JP5170673B2 - Attaching the toner sensor - Google Patents

Description

  The present invention relates to a differential transformer in which a plurality of coils are wound around a bobbin and a method for attaching a toner sensor having a differential transformer to a developer container in a state where a case is removed.

  In an electrophotographic developing apparatus using a magnetic developer containing toner, a differential transformer type toner sensor is installed in a container containing the developer (hereinafter referred to as a developer container) in order to obtain a clear image. The toner density and the remaining amount of toner are detected, and a DC voltage corresponding to the toner concentration and the remaining amount of toner is output to a circuit that drives the toner replenishing means. This toner sensor is equipped with a detection circuit element to extract the differential output of the detection coil and the reference coil from a differential transformer having a detection coil and a reference coil differentially connected to the primary coil connected to the AC power supply. After being accommodated in the case together with the printed board, it is attached to the developing device (see, for example, Patent Document 1).

In order to reduce the cost of the toner sensor, it has been proposed to attach the toner sensor to the developing device with the case and cover removed from the differential transformer and the circuit board. For example, in Patent Documents 2 and 3, a concave hole is formed between the outer surface of the housing of the developing device and the inner surface through a thin portion, and the sensor portion of the toner density sensor without a cover is positioned in the thin portion. Is described.

Japanese Patent No. 3900442 (page 4-6, FIGS. 1 and 2) Utility Model Registration No. 2553757 (page 2-3, FIG. 1, FIG. 2, FIG. 3) Japanese Patent Laying-Open No. 2004-139038 (page 2-3)

  As described in Patent Document 2, accurate detection may not be performed simply by inserting the sensor unit into the recess of the housing of the developing device. That is, in order to enable normal toner density detection with the cover removed from the toner density sensor, it is possible to prevent the developer from entering the circuit section and to detect the detection coil of the differential transformer (sensor section). It is necessary that the side end surface is in close contact with the developing device. Therefore, by devising the structure of the developing device, for example, by providing a portion for isolating the differential transformer and the developer in the developer container, the developer can be prevented from entering the detection circuit portion of the toner sensor. Can do. In order to bring the end face on the detection coil side of the differential transformer into close contact with the developer container, it is first considered to fix the differential transformer with an adhesive. However, when using an adhesive, it is necessary to fix the differential transformer to the developer container with a jig until the adhesive is cured, and the developer container itself is used to cure the adhesive. Therefore, there is a problem that a considerable work space is required.

  Therefore, an object of the present invention is to provide a differential transformer that can be mechanically fixed to a developing device.

  Another object of the present invention is to provide a toner sensor mounting method capable of firmly and easily fixing a differential transformer to a developing device.

  In order to achieve the above object, a differential transformer according to the present invention is a cylinder in which a reference coil, a detection coil, and a primary coil, which are differentially connected via a base and a flange, are wound and hold a differential output adjusting member. A bobbin having a guide portion and a terminal to which a coil end is connected, and has a protrusion extending from the surface of the pedestal to a position higher than the guide portion and the terminal, and the protrusion is viewed from a plane. The protrusion is present in a region inside the collar portion on the opposite side of the pedestal, and the projecting portion has a tapered shape toward the top.

  In the present invention, when there are a plurality of the projecting portions, the first straight line passes through the center of the guide portion as viewed from above and is perpendicular to the first straight line parallel to the terminals. It is preferable that they are arranged at positions sandwiching a straight line.

  In this invention, when the said protrusion part is a single protrusion part, it is preferable to arrange | position on the straight line which passes along the center of the said guide part seeing from a plane, and is parallel to the said terminal.

  According to another aspect of the present invention, there is provided a toner sensor including a toner sensor including the above-described differential transformer, and a circuit board that converts a differential output extracted from the reference coil and the detection coil into a toner density. A transformer is set in a sensor hole of a container for storing a developer, and the protruding portion is pressed by a free end of an elastically deformable pressing member having one end fixed to the container.

  In the present invention, the pressing member preferably has a shape that avoids the guide portion.

  According to the differential transformer of the present invention, the protrusion has a protrusion extending from the surface of the pedestal to a position higher than the other part, and the protrusion is an area inside the collar portion on the opposite side of the pedestal when seen from the plane. Since the protrusion has a tapered shape toward the top, the bobbin is set on the developing device, and the end surface of the bobbin on the detection coil side is in close contact with the developing device simply by pressing the protrusion. Can be realized.

  According to the toner sensor mounting method of the present invention, the end surface of the bobbin on the detection coil side is in a state in which the end surface on the detection coil side of the bobbin is in close contact with the developing device by simply pressing the end surface with a springy member. Can be realized.

