JP2019045461A - Permeability sensor and method for detecting permeability - Google Patents

Abstract

To provide a permeability sensor and a method for detecting a permeability using the permeability sensor that can precisely detect a change of the permeability of an object by suppressing influence of temperature variations, in spite of a small and simple configuration.SOLUTION: The present invention includes: a first coil 1 and a second coil 2; a first oscillation circuit 6 for oscillating by including the first coil 1; a second oscillation circuit 7 for oscillating by including the second coil 2; a measurement unit 41 for measuring the respective numbers of oscillation pulses in the first and second oscillation circuits 6 and 7; an adjustment unit 42 for adjusting at least one of the time for measuring the number of oscillation pulses in the first oscillation circuit 6 by the measurement unit 41 and the number of oscillation pulses in the second oscillation circuit 7 by the measurement unit 41; a calculation unit 43 for calculating the difference in the number of the oscillation pulses measured by the measurement unit 41; and a conversion unit 44 for converting the difference calculated by the calculation unit 43 into a permeability.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a magnetic permeability sensor for detecting the magnetic permeability of an object to be detected, and a magnetic permeability detection method using the magnetic permeability sensor.

  An electrophotographic copying machine or printer includes a toner sensor that magnetically detects the density or remaining amount of toner in a developing unit used to develop an electrostatic image formed on a photosensitive member. . Patent Document 1 discloses an example of such a toner sensor. In the sensor disclosed in Patent Document 1, four coils are used, and the toner density is detected by the differential transformer method.

  Further, in Patent Document 2, a phase shift is generated in the first oscillation circuit that causes a phase shift in an oscillation wave corresponding to a change in inductance of the first detection coil, and a phase shift in an oscillation wave according to a inductance change in a second detection coil. There is disclosed a technique of detecting a metal state by providing a second oscillation circuit and determining the difference between the phase shift of the two.

JP 2001-165910 A JP, 2009-31257, A

  The toner sensor of Patent Document 1 adopts the differential transformer method, and when the drive coil and the differential coil are located in the vicinity, the influence of the toner affects both, so the toner is the drive coil and the differential. It is difficult to completely eliminate the influence on the coil. Further, when the oscillation circuit is configured to include the flat coil, the change in the degree of coupling of the inductance when the magnetic body approaches is small, and it is difficult to operate such a flat coil with an analog circuit.

  In Patent Document 2, the oscillation waves from the first oscillation circuit and the second oscillation circuit are measured, the time when the measured value reaches a predetermined value is measured, and the phase of the accumulated oscillation wave is measured based on the measured time. Since the shift is detected, there is a problem that the process of detecting is complicated. In Patent Document 2, a coil wound on a high magnetic permeability material is used, and since the oscillation frequency is low, the time for obtaining the same resolution can be shortened, so a method of detecting a phase shift is advantageous. It is a disadvantage when using Further, Patent Document 2 is a technique for magnetically detecting the torque of the rotating shaft, and the application to a sensor for detecting the concentration of toner is neither disclosed nor suggested.

  In a sensor that detects magnetic permeability using two coils, the two coils are arranged horizontally apart in order to prevent the other coil from being affected by the magnetic flux generated by one coil. The configuration is common. Specifically, one coil is disposed in the vicinity of the object to be detected (magnetic material) to make it susceptible to a change in magnetic permeability, and the other coil is disposed away from the object to be detected (magnetic material) Make it less susceptible to changes in permeability. Such arrangement of the plurality of coils in the horizontal direction has a problem that the sensor can not be miniaturized.

  Further, although the magnetic permeability is detected according to the change in the inductance of the plurality of coils, a large number of circuit parts are used for this detection. There is a variation in the characteristics of the circuit components, and furthermore, the circuit components are susceptible to the detection environment, so there is a problem that high-accuracy detection can not be achieved.

  The present invention has been made in view of such circumstances, and is a magnetic permeability sensor which can detect the change of the magnetic permeability of an object to be detected with high accuracy by suppressing the influence of temperature fluctuation even with a small and simple configuration. An object of the present invention is to provide a permeability detection method using a permeability sensor.

  A magnetic permeability sensor according to the present invention is a magnetic permeability sensor for detecting the magnetic permeability of an object to be detected, wherein the first oscillation circuit oscillates including the first coil receiving magnetism from the object to be detected; and the object to be detected A second oscillation circuit that oscillates including a second coil receiving magnetism, a measurement unit that measures the number of oscillation pulses in each of the first oscillation circuit and the second oscillation circuit, and oscillation in the first oscillation circuit by the measurement unit Adjustment unit that adjusts at least one of measurement time of pulse number and measurement time of oscillation pulse number in the second oscillation circuit by the measurement unit, and calculation unit that calculates difference of oscillation pulse measured by the measurement unit And a conversion unit for converting the difference calculated by the calculation unit into a magnetic permeability. Here, "to receive magnetism" means to magnetically couple with an object to be detected.

  In the present invention, the number of oscillation pulses refers to the number of pulses within a predetermined measurement time at each oscillation frequency oscillated in each oscillation circuit. Therefore, if the measurement time is the same, the difference in the number of oscillation pulses can be regarded as synonymous with the difference in the oscillation frequency.

  A magnetic permeability detection method according to the present invention is a magnetic permeability detection method for detecting the magnetic permeability of an object to be detected, wherein the first coil and the second coil are arranged with different distances from the object to be detected. The number of oscillation pulses of the oscillation circuit that oscillates including one coil and the number of oscillation pulses of the oscillation circuit that oscillates including the second coil are each measured, and the number of oscillation pulses of the first oscillation circuit is measured. At least one of the measurement time and the second measurement time for measuring the number of oscillation pulses of the second oscillation circuit is adjusted, the difference between the measured number of oscillation pulses is calculated, and the calculated difference is converted to permeability. It features.

  In the magnetic permeability detection method according to the present invention, the first measurement time is the second measurement when the distance of the first coil from the object is shorter than the distance of the second coil from the object. At least one of the first measurement time and the second measurement time may be adjusted to be longer than time.

  In the magnetic permeability sensor of the present invention, the number of oscillation pulses of the first oscillation circuit including the first coil disposed in the vicinity of the object to be detected and the first coil in the vicinity of the object to be detected are directed to the object to be detected. The measurement unit measures the number of oscillation pulses of the second oscillation circuit including the second coils arranged at different distances. The calculation unit calculates the difference between the numbers of oscillation pulses measured by the measurement unit, and the conversion unit converts the difference calculated by the calculation unit into permeability. When the permeability of the object to be detected is increased, the inductance of the coil is increased, and the number of oscillation pulses of the oscillation circuit including the coil is decreased. Here, since the coil closer to the object to be detected has a large amount of change in inductance according to the change in magnetic permeability, the variation in the number of oscillation pulses in the oscillation circuit also becomes large. Therefore, the permeability can be detected from the difference of the number of oscillation pulses by each oscillation circuit using two coils arranged with different distances from the object to be detected.

