阅读说明：本技术 定子、步进马达、钟表用机芯、钟表及定子的制造方法 (Stator, stepping motor, movement for timepiece, and method of manufacturing stator ) 是由 山本幸祐 木下伸治 矶谷亮介 于 2020-01-10 设计创作，主要内容包括：本发明提供能够减小作用于转子的保持转矩的定子。定子(21)具备：具有贯通孔(31)的磁性体(30)；设置在贯通孔(31)的周围且在将线圈(23)励磁的情况下在贯通孔(31)的周围产生磁极的磁阻部(33)；以及通过热熔化设置在贯通孔(31)的周围与磁阻部(33)不同的位置,且以导磁率小于磁性体(30)的方式形成的非磁性部(35)。(The invention provides a stator capable of reducing holding torque acting on a rotor. The stator (21) is provided with: a magnetic body (30) having a through-hole (31); a magnetic resistance part (33) which is arranged around the through hole (31) and generates magnetic poles around the through hole (31) when the coil (23) is excited; and a non-magnetic part (35) which is provided around the through hole (31) at a position different from the position of the magnetic resistance part (33) by thermal fusion and is formed so that the magnetic permeability is smaller than that of the magnetic body (30).)

1. A stator is characterized by comprising:

a magnetic body having a through hole;

a magnetic resistance portion provided around the through hole, the magnetic resistance portion generating a magnetic pole around the through hole when the coil is excited; and

and a non-magnetic portion provided at a position different from the magnetic resistance portion around the through hole by thermal fusion, and formed so that magnetic permeability is smaller than that of the magnetic body.

2. The stator of claim 1, wherein:

the non-magnetic portion is provided on an inner peripheral surface of the through hole.

3. The stator of claim 1, wherein:

the non-magnetic portion is provided separately from the through hole.

4. A stator according to any one of claims 1 to 3, wherein:

the non-magnetic portion is provided only partially in a penetrating direction of the through hole.

5. The stator of claim 4, wherein:

the non-magnetic portion does not penetrate the magnetic body.

6. A stator according to any one of claims 1 to 3, wherein:

the magnetic body contains a Ni-Fe alloy,

the non-magnetic portion is formed so that the content of Cr is greater than that of the magnetic body.

7. The stator of claim 6, wherein:

the magnetic resistance part is provided by thermal fusion, and is formed in such a manner that the magnetic permeability is lower than that of the magnetic body and the Cr content is higher than that of the magnetic body.

8. The stator of claim 7, wherein:

the magnetic resistance part is formed from the 1 st surface of the magnetic body to the 1 st depth,

the non-magnetic portion is formed from the 1 st surface of the magnetic body to a 2 nd depth different from the 1 st depth.

9. The stator of claim 8, wherein:

the 2 nd depth is less than the 1 st depth.

10. A stator according to any one of claims 1 to 3, wherein:

the magnetic resistance part is formed in a manner that the magnetic permeability is smaller than that of the magnetic body,

the minimum distance from the through hole to the outer edge is 0.1mm or more.

11. A stepping motor is characterized by comprising:

a stator as claimed in any one of claim 1 to claim 3; and

and a rotor disposed in the through hole.

12. A timepiece movement comprising:

the stepper motor of claim 11; and

a gear set for transmitting the power of the stepping motor.

13. A timepiece comprising the timepiece movement according to claim 12.

14. A method of manufacturing a stator, wherein,

the stator includes:

a magnetic body having a through-hole and containing a Ni-Fe alloy;

a magnetic resistance part which is arranged around the through hole and generates magnetic poles around the through hole when the coil is excited; and

a non-magnetic portion provided at a position different from the magnetic resistance portion around the through hole and formed to have a magnetic permeability smaller than that of the magnetic body,

the manufacturing method of the stator is characterized by comprising the following steps:

a chromium disposing step of disposing a Cr material on a magnetic material;

a chromium melting step of irradiating the Cr material with a laser beam to melt and solidify the Cr material on the magnetic material; and

and a through-hole forming step of punching out the magnetic material to form the through-hole after the chromium melting step.

15. The method of manufacturing a stator according to claim 14,

the step of melting chromium comprises:

a 1 st irradiation step of irradiating the Cr material with a laser beam to form at least a part of the magnetoresistive portion; and

and a 2 nd irradiation step of irradiating the Cr material with a laser beam and applying energy smaller than the energy of the laser beam in the 1 st irradiation step to form at least a part of the nonmagnetic portion.

Technical Field

The invention relates to a stator, a stepping motor, a movement for a timepiece, and a method of manufacturing the stator.

Background

There are timepieces provided with a stepping motor for rotationally driving a hand such as an hour hand or a minute hand. The stepping motor includes a rotor rotatably disposed, a stator having a through hole formed therein for disposing the rotor, a magnetic core magnetically coupled to the stator, and a coil wound around the magnetic core. The stator is formed with a positioning portion for determining a stationary position of the rotor.