  Hereinafter, the details of the present invention will be described with reference to the accompanying drawings (FIGS. 1 to 12).

1 is a perspective view showing an example of a differential transformer, FIG. 2 is an arrow view when FIG. 1 is viewed from the A direction, FIG. 3 is an arrow view when FIG. 1 is viewed from the B direction, and FIG. FIG. 5 is a plan view showing a state where the toner sensor is attached to the developing device, and FIG. 6 is a cross-sectional view taken along the line CC of FIG. 5 (however, the differential transformer is a front view). 7 is a perspective view showing a second example of the differential transformer, FIG. 8 is an arrow view when FIG. 7 is viewed from the D direction, FIG. 9 is an arrow view when FIG. 7 is viewed from the E direction, 10 is a perspective view showing a third example of the differential transformer, FIG. 11 is an arrow view of FIG. 10 viewed from the F direction, and FIG. 12 is an arrow view of FIG. 10 viewed from the G direction. 7-12, the same part as FIG. 1 is shown with the same referential mark.

[Toner sensor]
The toner sensor includes a differential transformer and a circuit board (printed circuit board) on which elements (capacitors, diodes, logic ICs, resistors, etc.) constituting a detection circuit are mounted, and development is performed with the cover and case removed. It is installed in the apparatus (see FIGS. 5 and 6 described later).

[Differential transformer-example 1]
The structure of the differential transformer will be described with reference to FIGS. The differential transformer 2 includes a coil bobbin 31 that is a substantially cylindrical member having bases 30a and 30b and collar portions 31, 32, and 33 separated into two parts, and a coil L (primary coil L ₁₎ wound around the coil bobbin 31. , A reference coil L ₂ , a detection coil L ₃ ), terminal pins 4 to which terminals (winding start and winding end) of each coil are connected, and a predetermined interval along the circumferential direction on the inner peripheral side. And a guide 34 having a plurality of guide ribs 341. A screw core (not shown) made of a high magnetic permeability material is screwed into the guide 34. This screw core is a differential output adjusting member for changing the differential output obtained from the reference coil and the detection coil to an arbitrary value. After the sensor is installed in the developing device, it is rotated by a driver (not shown) or the like. The position is fixed at a position where a predetermined differential output is obtained.

  In particular, when the differential transformer 2 is attached to the developing device, two protrusions 35a and 35b are provided on the surface of the base 30a in order to prevent a gap between the detection side end surface and the developer container. Have. These protrusions 35 a and 35 b have a height that extends to a position higher than the guide portion 34 and the terminal 4. That is, the height h from the pedestal 30a to the top of the protruding portion 35a (35b) is higher than the height h1 from the pedestal 30a to the upper end surface of the guide portion 34 and the height h2 from the pedestal 30b to the tip (upper end) of the terminal 4. Is also set to be large (see FIG. 3). The protrusions 35a and 35b are symmetrically positioned on a straight line Y orthogonal to a straight line X (parallel to the terminal 4) passing through the central axis P of the bobbin 3 (see FIG. 2). Furthermore, these protrusions exist in a region R (shown by a broken line in FIG. 4) inside the collar portion 31 at the lowest stage (on the side opposite to the pedestal) when viewed from the plane. Furthermore, the protrusions 35a and 35b have a shape that tapers from the root toward the tip (for example, the cross section is an arc) so that the bobbin can be stably fixed to the developing device.

  Since five terminals are used in this example, the four terminals are connected to the start of the detection coil, the start of winding of the reference coil, the start of winding of the primary coil, and the end of winding, respectively. The bobbin 31 to which the winding start of the detection coil and the winding start of the reference coil are connected is preferably formed of a resin that has high electrical insulation and does not deform even when exposed to high temperatures. Specific examples of the resin include polyolefin resins such as polybutylene terephthalate (PBT) and polymethylpentene. In particular, polymethylpentene is a copolymer having 4 methylpentene-1 as a main monomer {manufactured and sold by Mitsui Chemicals, Inc. under the registered trademark of TPX. }, And is excellent in environmental characteristics (contamination resistance) in addition to high electrical insulation, and is therefore used effectively in the present invention.