  Here, at least one of the first measurement time in which the number of oscillation pulses of the first oscillation circuit is measured and the second measurement time in which the number of oscillation pulses of the second oscillation circuit is measured is adjusted by the adjustment unit. Specifically, when the distance from the object to be detected is shorter in the first coil than in the second coil, the inductance of the first coil is larger than the inductance of the second coil, and the number of oscillation pulses in the first oscillation circuit is Since the number of oscillation pulses is smaller than the number of oscillation pulses of the second oscillation circuit, the first measurement time is adjusted to be relatively longer than the second measurement time, and the number of oscillation pulses is adjusted to be the same. By performing such adjustment, the influence of temperature fluctuation at the time of actual detection is reduced.

  Under the present circumstances, flat coils, such as a coil formed by the patterning printing to a board | substrate, can be used as two coils, and a structure reduces in size. In the case of a coil having a small inductance such as a flat coil, the oscillation frequency is high (the number of pulses in a fixed time is large). As a result, since the number of clocks in a fixed time of the computer is smaller than the number of oscillation pulses, in the case of oscillation pulse number measurement, it is possible to shorten the measurement time for obtaining the same resolution. In addition, a series of processes of measuring the number of oscillation pulses, calculating the difference of the number of oscillation pulses, and converting the difference to the permeability can be performed by software using a microcomputer etc., and the number of parts can be reduced. It is less likely to be subject to

  The permeability sensor according to the present invention is characterized in that the measurement section alternately measures the number of oscillation pulses in the first oscillation circuit and the number of oscillation pulses in the second oscillation circuit. Do.

  In the magnetic permeability sensor of the present invention, measurement of the number of oscillation pulses in the first oscillation circuit and measurement of the number of oscillation pulses in the second oscillation circuit are alternately performed while switching. Therefore, when the number of oscillation pulses in one oscillation circuit is measured, the other oscillation circuit does not oscillate, so the measured value of the number of oscillation pulses in one oscillation circuit is not affected by the oscillation of the other oscillation circuit. Therefore, the accurate number of oscillation pulses in both oscillation circuits can be measured, and the detection accuracy of the permeability is high.

  The magnetic permeability sensor according to the present invention is characterized in that the first coil and the second coil are coaxially arranged.

  In the magnetic permeability sensor of the present invention, the first coil and the second coil are coaxially arranged. Therefore, the area required for the arrangement of the coils can be small, and the magnetic permeability sensor can be miniaturized.

  The magnetic permeability sensor according to the present invention is characterized in that constituent members of the first oscillation circuit and the second oscillation circuit are common except for the first coil and the second coil.

  In the magnetic permeability sensor of the present invention, in the first oscillation circuit and the second oscillation circuit, components other than the first coil and the second coil are common. Therefore, the number of oscillation pulses measured by each of the first oscillation circuit and the second oscillation circuit is not influenced by the variation in characteristics due to the different components other than the coil, and an accurate value is measured. Therefore, the detection accuracy of the permeability is high.

  The magnetic permeability sensor according to the present invention is characterized by including a substrate on which the first coil is disposed on one side and the second coil is disposed on the other side.

  In the magnetic permeability sensor of the present invention, the first coil is formed on one surface of the substrate, and the second coil is formed on the other surface of the substrate. Therefore, the coaxial arrangement of the first coil and the second coil can be realized with a simple configuration.

  A magnetic permeability sensor according to the present invention includes a first oscillation circuit that oscillates including a first coil that receives magnetism from an object to be detected, and a second oscillation circuit that oscillates that includes a second coil that receives magnetism from the object to be detected. A measurement unit that measures the number of oscillation pulses in each of the first oscillation circuit and the second oscillation circuit; and adjusting a measurement time so that the number of oscillation pulses in the first oscillation circuit by the measurement unit becomes a predetermined value (1) At least one of measurement time of the number of oscillation pulses in the first oscillation circuit adjusted by the first adjustment section and the first adjustment section and measurement time of the number of oscillation pulses in the second oscillation circuit under a predetermined environment Of the number of oscillation pulses measured by the measuring unit in the measurement time after adjustment by the second adjusting unit and the first adjusting unit and the second adjusting unit that adjust based on the respective oscillation pulse numbers measured The Comprising a calculating unit for output, and a converter for converting the difference calculated in the calculating section to the permeability.

  In the present invention, using two coils (the first coil and the second coil), the permeability can be detected from the difference in the number of oscillation pulses by each oscillation circuit.

  The permeability sensor according to the present invention is characterized in that the measurement time of the number of oscillation pulses in the second oscillation circuit is adjusted.

  In the present invention, it is possible to operate with the first oscillation circuit as a reference.

  In the magnetic permeability sensor according to the present invention, the calculation unit, under adjustment of the measurement time by the first adjustment unit and the second adjustment unit, performs the first adjustment unit and the first adjustment unit in the measurement unit under a predetermined environment. The difference of the number of oscillation pulses measured in the measurement time after adjustment by the second adjustment unit is calculated, and the number of oscillation pulses in the first oscillation circuit and the oscillation in the second oscillation circuit are calculated by the difference calculated by the calculation unit. The apparatus further comprises a third adjusting unit that adjusts at least one of the number of pulses.

  In the present invention, the difference between the number of oscillation pulses measured in the measurement time after adjustment by the first adjustment unit and the second adjustment unit is calculated, and the number of oscillation pulses in the first oscillation circuit and the calculated difference are Since at least one of the number of oscillation pulses in the second oscillation circuit is adjusted, it is possible to set the difference in permeability to 0 under a predetermined environment that should be the measurement center.

  The present invention is characterized in that it is realized using a reference magnetic plate under a predetermined environment.

  In the present invention, by using the reference magnetic plate, it is possible to set a predetermined magnetic permeability to the center of the measurement range.

  In the magnetic permeability detection method according to the present invention, the detection coil and the reference coil are arranged with different distances from the object to be detected, and the number of oscillation pulses of the reference oscillation circuit oscillating including the reference coil is predetermined. The first measurement time obtained by adjusting the initial measurement time is determined so that the measured number of oscillation pulses becomes a predetermined value by measuring the initial measurement time, and the same time as the obtained first measurement time is calculated as the second measurement time A detection oscillation circuit that oscillates including the detection coil for the number of oscillation pulses of the reference oscillation circuit in the first measurement time and the detection coil for the second measurement time after setting and arranging the reference magnetic plate in the vicinity of the detection coil At least one of the first measurement time and the second measurement time is adjusted based on the measured two oscillation pulse numbers, and the first oscillation time is adjusted in the first oscillation time. Number oscillation pulses, and an oscillation pulse number were respectively measured in said detection oscillation circuit in the second measurement time, calculates the difference between the number of oscillation pulses measured, and converting the calculated difference in permeability.

  In the present invention, using two coils (the first coil and the second coil), the permeability can be detected from the difference in the number of oscillation pulses by each oscillation circuit.

  The permeability detection method according to the present invention is characterized in that the second measurement time is adjusted.

  In the present invention, it is possible to use the first measurement time of the reference circuit as a reference.

