JP6572519B2 - Permeability detector, developing device and image forming apparatus - Google Patents

Description

  The present invention relates to a magnetic permeability detector, a developing device, and an image forming apparatus, and more particularly to adjustment of a temperature characteristic of a frequency of a detection signal output from a circuit.

  Based on the frequency of a signal output from an LC oscillation circuit using a coil formed on a plane, it is known that a sensor that detects the magnetic permeability of a space facing the plane on which the coil is formed is used ( For example, see Patent Document 1). In Patent Document 1, in an electrophotographic image forming apparatus, a sensor as described above is used as a sensor for detecting the concentration of a developer containing a magnetic substance in a container. Such a magnetic permeability sensor is based on the principle that the inductance of the coil changes depending on the magnetic permeability of the magnetic material to be detected. The magnetic permeability within the range where the magnetic flux of the magnetic permeability sensor acts by reading the oscillation frequency of the LC oscillation circuit for changes in physical properties such as magnetic permeability and electrical conductivity of the magnetic material and changes in the distance from the magnetic material. Can be detected. Japanese Patent Application Laid-Open No. H10-228867 discloses that a resistance component of the circuit is taken into consideration in addition to the elements of each element included in the circuit in order to enable a highly accurate design.

  The frequency of the signal output from the LC oscillation circuit is generally responsive to the environmental temperature. This is because the characteristics of each element constituting the circuit change according to the temperature. In the case of the LC oscillation circuit, it is known that the variation of the frequency with respect to the temperature when the temperature is on the horizontal axis and the frequency is on the vertical axis has a shape like a quadratic function having a negative coefficient.

  In order to improve the detection accuracy of the magnetic permeability, it is preferable to depend only on the magnetic permeability in a predetermined space region facing the coil surface within the range in which the magnetic flux of the magnetic permeability sensor acts. Therefore, it is preferable to minimize the frequency variation with respect to the temperature as described above, and adjustment of the temperature characteristics of the LC oscillation circuit is desired.

  As described above, the temperature characteristics of the oscillation frequency of the LC oscillation circuit are determined by the temperature characteristics of each component included in the circuit. However, since the coil and the capacitor generally included in the LC oscillation circuit affect the output frequency, it is optional. It is difficult to adjust to. According to the technique disclosed in Patent Document 1, the circuit resistance also affects the temperature characteristics of the frequency. However, since this circuit resistance is determined by the configuration of the entire circuit, it is also difficult to arbitrarily adjust the circuit resistance.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a magnetic permeability sensor capable of adjusting the temperature characteristics of an LC oscillation circuit.

In order to solve the above-described problem, an aspect of the present invention is a magnetic permeability detector using an LC oscillation circuit having a coil and a capacitor, and as a permeability detection unit in a resonance current loop in the LC oscillation circuit. said coil to comprise a serially connected resistor, said resistor, said the circuit resistance of the LC oscillator circuit is a further resistor, the on resistance of the circuit resistance, the predetermined that do not affect the inductance of the coil It arrange | positions so that resistance value may be added, It is characterized by the above-mentioned.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the magnetic permeability sensor which can adjust the temperature characteristic of LC oscillation circuit.

It is a figure which shows the function structure of the apparatus containing the magnetic permeability sensor which concerns on embodiment of this invention. It is a figure which shows the structure of the interface which processes the output signal of the magnetic permeability sensor which concerns on embodiment of this invention. It is a figure which shows the circuit structure of the magnetic permeability sensor which concerns on embodiment of this invention. It is a figure which shows the count aspect of the output signal of the magnetic permeability sensor which concerns on embodiment of this invention. It is a figure which shows the count aspect of the output signal of the magnetic permeability sensor which concerns on embodiment of this invention. It is a figure which shows the temperature characteristic of the oscillation frequency by the crystal oscillation circuit which concerns on embodiment of this invention. It is a figure which shows the temperature characteristic of the inductance of the coil which concerns on embodiment of this invention. It is a figure which shows the temperature characteristic of the capacity | capacitance of the capacitor | condenser which concerns on embodiment of this invention. It is a figure which shows the temperature characteristic of the resistance which concerns on embodiment of this invention. It is a perspective view which shows the external appearance of the magnetic permeability sensor which concerns on other embodiment of this invention. It is a figure explaining the magnetic flux which arises in the pattern resistance which concerns on embodiment of this invention. It is a figure which shows the difference of the temperature characteristic of the oscillation frequency by the some resistance value in the magnetic permeability sensor which concerns on embodiment of this invention. It is a figure which shows the formation aspect of the pattern resistance contained in the magnetic permeability sensor which concerns on embodiment of this invention. 1 is a diagram illustrating a mechanical configuration of an image forming apparatus including a developing device on which a magnetic permeability sensor according to an embodiment of the present invention is mounted. It is a perspective view which shows the developing device by which the magnetic permeability sensor which concerns on embodiment of this invention is mounted. It is a perspective view showing an outline of a magnetic permeability sensor concerning an embodiment of the present invention. It is a 6-face figure which shows the magnetic permeability sensor which concerns on embodiment of this invention. It is a figure which shows the mounting aspect to the developing device of the magnetic permeability sensor which concerns on embodiment of this invention. It is a figure which shows the example of the pattern resistance which concerns on other embodiment of this invention.

Embodiment 1 FIG.
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of a controller 1 of an apparatus including a magnetic permeability sensor 100 according to the present embodiment. As shown in FIG. 1, the controller 1 according to the present embodiment has the same configuration as an information processing apparatus such as a general PC (Personal Computer) or a server. That is, the controller 1 according to the present embodiment includes a CPU (Central Processing Unit) 10, a ROM (Read Only Memory) 20, a RAM (Random Access Memory Memory) 30, a DMA (Direct Memory Access Controller) 40, and an ASIC Accelerator Controller (ASIC). ) 50, an input / output control ASIC 60 and a crystal oscillation circuit 70.

  The CPU 10 is a calculation means and controls the operation of the entire controller 1. The ROM 20 is a read-only nonvolatile storage medium, and stores programs such as firmware. The RAM 30 is a volatile storage medium capable of reading and writing information at high speed, and is used as a work area when the CPU 10 processes information. The DMAC 40 controls direct access to the RAM 30 not via the CPU 10.

  The ASIC 50 functions as a connection interface between the system bus to which the CPU 10 and the RAM 30 are connected and other devices. The input / output control ASIC 60 acquires a detection signal output from the magnetic permeability sensor 100 and converts it into information that can be processed in the controller 1. That is, the magnetic permeability sensor 100 is used as a magnetic permeability detector. The crystal oscillation circuit 70 oscillates a reference clock for operating each device in the controller 1.

  FIG. 2 is a block diagram showing in detail the functional configuration of the input / output control ASIC 60 in the controller 1 according to the present embodiment. As shown in FIG. 2, the input / output control ASIC 60 according to the present embodiment includes a counter 61, a read signal acquisition unit 62, and a count value output unit 63. The magnetic permeability sensor 100 according to the present embodiment is an oscillation circuit that outputs a rectangular wave having a frequency corresponding to the magnetic permeability in a space to be detected. The counter 61 is a counter that increments, that is, increments a value in accordance with the rectangular wave output by the magnetic permeability sensor 100.

