JP2013101103A - Differential transformer type magnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform zero adjustment on a substrate when a planar coil arranged on the substrate is made into a drive coil and a differential coil.SOLUTION: A first differential coil 6 is a planar coil arranged on a first surface of a substrate. Five first branch lines 6c1-6c5 to which a wire rod constituting the outermost periphery of the first differential coil 6 is branched are arranged so that magnetic flux quantities passing through each of the first branch lines 6c1-6c5 are different from one another when a first drive coil 4 is driven. A second differential coil 7 is a planar coil arranged on a second surface of the substrate. Five second branch lines 7c1-7c5 to which a wire rod constituting the outermost periphery of the second differential coil 7 is branched are arranged so that magnetic flux quantities passing through each of the second branch lines 7c1-7c5 are different from one another when a second drive coil 5 is driven. Any one of the first branch lines 6c1-6c5 is selected and any one of the second branch lines 7c1-7c5 is selected to perform zero adjustment.

Description

  The present invention relates to a differential transformer type magnetic sensor using a planar coil.

  In an image forming apparatus that uses toner as a developer, a magnetic sensor is used to detect the remaining amount and density of toner. There are various types of magnetic sensors, and a differential transformer type magnetic sensor has a configuration in which a driving coil, a differential coil that functions as a detection coil, and a differential coil that functions as a reference coil are arranged in the same core. .

  As an example of a differential transformer type magnetic sensor, a first coil (drive coil) is formed on the first layer, a second coil (differential coil) is formed on the second layer, and a third coil (differential coil) is formed on the third layer. There has been proposed a structure in which a fourth coil (drive coil) is arranged in the fourth layer and an insulating substrate is arranged between the layers (for example, see Patent Document 1).

  As another example of the differential transformer type magnetic sensor, a first coil (driving coil) and a third coil (differential coil) are arranged side by side on one surface of an insulating magnetic substrate, and an insulating There has been proposed a structure in which a second coil (drive coil) and a fourth coil (differential coil) are arranged side by side on the other surface of the magnetic substrate (see, for example, Patent Document 2).

JP 2001-165910 A JP-A-10-104934

  The differential transformer type magnetic sensor requires zero adjustment, that is, adjustment that balances the electromotive voltage generated in one differential coil (detection coil) and the electromotive voltage generated in the other differential coil (reference coil). . A mechanism for adjusting the core position of the differential transformer is provided in the magnetic sensor, and the zero position can be adjusted by adjusting the core position. However, in the case of a differential transformer that uses a planar coil patterned on a printed circuit board as a drive coil and a differential coil, it is difficult to provide the mechanism on the printed circuit board.

  An object of the present invention is to provide a differential transformer type magnetic sensor that can be zero-adjusted on a substrate when the planar coil disposed on the substrate is a drive coil and a differential coil.

  A differential transformer type magnetic sensor according to one aspect of the present invention that achieves the above object includes a substrate, a drive coil including a planar coil disposed on the substrate, and a planar coil disposed on the substrate. Including a first differential coil that generates an electromotive voltage when the driving coil is driven, and a planar coil disposed on the substrate, and is connected to the first differential coil, And a second differential coil that generates an electromotive voltage when the drive coil is driven, wherein the first differential coil is an outermost periphery of the first differential coil. The second differential coil includes a plurality of second branch lines that are branched from the wire that constitutes the outermost periphery of the second differential coil. A plurality of first branch lines including the branch line; When the drive coil is driven, the plurality of second branch lines are arranged so that the amount of magnetic flux passing through each of the plurality of first branch lines is different. , The magnetic flux passing through each of the plurality of second branch lines is different, and the differential transformer type magnetic sensor is used for zero adjustment of the differential transformer, One of the branch lines can be selected, and is used for zero adjustment of the first selection unit arranged on the substrate and the differential transformer, and selects any one of the plurality of second branch lines. And a second selection unit disposed on the substrate.

  In the differential transformer type magnetic sensor according to one aspect of the present invention, when the drive coil is driven, the plurality of first branch lines have different amounts of magnetic flux passing through each of the plurality of first branch lines. Is arranged. For this reason, the magnitude | size of the electromotive force which arises in a 1st differential coil can be adjusted by selecting any one of several 1st branch lines by a 1st selection part. Similarly, the plurality of second branch lines are arranged such that the amount of magnetic flux passing through each of the plurality of second branch lines is different when the drive coil is driven. For this reason, the magnitude | size of the electromotive force which arises in a 2nd differential coil can be adjusted by selecting any one of several 2nd branch line by a 2nd selection part. As described above, according to the differential transformer type magnetic sensor according to one aspect of the present invention, when the planar coil disposed on the substrate is the drive coil and the differential coil, zero adjustment can be performed on the substrate.

  In the above configuration, the plurality of first branch lines have different lengths, and the plurality of second branch lines have different lengths.

  According to this configuration, since the lengths of the plurality of first branch lines are different from each other, the amount of magnetic flux passing through each of the plurality of first branch lines is different when the drive coil is driven. can do. Similarly, since the lengths of the plurality of second branch lines are made different from each other, when the drive coil is driven, the amount of magnetic flux passing through each of the plurality of second branch lines may be made different. it can.

  In the above-described configuration, the distance between the adjacent first branch lines is that of the first differential coil before the wire constituting the first differential coil branches to the plurality of first branch lines. The distance between the adjacent second branch lines is greater than the distance between the adjacent wire rods, and the distance between the adjacent second branch wires is the first before the wire rods constituting the second differential coil branch to the plurality of second branch wires. It is made larger than between the adjacent wire rods of two differential coils.

  According to this configuration, the distance between the adjacent first branch lines is adjacent to the first differential coil before the wire constituting the first differential coil branches to the plurality of first branch lines. Since it is made larger than between the wire rods, the distance between the adjacent first branch lines can be made relatively large. Thereby, when the drive coil is driven, the amount of magnetic flux passing through each of the plurality of first branch lines can be made different. Similarly, the distance between the adjacent second branch lines is greater than the distance between the adjacent differential wires of the second differential coil before the wire constituting the second differential coil branches into the plurality of second branch lines. Since it is enlarged, the distance between adjacent second branch lines can be made relatively large. Thereby, when the drive coil is driven, the amount of magnetic flux passing through each of the plurality of second branch lines can be made different.

  In the above configuration, a first wiring connectable to the plurality of first branch lines, a second wiring connectable to the plurality of second branch lines, the first wiring, and the second wiring A differential voltage between an electromotive voltage generated in the amplifier connected to the wiring and the electromotive voltage generated in the first differential coil and the electromotive voltage generated in the second differential coil; A resistor used for setting and a capacitor that cuts a DC component of the differential voltage, and the first selection unit uses one of the resistor and the capacitor to form the plurality of first branch lines. Any one of the plurality of first branch lines is selected by connecting any one of the first wiring and the first wiring, and the second selection unit uses the other of the resistor and the capacitor. Any one of the plurality of second branch lines and the first branch line. By connecting of the wiring, any one of said plurality of second branch line is selected.

  According to this configuration, one of the resistor used for setting the amplification factor at which the differential voltage is amplified by the amplifier and the capacitor that cuts the DC component of the differential voltage is one of the plurality of first branch lines. The connecting member is used to connect one to the first wiring. The other of the resistor and the capacitor is a connecting member used for connecting any one of the plurality of second branch lines to the second wiring. Therefore, it is not necessary to newly provide these connecting members.

  The said structure WHEREIN: The said board | substrate is located in the 1st surface where the said 1st differential coil is arrange | positioned, and the said 1st surface and the other side, and the 2nd where the said 2nd differential coil is arrange | positioned. The first differential coil has a function of a reference coil, the second differential coil has a function of a detection coil, and the first selection unit and the second selection The part is disposed on the first surface.

  According to this configuration, the first selection unit and the second selection unit are arranged on the first surface on which the reference coil is arranged. Therefore, since the projections such as the first selection unit and the second selection unit are not arranged on the second surface (detection coil surface) on which the detection coil is arranged, the second surface (detection coil). Surface) and the magnetic material can be shortened. Therefore, a highly accurate differential transformer type magnetic sensor can be realized.