In order to rotate the rotor, drive pulses of different polarities are alternately supplied from a drive circuit to the coils. The leakage magnetic flux of different polarities is alternately generated in the stator in accordance with the supplied drive pulse. Then, the rotor is rotated 180 degrees in a predetermined direction (forward direction) in accordance with the supplied drive pulse, and stopped at a position corresponding to the positioning portion.

Generally, a stepping motor employs an integrated stator having narrow portions with a narrow width at 2 positions (180 ° apart) around a through hole formed for arranging a rotor, so that magnetic flux is easily saturated. With this configuration, leakage magnetic flux of the drive rotor can be easily obtained.

As a stator for easily obtaining leakage magnetic flux for driving a rotor, a so-called double-body stator is known (for example, see patent document 1). The stator is formed as follows. First, the stator is cut at 2 places (at intervals of 180 degrees) around the through hole where the cross-sectional area of the magnetic circuit becomes the smallest, and the stator is divided into 2 parts. Next, a slit (slit) material made of a low-permeability material or a non-magnetic material is inserted into the cut portion. Subsequently, the slit material is welded/joined to the divided stator.

In addition, in the conventional stepping motor, a technique of providing a notch, a step shape, or the like as the positioning portion in the through hole of the stator is adopted. By providing a step shape, a notch, or the like in the through hole of the stator, a difference occurs in magnetic potential of the rotor according to the position (angle) of the rotor. Thereby, the holding torque acts on the rotor, and the stationary position of the rotor can be determined.

[ Prior art documents ]

[ patent document ]

[ patent document 1 ] Japanese examined patent publication No. 5-56109.

Disclosure of Invention

[ problem to be solved by the invention ]

However, since a battery that can be mounted in a small timepiece is also small, it is necessary to reduce the holding torque acting on the rotor and reduce the power consumption associated with driving the stepping motor. In the case where the through hole of the stator is provided with a notch or a step as the positioning portion, the notch or the step needs to be reduced in order to reduce the holding torque acting on the rotor. Therefore, the stepping motor of the related art has a problem of reducing the holding torque acting on the rotor.

It is therefore an object of the present invention to provide a stator, a stepping motor, a timepiece movement, a timepiece, and a method of manufacturing the stator, which can reduce a holding torque acting on a rotor.

[ MEANS FOR solving PROBLEMS ] A method for solving the problems

The stator of the present invention is characterized by comprising: a magnetic body having a through hole; a magnetic resistance portion provided around the through hole, the magnetic resistance portion generating a magnetic pole around the through hole when the coil is excited; and a non-magnetic portion provided at a position different from the magnetic resistance portion around the through hole by thermal fusion, and formed so that magnetic permeability is smaller than that of the magnetic body.

According to the present invention, by providing the non-magnetic portion having a magnetic permeability smaller than that of the magnetic body around the through hole of the magnetic body, it is possible to generate a difference in magnetic potential of the rotor according to the rotational position of the rotor without providing a notch (notch) or a step shape in the through hole. Therefore, by appropriately adjusting the shape, size, magnetic permeability, and the like of the non-magnetic portion, the holding torque acting on the rotor can be adjusted. Thus, according to the stator of the present invention, the holding torque acting on the rotor can be reduced.

In the stator, the nonmagnetic portion may be provided on an inner peripheral surface of the through hole.

According to the present invention, the non-magnetic portion can be provided at a position directly facing the rotor. Therefore, the difference in the magnetic potential of the rotor corresponding to the rotational position of the rotor can be reliably generated. Therefore, the shortage of the holding torque acting on the rotor can be suppressed.

In the stator, the non-magnetic portion may be provided separately from the through hole.

According to the present invention, the non-magnetic portion is provided in the range where the magnetic field of the rotor reaches, so that the difference in magnetic potential of the rotor can be generated according to the rotational position of the rotor. Thus, a stator capable of reducing the holding torque acting on the rotor can be provided.

In the stator, the non-magnetic portion may be provided only partially in a penetrating direction of the through hole.

According to the present invention, as compared with the case where the nonmagnetic section is provided over the entire region in the penetrating direction of the through hole, the range of the magnetic field of the rotor with respect to the nonmagnetic section is reduced, and the difference in magnetic potential of the rotor corresponding to the rotational position of the rotor can be reduced. That is, by appropriately adjusting the range in which the nonmagnetic portion is provided in the penetrating direction of the through hole, the holding torque acting on the rotor can be adjusted.

In the stator, the non-magnetic portion may not penetrate the magnetic body.

According to the present invention, the range of the magnetic field of the rotor and the nonmagnetic section can be reduced as compared with the case where the nonmagnetic section penetrates the magnetic body. Therefore, the maximum value of the magnetic potential is reduced in relation to the magnetic potential and the rotational position of the rotor. Therefore, excessive holding force acting on the rotor can be suppressed.

In the stator, the magnetic body may include a Ni — Fe alloy, and the nonmagnetic portion may be formed so that a Cr content is larger than that of the magnetic body.