  In the present invention, even with a small and simple configuration, the magnetic permeability of the object to be detected can be detected with high accuracy by suppressing the influence of temperature fluctuation.

It is a perspective view which shows the structure of the magnetic permeability sensor of this invention. It is sectional drawing which shows the structure of the magnetic permeability sensor of this invention. It is a sectional view showing an example of attachment to a development unit of a permeability sensor of the present invention. It is a block diagram which shows the function structure of the magnetic permeability sensor of this invention. It is a circuit diagram showing an example of 1 composition of a permeability sensor of the present invention. It is a timing chart for explaining the operation of the permeability sensor of the present invention. It is sectional drawing which shows the example of attachment to the image development unit of the magnetic permeability sensor of a prior art example. 5 is a graph showing detection sensitivity characteristics of toner concentration in the present invention example and the conventional example. It is a graph which shows the control voltage characteristic for performing offset control in an example of the present invention, and a conventional example. It is sectional drawing which shows the structure of the magnetic permeability sensor in a 1st modification. It is sectional drawing which shows the structure of the magnetic permeability sensor in a 2nd modification. It is sectional drawing which shows the structure of the magnetic permeability sensor in a 3rd modification. It is sectional drawing which shows the structure of the magnetic permeability sensor in a 4th modification. It is a top view which shows the structure of the shield member suitable for the magnetic permeability sensor of this invention. It is a flowchart which shows the process sequence example of measurement time adjustment processing. It is a flowchart which shows the process sequence example of an initial stage correction process. It is a flowchart which shows the process procedure example of a correction process. It is a flowchart which shows the process sequence example of a forced correction process. It is a flowchart which shows the processing procedure example of forced correction | amendment after the correction | amendment of permeability correction process.

  Hereinafter, the present invention will be specifically described based on the drawings showing the embodiments thereof. 1 and 2 are a perspective view and a sectional view showing the configuration of the magnetic permeability sensor of the present invention.

  In FIG. 1 and FIG. 2, 10 is a flat rectangular substrate. The first coil 1 is formed on one surface (upper surface) of one end portion of the substrate 10. In addition, a second coil 2 is formed on the other surface (lower surface) of one end of the substrate 10 coaxially with the first coil 1 (see FIG. 2). The first coil 1 and the second coil 2 are formed, for example, by printing a copper foil pattern on the substrate 10.

  The connector 3 is mounted on the upper surface of the other end of the substrate 10 with a part thereof protruding from the other end. On the upper surface of the central portion of the substrate 10, an electronic chip 4 composed of a microcomputer for performing various processes described later is mounted. Furthermore, the circuit component 5 is mounted in the vicinity of the electronic chip 4. The circuit component 5 includes a capacitor or the like for forming an oscillation circuit with the first coil 1 or the second coil 2. The magnetic permeability sensor 20 of the present invention is configured as described above.

  FIG. 3 is a cross-sectional view showing an example of attachment of the magnetic permeability sensor 20 of the present invention to the developing unit. In FIG. 3, reference numeral 30 denotes a partition that partitions the inside and the outside of the developing unit. A recess 31 is formed in the partition wall 30, and the magnetic permeability sensor 20 is attached to the developing unit in a state of being housed in the case 21 so as to be fitted into the recess 31. The end of the connector 3 protrudes from the case 21.

  At this time, the permeability sensor 20 is attached to the partition 30 of the developing unit so that the lower surface side of the substrate 10 shown in FIGS. 1 and 2 is on the partition 30 side. Therefore, the second coil 2 is disposed at a position closer to the inside of the developing unit than the first coil 1, that is, at a position closer to the developer in the developing unit. The recess 31 to which the magnetic permeability sensor 20 is attached is sealed by a seal 32.

  FIG. 4 is a block diagram showing a functional configuration of the magnetic permeability sensor 20 of the present invention. In FIG. 4, the same or similar parts as in FIGS. 1 and 2 are denoted by the same reference numerals.

  A first oscillation circuit 6 is configured by the first coil 1 and a part of the circuit component 5, and a second oscillation circuit 7 is configured by the second coil 2 and a part of the circuit component 5. In the magnetic permeability sensor 20 of the present invention, in the first oscillation circuit 6 and the second oscillation circuit 7, the other constituent members except the first coil 1 and the second coil 2 are common. Therefore, the number of oscillation pulses measured by each of the first oscillation circuit 6 and the second oscillation circuit 7 is not influenced by the variation of the characteristics due to the different constituent members, and an accurate value is measured. Therefore, the detection accuracy of the permeability is high.

  In the electronic chip 4, the measurement unit 41 that measures the number of oscillation pulses in each of the first oscillation circuit 6 and the second oscillation circuit 7 and the measurement time of the oscillation pulse number in the first oscillation circuit 6 in the measurement unit 41 An adjustment unit (first adjustment unit, second adjustment unit, third adjustment unit) 42 for adjusting at least one of measurement time (second measurement time) of oscillation pulse number in first oscillation time and second oscillation circuit 7; The calculation unit 43 functionally calculates the difference of the number of oscillation pulses measured by the measurement unit 41, and the conversion unit 44 converts the difference calculated by the calculation unit 43 into the magnetic permeability.

  FIG. 5 is a circuit diagram showing one configuration example of the magnetic permeability sensor 20 of the present invention. In FIG. 5, the coil L1 and the coil L2 correspond to the first coil 1 and the second coil 2 described above, respectively. The microcomputer U1 corresponds to the electronic chip 4 described above.

  One end of the coil L1 is connected to the sixth terminal of the microcomputer U1, and one end of the coil L2 is connected to the third terminal of the microcomputer U1. The other end of the coil L1 and the other end of the coil L2 are connected to the base of the transistor Q1 via a capacitor C1. A resistor R2 is provided between the base and the collector of the transistor Q1, and a capacitor C2 is provided between the base and the emitter of the transistor Q1. The collector of the transistor Q1 is connected to the second terminal of the microcomputer U1 and grounded via the resistor R3.

  The input terminal of the power supply voltage Vdd is connected to the first terminal of the microcomputer U1. The input terminal of the power supply voltage Vdd is connected to the emitter of the transistor Q1 via the resistor R1. One end of a capacitor C3 is connected between the resistor R1 and the emitter of the transistor Q1, and the other end of the capacitor C3 is grounded. One end of a capacitor C6 is connected between the input terminal of the power supply voltage Vdd and the first terminal, and the other end of the capacitor C6 is grounded. A terminal for grounding is connected to the eighth terminal of the microcomputer U1.

  An output terminal for outputting a detection voltage Vout corresponding to the magnetic permeability is connected to the seventh terminal of the microcomputer U1 through the resistor R4. One end of a capacitor C7 is connected between the output terminal and the resistor R4, and the other end of the capacitor C7 is grounded. An input terminal for inputting a control voltage Vcont for performing offset control is connected to the fifth terminal of the microcomputer U1 via the resistor R6. One end of a capacitor C4 is connected between the fifth terminal of the microcomputer U1 and the resistor R6, and the other end of the capacitor C4 is grounded.

