmischung des Entwicklervorrates 8 in der Entwicklerwanne 14 sorgt. Mit der Entwicklungsvorrichtung 1 ist in integrierter Bauweise ein Absauggehäuse 13 einer Absaugung 11 verbunden, die an die Entwicklerwanne 14 angrenzt und dafür sorgt, daß außerhalb der Entwicklerwanne 14 freischwebendes Entwicklergemisch abgesaugt wird.The developing device 1 is fastened on a support frame 9 which is arranged on a console 36. A cover 12 closes the developing device 1 upwards. A mixer shaft 10, which rotates about its longitudinal axis 38, is provided near the bottom of the developer tub 14 and ensures appropriate mixing of the developer supply 8 in the developer tub 14. With the development device 1, a suction housing 13 of a suction 11 is connected in an integrated construction, which adjoins the developer tub 14 and ensures that free-floating developer mixture is sucked outside the developer tub 14.

Das nicht an die Oberfläche der Trommel 2 angetragene Entwicklergemisch 7 gelant auf ein Ableitblech 4, das schräg und tangential zu der Oberfläche des Zylinders 3 verläuft. Das Ableitblech 4 ist au einer Befestigungsstütze 19 angebracht und kann beispielsweise über seine Breite, d.h. senkrecht zu der Zeichnungsebene, sägezahnartig ausgebildet sein, wobei die Spitzen der Sägezähne 4' hochgeknickt sein können. Das Entwicklergemisch 7 rieselt über das Ableitblech 4 in die Entwicklerwanne 14 zu dem Entwicklervorrat 8 zurück. Im oberen Teil des Ableitbleches nahe dem Zylinder 3 der Magetbürste ist eine sich über die Breite des Ableitbleches 4 erstreckende Platine 21 angeordnet, die mehrere mit ihren Leiterbahnen in der Platinenebene liegende Flachspulen 6, 6', 6" trägt. Das untere Ende des Ableitbleches 4 liegt gegen eine weitere Befestigungsstütze 20 an, an der seitliche Begrenzungen des Ableitbleches 4 angebracht sind, die nicht dargestellt sind.The developer mixture 7 not applied to the surface of the drum 2 gelant on a baffle 4, the oblique and tangential to the Surface of the cylinder 3 runs. The deflector plate 4 is attached to a fastening support 19 and can be designed, for example, over its width, ie perpendicular to the plane of the drawing, in a sawtooth manner, wherein the tips of the saw teeth 4 'can be bent up. The developer mixture 7 trickles through the baffle 4 into the developer tank 14 back to the developer supply 8. In the upper part of the deflector plate near the cylinder 3 of the magnetic brush there is a circuit board 21 which extends across the width of the deflector plate 4 and which carries a plurality of flat coils 6, 6 ', 6 "with its conductor tracks in the plane of the circuit board. The lower end of the deflector plate 4 bears against a further fastening support 20, on which lateral limits of the deflector plate 4 are attached, which are not shown.

Das Spulensystem 6, 6', 6" ist bestandteil einer Schaltung zum Feststellen von Änderungen der Induktivität des Spulensystems 6, 6', 6" in Abhängigkeit von Anderungen der Konzentration des Toners in dem Entwicklergemisch 7, wobei die Schaltung auch Signale zur Betätigung einer nicht dargestellten Tonerzufuhreinrichtung erzeugt.The coil system 6, 6 ', 6 "is part of a circuit for determining changes in the inductance of the coil system 6, 6', 6" as a function of changes in the concentration of the toner in the developer mixture 7, the circuit also not actuating signals shown toner supply device generated.