  The read signal acquisition unit 62 acquires a read signal that is an instruction to acquire the count value of the counter 61 from the CPU 10 via the ASIC 50. When the read signal is acquired from the CPU 10, the read signal acquisition unit 62 inputs a signal for causing the count value output unit 63 to output a count value. The count value output unit 63 outputs the count value of the counter 61 in accordance with the signal from the read signal acquisition unit 62.

  As shown in FIG. 2, the controller 1 includes a timer 11. The timer 11 outputs an interrupt signal to the CPU 10 every time the count value of the reference clock input from the crystal oscillation circuit 70 reaches a predetermined value. The CPU 10 outputs the above-described read signal in response to the interrupt signal input from the timer 11.

  Note that the CPU 10 accesses the input / output control ASIC 60 via, for example, a register. For this reason, the above-described read signal is performed by the CPU 10 writing a value in a predetermined register included in the input / output control ASIC 60. The count value is output by the count value output unit 63 when the count value is stored in a predetermined register included in the input / output control ASIC 60 and the CPU 10 acquires the value.

  Next, the internal configuration of the magnetic permeability sensor 100 according to this embodiment will be described with reference to FIG. As shown in FIG. 3, a magnetic permeability sensor 100 according to the present embodiment is an oscillation circuit based on a Colpitts type LC oscillation circuit, and includes a planar pattern coil 101 as a planar coil, a first capacitor 103 as a capacitor, A second capacitor 104, a feedback resistor 105, unbuffered ICs 106 and 107, and an output terminal 108 are included.

  The planar pattern coil 101 is a planar coil constituted by a conductive wire printed on a substrate constituting the magnetic permeability sensor 100, that is, a signal line. As shown in FIG. 3, the planar pattern coil 101 has an inductance L obtained by the coil. In the planar pattern coil 101, the value of the inductance L varies depending on the magnetic permeability of the space facing the plane on which the coil is formed. As a result, the magnetic permeability sensor 100 according to the present embodiment oscillates a signal having a frequency corresponding to the magnetic permeability of the space where the coil surfaces of the planar pattern coil 101 face each other. Here, the magnetic permeability of the space facing the plane on which the coil is formed is the magnetic permeability within the range in which the magnetic flux of the magnetic permeability sensor acts.

In addition, as a coil, as shown to Fig.10 (a), (b), the winding coil 1101 and the laminated chip coil 2101 can also be used. In the case of using the wound coil 1101, by superimposing winding a conductive wire, permeable to prevent or difference obliquely mounted on the sensor by the thickness of the magnetic permeability sensor 10 0 to definitive wound coil 1101 a winding coil 1101 the other part it may be such as providing a cover 1200 which covers the entire surface of the mounting side of the permeability sensor 10 0. Also in the case of using the laminated chip coil 2101, it is preferable to provide a cover 2200 as in the case of using the wound coil 1101.

  The first capacitor 103 and the second capacitor 104 are capacitors that together with the planar pattern coil 101 constitute a Colpitts LC oscillation circuit. Accordingly, the first capacitor 103 and the second capacitor 104 are connected in series with each other and are connected in parallel with the planar pattern coil 101. A resonance current loop is constituted by a loop constituted by the planar pattern coil 101, the first capacitor 103 and the second capacitor 104.

The feedback resistor 105 is inserted to stabilize the bias voltage. Due to the functions of the unbuffered IC 106 and the unbuffered IC 107, the fluctuation of the potential of a part of the resonant current loop is output from the output terminal 108 as a rectangular wave corresponding to the resonant frequency. With such a configuration, the magnetic permeability sensor 100 according to the present embodiment oscillates at a frequency corresponding to the inductance L, the capacitance C of the first capacitor 103 and the second capacitor 104, and a circuit resistance _RL described later.

  The electronic components including the first capacitor 103, the second capacitor 104, the feedback resistor 105, the unbuffer ICs 106 and 107, and the output terminal 108 described above are opposite to the surface on the side where the planar pattern coil 101 of the substrate is formed. It is preferable to be provided on the side surface. Moreover, in order not to form an unnecessary convex part on the surface on which the planar pattern coil 101 is formed, it is preferable that the electronic component is an SMT (Surface Mount Technology) product.

  When a lead wire type electronic component such as an axial type is used, a through hole called a through hole is formed in the substrate, and the lead wire is soldered to the through hole. As a result, the tip of the lead wire after cutting of the lead wire and the bulge of the solder are formed on the formation surface of the flat pattern coil 101, and the flatness is lost, resulting in unevenness, and a detection error occurs because it cannot be accurately attached. This is because there is a risk of losing.

The inductance L also changes depending on the presence and concentration of the magnetic material in the vicinity of the planar pattern coil 101 as a planar coil. Therefore, the permeability in the space near the planar pattern coil 101 can be detected by the oscillation frequency of the permeability sensor 100. In addition, as shown in FIG. 3, in designing the oscillation frequency of the magnetic permeability sensor 100 with high accuracy, the circuit resistance _RL generated by a conducting wire constituting the circuit, that is, a signal line cannot be ignored. The frequency corresponding to the parameter value of each part constituting the magnetic permeability sensor 100 will be described in detail later.

  FIG. 4 is a diagram showing an aspect of the count value of the magnetic permeability sensor 100 counted by the function of the input / output control ASIC 60 according to the present embodiment. If there is no change in the concentration of the magnetic substance present around the magnetic permeability sensor 100, the magnetic permeability sensor 100 continues to oscillate at the same frequency in principle. As a result, as shown in FIG. 4, the count value of the counter 61 increases uniformly with time.

When an interrupt signal is input from the timer 11 to the CPU 10, the CPU 10 outputs a read signal to the input / output control ASIC 60, and the count value of the counter 61 at that timing is acquired by the CPU 10. As shown in FIG. 4, at t ₁ , t ₂ , t ₃ , t ₄ , and t ₅ , count values such as aaaah, bbbbh, cccch, ddddh, AAAAh are acquired.

When the CPU 10 acquires the count value at each timing, the CPU 10 calculates the frequency in each of the periods T ₁ , T ₂ , T ₃ , and T ₄ shown in FIG. The timer 11 according to the present embodiment outputs an interrupt signal when a reference clock corresponding to 2 (msec) is counted. Therefore, the CPU 10 divides the count value of the counter 61 in each period by 2 (msec) to thereby oscillate the permeability sensor 100 in each period T ₁ , T ₂ , T ₃ , T ₄ shown in FIG. f (Hz) is calculated.

Moreover, as shown in FIG. 4, the upper limit of the count value of the counter 61 according to the present embodiment is FFFFh. Therefore, CPU 10 may, when calculating the frequency in the period _{T 4,} a value obtained by subtracting ddddh from FFFFh, calculates the oscillation frequency f (Hz) by dividing the sum of the values of the AAAAh in 2 (msec).

  FIG. 5 is a diagram showing another aspect of the count value of the magnetic permeability sensor 100 counted by the function of the input / output control ASIC 60 according to the present embodiment. In the case of FIG. 5, in the input / output control ASIC 60, the counter 61 resets the count value after the count value is read by the count value output unit 63. In this reset process, the count value output unit 63 may input a reset signal to the counter 61 after reading the count value, or as a specification of the counter 61, the count value is reset each time the count value is read. A function may be provided.