According to the present invention, since the non-magnetic region in which Cr is diffused and which becomes an austenite single phase has a lower magnetic permeability than the surrounding region, the non-magnetic portion having a lower magnetic permeability than the magnetic material can be formed.

In the stator, the magnetic resistance part may be provided by thermal fusion, and may be formed so that the magnetic permeability is smaller than that of the magnetic body and so that the Cr content is larger than that of the magnetic body.

Conventionally, in order to magnetically divide a stator to generate magnetic poles, a gap from a through hole to an outer edge of the stator is sometimes reduced to cause saturation (magnetic saturation) of magnetic flux density by a magnetic field of a coil. According to the present invention, since the magnetic resistance portion is formed so that the magnetic permeability is smaller than that of the magnetic material by the nonmagnetic region into which Cr is diffused to become the austenite single phase, the stator can be magnetically divided by the magnetic resistance portion to generate the magnetic poles without using the above-described conventional technique.

In the stator, the magnetic resistance portion may be formed to a 1 st depth from a 1 st surface of the magnetic body, and the non-magnetic portion may be formed to a 2 nd depth different from the 1 st depth from the 1 st surface of the magnetic body.

In the present invention, the magnetoresistive portion and the nonmagnetic portion are formed at different depths from each other. Here, in order to suppress an excessive magnetic flux required for magnetic saturation when a magnetic pole is generated, it is preferable to appropriately set the depth of the magnetic resistance portion. In addition, in order to suppress an excessive holding force acting on the rotor, it is preferable to appropriately set the depth of the nonmagnetic portion. By forming the magnetic resistance portion and the non-magnetic portion at different depths from each other, it is possible to suppress an excessive magnetic flux when a magnetic pole is generated and an excessive holding force acting on the rotor. Thus, the current flowing through the coil when the rotor rotates can be reduced.

In the stator, the 2 nd depth may be smaller than the 1 st depth.

According to the present invention, the depth of the nonmagnetic section is set to obtain a desired holding force acting on the rotor, and the magnetoresistive section can be formed deeper than the nonmagnetic section to reduce the magnetic flux required for magnetic saturation. Therefore, excessive magnetic flux generated when the magnetic pole is generated and excessive holding force acting on the rotor can be suppressed. Therefore, the current flowing through the coil when the rotor rotates can be reduced.

In the stator, the magnetic resistance part may be formed so as to have a magnetic permeability smaller than that of the magnetic body, and a minimum distance from the through hole to an outer edge may be 0.1mm or more.

Conventionally, in order to magnetically divide a stator to generate magnetic poles, a gap from a through hole to an outer edge of the stator is sometimes reduced to cause saturation of magnetic flux density by a magnetic field of a coil. According to the present invention, the magnetic reluctance portion is formed to have a magnetic permeability smaller than that of the magnetic body, so that the stator can be magnetically divided by the magnetic reluctance portion to generate magnetic poles without using the conventional technique described above. Therefore, even if the minimum distance from the through hole to the outer edge of the stator is 0.1mm or more, magnetic poles can be generated by the magnetic resistance portion, and therefore, the strength of the stator can be improved as compared with the above-described conventional technique.

The stepping motor of the present invention is characterized by comprising: the above stator; and a rotor disposed in the through hole.

The movement for a timepiece of the present invention is characterized by comprising: the above-mentioned stepping motor; and a gear set transmitting power of the stepping motor.

According to the present invention, since the stator capable of reducing the holding torque acting on the rotor is provided, the current flowing through the coil when the rotor rotates can be reduced. Thus, power consumption can be reduced.

The timepiece of the invention is characterized in that: the timepiece movement is provided.

According to the present invention, a timepiece with low power consumption can be provided. In particular, the present invention is suitable for a small timepiece having a small battery.

The method for manufacturing a stator according to the present invention includes: a magnetic body having a through-hole and containing a Ni-Fe alloy; a magnetic resistance part which is arranged around the through hole and generates magnetic poles around the through hole when the coil is excited; and a non-magnetic portion provided at a position different from the magnetic resistance portion around the through hole and formed to have a magnetic permeability smaller than that of the magnetic body, wherein the method of manufacturing the stator includes: a chromium disposing step of disposing a Cr material on a magnetic material; a chromium melting step of irradiating the Cr material with a laser beam to melt and solidify the Cr material on the magnetic material; and a through-hole forming step of punching out the magnetic material to form the through-hole after the chromium melting step.

According to the present invention, the through-hole is formed after melting and solidifying the Cr material, so that thermal deformation of the through-hole can be suppressed. Thus, the stator can be formed with high accuracy.

In the above method for manufacturing a stator, the step of melting chromium may include: a 1 st irradiation step of irradiating the Cr material with a laser beam to form at least a part of the magnetoresistive portion; and a 2 nd irradiation step of irradiating the Cr material with a laser beam and applying energy smaller than that of the laser beam in the 1 st irradiation step to form at least a part of the nonmagnetic portion.