Die in Fig. 2a gezeigte Ausführungsform eines Spulensystems weist mehrere, mit ihren Leiterbahnen in der Platinenebene liegende Flachspulen 6, 6', 6",... auf, die in Reihe miteinander elektrisch verbunden sind. Diese Flachspulen 6, 6', 6" erstrecken sich nahezu über die Gesamtlänge der Platine 21 und damit auch über die Gesamtbreite des Ableitbleches 4. Die Leiterbahnen 22 dieser Spulen weisen die Form von nicht geschlossenen Rechtecken auf, wobei die einzelnen Leiterbahnen von jeweils einem zentralen Teil 23 jeder Spule 6, 6' bzw. 6",... ausgehen und nach außen hin länger werdende Seitenkanten 24, 25 besitzen. Die Verbindung der einzelnen Spulen 6, 6', 6" von der nicht dargestellten Durchkontaktierungsstelle des zentralen Teils 23 der einzelnen Spule zu der anschleißenden Spule ist teilweise gestrichelt eingezeichnet.The embodiment of a coil system shown in FIG. 2a has a plurality of flat coils 6, 6 ', 6 ",... With their conductor tracks in the plane of the circuit board, which are electrically connected to one another in series. These flat coils 6, 6', 6" extend almost over the entire length of the circuit board 21 and thus also over the entire width of the diverter plate 4. The conductor tracks 22 of these coils have the shape of non-closed rectangles, the individual conductor tracks each having a central part 23 of each coil 6, 6 'or . 6 ", ... go out and have side edges 24, 25 that become longer towards the outside. The connection of the individual coils 6, 6 ', 6" from the via point, not shown, of the central part 23 of the individual coil to the splicing coil is partial shown in dashed lines.

Die Leiterbahnen 22 der Spulen 6, 6', 6" werden durch Ätzen der Oberfläche einer elektrisch leitenden Platte erhalten. Dies kann beispielweise in bekannter Weise durch Überziehen der Platte mit einer lichtempfindlichen Schicht geschehen, auf die ein Negativ der Spule kopiert wird. Anschließend wird entwickelt und geätzt. Das Ergebnis ist eine Hoch- ätzung, d.h. die Spule erscheint erhaben. Selbstverständlich kann anstelle einer Platte auch eine Metallfolie, dünnes Metallblech oder dgl. zur Herstellung des Spulensystems verwendet werden, das dann anschleißend mit der Platine 21 verbunden wird.The conductor tracks 22 of the coils 6, 6 ', 6 "are obtained by etching the surface of an electrically conductive plate. This can be done, for example, in a known manner by coating the plate with a light-sensitive layer onto which a negative of the coil is copied The result is an overetch, ie the coil appears raised. Of course, instead of a plate, a metal foil, thin metal sheet or the like can also be used to produce the coil system, which is then connected to the board 21.

Fig. 2b zeigt eine weitere Ausführungsform des Spulensystems mit einer Anzahl von mit ihren Leiterbahnen in der Platinenebene liegenden Flachspulen 6, 6', 6" ..., deren Leiterbahnen 26 von innen nach außen spiralförmig verlaufen. Diese Spulen sind gleichfalls in Reihe miteinander elektrisch verbunden.2b shows a further embodiment of the coil system with a number of flat coils 6, 6 ', 6 "... With their conductor tracks in the plane of the circuit board, the conductor tracks 26 of which run spirally from the inside to the outside. These coils are likewise electrical in series with one another connected.

Für den Fachman ist es selbstverständlich, daß die Leiterbahnen der einzelnen Spulen auch noch anders wie in den bevorzugten Ausführungsbeispielen dargestellt, geführt sein können und daß die Herstellung der einzelnen Spulen auch nach anderen Ätzverfahren oder sonstigen Verfahren, wie beispielweise Aufgalvanisieren der Leiterbahnen auf die Platine, erfolgen kann.It is self-evident to the person skilled in the art that the conductor tracks of the individual coils can also be guided differently from the preferred exemplary embodiments, and that the manufacture of the individual coils can also be carried out by other etching processes or other methods, such as, for example, galvanizing the conductor tracks onto the circuit board. can be done.

Zur Vermeidung einer elektrisch leitenden Berührung zwischen dem Entwicklergemisch 7 und den Leiterbahnen 22 bis 26 der Flachspulen 6, 6', 6" auf der Platine 21 sind diese mit einem elektrisch isolierenden, transparenten Material 27 vergossen.In order to avoid an electrically conductive contact between the developer mixture 7 and the conductor tracks 22 to 26 of the flat coils 6, 6 ′, 6 ″ on the circuit board 21, they are encapsulated with an electrically insulating, transparent material 27.

