JP2005031119A - Lc type resonant circuit electronic part, toner concentration detecting device using the part, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic part using an LC type resonant circuit that hinders variation in resonance frequency due to humidity, to provide a toner concentration detecting device which uses the electronic part, thereby ensuring correct detection without being affected by humidity, and to provide an image forming apparatus using the toner concentration detecting device. <P>SOLUTION: The electronic part comprises a substrate 14 having the resonant circuit including at least one capacitor and at least one coil 12 mounted on a coil support comprising a bobbin 13. And a material whose water absorption percentage is 0.3% or less and relative dielectric consonant is 4 or less is used as the material of the bobbin, and a material whose water absorption percentage is 0.3% or less is used as the material of the substrate 14. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic component having an LC-type resonance circuit in which fluctuations in oscillation frequency due to humidity are small, or toner density detection provided in an image forming apparatus such as an electrophotographic copying machine, facsimile, or printer using the electronic component. Relates to the device.
[0002]
[Prior art]
An image forming apparatus such as a copying machine controls an image forming process by using various detection devices in order to ensure higher image quality.
As one of means for managing the state of the developer used at the time of image formation, for example, the toner concentration of the developer is detected using a toner concentration detection device as described in Patent Documents 1, 2, 3, and 4. Then, there is a control to adjust the toner density so that the developer always has a constant toner density. In this control, it is necessary to accurately detect the toner concentration of the developer. However, the detection capability of the toner concentration detection device, specifically the detection voltage value, changes in the environment during image formation, particularly in high humidity. Therefore, accurate control is not reflected on the change in toner density.
[0003]
In addition, in an electronic component of an LC resonance circuit using a coil and a capacitor, there is a problem that when the substrate on which these are mounted absorbs moisture, the dielectric constant inherent to the substrate changes and the resonance frequency changes. In order to prevent this, as described in Patent Document 5, the substrate itself is thinned, the area is reduced, and a chip-type tuning capacitor is separately mounted. Some have been made so as not to affect the resonance frequency, but the problem of the strength of the substrate due to the reduction in thickness and the increase in cost due to the mounting of the tuning capacitor can be considered.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-296893 [Patent Document 2]
JP 2002-296890 A [Patent Document 3]
JP 2002-296240 A [Patent Document 4]
JP 2002-296236 A [Patent Document 5]
Japanese Patent Laid-Open No. 2000-48153
[Problems to be solved by the invention]
In view of the above problems, the present invention provides an electronic component using an LC type resonance circuit that suppresses variations in resonance frequency due to humidity, and using this, a toner concentration detection device capable of accurate detection regardless of humidity. It is another object of the present invention to provide an image forming apparatus using the toner density detecting device.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present invention according to claim 1 is an electronic component comprising a substrate having a resonance circuit including at least one coil and at least one capacitor mounted on a coil support that is a bobbin. An electronic component characterized in that a member that does not absorb moisture is used as a member in the vicinity of the resonance circuit.
[0007]
According to a second aspect of the present invention, in the electronic component according to the first aspect, the electronic component is a bobbin made of a material having a water absorption rate of 0.3% or less.
[0008]
According to a third aspect of the present invention, in the electronic component according to the first or second aspect, the electronic component uses a material having a relative dielectric constant of 4 or less as a bobbin material. It is.
[0009]
According to a fourth aspect of the present invention, in the electronic component according to any one of the first to third aspects, the electronic component uses a material having a water absorption rate of 0.3% or less as a material of the substrate. It is an electronic component.
[0010]
According to a fifth aspect of the present invention, in the electronic component according to any one of the first to fourth aspects, the proportion of the ground line in the back surface of the component mounting surface of the substrate is 40% of the area of the back surface. % Or less.
[0011]
According to a sixth aspect of the present invention, there is provided a toner concentration detection device using the electronic component according to any one of the first to fifth aspects.