According to the present invention, the larger the energy applied, the deeper the Cr melt-diffusion depth becomes, so that the nonmagnetic portion can be formed shallower than the magnetoresistive portion. Therefore, it is possible to suppress an excessive magnetic flux generated in the vicinity of the magnetic resistance portion and an excessive holding force acting on the rotor. Thus, it is possible to provide a stator capable of reducing the current flowing through the coil when the rotor rotates.

[ Effect of the invention ]

According to the present invention, the holding torque acting on the rotor can be reduced.

Drawings

Fig. 1 is a block diagram showing a timepiece according to embodiment 1.

Fig. 2 is a perspective view showing a schematic configuration example of the stepping motor 7 according to embodiment 1.

Fig. 3 is a plan view schematically showing a stepping motor according to embodiment 1.

Fig. 4 is a cross-sectional view of the stator taken along line IV-IV of fig. 3.

Fig. 5 is a flowchart illustrating a method of manufacturing a stator according to embodiment 1.

Fig. 6 is a schematic view for explaining a method of manufacturing a stator according to embodiment 1.

Fig. 7 is a plan view schematically showing a stepping motor according to embodiment 2.

Fig. 8 is a cross-sectional view of the stator taken along line VIII-VIII of fig. 7.

Fig. 9 is a plan view schematically showing a stepping motor according to embodiment 3.

Fig. 10 is a plan view schematically showing a stepping motor according to embodiment 4.

Fig. 11 is a sectional view of a stator according to embodiment 4, where (a) is a sectional view of the stator taken along line Xa-Xa in fig. 10, and (b) is a sectional view of the stator taken along line Xb-Xb in fig. 10.

Fig. 12 is a cross-sectional view of a stator according to a modification of embodiment 4, and is a view showing a cross-section of a portion corresponding to line Xa-Xa in fig. 10.

Fig. 13 is a flowchart illustrating a method of manufacturing a stator according to embodiment 4.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same reference numerals are used for the structures having the same or similar functions. In addition, a repetitive description of these configurations may be omitted. In the embodiments described below, an analog electronic timepiece is illustrated as an example of a timepiece.

[ embodiment 1 ]

(clock and movement)

Fig. 1 is a block diagram showing a timepiece according to embodiment 1.

As shown in fig. 1, the timepiece 1 includes: battery 2, oscillation circuit 3, frequency dividing circuit 4, control circuit 5, pulse drive circuit 6, stepping motor 7, and analog clock unit 8.

The analog timepiece unit 8 includes a gear train 11, an hour hand 12, a minute hand 13, a second hand 14, a calendar display unit 15, a timepiece case 16, and a movement 17 (timepiece movement). In the present embodiment, the hour hand 12, the minute hand 13, and the second hand 14 are referred to as "hands" when one of them is not specified. The oscillation circuit 3, the frequency dividing circuit 4, the control circuit 5, the pulse drive circuit 6, the stepping motor 7, and the gear group 11 are components of the movement 17.

The battery 2 is a so-called button cell battery such as a silver oxide battery or a lithium battery. Further, the battery 2 may be a solar cell and a storage battery that stores electric power generated by the solar cell. The battery 2 supplies electric power to the control circuit 5.

The oscillation circuit 3 is a passive element used to generate a predetermined frequency by mechanical resonance, for example, using a piezoelectric phenomenon of quartz. Here, the predetermined frequency is, for example, 32[ kHz ].

The frequency dividing circuit 4 divides the signal of a predetermined frequency output from the oscillation circuit 3 into a desired frequency, and outputs the divided signal to the control circuit 5.

The control circuit 5 performs timing using the frequency-divided signal output from the frequency dividing circuit 4, and generates a drive pulse based on the result of the timing. When the hand is moved in the forward direction, the control circuit 5 generates a drive pulse for forward rotation. When the hand is moved in the reverse direction, the control circuit 5 generates a drive pulse for reverse rotation. The control circuit 5 outputs the generated drive pulse to the pulse drive circuit 6.

The pulse drive circuit 6 generates a drive pulse for each pointer in response to a drive instruction output from the control circuit 5. The pulse drive circuit 6 outputs the generated drive pulse to the stepping motor 7.

The stepping motor 7 moves the hand in response to a drive pulse output from the pulse drive circuit 6. In the example shown in fig. 1, for example, one stepping motor 7 is provided for each of the hour hand 12, minute hand 13, and second hand 14. The power of the stepping motor 7 is transmitted to the hands through the gear train 11.

The hour hand 12, minute hand 13, and second hand 14 are driven by the power of the stepping motor 7. Hour hand 12 rotates once in 12 hours by driving stepping motor 7 with pulse drive circuit 6. The minute hand 13 is rotated once in 60 minutes by driving the stepping motor 7 by the pulse drive circuit 6. The second hand 14 rotates once for 60 seconds by driving the stepping motor 7 by the pulse drive circuit 6.

(Structure of stepping motor)

Fig. 2 is a perspective view showing a schematic configuration example of the stepping motor 7 according to embodiment 1.