Fig. 2c zeigt eine weitere Ausführungsform des Spulensystems, die eine Induktivität aus einer Anzahl von Flachspulen 6, 6',6", ... trägt, die in der Zeichnung schematisch dargestellt sind. Die Gestalt einer einzelnen Flachspule entspricht einer der anhand der Fig. 2a oder 2b beschriebenen Spulenformen.2c shows a further embodiment of the coil system, which carries an inductance from a number of flat coils 6, 6 ', 6 ", ..., which are shown schematically in the drawing. The shape of an individual flat coil corresponds to one of those shown in FIG 2a or 2b described coil forms.

Die Flachspulen sind auf beiden Seiten eines Streifens 39 und auf jeder Seite geometrisch nebeneinander angeordnet. Zur Vermeidung einer elektrisch leitenden Berührung zwischen dem Entwicklergemisch 7 und den Spulen sind diese von einer Schicht aus elektrisch isolierendem, transparentem Material 27 umgeben. Der Streifen 39 besteht beispielsweise aus einer Kunststoff-Folie, die zu beiden Seiten mit Kupfer beschichtet ist. Die einzelnen Flachspulen werden, wie schon voranstehend beschrieben wurde, aus der Kupferschicht auf jeder Seite des Streifens 39 herausgeätzt. Der zentrale Teil 23 einer der Flachspulen 6, 6', 6",... ist über eine Durchkontaktierungsstelle 40 mit der entsprechenden, gegenüberliegenden Flachspule 6, 6', 6", ... auf der anderen Seite des Streifens 39 elektrisch verbunden. Wie schematisch in Fig. 2c angedeutet, sind die Spulen 6, 6', 6", ... in einer Matrix 41 derart zusammengeschaltet, daß die Spulen in einer einzelnen Zeile 42 der Matrix 41 elektrisch in Reihe miteinander verbunden sind. Die Reihen der Matrix 41 untereinander sind dagegen elektrisch parallel geschaltet. Handelt es sich beispielsweise um eine quadratische Matrix, so ist die Gesamtinduktivität der Matrix gleich der Induktivität der einzelnen Spule 6, 6' bzw. 6" usw. In der Praxis hat sich eine Matrix aus 25 Spulen, die in 5 Reihen zu je 5 Spulen angeordnet sind, bewährt. Selbstverständlich kann auch eine Matrix gewählt werden, die nicht quadratisch sondern rechteckig ist. Darüber hinaus sind die verschiedensten Kombinationen von Reihen-und Parallelschaltungen innerhalb der Matrix denkbar. Die geometrische Anordnung der Spulen nebeneinander auf jeder Seite des Streifens 39 bedeutet nicht, daß nebeneinanderliegende Spulen auch elektrisch miteinander verbunden sein müssen, da die Spulen untereinander beliebig zu einer bestimmten Matrix zusammengeschaltet sein können.The flat coils are arranged geometrically next to one another on both sides of a strip 39 and on each side. To avoid an electrically conductive contact between the developer mixture 7 and the coils, these are surrounded by a layer of electrically insulating, transparent material 27. The strip 39 consists, for example, of a plastic film which is coated on both sides with copper. As already described above, the individual flat coils are etched out of the copper layer on each side of the strip 39. The central part 23 of one of the flat coils 6, 6 ', 6 ", ... is electrically connected via a via point 40 to the corresponding, opposite flat coil 6, 6', 6", ... on the other side of the strip 39. As indicated schematically in FIG. 2c, the coils 6, 6 ', 6 ", ... are connected together in a matrix 41 in such a way that the coils in a single row 42 of the matrix 41 are electrically connected to one another in series Matrix 41, on the other hand, are electrically connected in parallel. If, for example, it is a square matrix, the total inductance of the matrix is equal to the inductance of the individual coils 6, 6 'or 6 "etc. In practice, there is a matrix of 25 coils , which are arranged in 5 rows of 5 coils, have proven their worth. Of course, you can also choose a matrix that is not square but rectangular. In addition, the most varied combinations of series and parallel connections are conceivable within the matrix. The geometrical arrangement of the coils next to each other on each side of the strip 39 does not mean that coils lying next to one another must also be electrically connected to one another, since the coils can be interconnected to form a specific matrix.