In the case of the aspect of FIG. 5, the count value acquired at each timing is a value counted within each period T ₁ , T ₂ , T ₃ , T ₄ . Therefore, the CPU 10 calculates the oscillation frequency f (Hz) by dividing the count value acquired at each timing by 2 (msec).

  Thus, in the controller 1 according to the present embodiment, the frequency of the signal oscillated by the magnetic permeability sensor 100 is acquired, and an event corresponding to the oscillation frequency of the magnetic permeability sensor 100 can be determined based on the acquisition result. it can. In the magnetic permeability sensor 100 according to the present embodiment, the inductance L changes in accordance with the concentration of the magnetic material existing in the space where the coil surfaces of the planar pattern coil 101 face each other, and as a result, is output from the output terminal 108. The frequency of the signal changes. As a result, the controller 1 can detect the concentration of the magnetic material existing in the space where the coil surfaces of the planar pattern coil 101 face each other.

  Such a magnetic permeability sensor 100 oscillates at a frequency corresponding to the concentration of the magnetic material in a predetermined space as described above. The crystal oscillation circuit 70 oscillates at a predetermined frequency. The magnetic permeability sensor 100 and the crystal oscillation circuit 70 have a temperature characteristic in which the oscillation frequency varies according to the temperature of the usage environment. FIG. 6 is a diagram showing a temperature characteristic graph of the crystal oscillation circuit 70 which is a tuning fork type. The broken line shown in FIG. 6 is an example of the adjustment range of the oscillation frequency. As shown by a solid line and a broken line in FIG. 6, the crystal oscillation circuit 70 has a parabolic temperature characteristic having a certain temperature as a peak.

  In the controller 1, in order to detect the concentration of the magnetic material in a predetermined space with high accuracy based on the frequency of the signal oscillated by the magnetic permeability sensor 100, the oscillation frequency of the magnetic permeability sensor 100 and the crystal oscillation circuit according to the temperature variation. The relative change in the oscillation frequency of 70 is preferably as small as possible. As described above, the calculation of the oscillation frequency in the controller 1 is performed by obtaining a count value every 2 (msec) counted by the timer 11 and dividing the count value by 2 (msec).

  Here, since the timer 11 counts 2 (msec) based on the reference clock input from the crystal oscillation circuit 70, if the oscillation frequency of the crystal oscillation circuit 70 fluctuates due to temperature characteristics as shown in FIG. As long as the count values for (msec) are the same, the count period for 2 (msec) varies. As a result, an error occurs in the oscillation frequency of the magnetic permeability sensor 100 calculated by the CPU 10.

  On the other hand, if the temperature characteristic of the magnetic permeability sensor 100 is similar to the temperature characteristic of the crystal oscillation circuit 70 as shown in FIG. 6, it is possible to cancel the oscillation frequency calculation error as described above. is there. That is, even if the oscillation frequency of the crystal oscillation circuit 70 varies due to temperature variation, if the oscillation frequency of the magnetic permeability sensor 100 also varies in the same way, the count counted by the counter 61 in the count period of 2 (msec). Since the fluctuation of the value is reduced, the error of the oscillation frequency of the finally calculated permeability sensor 100 can be reduced.

  In this way, the concentration of the magnetic material in the predetermined space can be detected with high accuracy based on the frequency of the signal oscillated by the magnetic permeability sensor 100. Therefore, it is required that the temperature characteristic of the oscillation frequency of the magnetic permeability sensor 100 can be adjusted to be similar to the temperature characteristic of the oscillation frequency of the crystal oscillation circuit 70.

  Here, a characteristic configuration of the magnetic permeability sensor 100 according to the present embodiment will be described below. The magnetic permeability sensor 100 applies a power supply voltage to cause a current to flow through the planar pattern coil 101. This current generates a magnetic flux in a predetermined direction, and outputs a signal having a frequency corresponding to the magnetic permeability within the range in which the magnetic flux acts. It is configured to output from the terminal 108.

First, the oscillation frequency of the LC oscillation circuit will be described. When considering the circuit resistance RL generated by the conducting wire or the like constituting the circuit, the oscillation frequency f ₀ of the LC oscillation circuit is expressed by the following equation (1).

Therefore, the oscillation frequency of the magnetic permeability sensor 100 is a function of the inductance L obtained by the planar pattern coil 101 as a planar coil, the capacitance C of the first capacitor 103 and the second capacitor 104 as capacitors, and the circuit resistance _RL . It is represented by Therefore, in order to adjust the temperature characteristics of the oscillation frequency of the magnetic permeability sensor 100, the temperature characteristics of the parameters “L”, “C”, and “R _L ” included in the above equation (1) should be taken into consideration. It will be adjusted. FIG. 7 is a graph showing a temperature characteristic graph of the inductance L of the planar pattern coil 101. As shown in FIG. 7, the inductance L of the planar pattern coil 101 has a characteristic that the printed circuit board expands as the temperature rises, whereby the coil dimension increases and the inductance increases.

FIG. 8 is a graph showing a temperature characteristic graph of the capacitance C of the first capacitor 103 and the second capacitor 104. As shown in FIG. 8, the capacitance C of the first capacitor 103 and the second capacitor 104 has a characteristic of decreasing as the temperature rises. FIG. 9 is a graph showing a temperature characteristic graph of the circuit resistance _RL . As shown in FIG. 9, the circuit resistance _RL has a characteristic that increases as the temperature rises.

  If each parameter can be adjusted while taking into consideration the temperature characteristics of each component of the magnetic permeability sensor 100, the fluctuation of the oscillation frequency with respect to the temperature change of the magnetic permeability sensor 100 can be adjusted, The temperature characteristics can be adjusted to match the temperature characteristics of the crystal oscillation circuit 70 described with reference to FIG.

However, the parameters “L”, “C”, and “R _L ” included in the above formula (1) have a predetermined correlation on the assumption that the function as the magnetic permeability sensor is established. It was difficult to adjust each independently. Specifically, the circuit resistance _RL is affected by the length of the conductive wire that changes according to the number of coil turns of the planar pattern coil 101, and the inductance L of the planar pattern coil 101 is determined according to the number of coil turns. The number of turns has a correlation that affects the sensing function of the magnetic permeability sensor 100 , that is, the detection function.

Therefore, in the magnetic permeability sensor 100 according to the present embodiment, as shown in FIG. 3, an adjustment resistance portion as a resistance that does not affect the coil inductance L of the planar pattern coil 101 is provided by the pattern resistance 102 to adjust the circuit resistance _RL . adjustably configured by the resistance value R _P of the resistor portion. By providing this adjustment resistor section, the circuit resistance _RL can be adjusted independently so as not to affect the inductance L of the coil, so that it does not affect the sensing function of the magnetic permeability sensor 100, that is, the detection function. In addition, the temperature characteristics can be adjusted.

  The pattern resistor 102 as the adjustment resistor unit according to the present embodiment, together with the planar pattern coil 101, the first capacitor 103, and the second capacitor 104, forms a resonance current loop in the Colpitts LC oscillation circuit of the permeability sensor 100. It is provided in series with the planar pattern coil 101 and in parallel with the first capacitor 103 and the second capacitor 104. In the present embodiment, the pattern resistor 102 is used as the adjustment resistor unit. However, as shown in FIG. 10A, it is also possible to use a single resistor element 1102 having a small variation in temperature characteristics among components.