Said coils, an oscillation circuit primary coil L ₁ connected to the (not shown), coupled to the sensing coil L ₃ in which the output voltage varies in accordance with the toner concentration is coupled to the primary coil L ₁ primary coil L ₁ output voltage becomes a reference coil L ₂ does not change depending on the toner density detection coil L ₃ and the reference coil L ₂ is wound in a direction in which the output voltage cancel each other (are differentially connected) is formed The According to this toner sensor, applied when the two-component developer comprising a magnetic carrier and a nonmagnetic toner in the vicinity of the detection coil L ₃ is present, the high frequency voltage primary coil L ₁ output from the oscillator circuit Once, the inductance of the reference coil L ₂ does not change, the inductance of the detection coil L ₃ is changed according to the change in the apparent magnetic permeability of the developer based on a change of the toner concentration, changes in amplitude and phase of the output voltage To do. The phase of the output voltage is compared with the phase of the AC voltage on the primary side, a signal corresponding to the phase difference is output, the output signal is smoothed, and a DC voltage corresponding to the toner density is output.

[Attaching the toner sensor]
A toner sensor mounting structure according to the present invention will be described with reference to FIGS. The toner sensor 1 includes the differential transformer 2 and a circuit board 5 to which terminals provided therein are electrically connected. In the toner sensor 1, the differential transformer 3 is inserted into the sensor hole 60 formed in the developer container 6 containing the developer 7 therein, and then one end side of the pressing member 8 is connected to the developer container by the small screw 9. 6, and the other end side (free end portions 81, 82) of the pressing member 8 is attached to the projecting portions 35 a, 35 b by pressing. The developer 7 is a mixture of toner particles including a binder resin and a colorant and ferromagnetic particles such as iron powder or ferrite particles, and the toner concentration is set to a predetermined ratio in the range of 3 to 10% by mass, for example. Is done. According to the differential transformer 2, the upper ends of the protrusions 35a and 35b provided on the pedestal side are pressed by the pressing member 8 with the same pressure, and the upper ends of the protrusions 35a and 35b are the free ends of the pressing member. Since the portions 81 and 82 are in substantially point contact, the end surface 310 (see FIG. 6) of the collar portion 31 can be brought into close contact with the bottom surface 600 of the sensor hole 60.

  The pressing member 8 is made of an elastically deformable material so that the collar portion 31 of the bobbin 3 can be in close contact with the bottom surface of the sensor hole 60. Specifically, as the pressing member 8, a thin plate made of a nonmagnetic metal material (conductive material) such as austenitic stainless steel or a thin plate made of a nonconductive (preferably insulating) material such as resin (plastic) is used. can do. When using a thin metal plate, an eddy current is generated by an alternating magnetic field from the differential transformer, and the operation output is offset. Therefore, after the developer is put into the developer container, the screw is moved in a direction to cancel the offset. Just turn the core. When a thin plate made of a non-conductive material is used, there is an advantage that an eddy current is not generated, and an operation for canceling the offset becomes unnecessary. Further, the pressing member 8 may be a member whose free end side is formed in a strip shape (U shape) as shown in FIG. 5 (having a shape avoiding the guide 34) in order to prevent interference with the screw core. desirable.

[Differential transformer-example 2]
Another structure of the differential transformer will be described with reference to FIGS. The differential transformer 2 includes a coil bobbin 31 that is a substantially cylindrical member having bases 30a and 30b and collar portions 31, 32, and 33 separated into two parts, and a coil L (primary coil L ₁₎ wound around the coil bobbin 31. , A reference coil L ₂ , a detection coil L ₃ ), a terminal 4 to which terminals (winding start and winding end) of each coil are connected, and a predetermined interval along the circumferential direction on the inner peripheral side. A guide 34 having a plurality of guide ribs 341 is provided. The differential transformer 2 has a single protrusion 36 on the surface of the base 30a in order to prevent a gap from being generated when it is attached to the developing device. The protruding portion 36 has a height that extends to a position higher than the guide portion 34 and the terminal 4 (see FIG. 9). Moreover, the protrusion part 36 is located on the line of the straight line X which passes along the central axis P of the bobbin 3 (refer FIG. 8). Further, like the differential transformer of FIG. 1, the protruding portion 36 exists in a region (see FIG. 4) inside the collar portion 31 at the lowest stage (on the side opposite to the pedestal) when viewed from the plane. Further, the protruding portion 36 has a shape that tapers (spherical surface) from the base toward the tip so that the bobbin can be stably fixed to the developing device.

  According to the differential transformer 2, the tip end portion of the projecting portion 36 provided on the pedestal side center line is pressed by the pressing member 8, and the tip end portion of the projecting portion 36 is substantially in point contact with the free end side of the pressing member. Therefore, the end surface of the collar portion 31 can be brought into close contact with the bottom surface of the sensor hole 60 (see FIG. 6).