Fig. 3 zeigt ein Blockschaltbild der Vorrichtung zur Messung der Tonerkonzentration des Entwicklergemisches 7. Die Flachspulen auf der Platine zind Bestandteile eines Meßoszillators 34, der mit einem Referenzoszillator 28 verbunden ist. Die beiden Oszillatoren werden von einem Zeitgeber 30 angesteuert, der entweder den Meßoszillator 34 oder den Referenzoszillator 28 schaltet, so daß an einem Frequenz/Spannung-Wandler 29 nur jeweils die Ausgangsfrequenz eines der beiden Oszillatoren anliegt. Die Ausgangsspannung des Wandlers 29 wird in einem Verstärker 31 entsprechend verstärkt und steuert eine Schmitt-Triggerstufe 32 an. Diese ist so eingestellt, daß ein mit ihr verbundener Motor 33 eingeschaltet wird, wenn es erforderlich ist, das Entwicklergemisch durch nachzufüllenden Toner Aufzufrischen, und ausgeschaltet wird, wenn das Entwicklergemisch die gewünschte Tonerkonzentration aufweist. Der Motor 33 betätigt eine nicht gezeigte Tonerzufuhreinrichtung.Fig. 3 shows a block diagram of the device for measuring the toner concentration of the developer mixture 7. The flat coils on the circuit board are components of a measuring oscillator 34 which is connected to a reference oscillator 28. The two oscillators are controlled by a timer 30, which either switches the measuring oscillator 34 or the reference oscillator 28, so that only the output frequency of one of the two oscillators is applied to a frequency / voltage converter 29. The output voltage of the converter 29 is amplified accordingly in an amplifier 31 and controls a Schmitt trigger stage 32. This is set such that a motor 33 connected to it is switched on when it is necessary to replenish the developer mixture with toner to be replenished, and is switched off when the developer mixture has the desired toner concentration. The motor 33 actuates a toner supply device, not shown.

Der Schaltungsaufbau des Meßoszillators 34 ist an sich bekannt und umfaßt einen Schwingkreis, gebildet aus einem Kondensator und der Induktivität der Spulen der Platine 21. Dieser Schwingkreis ist in der Kollektorstrecke eines Transistors angeordnet, dessen Basis mit einer Spannungsquelle verbunden ist. Der Transistor ist Bestandteil einer Oszillatorschaltung, die einen weiteren Transistor aufweist. Die Emitter der beiden Transistoren sind mit dem Kollektor eines weiteren Transistors verbunden, der als Schalttransistor arbeitet und vom Zeitgeber 30 geöffnet oder geschlossen wird.The circuit structure of the measuring oscillator 34 is known per se and comprises an oscillating circuit, formed from a capacitor and the inductance of the coils of the circuit board 21. This oscillating circuit is arranged in the collector path of a transistor, the base of which is connected to a voltage source. The transistor is part of an oscillator circuit which has a further transistor. The emitters of the two transistors are connected to the collector of a further transistor which works as a switching transistor and is opened or closed by the timer 30.

Jede Änderung der Streuinduktivität der Kombination von Spulen 6, 6', 6",... auf der Platine 21 ändert die Frequenz des Meßoszillators 34. Die Ausgangsfrequenz des Meßoszillators 34 wird mit der festen Ausgangsfrequenz des Referenzoszillators 28 verglichen. Im allgemeinen ist die Einstellung derart, daß bei sinkender Tonerkonzentration im Entwicklergemisch die Resonanzfrequenz des Meßoszillators 34 zunimmt und damt die Abweichung dieser Frequenz von der festen Bezugsfrequenz des Referenzoszillators 28 nach oben hin zunimmt. Entsprechend dem gewählten Verstärkungsgrad des Verstärkers 31 und der Auslösespannung für die Schmitt-Triggerstufe 32 wird dann der Motor 33 in Betrieb gesetzt. Solange die Ausgangsfrequenz des Meßoszillators 34 unter dem Wert der festen Frequenz des Referenzoszillators 28 liegt, spricht die Schmitt-Triggerstufe 32 nicht an und Motor 33 steht still, so daß kein Toner dem Entwicklergemisch zugefürht wird.Any change in the leakage inductance of the combination of coils 6, 6 ', 6 ", ... on the board 21 changes the frequency of the measuring oscillator 34. The output frequency of the measuring oscillator 34 is compared with the fixed output frequency of the reference oscillator 28. In general, the setting is such that as the toner concentration in the developer mixture decreases, the resonance frequency of the measuring oscillator 34 increases and the deviation of this frequency from the fixed reference frequency of the reference oscillator 28 increases upwards. According to the selected amplification level of the amplifier 31 and the trigger voltage for the Schmitt trigger stage 32 the motor 33 is put into operation. As long as the output frequency of the measuring oscillator 34 is below the value of the fixed frequency of the reference oscillator 28, the Schmitt trigger stage 32 does not respond and motor 33 stands still, so that no toner is supplied to the developer mixture.