  A differential transformer type magnetic sensor according to another aspect of the present invention includes a substrate, a drive coil including a planar coil disposed on the substrate, and a planar coil disposed on the substrate. A first differential coil that generates an electromotive voltage when the coil is driven and a planar coil disposed on the substrate are connected to the first differential coil, and the drive coil is driven. Then, a differential transformer type magnetic sensor comprising a second differential coil that generates an electromotive voltage, wherein the first differential coil is a wire that constitutes the outermost periphery of the first differential coil. The plurality of first branch lines include a plurality of branched first branch lines, and the plurality of first branch lines have different amounts of magnetic flux passing through the plurality of first branch lines when the drive coil is driven. The differential transformer type magnetic sensor. Sir is used for zero adjustment of the differential transformer, can select any one of the plurality of first branch line includes a first selection unit arranged on the substrate.

  In the differential transformer type magnetic sensor according to another aspect of the present invention, when the drive coil is driven, the plurality of first branch lines have different amounts of magnetic flux passing through each of the plurality of first branch lines. Is arranged. For this reason, the magnitude | size of the electromotive force which arises in a 1st differential coil can be adjusted by selecting any one of several 1st branch lines by a 1st selection part. Thereby, when the plane coil arrange | positioned on a board | substrate is made into a drive coil and a differential coil, zero adjustment can be carried out on a board | substrate.

  A differential transformer type magnetic sensor according to still another aspect of the present invention includes a substrate, a drive coil including a planar coil disposed on the substrate, and a planar coil disposed on the substrate, A first differential coil that generates an electromotive voltage when the drive coil is driven and a planar coil disposed on the substrate are connected to the first differential coil, and the drive coil is driven A differential transformer type magnetic sensor comprising a second differential coil that generates an electromotive voltage when the drive coil is driven, the wire constituting the outermost periphery of the first differential coil The amount of magnetic flux passing through (one of the plurality of first branch lines), the amount of magnetic flux passing through the wire material (one of the plurality of second branch lines) constituting the outermost periphery of the second differential coil, Have been made different.

  If the combination of the first branch line and the second branch line used for zero adjustment is already known among the plurality of first branch lines and the plurality of second branch lines, this is unnecessary as in this aspect. It is possible to adopt a configuration in which a simple branch line is deleted.

  According to the present invention, when the planar coil disposed on the substrate is a drive coil and a differential coil, zero adjustment can be performed on the substrate.

1 is a diagram showing an outline of an internal structure of an image forming apparatus to which a differential transformer type magnetic sensor according to an embodiment of the present invention can be applied. FIG. 2 is a block diagram illustrating a configuration of the image forming apparatus illustrated in FIG. 1. It is a figure which shows an example of the circuit diagram of the differential transformer type magnetic sensor which concerns on this embodiment. It is a top view which shows the 1st surface of an example of the board | substrate with which the differential transformer type magnetic sensor which concerns on this embodiment is formed. It is a top view which shows the 2nd surface of an example of the board | substrate with which the differential transformer type magnetic sensor which concerns on this embodiment is formed. It is a top view which shows an example of the layout of a 1st drive coil, a 1st differential coil, and a connection pattern. It is a top view which shows the state which extracted the 1st drive coil from the 1st drive coil shown in FIG. 6, a 1st differential coil, and a connection pattern. It is a top view which shows the state which extracted the 1st differential coil from the 1st drive coil shown in FIG. 6, a 1st differential coil, and a connection pattern. It is a top view which shows the state which extracted the connection pattern from the 1st drive coil shown in FIG. 6, a 1st differential coil, and a connection pattern. It is a top view which shows an example of the layout of a 2nd drive coil and a 2nd differential coil. It is a top view which shows the state which extracted the 2nd drive coil from the 2nd drive coil and 2nd differential coil which are shown in FIG. It is a top view which shows the state which extracted the 2nd differential coil from the 2nd drive coil and 2nd differential coil which are shown in FIG. It is a perspective view which shows the coil arrange | positioned at a 1st outer side area | region and a 2nd outer side area | region. It is a perspective view which shows the coil arrange | positioned at a 1st inner side area | region and a 2nd inner side area | region. It is a figure which shows an example of the relationship between a 1st branch line and a magnetic force line. It is a perspective view which shows the board | substrate of the vicinity of the selection part area | region shown in FIG. It is sectional drawing of the board | substrate with which the differential transformer type magnetic sensor which concerns on the modification of this embodiment was formed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing an outline of an internal structure of an image forming apparatus 1 to which a differential transformer type magnetic sensor according to an embodiment of the present invention can be applied. The image forming apparatus 1 can be applied to, for example, a digital multi-function peripheral having a copy, printer, scanner, and facsimile function. The image forming apparatus 1 includes an apparatus body 100, a document reading unit 200, and a document feeding unit 300.

  A document reading unit 200 is disposed on the apparatus main body 100, and a document feeding unit 300 is disposed on the document reading unit 200.

  The document feeder 300 functions as an automatic document feeder, and can continuously send a plurality of documents placed on the document placement unit 301 to the document reading unit 200.

  The document reading unit 200 includes a carriage on which an exposure lamp or the like is mounted, a document table made of a transparent member such as glass, a CCD (Charge Coupled Device) sensor, and a document reading slit (all not shown). The CCD sensor outputs the read original as image data.

  The apparatus main body 100 includes a sheet storage unit 101, an image forming unit 103, and a fixing unit 105. The sheet storage unit 101 is disposed at the lowermost part of the apparatus main body 100 and includes a plurality of sheet cassettes that can store a bundle of sheets. In FIG. 1, only the uppermost paper cassette 107a appears.

  Among a plurality of paper cassettes including the paper cassette 107a, in the bundle of paper stored in the selected cassette, the uppermost paper is directed toward the paper conveyance path 107 of the apparatus main body 100 by driving a pickup roller (not shown). Are sent out. The sheet is conveyed to the image forming unit 103 through the sheet conveyance path 107.

  The sheet conveyance path 107 extends in a substantially vertical direction from the lower side to the upper side along one side surface (right side surface in FIG. 1) of the apparatus main body 100, and the other side surface (left side surface in FIG. 1) above. And extends substantially horizontally along the lower side of the document reading unit 200. A discharge tray 131 is provided at the end.

  The image forming unit 103 forms a toner image on the conveyed paper. The image forming unit 103 includes a yellow image forming unit 111Y, a magenta image forming unit 111M, a cyan image forming unit 111C, and a black image forming unit 111BK, which are arranged according to the order in which the toner images are transferred to the transfer belt 113. These units have the same configuration and will be described by taking the yellow image forming unit 111Y as an example.

  The yellow image forming unit 111Y includes a photosensitive drum 115 and an exposure device 117. Around the photosensitive drum 115, a charging device 119, a developing device 121, and a cleaning device 123 are arranged. In the developing device 121, a two-component developer in which yellow toner and a carrier are mixed is accommodated. The charging device 119 uniformly charges the peripheral surface of the photosensitive drum 115. The exposure device 117 generates light modulated in accordance with image data (image data output from the document reading unit 200, image data transmitted from a personal computer, image data received by facsimile), and is uniformly charged. Irradiate the peripheral surface of the photosensitive drum 115. As a result, an electrostatic latent image corresponding to yellow image data is formed on the peripheral surface of the photosensitive drum 115. In this state, by supplying yellow toner from the developing device 121 to the peripheral surface of the photosensitive drum 115, a toner image corresponding to yellow image data is formed on the peripheral surface.

  The transfer belt 113 can move counterclockwise while being sandwiched between the photosensitive drum 115 and the primary transfer roller 125. The yellow toner image is transferred from the photosensitive drum 115 to the transfer belt 113. The yellow toner remaining on the peripheral surface of the photosensitive drum 115 is removed by the cleaning device 123. The above is the description of the yellow image forming unit 111Y.