  A pattern resistance 102 as a planar resistance which is an adjustment resistance portion of the magnetic permeability sensor 100 in the present embodiment is a planar resistance in which a conductive wire is printed on a substrate in the same manner as the planar pattern coil 101. The pattern resistor 102 can be formed in various shapes such as a straight line or a curved line. However, since the corresponding length is required to function as a resistor, the sensor becomes large.

Actually, it is necessary to arrange a conductive wire having a length that functions as a resistor in a region excluding the planar pattern coil 101 as a planar coil within a limited area on the substrate. Therefore, the pattern resistor 102 as an adjustment resistor portion in the present embodiment, one from the head to the other on the substrate, it suited to one from the other, folded so as to reciprocate for a plurality of times a given direction as will gutter Formed.

  Specifically, as shown in FIG. 11, a shape composed only of a straight line and a right angle, as shown in FIG. 19 (a), a sine curve-like curve shape, and as shown in FIG. 19 (b), from a straight line and an acute angle. As shown in FIGS. 19 (c) and 19 (d), the shape shown in FIGS. 19 (a) and 19 (b) can be used in which the angles of the peaks and valleys are inclined. In this way, the shape bent so as to reciprocate in a predetermined direction a plurality of times may be hereinafter referred to as a zigzag folded shape.

  The planar pattern coil 101 and the pattern resistor 102 are formed by the following process. First, copper foil is plated with a predetermined thickness on the front and back of a printed board which is a glass epoxy board. As the glass epoxy substrate, for example, FR-4, CEM-3 or the like can be used. Then, a dry film having a property of curing when exposed to light is coated thereon, and two layers of different materials are attached to the front and back surfaces of the glass epoxy substrate. Then, a mask pattern film on which a circuit pattern is laid out is brought into close contact with the dry film, and further fixed by increasing the degree of contact by vacuum suction.

  After that, when light is exposed from the top with a predetermined wavelength, light amount and exposure time, the part with the mask is blocked by light and the dry film does not cure, while the dry film in the part exposed to light cures. To expose the substrate in the etchant. Then, the portion with the mask, that is, the uncured portion of the dry film is dissolved by the etching solution, and at the same time, the copper foil portion below the portion is dissolved and disappears. The unmasked portion exposed to light remains without being dissolved in the etching solution by the curing action of the dry film, and at the same time, the copper foil remains as it is.

  Subsequently, by removing the dry film, only a fine pattern of a copper foil pattern having a width of about 100 μm remains on the substrate. Finally, if necessary, a resist coating solution having a constant thickness is applied to the entire surface and thermally cured to prevent oxidation of the copper foil or pattern loss due to scratches. As described above, the planar pattern coil 101 and the pattern resistor 102 can be formed on the printed board.

  If the planar pattern coil 101 is disposed on the back surface of the substrate and the pattern resistor 102 is disposed on the surface of the substrate, the substrate is exposed to different etching solutions across the substrate in the printed circuit board manufacturing process described above. This is because etching is performed in a large container, but the concentration of the etching solution changes between the back and the surface when viewed partially. As a result, a difference appears in the etching conditions. Therefore, it is conceivable that the remaining dry film width, that is, the copper foil pattern width is slightly different between the front and back surfaces, and the temperature characteristics of the oscillation frequency of the magnetic permeability sensor 100 may be shifted from the target.

  In order to eliminate such a manufacturing variation factor, in the magnetic permeability sensor 100 according to the present embodiment, the planar pattern coil 101 and the pattern resistor 102 are provided on the same substrate surface of the printed circuit board. In addition, the electronic components such as the first capacitor 103 and the second capacitor 104 have a board surface on the printed circuit board on which the planar pattern coil 101 and the pattern resistor 102 are provided in order to accurately attach the planar pattern coil 101 to the detection target. Are provided on the opposite substrate surface.

Also, considering the resistance value R _P of the resistor unit 102, the oscillation frequency f of the LC oscillation circuit according to the present embodiment is expressed by the following equation (2).

As described above _{"R L", "L"} , the adjustment of the value of "C" is difficult, R _P is able to adjust independently of other parameters. As described in FIG. 9, the response of resistance to commonly temperature variations because of the proportional relationship, the resistance value R _P of the adjusting resistor unit acts in a direction to decrease the oscillation frequency f in response to an increase in temperature.

Here, the resistance value R _P by the pattern resistor 102 as planar resistor is adjusted resistance of the resistor in the present embodiment, a configuration for adjusting so as not to affect the inductance L of the plane pattern coil 101 as the planar coil Figure This will be described with reference to 11 (a) to (c).

  FIG. 11A is a diagram showing how the pattern resistor 102 is formed, and FIG. 11B is a cross-sectional view taken along the cutting line AA in FIG. As shown in FIG. 11B, when a current flows through the pattern resistor 102, a magnetic flux around the conductor as shown by a broken line in the figure is generated according to the ampere right-hand rule. Since the magnetic flux between adjacent patterns is strengthened, as indicated by the solid line in FIG. 11B, the magnetic flux in the direction perpendicular to the surface on which the zigzag pattern is formed is between the adjacent patterns. Will occur.

  However, as shown in FIG. 11 (b), the magnetic flux generated between the first adjacent conductors and the magnetic flux generated between the next adjacent conductors are in opposite directions, and in order Since they occur in different directions, the magnetic fluxes that are opposite to each other cancel each other. Therefore, the magnetic flux in the direction perpendicular to the surface on which the zigzag pattern is formed is canceled as a whole of the zigzag pattern resistor 102.

Therefore, the zigzag pattern resistance 102 substantially generates a magnetic flux in the direction perpendicular to the surface on which the zigzag pattern is formed, which is the same direction as the direction in which the magnetic flux of the planar pattern coil 101 is generated. Will not. Therefore, zigzag-shaped pattern resistor 102 can be considered without being affected by the ambient magnetic permeability, as no resistance R _P of the sensing function for permeability. In other words, it can be said that the resistance value does not affect the inductance L of the planar pattern coil 101.

  In addition, regarding the zigzag folded pattern resistor 102, magnetic fluxes that are opposite to each other by forming a zigzag folded shape having symmetry so that the number of times of folding from one to the other and the number of times of folding from the other to the same are the same. Can be matched. Specifically, as shown in FIG. 11C, the zigzag pattern resistor 102 is in relation to the midpoint of the line segment connecting one end and the other end of the pattern resistor 102 connected to the LC oscillation circuit. It is a point target.

  Various patterns of the zigzag pattern resistor 102 can be conceived as shown in FIGS. 16 and 19A to 19D. However, as shown in FIG. 16, adjacent conductors are parallel to each other. The folded structure is excellent in terms of canceling the magnetic flux.

The magnetic permeability sensor 100 according to the present embodiment is provided with a printed wiring portion 102 ′ for inspection having the same shape as the pattern resistor 102 on the substrate surface opposite to the substrate surface on which the pattern resistor 102 is provided. Te Yes, by measuring the resistance of the test printed circuit portion 102 ', and determines the resistance value R _P of the pattern resistors 102. If the resistance value of the pattern resistor 102 is directly set, the pattern resistor 102 made of fine printed wiring is damaged, or the flat pattern coil 101 which is a flat coil provided on the same substrate surface as the pattern resistor 102 is damaged. This is because there is a fear.