As shown in fig. 2, the stepping motor 7 includes: a rotor 20 magnetized to two poles (S pole and N pole); a stator 21 that generates magnetic poles opposing the rotor 20; a magnetic core 22 magnetically coupled to the stator 21; a coil 23 wound around the core 22 to excite the stator 21; and a screw 24 engaging the stator 21 and the magnetic core 22. The rotor 20 is rotatably supported by a bottom plate or the like constituting a base plate of the movement 17. The rotor 20 is provided with a pinion gear that meshes with the gear train 11.

Here, the structure of the stator 21 will be described in detail.

Fig. 3 is a plan view schematically showing a stepping motor according to embodiment 1.

As shown in fig. 3, the stator 21 extends so as to be connected to both end portions of the core 22. The stator 21 is a plate-like magnetic body 30 formed of a magnetic material, except for a magnetic resistance portion 33 and a non-magnetic portion 35, which will be described later. In the present embodiment, an Fe-38% Ni-8% Cr alloy (so-called 38 permalloy) is used as the magnetic material. A through hole 31 for disposing the rotor 20 is formed in an intermediate portion of the magnetic body 30 of the stator 21. The term "intermediate" used in this embodiment means not only the center between both ends of the object but also an inner range between both ends of the object. The through-hole 31 penetrates the magnetic body 30 of the stator 21 in the thickness direction. The through-hole 31 is formed in a circular shape having a constant curvature over the entire circumference as viewed in the thickness direction of the magnetic body 30 of the stator 21. The through hole 31 is formed coaxially with the rotor 20 and has a larger diameter than the rotor 20.

The stator 21 includes a magnetic circuit R, a pair of magnetic resistance portions 33, and a pair of nonmagnetic portions 35.

The magnetic circuit R is provided in the magnetic body 30 around the through-hole 31. The magnetic flux lines of the magnetic field generated by exciting the coil 23 pass through the magnetic circuit R. The magnetic path R is the magnetic body 30 between the through hole 31 and the outer edge 21a of the stator 21. That is, the magnetic paths R are provided on both sides of the holding through-hole 31 in the direction orthogonal to the extending direction of the stator 21.

The pair of magnetic resistance portions 33 generate magnetic poles around the through-hole 31 when the coil 23 is excited. One pair of magnetic resistance portions 33 is provided for each magnetic path R. The pair of magnetic resistance portions 33 are provided at 2 locations around the through-hole 31 where the cross-sectional area of the magnetic path R becomes the smallest. That is, the pair of magnetic resistance portions 33 are provided around the through hole 31 at a position where the distance between the through hole 31 and the outer edge 21a of the stator 21 is narrow. For example, the pair of magnetic resistance portions 33 are provided at positions shifted from each other by 180 ° around the rotation center of the rotor 20. The pair of magnetic resistance portions 33 increase the magnetic resistance against the magnetic field generated by the coil 23, and generate leakage magnetic flux in the through hole 31. The leakage magnetic flux is generated so as to be orthogonal to a line segment connecting the pair of magnetic resistance portions 33. This generates magnetic poles around the through-hole 31.

In the present embodiment, the magnetoresistive portion 33 is formed of a nonmagnetic material. The magnetic resistance portion 33 is formed by non-contact processing using thermal melting. Specifically, Cr is melt-diffused into the magnetic body 30 forming the stator 21, and the magnetic resistance portion 33 of the present embodiment is formed so that the content of Cr is larger than that of the magnetic body 30. Thus, the magnetic resistance portion 33 is formed so as to have a lower magnetic permeability than the magnetic body 30, and increases the magnetic resistance against the magnetic field generated by the coil 23. For example, the maximum value of the Cr concentration in the magnetic resistance portion 33 is preferably 15 mass% or more and 80 mass% or less from the viewpoint of lowering the magnetic permeability of the magnetic resistance portion 33. The Cr concentration in the magnetic resistance portion 33 increases from the 2 nd main surface 21c side to the 1 st main surface 21b side of the stator 21. The pair of magnetic resistance portions 33 are provided continuously from the through hole 31 to the outer edge 21a of the stator 21 on at least the 1 st main surface 21b of the stator 21. The minimum distance g from the through hole 31 in the magnetic resistance part 33 to the outer edge 21a of the stator 21 is 0.1mm or more.

The pair of nonmagnetic portions 35 are provided at positions different from the pair of magnetic resistance portions 33 around the through hole 31. For example, the pair of nonmagnetic portions 35 are provided at positions shifted from each other by 180 ° around the rotation center of the rotor 20. For example, the pair of nonmagnetic sections 35 are provided: the line segment connecting the pair of nonmagnetic sections 35 is inclined at a predetermined angle with respect to the line segment connecting the pair of magnetic resistance sections 33 in the normal rotation direction of the rotor 20.