  The coil L1, the two capacitors C2 and C3 and the transistor Q1 constitute the above-described first oscillation circuit 6 (Colpitts oscillation circuit), and the coil L2, the two capacitors C2 and C3 and the transistor Q1 described above A second oscillation circuit 7 (Colpitts oscillation circuit) is configured. Then, the first oscillation circuit 6 and the second oscillation circuit 7 are adjusted by the adjustment unit 42 by the switching operation of the microcomputer U1 (the switching operation is performed at the third terminal and the sixth terminal of the microcomputer U1). It oscillates alternately for each measurement time.

  Next, the operation of the magnetic permeability sensor 20 of the present invention will be described. FIG. 6 is a timing chart for explaining the operation of the magnetic permeability sensor 20 of the present invention.

  A process of causing the first oscillation circuit 6 to oscillate and measuring the number of oscillation pulses by the measurement unit 41 over the first measurement time adjusted by the adjustment unit 42, and the second adjusted by the adjustment unit 42 Over the measurement time, the second oscillation circuit 7 is oscillated, and the process of measuring the number of oscillation pulses by the measurement unit 41 is performed alternately. At this time, as shown in FIG. 6, the second oscillation circuit 7 is not oscillated during the period in which the first oscillation circuit 6 is oscillated and the number of oscillation pulses is measured, and the second oscillation circuit 7 is oscillated and The first oscillation circuit 6 is not oscillated in a period in which the number of oscillation pulses is measured. Therefore, since the number of oscillation pulses is measured without being affected by the oscillation, the measurement value is high in accuracy.

  When the measurement of the number of oscillation pulses for each predetermined time (the first measurement time and the second measurement time) is completed, the number of oscillation pulses measured (derived from the first coil 1) in the first oscillation circuit 6 and the second oscillation The difference with the measured number of oscillation pulses (derived from the second coil 2) in the circuit 7 is calculated by the calculation unit 43. Then, the calculated difference is converted into the magnetic permeability by the conversion unit 44, and the change amount of the magnetic permeability is obtained. Specifically, the median of the detection range of the desired permeability is set to 0, and the amount of change from the median is determined based on the degree of the calculated difference compared to the difference corresponding to the median. A magnetic permeability sensor (toner sensor) 20 attached to the developing unit detects the density of toner.

  Further, in a period in which the first oscillation circuit 6 is oscillated and the number of oscillation pulses is measured, the difference between the measurement values (for example, A ′ and B ′) of the first oscillation circuit 6 and the second oscillation circuit 7 before that is calculated. Since the calculated difference is calculated by the calculation unit 43 and converted by the conversion unit 44 to the permeability to obtain the change amount of the permeability, the change of the permeability at the timing of the measurement start of the number of oscillation pulses of each oscillation circuit An update of the quantity takes place sequentially.

  Hereinafter, the principle by which the magnetic permeability can be detected (the toner concentration can be detected) will be described according to the above-described procedure.

  When the permeability of the object to be detected is increased, the inductance of the coil disposed in the vicinity of the object to be detected is increased according to the fluctuation of the permeability. As a result, the number of oscillation pulses of the oscillation circuit including the coil decreases. Here, in the case where two coils are arranged with different distances from the object to be detected, the inductance increases in any of the coils and the number of oscillation pulses in any of the oscillation circuits decreases. However, since the coil closer to the object to be detected is more affected by the change in magnetic permeability than the coil farther from the object to be detected, in the above case, the increase in inductance increases and the decrease in the number of oscillation pulses also decreases. growing. Therefore, in the number of oscillation pulses in the two oscillation circuits including the two coils, a difference corresponding to the degree of change in the permeability is generated. As described above, since there is a correlation between the difference between both oscillation pulse numbers and the permeability, in the present invention, the permeability of the object to be detected is detected based on the difference between the oscillation pulse numbers of both oscillation circuits. It is possible.

  In the magnetic permeability sensor 20 in the embodiment described above, the first coil 1 corresponds to the coil farther from the above-mentioned object to be detected, and the second coil 2 corresponds to the coil closer to the above-mentioned object to be detected. In the present invention, the coil closer to the object to be detected is a detection coil, and the coil farther to the object is a reference coil.

  The developer in the developing unit is a mixture of toner and magnetic material (iron powder). At the time of copying, toner is attached to the sheet and magnetic material is hardly attached. Therefore, as the copying process progresses, the amount of toner decreases but the amount of magnetic material hardly changes, so the permeability of the developer increases. Therefore, there is an inverse correlation between the magnetic permeability in the developing unit and the toner concentration. In the present invention, as described above, since the magnetic permeability of the object to be detected (developer) can be detected, the density of the toner can be detected based on the detected magnetic permeability of the developer in the developing unit.

  Here, adjustment processing of at least one of the first measurement time and the second measurement time in the adjustment unit 42 will be described.

  Since the use environment is different between the first coil 1 close to the object to be detected and the second coil 2 far from the object to be detected, the detection characteristic of the magnetic permeability sensor is easily influenced by temperature fluctuation. Further, as described above, since the first coil 1 and the second coil 2 are formed by printing the copper foil pattern on the substrate 10, the first coil 1 and the second coil 2 caused by the difference in the forming conditions Differences in properties are inevitable.

  The permeability sensor 20 of the present invention adjusts at least one of the first measurement time and the second measurement time to solve such a problem. This adjustment processing is performed before actual permeability detection processing is performed, such as at the time of shipment of the permeability sensor 20 or at the time of copying by a copying machine provided with the permeability sensor 20. These measurement times are adjusted so that there is no difference in the number of pulses in one measurement period in the first coil 1 and the second coil 2 in the situation of the median value of the desired detection range. In addition, it is troublesome to prepare the toner in order to create the condition of the median of this detection range, so metals having the same permeability (the above-mentioned median) are used. The ambient temperature at this time is normal temperature.

  The second coil 2 disposed at a position close to the developer is greatly affected by the magnetic material (developer) and the inductance is increased. On the other hand, the first coil 1 disposed at a position far from the developer is hardly affected by the magnetic material (developer) and the inductance is not increased so much. The oscillation frequency is approximately in inverse proportion to the inductance, so the number of oscillation pulses of the second oscillation circuit 7 is smaller than the number of oscillation pulses of the first oscillation circuit 6. Therefore, adjustment is performed such that the second measurement time is relatively longer than the first measurement time by an amount that compensates for the difference due to the magnitude of the influence of the magnetic material (developer). Specifically, the measurement time is adjusted so that the number of oscillation pulses of the first oscillation circuit 6 and the number of oscillation pulses of the second oscillation circuit 7 become the same.

  When performing adjustment such that the second measurement time is relatively longer than the first measurement time, adjustment to shorten the first measurement time without changing the second measurement time, adjustment without changing the first measurement time The adjustment may be either an adjustment to increase the second measurement time or an adjustment to shorten the first measurement time to increase the second measurement time.