Here, in the circuit shown in FIG. 3, the resistance value RP of the pattern resistor 102 is changed variously, and the results of measuring the change in the oscillation frequency of the magnetic permeability sensor 100 with respect to the temperature change are shown in FIGS. Shown in In FIGS. 12A to 12D, R _P1 <R _P2 <R _P3 <R _P4 . As shown in FIGS. 12A to 12D, the oscillation frequency of the magnetic permeability sensor 100 changes in a parabolic shape with respect to temperature fluctuation. Then, as the resistance value R _P of the pattern resistors 102 is large, the peak of the oscillation frequency, temperature i.e. an extreme value moves to the low temperature side. Therefore, it can be seen that the temperature characteristic of the oscillation frequency of the magnetic permeability sensor 100 can be adjusted by adjusting the resistance value RP of the pattern resistor 102.

Here will be described a method of adjusting the resistance value R _P of the pattern resistors 102. FIGS. 13A to 13D are diagrams showing how the pattern resistors 102 corresponding to R _{P1 to} R _P4 shown in FIGS. 12A to 12D are formed. As shown in FIGS. 13A to 13D, the resistance value of the zigzag pattern resistor 102 is increased by increasing the number of zigzag folds, that is, the number of times of reciprocation from one to the other and from the other to the other. it is possible to increase the R _P.

In other words, by increasing the number of folding of zigzag, it is possible to increase the resistance value R _P added to the circuit resistance R _L. The peak of the oscillation frequency of the magnetic permeability sensor 100, that is, the extreme temperature can be moved to the low temperature side without affecting the inductance L of the planar pattern coil 101.

  As described above, the temperature characteristic of the oscillation frequency of the magnetic permeability sensor 100 can be adjusted and created so as to be similar to the temperature characteristic of the oscillation frequency of the crystal oscillation circuit 70 obtained in advance. . If such a permeability sensor 100 is used, even if the oscillation frequency of the crystal oscillation circuit 70 varies due to temperature variations, the oscillation frequency of the permeability sensor 100 also varies in the same manner. An error of 100 oscillation frequencies can be reduced.

  Therefore, the magnetic permeability (concentration of the magnetic material) within a range where the magnetic flux of the magnetic permeability sensor 100 acts (within a predetermined space region facing the coil surface of the planar pattern coil 101) can be detected with high accuracy.

Assuming a temperature range of 10 to 50 (° C.) as the temperature range in the usage environment of the magnetic permeability sensor 100, the fluctuation of the oscillation frequency of the crystal oscillation circuit 70 was measured, and ± 10 to 40 (ppm: part per million) It was the result. Then, the peak temperature of the parabola in the temperature characteristic of the crystal oscillation circuit 70 shown in FIG. 6, such that the peak temperature of the parabola in the temperature characteristics of the magnetic permeability sensor 100 matches, adjusting the resistance value R _P of the pattern resistors 102 As a result, when 0.3 (Ω), the two could be almost matched.

  The fluctuation of the oscillation frequency in the range of 10 to 50 (° C.) of the magnetic permeability sensor 100 thus produced results in ± 37 (ppm), and ± 10 to 40 which is the fluctuation range of the frequency of the crystal oscillation circuit 70. (Ppm) was almost matched.

As described above, in the present embodiment, in the resonance current loop in the Colpitts LC oscillation circuit, the pattern resistor 102 as the adjustment resistor unit is provided in series with the planar pattern coil 101 as the detection unit. Thus, it is possible to provide a magnetic permeability sensor that can be adjusted to match the temperature characteristic of the oscillation frequency with the temperature characteristic of the oscillation circuit that outputs the signal.

Embodiment 2. FIG.
In the present embodiment, the magnetic permeability sensor 100 described in the first embodiment is placed in a toner container that is a developer filled in a developing unit that develops an electrostatic latent image in an electrophotographic image forming apparatus. As an example, a case where the sensor is used as a sensor for measuring the concentration of the liquid will be described. FIG. 14 is a side view showing a mechanism for image formation output included in the image forming apparatus 200 according to the present embodiment.

  As shown in FIG. 14, the image forming apparatus 200 according to the present embodiment includes a configuration in which image forming units 206 </ b> K to 206 </ b> Y for each color are arranged along a conveyor belt 205 that is an endless moving unit. It is said to be a tandem type. That is, along the transport belt 205, which is an intermediate transfer belt on which an intermediate transfer image is formed to be transferred from a paper feed tray 201 to a sheet (an example of a recording medium) 204 separated and fed by a paper feed roller 202. A plurality of image forming units (electrophotographic process units) 206Y, 206M, 206C, and 206K (hereinafter collectively referred to as image forming unit 206) are arranged in order from the upstream side of the conveying belt 205 in the conveying direction.

  The paper 204 fed from the paper feed tray 201 is stopped once by the registration rollers 203 and sent out to the image transfer position from the transport belt 205 in accordance with the image formation timing in the image forming unit 206.

  The plurality of image forming units 206Y, 206M, 206C, and 206K have the same internal configuration except that the colors of toner images to be formed are different. The image forming unit 206K forms a black image, the image forming unit 206M forms a magenta image, the image forming unit 206C forms a cyan image, and the image forming unit 206Y forms a yellow image. In the following description, the image forming unit 206Y will be described in detail. However, since the other image forming units 206M, 206C, and 206K are the same as the image forming unit 206Y, the image forming units 206M, 206C, and 206K. For each of these components, instead of Y added to each component of the image forming unit 206Y, only the symbols distinguished by M, C, and K are displayed in the figure, and the description thereof is omitted.

  The conveyor belt 205 is an endless belt, that is, an endless belt that is stretched between a driving roller 207 and a driven roller 208 that are rotationally driven. The drive roller 207 is driven to rotate by a drive motor (not shown), and the drive motor, the drive roller 207, and the driven roller 208 function as a drive unit that moves the conveyance belt 205 that is an endless moving unit. .

At the time of image formation, the first image forming unit 206Y transfers a yellow toner image to the conveyance belt 205 that is rotationally driven. The image forming unit 206Y includes a photoconductor drum 209Y as a photoconductor, a charger 210Y disposed around the photoconductor drum 209Y, an optical writing device 211, a developing device 212Y, a photoconductor cleaner 213Y, and a static eliminator (not shown). ) Etc. The optical writing device 211 is configured to irradiate the respective photoconductive drums 209Y, 209M, 209C, and 209K (hereinafter collectively referred to as “photosensitive drum 209”).

  In the image formation, the outer peripheral surface of the photosensitive drum 209Y is uniformly charged by the charger 210Y in the dark, and then writing is performed by light from the light source corresponding to the yellow image from the optical writing device 211. An electrostatic latent image is formed. The developing device 212Y visualizes the electrostatic latent image with yellow toner, thereby forming a yellow toner image on the photosensitive drum 209Y.