According to a seventh aspect of the present invention, there is provided an image forming apparatus using the toner density detecting device according to the sixth aspect.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
A toner concentration detection apparatus according to one embodiment of the present invention will be described.
FIG. 1 is a perspective view showing a toner concentration detection device.
As shown in FIG. 1, the present toner concentration detection device includes a sensor case 11, a coil 12, a coil bobbin 13, a PCB substrate 14, a harness portion 15, and the like.
[0013]
FIG. 2 is a diagram showing a resonance circuit including the primary coil 31 and the secondary coil 32 and the capacitors 33, 34, 34 and 35.
In the development stage of this toner concentration detection device, an environmental test was performed in which the humidity was changed from low humidity (evaluation condition: 30% RH) to high humidity (evaluation condition: 90% RH). A bug was confirmed. In order to perform precise toner density control, the detection voltage fluctuation needs to be 0.35 V or less (specification value), and the ability level is preferably 0.2 V or less. As a result of investigating the cause, it was confirmed that the constituent members of the toner concentration detecting device absorbed moisture, and the capacitance contributing to the resonance condition of the resonance circuit was changed. Since this toner concentration detection device has a feature that reacts sensitively to changes in the L value and C value of the resonance circuit, the change in electrostatic capacity of the component due to humidity cannot be ignored.
[0014]
First, attention was paid to moisture absorption of the PCB substrate 14 on which the capacitor is mounted. Substrate stray capacitance is slightly formed on the actual PCB substrate 14 by turning the wiring pattern. It has been found that the toner concentration detection device causes the substrate floating capacity to increase due to the moisture absorption of the PCB substrate 14 to cause a change in the capacitance, resulting in variations in resonance conditions.
[0015]
Therefore, when evaluation was made using substrates of materials having different hygroscopic properties, paper phenol FR-1, paper phenol FR-2, and paper phenol XXPC having high water absorption have large fluctuations in detection voltage due to humidity, and glass fluororesin. It was confirmed that the fluctuation of the detection voltage can be suppressed to a small value by using a material having a low water absorption rate, such as glass epoxy FR-4, NewSem3 CEM-3, modified polyimide GPY, and polyimide GPY.
[0016]
FIG. 3 is a diagram illustrating the relationship between the moisture absorption rate (%) of the substrate material and the detection voltage fluctuation (V). By using paper epoxy FR-3 having a water absorption rate of 0.3%, it was confirmed that the detection voltage fluctuation was within 0.2V. Therefore, it is considered that fluctuation of the detection voltage due to humidity can be suppressed by using a substrate made of a material having a water absorption rate of 0.3% or less.
This board uses a double-sided board, and ground wiring is applied to the back surface of the mounting. Since the substrate stray capacitance is mainly formed between the pattern terminal and the ground, if the substrate pattern is devised and the substrate stray capacitance itself is reduced, the change in the stray capacitance due to moisture absorption will be reduced. By making the ground plane in the vicinity of the resonance circuit composed of the coil 12 and the capacitor as small as possible and making the proportion of the ground line in the entire back surface of the substrate be 40% or less, the change in capacitance due to moisture absorption of the substrate stray capacitance can be ignored. It has been found that it can be reduced to the extent.
[0017]
This toner concentration detection device is configured to form a capacitor between the coil 12 and the substrate pattern via the coil bobbin 13 (the coil and substrate pattern are electrodes, and the bobbin is a dielectric). It is considered that the bobbin material absorbs moisture and the bobbin capacitance changes, and the change in the bobbin capacitance contributes to the change in inductance and causes variations in resonance conditions.
[0018]
Therefore, the material of the coil bobbin 13 that fixes the coil 12 of the resonance circuit was evaluated.