  Above the yellow image forming unit 111Y, the magenta image forming unit 111M, the cyan image forming unit 111C, and the black image forming unit 111BK, containers containing corresponding color toners, that is, a yellow toner container 127Y, a magenta toner container 127M, A cyan toner container 127C and a black toner container 127BK are arranged. Each color developing device 121 is supplied with toner from a corresponding container.

  As described above, the yellow toner image is transferred to the transfer belt 113, and the magenta toner image is transferred onto the toner image. Similarly, the cyan toner image and the black toner image are transferred onto the transfer belt 113. As a result, a color toner image is formed on the transfer belt 113. In this way, a toner image of each color pattern is superimposed and transferred onto the transfer belt 113, whereby a color toner image is formed on the transfer belt 113. The color toner image is transferred by the secondary transfer roller 129 onto the sheet conveyed from the sheet storage unit 101 described above.

  The sheet on which the color toner image is transferred is sent to the fixing unit 105. The fixing unit 105 includes a heating roller and a fixing roller. The paper on which the color toner image is transferred is sandwiched between these rollers. As a result, heat and pressure are applied to the color toner image and the paper, and the color toner image is fixed to the paper. The sheet is discharged to a discharge tray 131.

  FIG. 2 is a block diagram showing a configuration of the image forming apparatus 1 shown in FIG. The image forming apparatus 1 includes an apparatus main body 100, a differential transformer type magnetic sensor 3, toner containers 127Y, 127M, 127C, and 127BK, a document reading unit 200, a document feeding unit 300, an operation unit 400, a control unit 500, and a communication unit 600. Are connected to each other by a bus. Since the apparatus main body 100, the toner containers 127Y, 127M, 127C, and 127BK, the document reading unit 200, and the document feeding unit 300 have already been described, description thereof will be omitted.

  The differential transformer type magnetic sensor 3 is used for measuring the mixing ratio of toner and carrier in the developing device 121. That is, in the two-component development method, when the toner (nonmagnetic material) decreases in the developing device 121, the ratio of the carrier (magnetic material) increases. As a result, the amount of magnetic material in the unit volume increases in the vicinity of the detection surface of the differential transformer type magnetic sensor 3. On the other hand, in the developing device 121, as the amount of toner increases, the carrier ratio decreases. As a result, the amount of magnetic material in the unit volume decreases near the detection surface of the differential transformer type magnetic sensor 3. By detecting this change in the amount of magnetic material by the differential transformer type magnetic sensor 3, the mixing ratio of the toner and the carrier in the developing device 121 is controlled. The differential transformer type magnetic sensor 3 will be described in detail later.

  In this embodiment, the two-component development method is described. However, the differential transformer type magnetic sensor 3 can be used also in a one-component development method using toner containing a magnetic material. In this case, the remaining amount of magnetic toner in the developing device or the toner container is measured by attaching the differential transformer type magnetic sensor 3 to the developing device or the toner container.

  The operation unit 400 includes an operation key unit 401 and a display unit 403. The display unit 403 has a touch panel function, and displays a screen including soft keys. The user operates the soft keys while viewing the screen to make settings necessary for executing functions such as copying.

  The operation key unit 401 is provided with operation keys including hard keys. Specifically, a function switch key for switching between a start key, a numeric keypad, a stop key, a reset key, a copy, a printer, a scanner, and a facsimile is provided.

  The start key is a key for starting operations such as copying and facsimile transmission. The numeric keypad is a key for inputting numbers such as the number of copies and a facsimile number. The stop key is a key for stopping the copy operation or the like halfway. The reset key is a key for returning the set contents to the initial setting state.

  The function switching key includes a copy key, a transmission key, and the like, and is a key for switching between a copy function, a transmission function, and the like. When the copy key is operated, an initial copy screen is displayed on the display unit 403. When the transmission key is operated, an initial screen for facsimile transmission and mail transmission is displayed on the display unit 403.

  The control unit 500 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an image memory, and the like. The CPU executes control necessary for operating the image forming apparatus 1 on the above-described components of the image forming apparatus 1 such as the apparatus main body 100. The ROM stores software necessary for controlling the operation of the image forming apparatus 1. The RAM is used for temporary storage of data generated during execution of software, storage of application software, and the like. The image memory temporarily stores image data (image data output from the document reading unit 200, image data transmitted from a personal computer, image data received by facsimile, etc.).

  The communication unit 600 includes a facsimile communication unit 601 and a network I / F unit 603. The facsimile communication unit 601 includes an NCU (Network Control Unit) for controlling connection of a telephone line with a destination facsimile and a modulation / demodulation circuit for modulating / demodulating a signal for facsimile communication. The facsimile communication unit 601 is connected to the telephone line 605.

  A network I / F unit 603 is connected to a LAN (Local Area Network) 607. A network I / F unit 603 is a communication interface circuit for executing communication with a terminal device such as a personal computer connected to the LAN 607.

  FIG. 3 is a diagram showing an example of a circuit diagram of a differential transformer type magnetic sensor 3 (hereinafter also referred to as a magnetic sensor 3) according to an embodiment of the present invention. The differential transformer type magnetic sensor 3 includes a first drive coil 4, a second drive coil 5, a first differential coil 6, a second differential coil 7, an oscillation circuit 11, an amplification circuit 12, a resistor 13, and A capacitor 14 is provided.

  The oscillation circuit 11 generates a high-frequency current that drives the first drive coil 4 and the second drive coil 5. The first drive coil 4 and the second drive coil 5 are connected in series. When a high frequency current flows through the first drive coil 4 and the second drive coil 5, the magnetic flux generated by the first drive coil 4 and the magnetic flux generated by the second drive coil 5 are in the same direction. Thus, one end of the first drive coil 4 and one end of the second drive coil 5 are connected. This prevents the magnetic flux generated by the first drive coil 4 and the magnetic flux generated by the second drive coil 5 from canceling each other. The other end of the first drive coil 4 and the other end of the second drive coil 5 are connected to the oscillation circuit 11.

  The first differential coil 6 is magnetically coupled to the first drive coil 4. The second differential coil 7 is magnetically coupled to the second drive coil 5. The first differential coil 6 and the second differential coil 7 are connected in series. When an induced current flows through the first differential coil 6 and the second differential coil 7, the magnetic flux generated by the first differential coil 6 and the magnetic flux generated by the second differential coil 7 Are connected to one end of the first differential coil 6 and one end of the second differential coil 7 so that they are in the opposite direction. As a result, the differential voltage V0 (= the electromotive voltage V1 of the first differential coil 6 -the electromotive voltage V2 of the second differential coil 7) is input to the amplifier circuit 12.

  The other end of the first differential coil 6 is connected to the amplifier circuit 12 via the resistor 13, and the other end of the second differential coil 7 is connected to the amplifier circuit 12 via the capacitor 14. The resistor 13 is connected to the base of the bipolar transistor in the amplifier circuit 12 and is used for setting the amplification factor of the amplifier circuit 12.

  The capacitor 14 has a function of cutting a DC component of the differential voltage V0. As a result, only the AC component of the differential voltage V0 is input to the amplifier circuit 12.

  The resistor 13 is attached at any one of the positions P1 to P5. The capacitor 14 is attached at any one of the positions P6 to P10. A portion for adjusting the position where the resistor 13 is attached is referred to as a first selection unit 15. A portion for adjusting the position where the capacitor 14 is attached is referred to as a second selection unit 16. The position where the resistor 13 is attached and the position where the capacitor 14 is attached are adjusted, and zero adjustment of the differential transformer of the magnetic sensor 3 is performed. This will be described later.

  The operation of the magnetic sensor 3 will be briefly described. When the high-frequency current generated by the oscillation circuit 11 flows through the first drive coil 4 and the second drive coil 5, an electromotive voltage V1 is generated in the first differential coil 6, and an electromotive voltage is generated in the second differential coil 7. V2 is generated. The first differential coil 6 has a function of a reference coil, and the second differential coil 7 has a function of a detection coil. In the vicinity of the second differential coil 7, when the ratio of the magnetic substance (carrier) increases, the electromotive voltage V2 becomes larger than the electromotive voltage V1, so the differential voltage V0 does not become 0V. The differential voltage V0 is amplified by the amplifier circuit 12, and the toner remaining amount is detected by using the signal output from the amplifier circuit 12 and the mixing ratio of toner and carrier (the remaining toner amount in the one-component development method).