  This toner image is transferred onto the conveyance belt 205 by the action of the transfer unit 215Y at a position (transfer position) where the photosensitive drum 209Y and the conveyance belt 205 are in contact with or closest to each other. By this transfer, an image of yellow toner is formed on the conveyor belt 205. After the transfer of the toner image is completed, the photosensitive drum 209Y is wiped away with unnecessary toner remaining on the outer peripheral surface by the photoconductor cleaner 213Y, and then is neutralized by the static eliminator and stands by for the next image formation.

  As described above, the yellow toner image transferred onto the conveying belt 205 by the image forming unit 206Y is conveyed to the next image forming unit 206M by driving the rollers of the conveying belt 205. In the image forming unit 206M, a magenta toner image is formed on the photosensitive drum 209M by a process similar to the image forming process in the image forming unit 206Y, and the toner image is superimposed and transferred onto the already formed yellow image. Is done.

  The yellow and magenta toner images transferred onto the conveyance belt 205 are further conveyed to the next image forming units 206C and 206K, and the cyan toner image formed on the photosensitive drum 209C and the photosensitive drum are subjected to the same operation. The black toner image formed on the body drum 209K is superimposed on the already transferred image and transferred. Thus, a full-color intermediate transfer image is formed on the conveyance belt 205.

  The sheets 204 stored in the sheet feeding tray 201 are sent out in order from the top, and the intermediate transfer image formed on the conveyance belt 205 is transferred at a position where the conveyance path is in contact with or closest to the conveyance belt 205. It is transferred onto the paper. As a result, an image is formed on the paper surface of the paper 204. The sheet 204 on which the image is formed on the sheet surface is further conveyed, and after the image is fixed by the fixing device 216, the sheet 204 is discharged outside the image forming apparatus.

  Further, a belt cleaner 218 is provided for the conveyor belt 205. As shown in FIG. 14, the belt cleaner 218 is a cleaning blade pressed against the conveyor belt 205 on the downstream side of the transfer position of the image from the conveyor belt 205 to the paper 204 and upstream of the photosensitive drum 209. And a toner removing unit that scrapes off toner adhering to the surface of the transport belt 205.

  The image forming apparatus 200 having such a configuration is controlled and driven by the controller 1 described with reference to FIG. In the configuration illustrated in FIG. 14, the magnetic permeability sensor 100 according to the present embodiment is provided in the developing device 212.

  Next, the configuration of the developing device 212 as the developing device according to the present embodiment will be described with reference to FIG. FIG. 15 is a perspective view showing an overview of the developing device 212. 15 shows the state in which the developing device 212 is mounted on the image forming apparatus 200, that is, the state in which the developing device 212 is used in an upside down manner. The longitudinal direction of the developing device 212 shown in FIG. 15 is a direction perpendicular to the drawing of FIG. 14, that is, a main scanning direction parallel to the belt surface of the conveying belt 205 and perpendicular to the conveying direction of the belt.

  As shown in FIG. 15, the developing device 212 is provided with conveying screws 212b and 212c for conveying the developer filled therein. When the conveying screws 212b and 212c are rotated in opposite directions, the developer filled therein is spread over the entire longitudinal direction described above inside the developing device 212. That is, the entire inside of the developing device 212 can be used as a developer accommodating portion.

  The developer transported by the transport screws 212b and 212c inside the developing device 212 is transferred from the transport path by the transport screw 212b to the transport path by the transport screw 212c at the end in the longitudinal direction. Accordingly, the space in which the developer moves between the respective conveyance paths at the end portion in the main scanning direction of the developing device 212 (hereinafter referred to as “developer movement space”) is the space where the developer is most concentrated. The magnetic permeability sensor 100 according to this embodiment is attached to a sensor attachment position 212a shown in FIG. 15 in order to detect the developer concentration in the developer movement space. Here, the developer concentration is the concentration of toner as a developer contained in the developer. Thereby, the magnetic permeability sensor 100 is used as a developer concentration detector. In other words, the developer concentration detector is a developer concentration detector.

  The reason why the magnetic permeability sensor 100 is attached to the position 212a facing the developer movement space will be described. The amount of change in the magnetic permeability increases as the developer density increases. Therefore, the magnetic permeability sensor 100 is attached at a position facing the developer moving space where the developer is most densely packed, so that the magnetic permeability of the space inside the developing device 212 can be detected more suitably. .

  Although the change in the magnetic permeability is large or small, the magnetic permeability sensor 100 does not necessarily have to be attached to the position 212a because the magnetic permeability is generated in any space filled with the developer. The magnetic permeability sensor 100 applies a power supply voltage to cause a current to flow through the planar pattern coil 101. This current generates a magnetic flux in a predetermined direction, and outputs a signal having a frequency corresponding to the magnetic permeability within the range in which the magnetic flux acts. It is configured to output from the terminal 108. Therefore, the magnetic permeability sensor 100 can detect the magnetic permeability no matter where it is attached as long as it is attached so that the magnetic flux of the planar pattern coil 101 acts in the space filled with the developer.

  Next, an overview of the magnetic permeability sensor 100 according to the present embodiment will be described. FIG. 16 is a perspective view showing an overview of the magnetic permeability sensor 100 according to the present embodiment. In FIG. 16, the substrate surface on which the planar pattern coil 101 as the planar coil and the pattern resistor 102 as the planar resistance are formed, that is, the detection surface facing the space where the magnetic permeability should be detected is directed to the upper surface. .

  As shown in FIG. 16, the pattern resistor 102 connected in series with the planar pattern coil 101 is printed on the detection surface provided with the planar pattern coil 101. As described with reference to FIG. 3, the planar pattern coil 101 is composed of a conductive wire as a signal line that is spirally printed on the substrate. The pattern resistor 102 is composed of a conductive wire as a signal wire printed in a zigzag pattern on the substrate, and the function of the magnetic permeability sensor 100 as described above is realized by these patterns. As shown in FIG. 16, a visually interesting pattern is obtained.

  The planar pattern coil 101 is a magnetic permeability detection unit in the magnetic permeability sensor 100 according to the present embodiment. When the magnetic permeability sensor 100 is attached to the developing device 212, the detection unit is attached so as to face the developer movement space described above. In other words, the magnetic permeability sensor 100 generates a magnetic flux toward the moving space described above, and the developing device 212 is configured so that at least a part of the moving space is included in a range in which the magnetic flux acts. Attached.

  FIGS. 17A to 17E are six views showing the magnetic permeability sensor 100 according to this embodiment. As shown in FIGS. 17B to 17D, the first capacitor 103, the second capacitor 104, the feedback resistor 105, the unbuffered ICs 106 and 107, and the output terminal 108 described in FIG. The substrate to be formed is formed on the substrate surface opposite to the substrate surface on which the planar pattern coil 101 and the pattern resistor 102 are provided.

  As a result, the unevenness of the surface of the magnetic permeability sensor 100 on the side attached to the developing device 212 can be almost eliminated. Therefore, the surface of the substrate on which the planar pattern coil 101 which is a portion that exhibits the sensing function in the magnetic permeability sensor 100 is provided. It is possible to install the magnetic permeability sensor 100 with the substrate surface in contact with the developer movement space described above for detecting the magnetic permeability.