  The adjustment of the measurement time is carried out by setting the measurement time of the first oscillation circuit 6 and the measurement of the number of oscillation pulses of the second oscillation circuit 7 first, and then calculating the difference between them. Adjust one or the other measurement time so that the difference is eliminated. In this case, the same number of oscillation pulses may not be obtained by adjustment of one measurement time, and in this case, adjustment is performed as follows. Specifically, the number of oscillation pulses by the first oscillation circuit 6 and the number of oscillation pulses by the second oscillation circuit 7 are measured again in the adjusted measurement time, and the difference between the oscillation pulse numbers is calculated to eliminate the difference. Adjust one or the other measurement time. Finally, the state where the difference between the number of oscillation pulses by the first oscillation circuit 6 and the number of oscillation pulses by the second oscillation circuit 7 is the smallest is set as the initial value (set as the central value of the detection range). You may This correction corresponds to step 2 (correction processing) described later.

The entire adjustment of the measurement time will be described using a flowchart. FIG. 15 is a flow chart showing an example of processing procedure of measurement time adjustment processing. The measurement time adjustment process is a process performed mainly by the adjustment unit 42 of the electronic chip 4. The adjustment unit 42 performs an initial correction process (step S1). The initial correction process is a process mainly intended to correct the error of the clock of the electronic chip 4. The adjustment unit 42 performs correction processing (step S2). The correction process is a process mainly intended to set the difference between the measurement pulse numbers of the first oscillation circuit 6 and the second oscillation circuit 7 to a minimum value (including 0) in an environment assumed to be the middle value of the measurement range . The adjustment unit 42 performs a forced correction process (step S3). The forced correction processing is processing for forcibly setting the difference between the measurement pulse numbers of the first oscillation circuit 6 and the second oscillation circuit 7 to 0 in an environment assumed to be mainly the middle value of the measurement range. The forced correction process is a process of forcibly setting the minimum value of the difference obtained in the correction process to 0, and is a process including a meaning of confirming that the difference becomes the minimum value in the correction process. The adjustment unit 42 ends the measurement time adjustment process.
Thereafter, the measurement of the magnetic permeability is repeated according to the procedure shown in FIG. 6 (step S4).

  FIG. 16 is a flow chart showing an example of the processing procedure of the initial correction processing. The coil constituting the first oscillation circuit 6 is a reference coil, the coil constituting the second oscillation circuit 7 is a detection coil, the first oscillation circuit 6 is a reference oscillation circuit, and the second oscillation circuit 7 is a detection oscillation circuit. The adjustment unit 42 measures the number of oscillation pulses of the first oscillation circuit 6 by the measurement unit 41 at a predetermined initial measurement time (t0) (step S11). The adjustment unit 42 calculates the difference between the number of pulses measured by the calculation unit 43 and the predetermined value (step S12). The measurement time of the first oscillation circuit 6 is corrected based on the predetermined value so that the number of oscillation pulses of the first oscillation circuit 6 becomes a predetermined value (step S13). The adjustment unit 42 ends the initial correction process and returns the process to the caller. The measurement time after correction is, for example, t0 + α. At step 13, the initial correction is completed. After step S13, the measuring unit 41 measures the number of oscillation pulses of the first oscillation circuit 6 at the measurement time t0 + α, and performs processing to check whether the measured number of oscillation pulses becomes a predetermined value. At the measurement time t0 + α, the number of oscillation pulses of the first oscillation circuit 6 is measured (step S14). The adjustment unit 42 determines whether the number of oscillation pulses has reached a predetermined value (step S15). If the adjustment unit 42 determines that the number of oscillation pulses does not reach the predetermined value (NO in step S15), the process returns to step S12. If the adjustment unit 42 determines that the number of oscillation pulses is a predetermined value (YES in step S15), the process ends and returns to the calling source. If the oscillation pulse number does not reach a predetermined value or if α does not converge, the value that minimizes the difference between the oscillation pulse number and the predetermined value is set to α. In addition, in order to simplify the process, the processes of steps S14 and S15 may be omitted.

  For example, the first oscillation circuit 6 is designed to oscillate at 10 MHz. Then, it is assumed that the number of oscillation pulses is measured 30,000 times. In this case, the initial measurement time t0 is 3 ms. The measuring unit 41 measures the number of oscillation pulses of the first oscillation circuit 6 for 3 ms. If the number of oscillation pulses measured falls below 30,000, the measurement time is extended by the number of pulses that fall below. That is, let α be a positive value. If the number of oscillation pulses measured exceeds 30,000, the measurement time is shortened by the number of pulses that are exceeded. That is, let α be a negative value. When the number of oscillation pulses measured is 30,000, α is set to 0.

  FIG. 17 is a flowchart showing an example of the processing procedure of the correction processing. The correction process is performed in an environment where the center of the measurement range and the permeability are measured. For example, a magnetic plate (reference magnetic plate) that produces such an environment is used. The adjustment unit 42 measures the number of oscillation pulses of the first oscillation circuit 6 by the measurement unit 41 at the measurement time t0 + α obtained in the initial correction process (step S21). The adjustment unit 42 stores the measured number of oscillation pulses of the first oscillation circuit 6 (step S22). The adjustment unit 42 measures the number of oscillation pulses of the second oscillation circuit 7 by the measurement unit 41 at the measurement time t0 + α obtained in the initial correction process (step S23). The adjustment unit 42 calculates a difference between the number of oscillation pulses of the second oscillation circuit 7 measured by the calculation unit 43 and the number of oscillation pulses of the first oscillation circuit 6 stored (step S24). The adjustment unit 42 ends the correction process and returns the process to the caller. The measurement time of the second oscillation circuit 7 is corrected so that the difference becomes 0 (step S25). The adjustment unit 42 sets, for example, t0 + α + β as the measurement time after the correction. When the number of pulses of the second oscillation circuit 7 is smaller than the number of oscillation pulses of the first oscillation circuit 6, β is set to a positive value. When the number of pulses of the second oscillation circuit 7 is larger than the number of oscillation pulses of the first oscillation circuit 6, β is set to a negative value. When the number of pulses of the second oscillation circuit 7 is equal to the number of oscillation pulses of the first oscillation circuit 6, β is set to zero. After step S25, measure the number of oscillation pulses of the first oscillation circuit 6 at the measurement time t0 + α, measure the number of pulses of the second oscillation circuit 7 at the measurement time t0 + α + β, and check whether the numbers of both pulses are equal You may If not equal, set β again. When β does not converge, the difference between the number of oscillation pulses and the predetermined value is set to the smallest value. Specifically, after step S25, the adjustment unit 42 determines whether the measured number of oscillation pulses of the first oscillation circuit 6 and the number of pulses of the second oscillation circuit 7 match. If the adjustment unit 42 determines that both pulse numbers match, the correction process ends. If the adjustment unit 42 determines that the numbers of pulses do not match, the process returns to step S21, and the process from step S21 is repeated. The measurement time at this time is t0 + α in the first oscillation circuit 6 (step S21), and is t0 + α + β in the second oscillation circuit 7 (step S23). In the same manner, while correcting the time of the second oscillation circuit 7, the number of oscillation pulses is corrected to be the same. Further, instead of correcting the measurement time of the second oscillation circuit 7, the measurement time of the first oscillation circuit 6 may be corrected.