  Next, the configuration of the differential transformer type magnetic sensor 3 according to the present embodiment will be described in detail. FIG. 4 is a plan view showing a first surface 31 of an example of the substrate 21 on which the magnetic sensor 3 is formed. FIG. 5 is a plan view showing a second surface 41 of an example of the substrate 21 on which the magnetic sensor 3 is formed. FIG. 5 shows the second surface 41 viewed from the first surface 31 side. The substrate 21 is an insulating single-layer printed circuit board, and includes a first surface 31 and a second surface 41 located on the opposite side of the first surface 31.

  The substrate 21 has a shape in which a portion including one corner of a rectangle is cut out. The substrate 21 has a portion 21a having a constant vertical dimension, a portion 21b that is continuous with the portion 21a, and a portion having a gradually decreasing vertical dimension, and a portion having a constant vertical dimension that is continuous with the portion 21b. 21c. In the portions 21a and 21b, coils of the magnetic sensor 3 and the like are arranged as described below. Various circuits (the oscillation circuit 11, the amplifier circuit 12, etc.) of the magnetic sensor 3 are arranged in the portion 21c.

  With reference to FIGS. 3 and 4, the first surface 31 includes a first inner region 32, a first outer region 33, and a selection unit region 34. These regions are located in the portions 21 a and 21 b of the substrate 21. The first differential coil 6 is disposed in the first inner region 32. The first outer region 33 surrounds the first inner region 32. The first differential coil 6 and the first drive coil 4 are disposed in the first outer region 33. The selection area 34 is adjacent to a part of the first outer area 33. In the selection unit region 34, the first selection unit 15 and the second selection unit 16 for adjusting the zero point of the differential transformer of the magnetic sensor 3 are arranged.

  With reference to FIGS. 3 and 5, the second surface 41 has a second inner region 42 and a second outer region 43. These regions are located in the portions 21 a and 21 b of the substrate 21. The second differential coil 7 is disposed in the second inner region 42. The second outer region 43 surrounds the second inner region 42. In the second outer region 43, the second differential coil 7 and the second drive coil 5 are arranged.

  FIG. 6 is a plan view showing an example of the layout of the first drive coil 4, the first differential coil 6, and the connection patterns 10a, 10b, 10c, 10d, 10e, 10f, and 10g. The first drive coil 4, the first differential coil 6, and the connection patterns 10 a to 10 g are disposed on the first surface 31 of the substrate 21. Since the first differential coil 6 functions as a reference coil, the first surface 31 can be referred to as a reference coil surface.

  First, the first drive coil 4 will be described. FIG. 7 is a plan view showing a state in which the first drive coil 4 is extracted from the first drive coil 4, the first differential coil 6, and the connection patterns 10a to 10g shown in FIG. Referring to FIGS. 4 and 7, the first drive coil 4 includes a planar coil disposed in the first outer region 33. Specifically, the first drive coil 4 is composed of a wire rod 4a wound in an octagon shape. The wire rod 4a is formed so that the octagonal dimension gradually increases in the counterclockwise direction starting from the terminal 4b. Patterned.

  Next, the first differential coil 6 will be described. FIG. 8 is a plan view showing a state in which the first differential coil 6 is extracted from the first drive coil 4, the first differential coil 6 and the connection patterns 10a to 10g shown in FIG. 4 and 8, the first differential coil 6 is wound in the same direction as the first drive coil 4 and is disposed in the first inner region 32 and the first outer region 33. Includes a planar coil. Specifically, the first differential coil 6 is composed of a wire rod 6a wound in an octagon shape, and the wire rod 6a is gradually increased in the counterclockwise direction starting from the terminal 6b. Are patterned.

  4 and 6, in the first outer region 33, the wire constituting the first differential coil 6 and the wire constituting the first drive coil 4 are alternately arranged. The first differential coil 6 includes five (a plurality of examples) first branch lines 6c1, 6c2, 6c3, 6c4, 6c5 from which the wire constituting the outermost periphery of the first differential coil 6 is branched. Including. If it is not necessary to distinguish the first branch lines 6c1 to 6c5, they are described as the first branch line 6c. The five first branch lines 6c are arranged so that the amount of magnetic flux passing through each of the first branch lines 6c is different when the first drive coil 4 is driven. Details of the first branch line 6c will be described later.

  FIG. 9 is a plan view showing a state in which the connection patterns 10a to 10g are extracted from the first drive coil 4, the first differential coil 6 and the connection patterns 10a to 10g shown in FIG. The connection patterns 10 a to 10 g are used for connection with the wire constituting the second differential coil 7. The connection patterns 10a to 10g will be described later together with the second differential coil 7.

  FIG. 10 is a plan view showing an example of the layout of the second drive coil 5 and the second differential coil 7. This figure is a view seen from the first surface 31 side. The second drive coil 5 and the second differential coil 7 are disposed on the second surface 41 of the substrate 21. Since the second differential coil 7 functions as a detection coil, the second surface 41 can be referred to as a detection coil surface.

  First, the second drive coil 5 will be described. FIG. 11 is a plan view showing a state in which the second drive coil 5 is extracted from the second drive coil 5 and the second differential coil 7 shown in FIG. Referring to FIGS. 5 and 11, the second drive coil 5 is wound in the opposite direction to the first drive coil 4 when viewed from the first surface 31 side, and is disposed in the second outer region 43. Including planar coils. Specifically, the second drive coil 5 is composed of a wire 5a wound in an octagon shape, and the wire 5a is patterned so that the octagonal dimension gradually increases in the clockwise direction starting from the terminal 5b. Has been.

  The second drive coil 5 is connected to the first drive coil 4. This will be described with reference to FIG. FIG. 13 is a perspective view showing coils disposed in the first outer region 33 and the second outer region 43. The first connection member 51 has conductivity and is embedded in a through hole (not shown) formed in the substrate 21. A terminal 4 b that is one end of the first drive coil 4 and a terminal 5 b that is one end of the second drive coil 5 are connected by a first connection member 51.

  Next, the second differential coil 7 will be described. FIG. 12 is a plan view showing a state in which the second differential coil 7 is extracted from the second drive coil 5 and the second differential coil 7 shown in FIG. Referring to FIGS. 5 and 12, the second differential coil 7 is wound in the opposite direction to the second drive coil 5 and disposed in the second inner region 42 and the second outer region 43. Includes a planar coil. More specifically, the second differential coil 7 is composed of a wire rod 7a wound in an octagonal shape, and the wire rod 7a is gradually increased in the counterclockwise direction starting from the terminal 7b. Are patterned.

  The second differential coil 7 is connected to the first differential coil 6. This will be described with reference to FIG. FIG. 14 is a perspective view showing coils disposed in the first inner region 32 and the second inner region 42. The second connection member 52 has conductivity and is embedded in a through hole (not shown) formed in the substrate 21. A terminal 6 b that is one end of the first differential coil 6 and a terminal 7 b that is one end of the second differential coil 7 are connected by a second connecting member 52.

  Referring to FIG. 12, the second differential coil 7 includes five (a plurality of examples) second branch lines 7c1 and 7c2 from which the wire material constituting the outermost periphery of the second differential coil 7 is branched. 7c3, 7c4, 7c5. If it is not necessary to distinguish the second branch lines 7c1 to 7c5, they are referred to as second branch lines 7c. The five second branch lines 7c are arranged so that the amount of magnetic flux passing through each of the second branch lines 7c is different when the second drive coil 5 is driven. Details of the second branch line 7c will be described later.

  6 and 10, the width of the wire rod of the first drive coil 4, the width of the wire rod of the second drive coil 5, the width of the wire rod of the first differential coil 6, and the second differential coil The width of the wire 7 and the widths of the connection patterns 10a to 10g are, for example, 0.15 mm. The interval between adjacent wires is, for example, 0.15 mm. The external dimensions of the first differential coil 6 and the second differential coil 7 are, for example, 24.0 mm. The external dimensions of the first drive coil 4 and the second drive coil 5 are, for example, 23.4 mm.