Claims (8)

1. A device for measuring the concentration of toner in a developer mixture composed of toner and a ferromagnetic carrier material in an electrophotographic developing device, including a deflection plate for the non applied developer mixture, extending tangentially and obliquely to the photoconductive surface of a cylinder, upon the deflection plate a coil is located, which rests on a member, said coil is a component of a measuring oscillator, wherein
a) the member is a plate bar (21) resting on the deflection plate (4) and extending over the entire width of the deflection plate (4),
b) the coil comprises a plurality of plate-shaped coils (6, 6', 6",...) which are extended over the entire width of the plate bar (21) and are electrically connected to one another, the conductor paths (22-26) of the plate-shaped coils are lying in the plane of the plate bar (21), and
c) the plate bar (21) is potted with an electrically insulating transparent material (27).
2. A device as claimed in claim 1, wherein the plate-shaped coils (6, 6', 6",...) are electrically connected to one another in series.
3. A device as claimed in claims 1 and 2, wherein the conductor paths (22) of the plate-shaped coils (6, 6', 6",.,.) comprise the form of rectangles the lateral edges (24, 25) of which starting from a central portion (23). increase in length in the outer portion.
4. A device as claimed in claims 1 and 2, wherein the conductor paths (26) of the plate-shaped coils (6, 6', 6",...) comprise the form of spirals with constant curvature.
5. A device as claimed in one or more of the claims 1 to 4, wherein several plate-shaped coils (6, 6', 6",...) are located geometrically adjacent to each other on both sides of a strip (39) mounted on the plate bar (21).
6. A device as claimed in claim 5, wherein the central part (23) of one plate-shaped coil (6, 6', 6",...) on one side of the strip (39) is electrically connected via a feed-through point (40) to the plate-shaped coil on the other side of the strip (39).
7. A device as claimed in one or more of the claims 1 to 6, wherein the plate-shaped coils (6, 6', 6",...) are arranged in form of a matrix (41) and the plate-shaped coils in each row (42) of the matrix (41) are electrically connected in series and the rows of the matrix (41) are electrically connected in parallel to one another.
8. A device as claimed in claim 7, wherein the matrix has a square form and the individual plate-shaped coils (6, 6', 6",...) have equal inductance values.
EP78100137A 1977-06-18 1978-06-12 Device for measuring the toner concentration in a development mixture Expired EP0000136B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE2727402A DE2727402C2 (en) 1977-06-18 1977-06-18 Device for measuring the toner concentration of a developer mixture
DE2727402 1977-06-18

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EP0000136A1 EP0000136A1 (en) 1979-01-10
EP0000136B1 true EP0000136B1 (en) 1982-09-22

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US (1) US4257348A (en)
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JP (1) JPS547938A (en)
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JPS56102874A (en) * 1980-01-19 1981-08-17 Canon Inc Developer replenishing device
JPS56121068A (en) * 1980-02-27 1981-09-22 Mita Ind Co Ltd Developing device of electrostatic copying machine
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JPS5726879A (en) * 1980-07-23 1982-02-13 Mita Ind Co Ltd Control device for replenishing of developer
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JPS547938A (en) 1979-01-20
EP0000136A1 (en) 1979-01-10
CA1111491A (en) 1981-10-27
JPS623950B2 (en) 1987-01-28
DE2727402C2 (en) 1979-04-19
US4257348A (en) 1981-03-24
DE2862038D1 (en) 1982-11-04
DE2727402B1 (en) 1978-08-17

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