FIG. 4 is a diagram showing the relationship between the water absorption rate (%) of the coil bobbin material and the detected voltage fluctuation (V). When it was confirmed that the toner concentration detector had a large humidity fluctuation, PA (nylon) 66 having high hygroscopicity was used as the bobbin material. Therefore, when a coil bobbin was made from materials having different water absorption rates such as PA (nylon) 66, PPE-M, PI, PBT, PC, PS and the like and a humidity test was performed, the result shown in FIG. 4 was obtained. PA (nylon) 66 and PI with high water absorption have large fluctuations in detection voltage, whereas materials with low water absorption such as PPE-M, PBT, PC, and PS have fluctuations in detection voltage of about 0.05V. Almost no change. It has been found that the material of the coil bobbin contributes to the detection characteristics in a high humidity environment.
[0019]
If the water absorption exceeds 0.3%, the relative permittivity with respect to the change in humidity increases.
Therefore, the results of FIG. 4 are shown in FIG. 5 in which the dielectric constant is represented on the horizontal axis.
FIG. 5 is a diagram showing the relationship between the relative dielectric constant of the coil bobbin material and the detected voltage fluctuation (V). As shown in FIG. 5, it can be confirmed that a material having a large relative permittivity similar to the water absorption rate has a large variation in detection voltage due to humidity, and a material having a small relative permittivity has a small variation in detection voltage. It has been found that the humidity variation can be suppressed by using a material having a relative dielectric constant of 4 or less for the coil bobbin 13.
[0020]
The material of the toner concentration detection device uses a material having a water absorption of 0.3% or less from FIG. 4 and a relative dielectric constant of 4 or less from FIG. Therefore, it is considered that the variation of the resonance frequency can be suppressed to a small value. That is, the toner density that enables stable detection against fluctuations in humidity by using a material having a water absorption of 0.3% or less or a relative dielectric constant of 4 or less, such as PPE-M, PBT, PC, PS, etc. A detection device can be realized.
The embodiment of the present invention is considered to be effective not only for the toner concentration detection device but also for electronic components using an LC resonance circuit.
[0021]
【The invention's effect】
As described above, the present invention can provide an electronic component using an LC resonance circuit that suppresses variation in resonance frequency due to humidity, and by using this, accurate detection is possible regardless of humidity. Therefore, it is possible to provide a toner concentration detecting device capable of performing the above and an image forming apparatus using the toner concentration detecting device.
[Brief description of the drawings]
FIG. 1 is a perspective view of a toner concentration detection apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram showing a resonance circuit including a coil and a capacitor according to an embodiment of the present invention.
FIG. 3 is a diagram showing a relationship between a moisture absorption rate of a substrate material and a detection voltage fluctuation according to an embodiment of the present invention.
FIG. 4 is a diagram showing the relationship between the water absorption rate of the coil bobbin material and the detection voltage fluctuation according to the embodiment of the present invention.
FIG. 5 is a diagram showing a relationship between a relative permittivity of a coil bobbin material and a detection voltage fluctuation according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Sensor case 12 Coil 13 Coil bobbin 14 PCB board 15 Harness part 31 Primary coil 32 Secondary coils 33, 34, 35, 36 Capacitor 37 Control voltage input part 38 Oscillator

Claims (7)

In an electronic component comprising a substrate having a resonance circuit including at least one coil and at least one capacitor mounted on a bobbin coil support,
An electronic component using a member that does not absorb moisture as a member in the vicinity of the resonance circuit. The electronic component according to claim 1,
The electronic component is characterized in that a material having a water absorption of 0.3% or less is used as the bobbin material. The electronic component according to claim 1 or 2,
In the electronic component, a bobbin is made of a material having a relative dielectric constant of 4 or less. The electronic component according to any one of claims 1 to 3,
The electronic component is characterized in that a material having a water absorption of 0.3% or less is used as the material of the substrate. The electronic component according to any one of claims 1 to 4,
In the electronic component, the proportion of the ground line in the back surface of the component mounting surface of the substrate is 40% or less of the area of the back surface. 6. A toner concentration detecting device using the electronic component according to claim 1. An image forming apparatus using the toner density detection device according to claim 6.

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