  In order to increase the accuracy of the magnetic sensor 3, it is necessary to change the differential voltage V0 greatly in the output range of the differential voltage V0 (for example, 0.2 to 3.3 V). For this purpose, the electromotive voltage V1 generated by the first differential coil 6 and the electromotive voltage V2 generated by the second differential coil 7 are balanced in the absence of a magnetic substance in the vicinity of the magnetic sensor 3. Is preferred. In order to balance the electromotive voltage V1 and the electromotive voltage V2, the following is performed. The number of turns of the first differential coil 6 and the number of turns of the second differential coil 7 are the same, and the pattern of the first differential coil 6 and the pattern of the second differential coil 7 form the substrate 21. The first differential coil 6 is disposed on the first surface 31 and the second differential coil 7 is disposed on the second surface 41 so as to overlap as much as possible. Similarly, the number of turns of the first drive coil 4 and the number of turns of the second drive coil 5 are the same (for example, the number of turns 7), and the pattern of the first drive coil 4 and the second drive coil 5 The first drive coil 4 is disposed on the first surface 31 and the second drive coil 5 is disposed on the second surface 41 so that the pattern overlaps with the substrate 21 as much as possible.

  With reference to FIGS. 5 and 10, the wire constituting the second differential coil 7 and the wire constituting the second drive coil 5 are alternately arranged in the second outer region 43. The second drive coil 5 is wound clockwise starting from the terminal 5b. The second differential coil 7 is wound counterclockwise starting from the terminal 7b. Since the second differential coil 7 is wound in the opposite direction to the second drive coil 5, the second differential coil 7 and the second drive coil 5 intersect in the second outer region 43. . In order to prevent the second differential coil 7 and the second drive coil 5 from contacting each other, the connection patterns 10a to 10g shown in FIG. The driving coil 5 is three-dimensionally crossed. This three-dimensional intersection will be described.

  Referring to FIG. 12, second differential coil 7 is wound counterclockwise starting from terminal 7b and reaches terminal 7d1. A second outer region 43 is formed from the terminal 7d1. The second differential coil 7 has a pattern in which part of the wire is missing in each circumference of the second differential coil 7 in the second outer region 43. In this pattern, in the second outer region 43, the first circumference of the second differential coil 7 starts from the terminal 7d2 and the terminal 7d3 ends, and the second circumference of the second differential coil 7 is the terminal. 7d4 is the starting point, terminal 7d5 is the end point, the third circumference of the second differential coil 7 is the terminal 7d6, the terminal 7d7 is the end point, and the fourth circumference of the second differential coil 7 is the end point. The terminal 7d8 is the start point, the terminal 7d9 is the end point, the fifth turn of the second differential coil 7 is the terminal 7d10, the terminal 7d11 is the end point, and the sixth turn of the second differential coil 7 The eye starts from the terminal 7d12 and ends at the terminal 7d13, and the seventh turn of the second differential coil 7 starts from the terminal 7d14 and reaches the five second branch lines 7c.

  Referring to FIGS. 9 and 10, terminal 7d1 and terminal 7d2 are connected to connection pattern 10a. The terminals 7d3 and 7d4 are connected to the connection pattern 10b. The terminals 7d5 and 7d6 are connected to the connection pattern 10c. The terminals 7d7 and 7d8 are connected to the connection pattern 10d. The terminals 7d9 and 7d10 are connected to the connection pattern 10e. The terminals 7d11 and 7d12 are connected to the connection pattern 10f. The terminals 7d13 and 7d14 are connected to the connection pattern 10g. The connection patterns 10 a to 10 g constitute a part of the second differential coil 7. The connection patterns 10 a to 10 g are arranged in the first outer region 33 at a position that three-dimensionally intersects with the wire constituting the second drive coil 5.

  A third connection member is used to connect the pair of terminals (for example, the terminal 7d1 and the terminal 7d2) and the connection patterns 10a to 10g. Referring to FIG. 13, the third connection members 53 a, 53 b, 53 c, 53 d have conductivity and are embedded in through holes (not shown) formed in the substrate 21. The terminal 7d1 and one end of the connection pattern 10a are connected by a third connection member 53a. The other end of the connection pattern 10a and the terminal 7d2 are connected by a third connection member 53b. The terminal 7d3 and one end of the connection pattern 10b are connected by a third connection member 53c. The other end of the connection pattern 10b and the terminal 7d4 are connected by a third connection member 53d. The remaining terminals 7d5 to 7d14 and the remaining connection patterns 10c to 10g are not shown, but are connected in the same manner. The above is the description of the three-dimensional intersection between the second differential coil 7 and the second drive coil 5.

  As described above, the five first branch lines 6c shown in FIG. 8 have different amounts of magnetic flux passing through the first branch lines 6c when the first drive coil 4 is driven. Has been placed. The five second branch lines 7c shown in FIG. 12 are arranged so that the amount of magnetic flux passing through each of the second branch lines 7c is different when the second drive coil 5 is driven. Since the first branch line 6c and the second branch line 7c are arranged in the same manner, description will be made using the first branch line 6c.

  6 and 8, the first differential coil 6 and the first drive coil 4 are wound in an octagonal shape. On the outermost periphery of the first drive coil 4, first branch lines 6 c 1, 6 c 2 and 6 c 3 are arranged along two consecutive sides of the octagon. The first branch lines 6c4 and 6c5 are arranged along the first side of the two sides. The first branch line 6c2 is disposed outside the first branch line 6c1, the first branch line 6c3 is disposed outside the first branch line 6c2, and the first branch line 6c3 is disposed outside the first branch line 6c3. A branch line 6c4 is arranged, and a first branch line 6c5 is arranged outside the first branch line 6c4. The lengths of the five first branch lines 6c are different, the first branch line 6c1 being the longest, the next being the first branch line 6c2, and the next being the first branch line 6c3. Yes, the next is the first branch line 6c4, and the next is the first branch line 6c5.

  On the first side of the two sides, the distance between the adjacent first branch lines 6c is the same as the distance before the wire constituting the first differential coil 6 branches to the five first branch lines 6c. It is made larger than the distance between the adjacent wire rods of one differential coil 6. For example, the distance d between the first branch line 6 c 1 and the first branch line 6 c 2 is larger than the distance D between adjacent wire rods of the first differential coil 6. Therefore, the distance between the adjacent first branch lines 6c can be made relatively large. Thereby, when the first drive coil 4 is driven, the amount of magnetic flux passing through each of the five first branch lines 6c can be made different.

  When the first drive coil 4 is driven, the amount of magnetic flux passing through the first branch line 6c is the length of the portion of the first branch line 6c that extends along the outermost periphery of the first drive coil 4, and It is influenced by the distance between the outermost periphery of the first drive coil 4 and the first branch line 6c. If the length of the portion of the first branch line 6c extending along the outermost periphery of the first drive coil 4 is small, the amount of magnetic flux passing through the first branch line 6c decreases, and if the length of the portion is large. The amount of magnetic flux passing through the first branch line 6c increases. Further, if the distance between the outermost periphery of the first drive coil 4 and the first branch line 6c is large, the amount of magnetic flux passing through the first branch line 6c decreases, and if the distance is small, the first branch line. The amount of magnetic flux passing through 6c increases.

  For example, as shown in FIG. 15, it is assumed that when the first drive coil 4 is driven, annular magnetic lines of force ML1, ML2, ML3, and ML4 are generated. The magnetic force lines ML3 and ML4 are concentric circles. The first branch line 6c1 passes through all the magnetic field lines ML1 to ML4. However, the first branch line 6c2 passes through the magnetic lines ML2 and ML4, but does not pass through the magnetic lines ML1 and ML3. Therefore, the amount of magnetic flux passing through the first branch line 6c1 is larger than the amount of magnetic flux passing through the first branch line 6c2.