The nonmagnetic section 35 is formed of a nonmagnetic material. The nonmagnetic section 35 is formed by non-contact processing using thermal melting. Specifically, Cr is melt-diffused into the magnetic plate material forming the stator 21, and the nonmagnetic section 35 according to the present embodiment is formed so that the Cr content is larger than that of the magnetic body 30. Thus, the non-magnetic portion 35 is formed so as to have a lower magnetic permeability than the magnetic body 30, and the magnetic resistance of the non-magnetic portion 35 is increased in comparison with the case where the portion is not provided. For example, from the viewpoint of reducing the magnetic permeability of the nonmagnetic section 35, the maximum value of the Cr concentration in the nonmagnetic section 35 is preferably 15 mass% or more and 80 mass% or less. The Cr concentration in the nonmagnetic portion 35 increases from the 2 nd main surface 21c side to the 1 st main surface 21b side of the stator 21, similarly to the magnetoresistive portion 33.

The nonmagnetic section 35 is formed in a semicircular shape on the 1 st main surface 21b of the stator 21. The nonmagnetic portion 35 is provided on the inner peripheral surface 31a of the through hole 31 (see also fig. 4). That is, a part of the nonmagnetic portion 35 constitutes the inner peripheral surface 31a of the through hole 31.

The pair of nonmagnetic portions 35 are configured as positioning portions for determining the stationary position of the rotor 20 in a state where the coil 23 is not excited. The rotor 20 is stationary at a position where the magnetic attraction is strongest. Since the non-magnetic portion 35 is formed so that the magnetic permeability is smaller than that of the surroundings, the rotor 20 is stationary at a position where the magnetic poles of the rotor 20 do not face the non-magnetic portion 35. In other words, the pair of nonmagnetic parts 35 generates a difference in magnetic potential of the rotor 20 according to the rotational position of the rotor 20. The rotor 20 is stationary at a position where the magnetic potential becomes extremely small. The holding torque acts on the rotor 20 to stay in this position. For example, the rotor 20 is stationary at a position where the magnetic pole axis a of the rotor 20 is orthogonal to a line segment connecting the pair of nonmagnetic sections 35.

Fig. 4 is a cross-sectional view of the stator taken along line IV-IV of fig. 3.

As shown in fig. 4, the nonmagnetic section 35 is formed by: the cross-sectional area of the stator 21 in the cross section perpendicular to the thickness direction gradually decreases from the 1 st main surface 21b to the 2 nd main surface 21c of the stator 21. In the present embodiment, the nonmagnetic section 35 is provided only partially in the thickness direction of the stator 21. Specifically, the non-magnetic portion 35 is formed so as not to reach the 2 nd main surface 21c from the 1 st main surface 21b of the stator 21, and does not penetrate the magnetic body 30.

(method of manufacturing stator)

Next, a method for manufacturing a stator according to embodiment 1 will be described.

Fig. 5 is a flowchart illustrating a method of manufacturing a stator according to embodiment 1. Fig. 6 is a schematic view for explaining a method of manufacturing a stator according to embodiment 1. In fig. 6, reference numeral 46 denotes a cutting position by press working.

As shown in fig. 5, the method of manufacturing the stator 21 according to the present embodiment includes a chrome placement step S10, a chrome melting step S20, and a pressing step S30 (through hole forming step).

As shown in fig. 6, in the chromium disposing step S10, a Cr material is disposed on the surface of the magnetic plate material 41 (magnetic material) forming the stator 21. The magnetic plate material 41 can be made of, for example, Fe-38% Ni-8% Cr (so-called 38 permalloy). For example, the Cr material is applied to the magnetic plate material 41 using a dispenser paste and then dried, and is disposed on the magnetic plate material 41. The arrangement of the Cr material is not limited to paste application, and, for example, plating of the magnetic plate material 41 may be applied.

In the chromium melting step S20, the Cr material is irradiated with a laser beam to melt and solidify the Cr material on the magnetic plate material 41. Specifically, the Cr material disposed on the surface of the magnetic plate material 41 is irradiated with a laser beam, and the Cr material is fused into the magnetic plate material 41 as the base material. Thereby, the Cr material is melted and diffused in the magnetic plate material 41, and Cr diffusion regions 43 and 44 in which the Cr weight ratio is locally increased are formed. The Cr diffusion regions 43 and 44 are formed at positions corresponding to the magnetic resistance portion 33 and the nonmagnetic portion 35 of the stator 21. The Cr diffusion region 43 is formed for the purpose of the magnetoresistive portion 33, and is formed, for example, in a continuous linear shape. The Cr diffusion region 44 is formed for the purpose of the nonmagnetic section 35, and is formed only locally at a position corresponding to the nonmagnetic section 35. Then, in order to remove the unnecessary Cr material, the magnetic plate material 41 in which the Cr material is solidified is melted needs to be cleaned.

The range of the Cr diffusion regions 43 and 44 is changed by the heat applied by the laser irradiation, and the greater the heat applied, the deeper the Cr melting diffusion depth. That is, the ranges of the Cr diffusion regions 43 and 44 can be set to arbitrary depths by adjusting the output of the laser, the irradiation time, the aperture diameter, and the like. For example, the Cr diffusion regions 43 and 44 may be formed from the 1 st main surface to the 2 nd main surface of the magnetic plate material 41, or may be formed from the 1 st main surface to the 2 nd main surface of the magnetic plate material 41. In the present embodiment, the Cr diffusion regions 43 and 44 are formed so as not to reach the 2 nd main surface from the 1 st main surface of the magnetic plate material 41.