[Differential transformer-example 3]
Another structure of the differential transformer will be described with reference to FIGS. The differential transformer 2 includes a coil bobbin 31 that is a substantially cylindrical member having bases 30a and 30b and collar portions 31, 32, and 33 separated into two parts, and a coil L (primary coil L ₁₎ wound around the coil bobbin 31. , A reference coil L ₂ , a detection coil L ₃ ), terminal pins 4 to which terminals (winding start and winding end) of each coil are connected, and a predetermined interval along the circumferential direction on the inner peripheral side. And a guide 34 having a plurality of guide ribs 341. The differential transformer 2 has two projecting portions 37a and 37b on the surface of the base 30a in order to prevent a gap from being generated when the differential transformer 2 is attached to the developing device. These protrusions 37a and 37b have a height that extends to a position higher than the guide portion 34 and the terminal 4 (see FIG. 12). The protrusions 37a and 37b are positioned symmetrically on a straight line Y orthogonal to the straight line X passing through the central axis P of the bobbin 3 (see FIG. 11). Further, like the differential transformer of FIG. 1, these projecting portions 37a and 37b are located in a region (see FIG. 4) inside the collar portion 31 at the lowest stage (opposite to the base) when viewed from above. Exists. Further, the protrusions 37a and 37b have a shape that tapers from the root toward the tip (for example, the cross section is an arc or a wedge) so that the bobbin can be stably fixed to the developing device.

  According to this differential transformer 2, the tip portions of the projecting portions 37a and 37b provided on the pedestal side are pressed by the pressing member 8 with the same pressure, and the upper ends of the projecting portions 35a and 35b are the free ends of the pressing member. As a result, the end surface of the collar portion 31 can be brought into close contact with the bottom surface of the sensor hole 60 (see FIG. 6).

  The present invention is not limited to the above example, and various modifications are possible. For example, the present invention can be applied to a differential transformer in which a reference coil and a detection coil are provided on the primary side and an oscillation coil is provided on the secondary side. Alternatively, it can be applied to a level sensor that detects the remaining amount of toner.

It is a perspective view which shows an example of a differential transformer. It is the arrow line view which looked at FIG. 1 from A direction. It is the arrow line view which looked at FIG. 1 from the B direction. It is a perspective view which shows the area | region which provides a projection part in the differential transformer of FIG. FIG. 4 is a plan view illustrating a state in which a toner sensor is attached to a developing device. It is the XX sectional view taken on the line of FIG. It is a perspective view which shows the 2nd example of a differential transformer. It is the arrow line view which looked at FIG. 7 from the C direction. It is the arrow line view which looked at FIG. 7 from the D direction. It is a perspective view which shows the 3rd example of a differential transformer. It is the arrow view which looked at FIG. 10 from the E direction. It is the arrow line view which looked at FIG. 10 from F direction.

Explanation of symbols

1: toner sensor, 2: differential transformer, 3: bobbin, 30: pedestal, 31, 32, 33: collar, 310: end face, 34: guide, 35a, 35b, 36, 37a, 37b: protrusion, 4 : Terminal, L ₁ : primary coil, L ₂ : reference coil, L ₃ : detection coil, 5: circuit board, 6: developer container, 60: sensor hole, 600: bottom surface, 7: developer, 8: pressing member 81, 82: free end, 9: machine screw

Claims (4)

The reference coil, the primary coil, and the detection coil are arranged in this order from the pedestal through the pedestal and the collar, and the differentially connected reference coil, the detection coil, and the primary coil are wound and hold the differential output adjustment member A bobbin having a cylindrical guide portion and a terminal to which a terminal of a coil is connected, and having a protrusion extending from the surface of the base to a position higher than the guide portion and the terminal, and the protrusion is from a plane. The protruding portion is taken out from the differential coil, the reference coil, and the detection coil , which are present in a region inside the collar portion on the opposite side of the pedestal as viewed, and the protruding portion is tapered toward the top. A toner sensor having a circuit board for converting the differential output into a toner density, and setting the differential transformer in a sensor hole of a container containing a developer; Mounting a toner sensor, characterized in that one end presses the protrusion at the free end of which is fixed an elastically deformable pressing member. The plurality of projecting portions are arranged at a position sandwiching the first straight line on a second straight line that passes through the center of the guide portion and is orthogonal to the first straight line parallel to the terminal when viewed from above. The toner sensor mounting method according to claim 1, wherein the toner sensor is mounted. The toner sensor mounting according to claim 1, wherein the protrusion is a single protrusion, and is disposed on a straight line passing through the center of the guide portion and parallel to the terminal when viewed from above. Method. The pressing member, the method of mounting the toner sensor according to any one of claims 1 to 3, characterized by having a shape which avoids the guide portion.

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