  In addition, on the substrate surface on the back side of the substrate surface on which the planar pattern coil 101 is provided, an electronic component or a signal line is not mounted on a region overlapping with the region on which the planar pattern coil 101 is provided. Thereby, it is possible to prevent other electronic components and conductors from affecting the magnetic permeability detection by the planar pattern coil 101 and improve the magnetic permeability detection accuracy.

  Next, how the magnetic permeability sensor 100 according to this embodiment is attached to the developing device 212 will be described with reference to FIG. FIG. 18 is a diagram illustrating a manner of attaching the magnetic permeability sensor 100 to the developing device 212. In FIG. 18, the developing device 212 is shown in a side sectional view. Further, FIG. 18 is shown upside down from the perspective view of FIG. Accordingly, FIG. 18 shows a state where the developing device 212 is mounted on the image forming apparatus 200, that is, a state when the developing device 212 is in use. As shown in FIG. 18, conveying screws 212b and 212c are arranged inside the developing device 212, and thereby the developer is conveyed in the longitudinal direction.

  The sensor mounting position 212a is formed in a flat shape so that the magnetic permeability sensor 100 configured on the basis of a flat substrate can be easily mounted. The magnetic permeability sensor 100 is attached to the developing device 212. As shown in FIG. 18, the housing of the developing device 212 is formed in accordance with the shapes of the two conveying screws 212b and 212c, and the portion including the sensor mounting position 212a is aligned with a circle that is the sectional shape of the conveying screw 212b. The cross-sectional shape is arcuate.

  Since the sensor attachment position 212a has a shape in which a flat surface is provided in a part of the arc-shaped housing, the planar pattern coil 101 of the magnetic permeability sensor 100 attached to the sensor attachment position 212a in the developer 212 and the inside of the developer 212 The distance from the developer moving space becomes narrow, and the range in which the magnetic flux acts can be directed to the developer moving space. Thus, the developer concentration in the developer movement space inside the developing device 212 can be more suitably detected by the magnetic permeability sensor 100 attached to the sensor attachment position 212a. Since the magnetic permeability in the developer movement space is determined by the concentration of the developer, the magnetic permeability sensor 100 can detect the magnetic permeability in the developer movement space.

  In such a configuration, the developer used in the electrophotographic image forming apparatus is a mixture of toner and carrier in the case of the two-component development system. In order to develop the electrostatic latent image formed on the photosensitive drum 209, it is necessary to maintain the toner density of the developer at a predetermined density or higher. The toner density of the developer fluctuates every time the electrostatic latent image formed on the photosensitive drum 209 is developed, and thus it is necessary to detect the toner density inside the developing device 212.

  In the present embodiment, when the toner density of the developer in the developing device 212 fluctuates, the magnetic permeability in the range in which the magnetic flux of the planar pattern coil 101 of the magnetic permeability sensor 100 acts changes. By detecting the change by the magnetic permeability sensor 100, it becomes possible to detect the toner density of the developer inside the developing device 212.

  As described above, according to the present embodiment, it is possible to configure a toner concentration detection mechanism for the developer inside the developing device 212 using the magnetic permeability sensor 100.

Other embodiments.
In the above embodiment, the magnetic permeability sensor 100 that detects the magnetic permeability in the range where the magnetic flux acts by using the planar pattern coil 101 as the planar coil has been described. On the other hand, assuming that the magnetic permeability in the range in which the magnetic flux of the planar pattern coil 101 acts is constant, the oscillation frequency fluctuation of the circuit shown in FIG. 3 will be described with reference to FIGS. It becomes only the fluctuation component with respect to such a temperature.

  Therefore, the magnetic permeability sensor 100 described in the above embodiment can be used not only as a magnetic permeability sensor but also as a temperature sensor. In this case, as the temperature characteristics described in FIGS. 12A to 12D, it is preferable to select a temperature characteristic that is simply increased or decreased in the temperature range to be detected. Thereby, it becomes possible to detect the temperature of the portion where the sensor is installed with a simple calculation based on the oscillation frequency of the sensor. Also from this point of view, it is significant that the temperature characteristic of the oscillation frequency of the circuit can be adjusted by adjusting the pattern resistance 102 as the planar resistance which is the adjustment resistance section as described above.

In addition, this invention also includes the aspect described below.
<Aspect A>
A magnetic permeability detector that outputs a signal having a frequency corresponding to the magnetic permeability of a predetermined space,
A coil formed on a substrate in a planar pattern, the inductance of which varies depending on the magnetic permeability of the predetermined space;
A capacitor connected to form a resonant current loop with the coil;
An output terminal for outputting a signal corresponding to a potential of a part of the resonance current loop;
A magnetic permeability detector including a pattern resistor connected in series to the resonance current loop and formed by a zigzag plane pattern.

<Aspect B>
The magnetic permeability detector according to aspect A, wherein an inductance component generated in the resonance current loop is adjusted by the pattern resistance by adjusting a number of spells for forming the pattern resistance.

<Aspect C>
The aspect A or aspect, wherein the coil and the pattern resistance are formed on the same surface on the substrate, and other components including the coil are formed on a surface different from the coil and the pattern resistance. The magnetic permeability detector according to B.

<Aspect D>
The other parts including the coil are formed on a different surface from the coil and the pattern resistance, and in a range different from the back side of the range where the coil and the pattern resistance are formed. The magnetic permeability detector according to aspect C, which is characterized.

<Aspect E>
A clock for operating the counter for counting the signal output from the output terminal is the extreme temperature in the change of the resonance frequency of the resonance current loop with respect to the temperature fluctuation of the portion where the magnetic permeability sensor is installed. A mode in which the number of spells for forming the pattern resistor is adjusted so as to be a value corresponding to an extreme temperature change in the oscillation frequency with respect to temperature fluctuation in the oscillation circuit that oscillates. The magnetic permeability detector according to any one of A to D.

<Aspect F>
A developer concentration detector for detecting the concentration of a developer for developing an electrostatic latent image in an image forming apparatus,
A coil that is formed in a planar pattern on a substrate and whose inductance varies depending on the magnetic permeability of the space filled with the developer;
A capacitor connected to form a resonant current loop with the coil;
An output terminal for outputting a signal corresponding to a potential of a part of the resonance current loop;
A pattern resistor connected in series to the resonant current loop and formed by a zigzag plane pattern;
A developer concentration detector, wherein a planar portion on which the coil is formed is disposed to face a space filled with the developer.

<Aspect G>
A developing device for developing an electrostatic latent image in an image forming apparatus,
A developer accommodating portion for accommodating a developer for developing the electrostatic latent image;
A developer concentration detector that detects the concentration of the developer in the developer container,
The developer concentration detector is
A coil formed on a substrate in a planar pattern, the inductance of which varies depending on the concentration of the developer in the developer container;
A capacitor connected to form a resonant current loop with the coil;
An output terminal for outputting a signal corresponding to a potential of a part of the resonance current loop;
A pattern resistor connected in series to the resonant current loop and formed by a zigzag plane pattern;
2. A developing device according to claim 1, wherein a flat surface portion on which the coil is formed is disposed to face the developer accommodating portion.