  Therefore, when the first drive coil 4 is driven, the first branch line 6c1, the first branch line 6c2, the first branch line 6c3, the first branch line 6c4, and the first branch line 6c5 are in this order. Thus, the amount of magnetic flux passing through the first branch line 6c is reduced. For the same reason, when the second drive coil 5 is driven, the second branch line 7c1, the second branch line 7c2, the second branch line 7c3, the second branch line 7c4, and the second branch line are driven. The amount of magnetic flux passing through the second branch line 7c decreases in the order of 7c5.

  The first branch line 6c1 and the second branch line 7c1 have substantially the same length and face each other. Similarly, the first branch line 6c2 and the second branch line 7c2 have substantially the same length and face each other. The first branch line 6c3 and the second branch line 7c3 have substantially the same length and face each other. The first branch line 6c4 and the second branch line 7c4 have substantially the same length and face each other. The first branch line 6c5 and the second branch line 7c5 have substantially the same length and face each other.

  The first branch line 6 c and the second branch line 7 c are used for zero adjustment of the differential transformer of the magnetic sensor 3. This will be described with reference to FIGS. As described above, the second drive coil 5 and the second differential coil 7 are arranged so that the wire constituting the second drive coil 5 and the wire constituting the second differential coil 7 do not come into contact with each other. Are three-dimensionally crossed. For this reason, the pattern of the second differential coil 7 arranged in the second outer region 43 cannot be made symmetrical to the pattern of the first differential coil 6 arranged in the first outer region 33. . As a result, a difference between the electromotive voltage V1 generated in the first differential coil 6 and the electromotive voltage V2 generated in the second differential coil 7 occurs.

  The first branch line 6c1 and the second branch line 7c1 are standard. If there is no magnetic material (for example, magnetic toner) in the vicinity of the magnetic sensor 3, if the electromotive voltage V1 generated in the first differential coil 6> the electromotive voltage V2 generated in the second differential coil 7, the electromotive voltage In order to reduce V1, one of the first branch lines 6c2 to 6c5 is selected instead of the first branch line 6c1. The electromotive voltage V1 can be minimized by the first branch line 6c5, the next is the first branch line 6c4, the next is the first branch line 6c3, and the next is the first branch line 6c3. This is the branch line 6c2.

  On the other hand, if there is no magnetic material near the magnetic sensor 3 and the electromotive voltage V1 <the electromotive voltage V2, the second branch line is used instead of the second branch line 7c1 in order to reduce the electromotive voltage V2. One of 7c2 to 7c5 is selected. The electromotive voltage V2 can be minimized by the second branch line 7c5, followed by the second branch line 7c4, followed by the second branch line 7c3, followed by the second branch line 7c3. This is the branch line 7c2.

  Next, the first selection unit 15 (FIG. 3) that selects any one of the five first branch lines 6c will be described. Referring to FIG. 6, the end of first branch line 6c1 is arranged at position P1, and functions as terminal 6d1. The end of the first branch line 6c2 is disposed at the position P2, and functions as the terminal 6d2. The end of the first branch line 6c3 is disposed at the position P3 and functions as the terminal 6d3. The end of the first branch line 6c4 is disposed at the position P4 and functions as the terminal 6d4. The end of the first branch line 6c5 is disposed at the position P5 and functions as the terminal 6d5.

  On the first surface 31, the first wiring 8 connected to the amplifier circuit 12 (FIG. 3) is arranged. The first wiring 8 is connectable to the five first branch lines 6c. The first wiring 8 is a terminal 8a1 used for connection with the first branch line 6c1, a terminal 8a2 used for connection with the first branch line 6c2, and a terminal used for connection with the first branch line 6c3. 8a3, a terminal 8a4 used for connection with the first branch line 6c4, and a terminal 8a5 used for connection with the first branch line 6c5.

  Any one of the five first branch lines 6c is connected to the first wiring 8 via the resistor 13 described in FIG. This will be described with reference to FIGS. FIG. 16 is a perspective view showing the substrate 21 in the vicinity of the selection area 34 shown in FIG. For example, when the resistor 13 is disposed at the position P1 and the terminal 6d1 and the terminal 8a1 are connected, the first branch line 6c1 is connected to the first wiring 8. That is, the first branch line 6c1 can be selected. The first selection is made by the terminals 6d1 and 8a1 at the position P1, the terminals 6d2 and 8a2 at the position P2, the terminals 6d3 and 8a3 at the position P3, the terminals 6d4 and 8a4 at the position P4, the terminals 6d5 and 8a5 at the position P5, and the resistor 13. Part 15 is configured. The first selection unit 15 is used for zero adjustment of the differential transformer of the magnetic sensor 3, and can select any one of the five first branch lines 6c.

  The second selection unit 16 (FIG. 3) that selects any one of the five second branch lines 7c1 will be described. Referring to FIG. 10, the end of second branch line 7c1 functions as terminal 7e1. The end of the second branch line 7c2 functions as a terminal 7e2. The end of the second branch line 7c3 functions as a terminal 7e3. The end of the second branch line 7c4 functions as a terminal 7e4. The end of the second branch line 7c5 functions as a terminal 7e5.

  On the second surface 41, the second wiring 9 connected to the amplifier circuit 12 (FIG. 3) is arranged. The second wiring 9 is connectable to the five second branch lines 7c. The second wiring 9 is a terminal 9a1 used for connection with the second branch line 7c1, a terminal 9a2 used for connection with the second branch line 7c2, and a terminal used for connection with the second branch line 7c3. 9a3, a terminal 9a4 used for connection with the second branch line 7c4, and a terminal 9a5 used for connection with the second branch line 7c5.

  The second branch line 7c and the second wiring 9 are connected at any one of the positions P6, P7, P8, P9, and P10 of the first surface 31 shown in FIG. 6 and 16, the position P6 is adjacent to the position P1, and the terminal 7f1 and the terminal 9b1 are arranged. The terminal 7f1 and the terminal 7e1 of the second branch line 7c1 are connected by the fourth connection member 54a. The terminal 9b1 and the terminal 9a1 of the second wiring 9 are connected by a fourth connecting member 54b.

  The position P7 is adjacent to the position P2, and the terminal 7f2 and the terminal 9b2 are arranged. The terminal 7f2 and the terminal 7e2 of the second branch line 7c2 are connected by a fourth connection member 54c. The terminal 9b2 and the terminal 9a2 of the second wiring 9 are connected by a fourth connecting member 54d.

  The position P8 is adjacent to the position P3, and the terminal 7f3 and the terminal 9b3 are arranged. The terminal 7f3 and the terminal 7e3 of the second branch line 7c3 are connected by a fourth connection member 54e. The terminal 9b3 and the terminal 9a3 of the second wiring 9 are connected by the fourth connecting member 54f.

  The position P9 is adjacent to the position P4, and the terminal 7f4 and the terminal 9b4 are arranged. The terminal 7f4 and the terminal 7e4 of the second branch line 7c4 are connected by the fourth connecting member 54g. The terminal 9b4 and the terminal 9a4 of the second wiring 9 are connected by a fourth connecting member 54h.

  The position P10 is adjacent to the position P5, and the terminal 7f5 and the terminal 9b5 are arranged. The terminal 7f5 and the terminal 7e5 of the second branch line 7c5 are connected by the fourth connecting member 54i. The terminal 9b5 and the terminal 9a5 of the second wiring 9 are connected by a fourth connecting member 54j.

  The fourth connection members 54 a to 54 j are embedded in through holes (not shown) formed in the substrate 21.

  Any of the five second branch lines 7c is connected to the second wiring 9 through the capacitor 14 described in FIG. Referring to FIG. 16, for example, when capacitor 14 is arranged at position P6 and terminal 7f1 and terminal 9b1 are connected, second branch line 7c1 is connected to second wiring 9. The second selector 16 includes the terminals 7f1 and 9b1 at the position P6, the terminals 7f2 and 9b2 at the position P7, the terminals 7f3 and 9b3 at the position P8, the terminals 7f4 and 9b4 at the position P9, the terminals 7f5 and 9b5 at the position P10, and the capacitor 14. Is configured. The second selection unit 16 is used for zero adjustment of the differential transformer of the magnetic sensor 3, and can select any one of the five second branch lines 7c.