  FIG. 18 is a flow chart showing an example of a processing procedure of forced correction processing. The forced correction process is a process of finally confirming the difference and forcibly setting the difference to 0 in the oscillation pulse number at the measurement time set in the correction process. The forced correction process is also performed in an environment where the magnetic permeability, which is the center of the measurement range, is measured using the reference magnetic plate as in the correction process. The adjustment unit 42 measures the number of oscillation pulses of the first oscillation circuit 6 by the measurement unit 41 at t0 + α (step S31). The adjustment unit 42 stores the measured number of oscillation pulses of the first oscillation circuit 6 (step S32). The adjustment unit 42 measures the number of oscillation pulses of the second oscillation circuit 7 by the measurement unit 41 at t0 + α + β (step S33). The adjustment unit 42 stores the measured number of oscillation pulses of the second oscillation circuit 7 (step S34). The adjustment unit 42 calculates the difference between the number of oscillation pulses of the first oscillation circuit 6 and the number of oscillation pulses of the second oscillation circuit 7 by the calculation unit 43 (step S35). After that, the difference is forced to be 0. By this processing, the value measured by the reference magnetic plate is set as the median value of the permeability (step S36). This process shows S52 to S57 described later.

  A series of flows of magnetic permeability correction processing (forced correction after correction) will be described using a flowchart. FIG. 19 is a flow chart showing an example of a processing procedure of forced correction after the correction of the permeability correction processing. The adjustment unit 42 sets the measurement time (first measurement time t1) of the first oscillation circuit 6 to t0 + α. The adjustment unit 42 sets the measurement time (second measurement time t2) of the second oscillation circuit 7 to t0 + α + β (step S51). The measurement unit 41 measures the number of oscillation pulses of the first oscillation circuit 6 at the first measurement time t1 (step S52). The measuring unit 41 stores the measured number of oscillation pulses of the first oscillation circuit 6 (step S53). The measurement unit 41 measures the number of oscillation pulses of the second oscillation circuit 7 at the second measurement time t2 (step S54). The measuring unit 41 stores the measured number of oscillation pulses of the second oscillation circuit 7 (step S55). The adjustment unit 42 corrects the number of oscillation pulses of the first oscillation circuit 6 or the number of oscillation pulses of the second oscillation circuit 7 using the difference (forced difference) obtained in the forced correction processing. If the number of oscillation pulses of the first oscillation circuit 6 is larger than the number of oscillation pulses of the second oscillation circuit 7 in the forced correction processing, the forcible difference is added to the value of the number of oscillation pulses of the second oscillation circuit 7. When the number of oscillation pulses of the first oscillation circuit 6 is smaller than the number of oscillation pulses of the second oscillation circuit 7, a forced difference is subtracted from the value of the number of oscillation pulses of the second oscillation circuit 7 (the difference is forcibly set to 0). Thus, the correction is completed (steps S56 and S57). By this processing, the measurement value of the reference magnetic plate is set as the median value of the magnetic permeability.

By performing the adjustment as described above, it is possible to suppress the fluctuation of the detection output due to the temperature fluctuation. In addition, as a result, compensation for differences in the characteristics of the first coil 1 and the second coil 2 at the time of formation as described above is also performed as a result. Therefore, in the magnetic permeability sensor 20 of the present invention, the magnetic permeability of the developer can be detected with high accuracy by suppressing the influence of the temperature fluctuation, and it is possible to obtain the accurate concentration of the toner.
The initial correction in step S1 and the forced correction in step S3 are not essential, and may be combined appropriately according to the required specifications.
When correction and forced correction are performed after the initial correction is performed, the measurement time of the reference coil (in this specification, the first coil 1) is fixed and the measurement time of the detection coil (in the present specification, the second coil 2) It is desirable to adjust the

  The following advantages are also provided in the present invention. Depending on the type of toner used, the control range of the toner concentration may change. In this case, the control range of the toner concentration is adjusted to an appropriate range for the toner to be used by externally controlling the voltage level of the unused terminal, for example, using the unused terminal of the microcomputer U1. Can provide an offset function.

  Further, in recent years, depending on the electrophotographic system, the particle size of the toner itself tends to be small in order to obtain high image quality. In addition, the amount of unnecessary toner is reduced as much as possible to reduce the cost and weight, and as a result, the change in the detectable permeability tends to be small. In order to accurately detect the reduced change in permeability, it is necessary to increase the measurement sensitivity by a method such as amplification in order to increase a small change in permeability. In this case, the change of the magnetic permeability may not be linear, which may make it impossible to accurately measure the magnetic permeability. According to the present invention, by using a method using software such as linear correction, it becomes possible to improve the deteriorated linearity, and it becomes possible to accurately grasp the change in permeability.

  Although FIG. 5 shows a microcomputer having eight terminals as an example, the present invention is not limited to this configuration. If necessary, microcomputers with different numbers of terminals can be used to transmit information such as permeability change to the upper control side by means such as serial communication, and to receive control signals from the upper side. is there.

  In the embodiment described above, the change in the inductance of the two coils (the first coil 1 and the second coil 2) coaxially disposed on the substrate 10 can be compared with the accuracy of the oscillator incorporated in the microcomputer (electronic chip 4). Detected as the difference between the number of oscillation pulses in the two oscillation circuits (the first oscillation circuit 6 and the second oscillation circuit 7) driven by various clock signals, and the difference (amount of change in the number of oscillation pulses) is calculated by the microcomputer Processing is to detect changes in permeability. Here, each of the two coils is alternately connected to the oscillation circuit, and the number of oscillation pulses is alternately measured by the microcomputer over a predetermined time, and the difference is calculated to detect the change in permeability. ing.

  In the present embodiment, since the first coil 1 and the second coil 2 are coaxially arranged on the upper and lower surfaces of the substrate 10, the area required for the arrangement of the coils can be reduced, and the narrowing in the horizontal direction can be achieved. . In addition, since the conductor pattern is printed on the substrate 10 to form the coil, the height can be reduced. Furthermore, since various processes are performed using a microcomputer, the number of parts can be reduced and the area for mounting circuit parts can be reduced. From the above, significant miniaturization of the permeability sensor can be realized.

  Since the measurement of the number of oscillation pulses in the two oscillation circuits is alternately performed, the measurement of the oscillation circuit including one coil is affected by the magnetic flux (inductance change in the other coil) generated in the other coil. Since the number of oscillation pulses can be accurately measured, the permeability can be detected with high accuracy.

  In the present embodiment, since the transistors and capacitors constituting the two oscillation circuits are shared, and the coils are disposed in each of the oscillation circuits, the number of parts can be reduced and cost can be reduced. In addition, since the number of parts is small, variations in part characteristics can be reduced, and further, the influence of disturbances such as temperature change and noise can be reduced, and accurate measurement can be performed.

  Since various processes are performed by software using a microcomputer, the number of circuit components as hardware can be reduced, and the influence of variations in characteristics of the circuit components is reduced. Moreover, since it processes by software, it becomes difficult to receive to the influence of environment (temperature, humidity, etc.). Thus, the accuracy of the detected permeability can be enhanced.