<Aspect H>
An image forming apparatus for forming an image by developing an electrostatic latent image formed on a photoreceptor,
A developer accommodating portion for accommodating a developer for developing the electrostatic latent image;
A developer concentration detector that detects the concentration of the developer in the developer container,
The developer concentration detector is
A coil formed on a substrate in a planar pattern, the inductance of which varies depending on the concentration of the developer in the developer container;
A capacitor connected to form a resonant current loop with the coil;
An output terminal for outputting a signal corresponding to a potential of a part of the resonance current loop;
A pattern resistor connected in series to the resonant current loop and formed by a zigzag plane pattern;
An image forming apparatus, wherein a planar portion on which the coil is formed is disposed to face the developer accommodating portion.

<Aspect I>
A magnetic permeability detection method for detecting the magnetic permeability of the predetermined space based on a signal whose frequency changes according to the magnetic permeability of the predetermined space,
A coil whose inductance changes depending on the magnetic permeability of the predetermined space is formed on the substrate by a plane pattern,
Connect a capacitor to form a resonant current loop with the coil,
A pattern resistor formed by a zigzag planar pattern is connected in series to the resonant current loop,
A magnetic permeability detection method, comprising: outputting a signal corresponding to a potential of a part of the resonance current loop.

<Aspect J>
A developer concentration detection method for detecting the concentration of a developer for developing an electrostatic latent image in an image forming apparatus,
A coil whose inductance changes depending on the magnetic permeability of the space filled with the developer is formed on the substrate by a planar pattern,
Connect a capacitor to form a resonant current loop with the coil,
A pattern resistor formed by a zigzag planar pattern is connected in series to the resonant current loop,
A method for detecting a developer concentration, wherein a signal corresponding to a potential of a part of the resonance current loop is output.

1 Controller 10 CPU
11 Timer 20 ROM
30 RAM
40 DMAC
50 ASIC
60 I / O ASIC
61 Counter 62 Read signal acquisition unit 63 Count value output unit 70 Crystal oscillation circuit 100 Magnetic permeability sensor 101 Planar pattern coil 102 Pattern resistor 103 First capacitor 104 Second capacitor 105 Feedback resistor 106, 107 Unbuffer IC
DESCRIPTION OF SYMBOLS 108 Output terminal 200 Image forming apparatus 201 Paper feed tray 202 Paper feed roller 203 Registration roller 204 Paper 205 Conveying belt 206K, 206C, 206M, 206Y Image forming unit 207 Drive roller 208 Driven roller 209K, 209C, 209M, 209Y Photosensitive drum 210K , 210C, 210M, 210Y Charger 211 Optical writing device 212K, 212C, 212M, 212Y Developer 212a Sensor mounting position 212b, 212c Transport screw 213K, 213C, 213M, 213Y Photoconductor cleaner 215K, 215C, 215M, 215Y Transfer device 216 Fixing device

JP-A-11-223620

Claims (18)

A magnetic permeability detector using an LC oscillation circuit having a coil and a capacitor,
A resistor connected in series with the coil as a magnetic permeability detector in a resonance current loop in the LC oscillation circuit;
The resistor is a resistor different from the circuit resistor of the LC oscillation circuit, and is arranged to add a predetermined resistance value that does not affect the inductance of the coil to the resistance value of the circuit resistor.
A magnetic permeability detector. The permeability detector according to claim 1,
The resistor is connected in parallel to the capacitor;
A magnetic permeability detector. The permeability detector according to claim 1 or 2,
A substrate having the coil, the capacitor, and the resistor;
A magnetic permeability detector. In the magnetic permeability detector according to claim 3,
The coil is a planar coil in which a conductive wire is printed on the substrate.
A magnetic permeability detector. In the magnetic permeability detector according to claim 3 or 4,
The resistance is a planar resistance obtained by printing a conductive wire on the substrate.
A magnetic permeability detector. In the magnetic permeability detector according to claim 3,
The coil is a planar coil in which a conductor is printed on the substrate, and the resistor is a planar resistor in which a conductor is printed on the substrate,
The planar coil and the planar resistance are provided on the same substrate surface of the substrate.
A magnetic permeability detector. A magnetic permeability detector using an LC oscillation circuit having a coil and a capacitor,
A substrate comprising a resistor connected in series to the coil, the capacitor, and the coil, and connected in parallel to the capacitor;
The resistance is a planar resistance obtained by printing a conductive wire on the substrate,
The planar resistance is connected to the LC oscillation circuit at one end and the other end, and is bent so as to reciprocate a plurality of times in a predetermined direction on the substrate,
The folded shape of the plane resistance is a shape having symmetry, and is point-symmetric with respect to the midpoint of a line segment connecting the one end and the other end.
A magnetic permeability detector. The permeability detector according to claim 7 , wherein
The coil is a planar coil in which a conductive wire is printed on the substrate,
The planar coil and the planar resistance are provided on the same substrate surface of the substrate.
A magnetic permeability detector. In magnetic permeability detector according to claim 6 or 8,
The said capacitor is provided in the board | substrate surface on the opposite side to the board | substrate surface in which the said planar coil and the said plane resistance in the said board | substrate are provided, The magnetic permeability detector characterized by the above-mentioned. In magnetic permeability detector according to claim 6 or 8,
A magnetic permeability, wherein a printed wiring portion for inspection printed in the same shape as the planar resistance is provided on a substrate surface opposite to the substrate surface on which the planar coil and the planar resistance are provided on the substrate. Detector. In magnetic permeability detector according to any one of claims 5-8,
2. The magnetic permeability detector according to claim 1, wherein the planar resistance has a shape bent so as to reciprocate a plurality of times in a predetermined direction. The permeability detector according to claim 11 ,
2. The magnetic permeability detector according to claim 1, wherein the planar resistance has a shape bent so that adjacent conductive wires are parallel to each other. The permeability detector according to claim 11 or 12 ,
2. The magnetic permeability detector according to claim 1, wherein the bent shape of the planar resistance is a shape having objectivity. In magnetic permeability detector according to any one of claims 1 to 13
The coil is configured to generate a magnetic flux in a predetermined direction by a current flowing through the coil by applying a power supply voltage to the permeability detector.
A magnetic permeability detector comprising: an output terminal that outputs a signal having a frequency corresponding to a magnetic permeability within a range in which the magnetic flux acts. The permeability detector according to claim 14 ,
The magnetic resistance detector according to claim 1, wherein the resistance is an adjustment resistance portion that does not affect the inductance of the coil even when the resistance value is changed. The permeability detector according to claim 15 ,
The adjustment resistor unit is configured to detect the LC oscillation of the permeability detector with respect to a temperature characteristic of an oscillation frequency of an oscillation circuit that oscillates a clock for operating a counter for counting a signal output from the output terminal. A magnetic permeability detector, wherein a resistance value of the adjustment resistor portion is set so that a temperature characteristic of an oscillation frequency of the circuit approaches. A developer accommodating portion for accommodating the developer;
A developer concentration detection unit that detects the concentration of the developer in the developer storage unit,
The developer concentration detector
As a magnetic permeability detector, comprising the magnetic permeability detector according to claim 16 ,
The magnetic permeability detector is attached so that the magnetic flux acts on the developer accommodating portion. In an image forming apparatus for forming an image by developing an electrostatic latent image formed on a photoreceptor with a developer,
A developing device according to claim 17 is provided as a developing device,
An image forming apparatus comprising: a controller having the oscillation circuit that oscillates a clock.