  The main effects of this embodiment will be described.

  With reference to FIGS. 6, 10, and 13, in the differential transformer including the first drive coil 4, the first differential coil 6, the second drive coil 5, and the second differential coil 7, The first drive coil 4 and the first differential coil 6 are wound in the same direction, and the second drive coil 5 and the second differential coil 7 are wound in opposite directions. In the present embodiment, in the first outer region 33 (FIG. 5), the wire constituting the first drive coil 4 and the wire constituting the first differential coil 6 are alternately arranged. The magnetic coupling of the coils can be increased. Further, in the second outer region 43 (FIG. 5), the wire constituting the second drive coil 5 and the wire constituting the second differential coil 7 are alternately arranged. Magnetic coupling can be increased.

  Since the second drive coil 5 and the second differential coil 7 are wound in opposite directions, the wire material constituting the second drive coil 5 and the wire material constituting the second differential coil 7 are Intersection is inevitable. When the second drive coil 5 and the second differential coil 7 come into contact with each other, a short circuit occurs between these coils. Therefore, in the present embodiment, the wire constituting the second drive coil 5 and the wire constituting the second differential coil 7 are three-dimensionally formed using the connection patterns 10a to 10g and the third connection members 53a to 53d. Crossed. This prevents the contact between the second drive coil 5 and the second differential coil 7 while crossing the wire constituting the second drive coil 5 and the wire constituting the second differential coil 7. It is out.

  In the present embodiment, the first drive coil 4 and the first differential coil 6 are disposed on the first surface 31 of the substrate 21, and the second surface 41 on the opposite side of the first surface 31 is the second surface 41. Two drive coils 5 and a second differential coil 7 are arranged. Thus, since the 1st drive coil 4, the 1st differential coil 6, the 2nd drive coil 5, and the 2nd differential coil 7 are arrange | positioned on the one board | substrate 21, the magnetic sensor 3 is provided. Can be miniaturized.

  As described above, according to this embodiment, the magnetic coupling between the first drive coil 4 and the first differential coil 6 and the magnetic coupling between the second drive coil 5 and the second differential coil 7 are performed. And the size of the magnetic sensor 3 can be reduced. In addition, the first drive coil 4, the first differential coil 6, the second drive coil 5, and the second differential coil 7 are arranged on a single layer substrate 21 instead of a multiple layer substrate. The cost of the magnetic sensor 3 can be reduced.

  In the present embodiment, the connection patterns 10 a to 10 g are three-dimensionally crossed by being part of the second differential coil 7. That is, as shown in FIG. 13, the connection patterns 10 a to 10 g are connected to the wire constituting the second differential coil 7 by the third connection members 53 a to 53 d, thereby the second differential coil 7. And the wire constituting the second drive coil 5 are three-dimensionally crossed. However, the connection patterns 10a to 10g may be three-dimensionally crossed by being part of the second drive coil 5. That is, the connection patterns 10a to 10g are connected to the wire constituting the second drive coil 5 by the third connection members 53a to 53d, so that the wire constituting the second differential coil 7 and the second The wire constituting the drive coil 5 is three-dimensionally crossed.

  In the present embodiment, the first differential coil 6 is a reference coil, and the second differential coil 7 is a detection coil. However, the first differential coil 6 is a detection coil and the second differential coil 7 is a reference. A coil may be used.

  With reference to FIG. 8 and FIG. 12, according to the present embodiment, the five first branch lines 6c are the five first branch lines 6c when the first drive coil 4 is driven. They are arranged so that the amount of magnetic flux passing through each of them is different. For this reason, the magnitude of the electromotive voltage V1 generated in the first differential coil 6 can be adjusted by selecting any one of the five first branch lines 6c by the first selection unit 15. it can. Similarly, the five second branch lines 7c are arranged so that the amount of magnetic flux passing through each of the five second branch lines 7c is different when the second drive coil 5 is driven. . For this reason, the magnitude of the electromotive voltage V2 generated in the second differential coil 7 can be adjusted by selecting any one of the five second branch lines 7c by the second selection unit 16. it can. As described above, according to the present embodiment, when the planar coil disposed on the substrate 21 is a drive coil and a differential coil, the differential transformer of the magnetic sensor 3 can be zero-adjusted on the substrate 21.

  In the present embodiment, the configuration including both the first selection unit 15 and the second selection unit 16 has been described, but the configuration including any one of the first selection unit 15 and the second selection unit 16 may be used. . This will be described using the first selection unit 15 as an example. The second branch lines 7c1 to 7c5 shown in FIG. 10 are one of the second branch lines 7c3. If the electromotive voltage V1 generated in the first differential coil 6> the electromotive voltage V2 generated in the second differential coil 7 with reference to the first branch line 6c3 shown in FIG. In addition, instead of the first branch line 6c3, one of the first branch lines 6c4 and 6c5 is selected. On the other hand, if the electromotive voltage V1 <the electromotive voltage V2, in order to increase the electromotive voltage V1, one of the first branch lines 6c1 and 6c2 is selected instead of the first branch line 6c3.

  Referring to FIG. 16, according to the present embodiment, the resistor 13 used for setting the amplification factor at which the differential voltage V0 is amplified by the amplifier circuit 12 is connected to one of the five first branch lines 6c. The connecting member used for connection with the first wiring 8 is used. The capacitor 14 that cuts the DC component of the differential voltage V0 is used as a connection member that is used to connect one of the five second branch lines 7c to the second wiring 9. Therefore, it is not necessary to newly provide these connecting members. Note that the capacitor 14 is a connection member used to connect any one of the five first branch lines 6c and the first wiring 8, and the resistor 13 is connected to any one of the five second branch lines 7c and the second line. A connecting member used for connection to the wiring 9 may be used. Also, instead of the resistor 13 and the capacitor 14, a zero ohm resistor that can be mounted on the surface of the substrate 21 can be used as a connecting member. A mechanical or electronic switch can also be used in place of the resistor 13, the capacitor 14, and the zero ohm resistor. In this case, one of the five first branch lines 6c and the first wiring 8 can be connected by the first switch, and any of the five second branch lines 7c can be connected by the second switch. The heel and the second wiring 9 can be connected.

  Referring to FIG. 6, according to the present embodiment, the first selection unit 15 and the second selection unit 16 are arranged on the first surface 31 on which the first differential coil 6 (reference coil) is arranged. It is arranged. Therefore, protrusions such as the first selection unit 15 and the second selection unit 16 are arranged on the second surface 41 (detection coil surface) on which the second differential coil 7 (detection coil) is arranged. Since this is not done, the distance between the second surface 41 and the magnetic body can be shortened. Therefore, a highly accurate differential transformer type magnetic sensor can be realized.

  When the combination of the first branch line 6c and the second branch line 7c used for zero adjustment among the five first branch lines 6c and the five second branch lines 7c is already known. The configuration may be such that unnecessary branch lines are deleted. For example, when it is already known that the zero adjustment can be performed by the combination of the first branch line 6c2 and the second branch line 7c5, the first branch lines 6c1, 6c3 to 6c5 and the second branch lines 7c1 to 7c4 are connected. The structure which is not provided may be sufficient. In this configuration, when the first drive coil 4 is driven, the amount of magnetic flux passing through the wire material (first branch line 6c2) constituting the outermost periphery of the first differential coil 6, and the second drive coil 5 It can be expressed that the amount of magnetic flux passing through the wire (second branch line 7c5) that constitutes the outermost periphery of the second differential coil 7 is different from each other.

  In the present embodiment, the first differential coil 6 is disposed in the first inner region 32 and the first outer region 33, and the second differential coil 7 is disposed in the second inner region 42 and the second outer region. 43. However, if there is no problem with the sensitivity of the first differential coil 6, the first differential coil 6 may not necessarily be disposed in the first inner region 32. Similarly, if there is no problem with the sensitivity of the second differential coil 7, the second differential coil 7 may not necessarily be disposed in the second inner region 42.