  In addition, even when the toner concentration to be set is different, it can be easily coped with by changing the contents of the software. Therefore, since management of each set value with different toner concentration is unnecessary, mass production becomes easy, and cost reduction can be achieved.

  Next, comparison of characteristics (detection of toner concentration) between the present invention example and the conventional example will be described. The magnetic permeability sensor (toner sensor) of the example of the present invention has the configuration shown in FIGS. 1 and 2 described above, and is attached to the developing unit as shown in FIG. 3 described above.

  FIG. 7 is a cross-sectional view showing an example of attachment of a conventional permeability sensor to a developing unit. In FIG. 7, the same or similar parts as in FIG. 3 are given the same reference numerals.

  A differential transformer 51 is provided on the upper surface side of one end of the substrate 10. The differential transformer 51 includes a drive coil to which an alternating current oscillation signal is applied, and a differential coil (a reference coil and a detection coil) coupled to the drive coil. A hole 33 is formed in the partition wall 30 at a position facing the differential transformer 51, and a part (detection coil side) of the differential transformer 51 protrudes from the hole 33, and the detection coil is used as a developer in the developing unit. It is designed to touch directly. A connector 3 is formed on the lower surface of the other end of the substrate 10 with a portion thereof protruding from the other end, and various circuit components 5 are mounted on the lower surface of the central portion of the substrate 10. The magnetic permeability sensor having such a configuration is attached to the recess 31 of the partition wall 30 in a state of being housed in the case 21.

  In the magnetic permeability sensor of the conventional example, since the differential transformer 51 protrudes, it is necessary to form the hole 33 in the partition wall 30, and there is a possibility that the developer may leak. Moreover, the magnetic permeability sensor of the conventional example has a large size as compared with the example of the present invention.

  FIG. 8 is a graph showing detection sensitivity characteristics of toner concentration in the present invention example and the conventional example. In FIG. 8, the horizontal axis represents the toner concentration, and the vertical axis represents the output voltage as the detection result of the magnetic permeability. Also, (a) and (b) in FIG. 8 show the characteristics of the example of the present invention and the conventional example, respectively.

  When the present invention example is compared with the conventional example, in the present invention example, the portion where the output voltage fluctuates linearly with respect to the change of the toner concentration is wider than the conventional example. Therefore, it is understood that the detection accuracy of the example of the present invention is superior to the detection accuracy of the conventional example.

  FIG. 9 is a graph showing control voltage characteristics for performing offset control in the example of the present invention and the conventional example. In FIG. 9, the horizontal axis represents the control voltage to be applied, and the vertical axis represents the output voltage. Also, (a) and (b) in FIG. 9 show the characteristics of the example of the present invention and the conventional example, respectively.

  When the present invention example and the conventional example are compared, in the conventional example, the output voltage fluctuates only partially in response to the change in the control voltage, whereas in the present invention example, the change in the control voltage On the other hand, the output voltage fluctuates linearly throughout. Therefore, it is understood that the precision of the offset control in the example of the present invention is superior to the precision of the conventional example.

  By the way, in the embodiment described above, the magnetic permeability sensor 20 is attached to the developing unit in a state of being housed in the case 21. However, in the present invention, there is no possibility that the developer leaks. good. In such a case, notches may be formed at a plurality of locations on the substrate 10, and the claws of the developing unit may be hooked on the notches to attach the permeability sensor 20 to the developing unit, or The magnetic permeability sensor 20 may be attached to the developing unit by bonding 30.

  In the embodiment described above, the conductor patterns are printed on the upper surface and the lower surface of the substrate 10 to form the first coil 1 and the second coil 2 coaxially, but the first coil 1 and the second coil are formed. The formation method of 2 is not limited to this, and may be another method. Hereinafter, these other methods will be described as modifications.

(First modification)
FIG. 10 is a cross-sectional view showing a configuration of a magnetic permeability sensor according to a first modification. In FIG. 10, the same or similar members as in FIGS. 1 and 2 are denoted by the same reference numerals. In the first modification, the first coil 1 and the second coil 2 are coaxially laminated on the lower surface of the substrate 10 by, for example, pattern printing of copper foil with an insulating layer interposed therebetween. In addition, no coil is formed on the upper surface of the substrate 10, and the electronic chip 4, the circuit component 5 and the connector 3 similar to those of the above-described embodiment are mounted. The first coil 1 and the second coil 2 are formed immediately below the mounting positions of the electronic chip 4 and the circuit component 5. Therefore, further miniaturization of the configuration of the magnetic permeability sensor can be achieved.

(2nd modification)
FIG. 11 is a cross-sectional view showing a configuration of a magnetic permeability sensor according to a second modification. In FIG. 11, the same or similar members as in FIGS. 1 and 2 are denoted by the same reference numerals. In the second modification, an air core coil of another part is mounted on the lower surface of one end of the substrate 10 to form the second coil 2, and the upper surface of one end of the substrate 10 is coaxial with the second coil 2. The air-cored coil of another part is mounted to form the first coil 1. In the remaining area of the upper surface of the substrate 10, the electronic chip 4, the circuit component 5 and the connector 3 similar to those of the above-described embodiment are mounted.

(Third modification)
FIG. 12 is a cross-sectional view showing a configuration of a magnetic permeability sensor according to a third modification. In FIG. 12, the same or similar members as in FIGS. 1 and 2 are denoted by the same reference numerals. In the third modification, two air-cored coils, which are separate components, are stacked and mounted on the upper surface of one end of the substrate 10 to form the first coil 1 and the second coil 2. In the remaining area of the upper surface of the substrate 10, the electronic chip 4, the circuit component 5 and the connector 3 similar to those of the above-described embodiment are mounted. Unlike the configuration shown in FIG. 12, the first coil 1 and the second coil 2 may be formed on the lower surface of the substrate 10 in a stacked configuration of two air core coils as described above.

(4th modification)
FIG. 13 is a cross-sectional view showing a configuration of a magnetic permeability sensor according to a fourth modification. In FIG. 13, the same or similar members as in FIGS. 1 and 2 are denoted by the same reference numerals. In the fourth modification, a plurality of chip coils are mounted on the lower surface of one end of the substrate 10 to form the second coil 2, and the upper surface of one end of the substrate 10 is coaxial with the second coil 2, A plurality of chip coils are mounted to form the first coil 1. In the remaining area of the upper surface of the substrate 10, the electronic chip 4, the circuit component 5 and the connector 3 similar to those of the above-described embodiment are mounted.

  In the present invention, the first coil and the second coil may be covered with an electrostatic shield. The coil described in the present invention uses an air core coil, and if there is a coil having a close dielectric constant in the vicinity of the coil, the measurement value may vary due to a change in capacitance. In such a case, by covering the coil with a shield member made of copper or the like, the influence from the outside can be suppressed. However, in the case of the magnetic permeability sensor of the present invention, it is conceivable that an eddy current is generated in the shield member due to a change in magnetic permeability, that is, a change in magnetic line of force, and this eddy current causes a measurement error in the magnetic permeability sensor. Therefore, it is necessary to provide a shield member in consideration of measures against eddy currents.