The pressing process S30 is performed after the chrome melting process S20. In the pressing step S30, the magnetic plate material 41 with the solidified Cr melted therein is punched out to form the outer shape of the stator 21 and the through-hole 31. At this time, the magnetic plate material 41 is cut so as to cross the Cr diffusion regions 43 and 44.

In this way, the stator 21 including the magnetic resistance portion 33 and the nonmagnetic portion 35 is formed.

The magnetic potential of the rotor 20 changes depending on the magnetic permeability, size, position, and the like of the pair of nonmagnetic sections 35. That is, the holding torque acting on the stationary rotor 20 can be adjusted by adjusting the depth of the formed Cr diffusion region 44 in the chromium melting step S20.

(action of stepping motor)

Next, the operation of the stepping motor according to embodiment 1 will be described.

As shown in fig. 3, when no current flows through the coil 23, the rotor 20 is stationary at a position where the magnetic potential is extremely small.

When a drive pulse signal is supplied from the pulse drive circuit 6 to between the terminals OUT1, OUT2 of the coil 23 (for example, the 1 st terminal OUT1 side is a positive electrode, and the 2 nd terminal OUT2 side is a negative electrode), and a current i flows in the direction indicated by the arrow in fig. 3, a magnetic flux is generated in the stator 21 in the direction indicated by the broken line arrow.

In the present embodiment, the magnetic resistance portion 33 is formed in the magnetic path R. Therefore, the leakage magnetic flux can be easily secured in the through-hole 31. Then, the rotor 20 is rotated by 180 ° in the arrow direction of fig. 3 by the interaction of the magnetic poles generated at the stator 21 and the magnetic poles of the rotor 20, and is stably stopped (stationary).

The rotation direction (counterclockwise direction in fig. 3) for normal operation (for example, hand movement operation of an analog electronic timepiece) by rotationally driving the stepping motor 7 is a normal rotation direction, and the opposite direction (clockwise direction) is a reverse rotation direction.

Then, when a drive pulse of opposite polarity is supplied from the pulse drive circuit 6 to the terminals OUT1, OUT2 of the coil 23 and a current flows in the direction indicated by the reverse arrow in fig. 3, a magnetic flux is generated in the stator 21 in the direction opposite to the direction indicated by the broken line arrow.

Thereafter, as described above, the rotor 20 is rotated by 180 ° in the same direction (forward rotation direction) as described above by the interaction between the magnetic poles generated in the stator 21 and the magnetic poles of the rotor 20, and is stopped (stationary) stably.

Hereinafter, by supplying signals (alternating signals) having different polarities to the coil 23 in this manner and repeating the above operation, the rotor 20 can be continuously rotated in the arrow direction every 180 °.

As described above, the stator 21 of the present embodiment includes: a magnetic resistance part 33 provided around the through hole 31 and generating magnetic poles around the through hole 31 when the coil 23 is excited; and a non-magnetic part 35 provided at a position different from the magnetic resistance part 33 around the through hole 31 and formed to have a magnetic permeability smaller than that of the magnetic body 30.

According to this configuration, by providing the non-magnetic portion 35 having a magnetic permeability smaller than that of the magnetic body 30 around the through hole 31, it is possible to generate a difference in magnetic potential of the rotor 20 according to the rotational position of the rotor 20 without providing the through hole 31 with a notch or a step shape. Therefore, by appropriately adjusting the shape, size, magnetic permeability, and the like of the non-magnetic portion 35, the holding torque acting on the rotor 20 can be adjusted. Thus, the stator 21 that can reduce the holding torque acting on the rotor 20 can be provided.

In addition, the nonmagnetic portion 35 is provided on the inner peripheral surface 31a of the through hole 31. According to this configuration, the nonmagnetic section 35 can be provided at a position directly facing the rotor 20. Therefore, the difference in the magnetic potential of the rotor 20 corresponding to the rotational position of the rotor 20 can be reliably generated. Therefore, the holding torque acting on the rotor 20 can be suppressed from being insufficient.

The stator 21 is made of a Ni — Fe alloy, and the nonmagnetic section 35 is formed so that the Cr content is locally increased. According to this configuration, since the non-magnetic region in which Cr is diffused and which becomes an austenite single phase has a lower magnetic permeability than the surrounding region, the non-magnetic portion 35 having a lower magnetic permeability than the magnetic body 30 can be formed.

The nonmagnetic portion 35 is provided only partially in the penetrating direction of the through hole 31 (i.e., the thickness direction of the stator 21). According to this configuration, the range in which the magnetic field of the rotor 20 reaches the nonmagnetic section 35 is reduced as compared with the case where the nonmagnetic section is provided over the entire region in the penetrating direction of the through hole 31, and the difference in the magnetic potential of the rotor 20 corresponding to the rotational position of the rotor 20 can be reduced. That is, by appropriately adjusting the range in which the nonmagnetic portion 35 is provided in the penetrating direction of the through hole 31, the holding torque acting on the rotor 20 can be adjusted.