  In the present embodiment, the substrate 21 having one insulating layer has been described as an example, but the present invention can also be applied to a substrate having a plurality of insulating layers. This will be described as a modification of the present embodiment. FIG. 17 is a cross-sectional view of a substrate 61 on which a differential transformer type magnetic sensor 60 according to a modification of the present embodiment is formed. The substrate 61 includes three insulating layers, that is, an insulating layer 62, an insulating layer 63 located thereon, and an insulating layer 64 located thereon.

  A planar coil-shaped first differential coil 65 is disposed on the upper surface of the insulating layer 64. Similarly to the first differential coil 6 shown in FIG. 8, the first differential coil 65 includes a plurality of first branch lines obtained by branching the wire constituting the outermost periphery of the first differential coil 65. Including.

  Between the lower surface of the insulating layer 64 and the upper surface of the insulating layer 63, a first drive coil 66 having a planar coil shape is disposed. Between the lower surface of the insulating layer 63 and the upper surface of the insulating layer 62, a second drive coil 67 having a planar coil shape is disposed. When high-frequency current flows through the first drive coil 66 and the second drive coil 67, the magnetic flux generated by the first drive coil 66 and the magnetic flux generated by the second drive coil 67 are in the same direction. In this way, one end of the first drive coil 66 and one end of the second drive coil 67 are connected using a connection member 68. The connection member 68 is embedded in a through hole formed in the insulating layer 63.

  A planar coil-shaped second differential coil 69 is disposed on the lower surface of the insulating layer 62. Similarly to the second differential coil 7 shown in FIG. 12, the second differential coil 69 includes a plurality of second branch lines obtained by branching the wire constituting the outermost periphery of the second differential coil 69. Including.

  When an induced current flows through the first differential coil 65 and the second differential coil 69, the magnetic flux generated by the first differential coil 65 and the magnetic flux generated by the second differential coil 69 One end of the first differential coil 65 and one end of the second differential coil 69 are connected using the connection member 70 so that the directions of the first and second differential coils 65 and 65 are opposite to each other. The connecting member 70 is embedded in a through hole that penetrates the insulating layers 62, 63, 64.

  On the upper surface of the insulating layer 64, a first selection unit 15 (FIG. 3) that is used for zero adjustment of the differential transformer and can select any one of a plurality of first branch lines is disposed. On the lower surface of the insulating layer 62, a second selection unit 16 (FIG. 3) that is used for zero adjustment of the differential transformer and can select any one of a plurality of second branch lines is disposed. Note that the second selection unit 16 may be disposed on the upper surface of the insulating layer 64.

  In the present embodiment, the configuration in which the first drive coil 4 corresponds to the first differential coil 6 and the second drive coil 5 corresponds to the second differential coil 7 has been described. However, the drive coil and the differential coil may not have a one-to-one correspondence. For example, when there are two insulating layers, the first differential coil is disposed on the upper surface of the first insulating layer, and the drive coil is disposed between the lower surface of the first insulating layer and the upper surface of the second insulating layer. And the structure which has arrange | positioned the 2nd differential coil in the lower surface of a 2nd insulating layer may be sufficient.

  In the present embodiment and its modifications, the differential transformer type magnetic sensor 3 has been described by taking as an example a sensor that detects the mixing ratio of the carrier and toner of the image forming apparatus 1 (the toner remaining amount in the one-component development method). However, the application of the differential transformer type magnetic sensor according to the present invention is not limited to detection of the remaining amount of toner in the image forming apparatus 1.

3 differential transformer type magnetic sensor 4 first drive coil 5 second drive coil 6 first differential coils 6c1 to 6c5 first branch line 7 second differential coils 7c1 to 7c5 second branch line 10a 10 g connection pattern 15 first selection unit 16 second selection unit 21 substrate 31 first surface 32 first inner region 33 first outer region 41 second surface 42 second inner region 43 second Outer region 51 First connection member 52 Second connection members 53a to 53d Third connection member 60 Differential transformer type magnetic sensor 61 Substrate

Claims (7)

A substrate,
A drive coil including a planar coil disposed on the substrate;
A first differential coil that includes a planar coil disposed on the substrate and generates an electromotive voltage when the drive coil is driven;
A differential including a planar coil disposed on the substrate, connected to the first differential coil, and generating a voltage when the drive coil is driven. A transformer type magnetic sensor,
The first differential coil includes a plurality of first branch lines branched from a wire constituting the outermost periphery of the first differential coil,
The second differential coil includes a plurality of second branch lines branched from a wire material constituting the outermost periphery of the second differential coil,
The plurality of first branch lines are arranged such that the amount of magnetic flux passing through each of the plurality of first branch lines is different when the drive coil is driven,
The plurality of second branch lines are arranged so that the amount of magnetic flux passing through each of the plurality of second branch lines is different when the drive coil is driven,
The differential transformer type magnetic sensor is:
A first selection unit that is used for zero adjustment of the differential transformer, can select any one of the plurality of first branch lines, and is disposed on the substrate;
A differential transformer type magnetic sensor that is used for zero adjustment of the differential transformer, and that can select any one of the plurality of second branch lines and is arranged on the substrate. The lengths of the plurality of first branch lines are different from each other,
The differential transformer type magnetic sensor according to claim 1, wherein the plurality of second branch lines have different lengths. The distance between the adjacent first branch lines is defined as the distance between the adjacent wire members of the first differential coil before the wire constituting the first differential coil branches to the plurality of first branch lines. Has been made bigger,
The distance between the adjacent second branch lines is defined as the distance between the adjacent differential wires of the second differential coil before the wire constituting the second differential coil branches to the plurality of second branch lines. The differential transformer type magnetic sensor according to claim 1 or 2, wherein the differential transformer type magnetic sensor is larger. A first wiring connectable to the plurality of first branch lines;
A second wiring connectable to the plurality of second branch lines;
An amplifier in which the first wiring and the second wiring are connected;
A differential voltage between an electromotive voltage generated in the first differential coil and an electromotive voltage generated in the second differential coil is used for setting an amplification factor amplified by the amplifier;
A capacitor that cuts a DC component of the differential voltage,
In the first selection unit, the one of the plurality of first branch lines is connected to the first wiring by using one of the resistor and the capacitor to connect the first wiring to the first wiring. One of the branch lines is selected,
In the second selection unit, by using the other of the resistor and the capacitor to connect any one of the plurality of second branch lines and the second wiring, The differential transformer type magnetic sensor according to any one of claims 1 to 3, wherein any one of the branch lines is selected. The substrate includes a first surface on which the first differential coil is disposed, and a second surface on the opposite side of the first surface and on which the second differential coil is disposed. Including
The first differential coil has the function of a reference coil;
The second differential coil has a function of a detection coil;
5. The differential transformer type magnetic sensor according to claim 1, wherein the first selection unit and the second selection unit are disposed on the first surface. 6. A substrate,
A drive coil including a planar coil disposed on the substrate;
A first differential coil that includes a planar coil disposed on the substrate and generates an electromotive voltage when the drive coil is driven;
A differential including a planar coil disposed on the substrate, connected to the first differential coil, and generating a voltage when the drive coil is driven. A transformer type magnetic sensor,
The first differential coil includes a plurality of first branch lines branched from a wire constituting the outermost periphery of the first differential coil,
The plurality of first branch lines are arranged such that the amount of magnetic flux passing through each of the plurality of first branch lines is different when the drive coil is driven,
The differential transformer type magnetic sensor is:
A differential transformer type magnetic sensor that is used for zero adjustment of the differential transformer, can select any one of the plurality of first branch lines, and includes a first selection unit disposed on the substrate. A substrate,
A drive coil including a planar coil disposed on the substrate;
A first differential coil that includes a planar coil disposed on the substrate and generates an electromotive voltage when the drive coil is driven;
A differential including a planar coil disposed on the substrate, connected to the first differential coil, and generating a voltage when the drive coil is driven. A transformer type magnetic sensor,
When the drive coil is driven, the amount of magnetic flux passing through the wire constituting the outermost periphery of the first differential coil is different from the amount of magnetic flux passing through the wire constituting the outermost periphery of the second differential coil. Differential transformer type magnetic sensor.

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