  FIG. 14A-C is a top view which shows the structure of the shield member suitable for the magnetic permeability sensor of this invention. In the example shown in FIG. 14A, a copper shield member 61 having a shape in which a plurality of comb teeth extend in the same direction is provided above the coil 60 formed on the substrate 10. The shield member 61 is grounded. Further, in the example shown in FIG. 14B, a copper shield member 62 having a shape in which a plurality of comb teeth are alternately extended in opposite directions is provided above the coil 60 formed on the substrate 10. The shield member 62 is grounded. By providing the shield member having such a configuration, the eddy current can be reduced.

  FIG. 14C shows an annular shield member. A shield member 63 in which a part of a copper ring is broken and made into a C shape is provided on the outer peripheral side of a coil 60 formed on the substrate 10. The shield member 63 is grounded. By providing the shield member 63, it is possible to reduce the eddy current. In the example of FIG. 14C, since the shield member 63 is provided on the same plane as the coil 60, the magnetic permeability sensor can be thinned. However, as compared with the mode in which the coil 60 is covered from the top as shown in FIGS. Shielding effect is small.

  The shield members as described above may be provided on both sides of the substrate 10, may be provided only on the side opposite to the developing unit, and as described above, the shield members are preferably grounded. However, the effect can be obtained even if it is not grounded.

  It should be understood that the disclosed embodiments are illustrative and non-restrictive in every respect. The scope of the present invention is indicated not by the above description but by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Reference Signs List 1 first coil 2 second coil 3 connector 4 electronic chip 5 circuit component 6 first oscillation circuit 7 second oscillation circuit 10 substrate 20 permeability sensor 41 measurement unit 42 adjustment unit 43 calculation unit 44 conversion unit

Claims (14)

In a permeability sensor for detecting the permeability of an object to be detected,
A first oscillation circuit that oscillates including a first coil that receives magnetism from the object to be detected;
A second oscillation circuit that oscillates including a second coil that receives magnetism from the object to be detected;
A measurement unit that measures the number of oscillation pulses in each of the first oscillation circuit and the second oscillation circuit;
An adjustment unit that adjusts at least one of measurement time of the number of oscillation pulses in the first oscillation circuit by the measurement unit, and measurement time of an oscillation frequency in the second oscillation circuit by the measurement unit;
A calculation unit that calculates the difference between the number of oscillation pulses measured by the measurement unit;
A conversion unit configured to convert the difference calculated by the calculation unit into a magnetic permeability.   The permeability according to claim 1, wherein the measurement unit is configured to alternately measure the number of oscillation pulses in the first oscillation circuit and the number of oscillation pulses in the second oscillation circuit. Sensor.   The permeability sensor according to claim 1, wherein the first coil and the second coil are coaxially disposed.   The magnetic permeability sensor according to any one of claims 1 to 3, wherein components of the first oscillation circuit and the second oscillation circuit are common except for the first coil and the second coil. .   The magnetic permeability sensor according to any one of claims 1 to 4, further comprising: a substrate on which the first coil is disposed on one side and the second coil is disposed on the other side. In a permeability detection method for detecting the permeability of an object to be detected,
The first coil and the second coil are arranged with different distances from the object to be detected.
Measuring the number of oscillation pulses of a first oscillation circuit oscillating including the first coil, and the number of oscillation pulses of a second oscillation circuit oscillating including the second coil;
Adjusting at least one of a first measurement time for measuring an oscillation frequency of the first oscillation circuit and a second measurement time for measuring an oscillation frequency of the second oscillation circuit;
Calculate the difference between the measured number of oscillation pulses,
A permeability detection method comprising converting the calculated difference into permeability.   The second measurement time is relatively longer than the first measurement time when the distance of the second coil from the detection object is shorter than the distance of the first coil from the detection object. The method according to claim 6, wherein at least one of the first measurement time and the second measurement time is adjusted. In a permeability sensor for detecting the permeability of an object to be detected,
A first oscillation circuit that oscillates including a first coil that receives magnetism from the object to be detected;
A second oscillation circuit that oscillates including a second coil that receives magnetism from the object to be detected;
A measurement unit that measures the number of oscillation pulses in each of the first oscillation circuit and the second oscillation circuit;
A first adjustment unit that adjusts a measurement time so that the number of oscillation pulses in the first oscillation circuit by the measurement unit becomes a predetermined value;
The measurement time of the oscillation pulse number in the first oscillation circuit adjusted by the first adjustment unit and / or the measurement time of the oscillation pulse number in the second oscillation circuit are each measured under a predetermined environment. A second adjustment unit that adjusts based on the number of oscillation pulses;
A calculation unit that calculates the difference between the number of oscillation pulses measured by the measurement unit in the measurement time after adjustment by the first adjustment unit and the second adjustment unit;
A conversion unit configured to convert the difference calculated by the calculation unit into a magnetic permeability.   The permeability sensor according to claim 8, wherein the second adjustment unit adjusts a measurement time of the number of oscillation pulses in the second oscillation circuit. After the adjustment of the measurement time by the first adjustment unit and the second adjustment unit, the calculation unit is adjusted by the first adjustment unit and the second adjustment unit by the measurement unit under a predetermined environment. Calculate the difference of the number of oscillation pulses measured in the measurement time,
A third adjustment unit for adjusting at least one of the number of oscillation pulses in the first oscillation circuit and the number of oscillation pulses in the second oscillation circuit based on the difference calculated by the calculation unit. The permeability sensor according to claim 8 or 9.   11. The permeability sensor according to claim 10, wherein the third adjustment unit adjusts the number of oscillation pulses in the second oscillation circuit. The permeability sensor according to any one of claims 8 to 11, wherein the predetermined environment is realized by using a reference magnetic plate. In a permeability detection method for detecting the permeability of an object to be detected,
The sensing coil and the reference coil are arranged with different distances from the object to be detected.
The number of oscillation pulses of a reference oscillation circuit that oscillates including the reference coil is measured in a predetermined initial measurement time,
Determining a first measurement time in which the initial measurement time is adjusted so that the measured number of oscillation pulses becomes a predetermined value;
After setting the same time as the determined first measurement time as the second measurement time and arranging the reference magnetic plate at a predetermined position near the detection coil,
Measuring the number of oscillation pulses of the reference oscillation circuit in the first measurement time and the number of oscillation pulses of the detection oscillation circuit that oscillates including the detection coil in the second measurement time;
Adjusting at least one of the first measurement time and the second measurement time based on the measured two oscillation pulse numbers;
Measuring an oscillation pulse number of the reference oscillation circuit in the first measurement time and an oscillation pulse number of the detection oscillation circuit in the second measurement time;
Calculate the difference between the measured number of oscillation pulses,
A permeability detection method comprising converting the calculated difference into permeability.   The magnetic permeability detection method according to claim 13, wherein the second measurement time is adjusted.

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