The magnetic resistance portion 33 is formed so that the magnetic permeability is locally reduced, and the minimum distance from the through hole 31 to the outer edge 21a of the stator 21 is 0.1mm or more. Conventionally, in order to magnetically divide a stator to generate magnetic poles, a gap from a through hole to an outer edge of the stator is sometimes reduced to cause saturation (magnetic saturation) of magnetic flux density by a magnetic field of a coil. According to the present embodiment, since the magnetic resistance portion 33 is formed to have a magnetic permeability smaller than that of the magnetic body 30, the stator 21 can be magnetically divided by the magnetic resistance portion 33 to generate magnetic poles without using the conventional technique described above. Therefore, even if the minimum distance g from the through hole 31 to the outer edge 21a of the stator 21 is 0.1mm or more, magnetic poles are generated by the magnetic resistance portion 33, and therefore, the strength of the stator 21 can be improved as compared with the above-described conventional technique.

The method for manufacturing the stator 21 according to the present embodiment includes: a chromium disposing step S10 of disposing a Cr material on the magnetic plate 41; a chromium melting step S20 of irradiating the Cr material with a laser beam to melt and solidify the Cr material on the magnetic plate material 41; and a punching step S30 of punching out the magnetic plate material 41 to form the through hole 31 after the chrome melting step S20. According to this structure, the through-hole 31 is formed after melting and solidifying the Cr material, so thermal deformation of the through-hole 31 can be suppressed. Thus, the stator 21 can be formed with high accuracy.

The stepping motor 7 of the present embodiment includes the stator 21 and the rotor 20 disposed in the through hole 31. The movement 17 of the present embodiment includes the stepping motor 7 and the gear train 11 that transmits power of the stepping motor 7. According to the present embodiment, since the stator 21 capable of reducing the holding torque acting on the rotor 20 is provided, the current flowing through the coil 23 when the rotor 20 rotates can be reduced. Thus, power consumption can be reduced.

Since the timepiece 1 of the present embodiment includes the movement 17, it can be a timepiece with low power consumption. In particular, the structure of the present embodiment is suitable for a small timepiece having a small battery that can be mounted.

[ 2 nd embodiment ]

(Structure of stepping motor)

Fig. 7 is a plan view schematically showing a stepping motor according to embodiment 2. Fig. 8 is a cross-sectional view of the stator taken along line VIII-VIII of fig. 7.

In embodiment 1 shown in fig. 3, the nonmagnetic portion 35 is provided on the inner peripheral surface 31a of the through hole 31. In contrast, in embodiment 2 shown in fig. 7, the nonmagnetic section 135 is provided separately from the through hole 31. In this regard, embodiment 2 is different from embodiment 1. The configuration other than the following description is the same as that of embodiment 1.

As shown in fig. 7, the non-magnetic portion 135 is formed in a circular shape on the 1 st main surface 21b of the stator 21.

As shown in fig. 8, the nonmagnetic section 135 is formed by: the cross-sectional area of the stator 21 in the cross section perpendicular to the thickness direction gradually decreases from the 1 st main surface 21b to the 2 nd main surface 21c of the stator 21. In the present embodiment, the non-magnetic portion 135 is provided only partially in the thickness direction of the stator 21. Specifically, the non-magnetic portion 135 is formed so as not to reach the 2 nd main surface 21c from the 1 st main surface 21b of the stator 21, and does not penetrate the magnetic body 30. The minimum distance between the nonmagnetic section 135 and the through hole 31 is, for example, 0.1mm or less.

As described above, according to the stator 21 of the present embodiment, the non-magnetic portion 135 is provided in the range where the magnetic field of the rotor 20 spreads, and a difference in the magnetic potential of the rotor 20 can be generated according to the rotational position of the rotor 20. Therefore, it is possible to provide the stator 21 capable of achieving the same operational effects as those of the above-described embodiment 1.

[ embodiment 3 ]

(Structure of stepping motor)

Fig. 9 is a plan view schematically showing a stepping motor according to embodiment 3.

In embodiment 1 shown in fig. 3, the magnetic resistance portion 33 is formed so as to have a magnetic permeability smaller than that of the magnetic body 30. In contrast, in embodiment 3 shown in fig. 9, the magnetic resistance portion 233 is a narrow portion formed by providing an outer notch 237 on the outer edge 21a of the stator 21. In this regard, embodiment 3 is different from embodiment 1. The configuration other than the following description is the same as that of embodiment 1.

As shown in fig. 9, a pair of outer notches 237 are formed in the outer edge 21a of the stator 21. The pair of outer notches 237 are provided on the opposite side of the through hole 31 with the magnetic path R therebetween. The outer recess 237 locally reduces the cross-sectional area of the magnetic circuit R.

The pair of magnetoresistive portions 233 are provided between the outer notch 237 of the magnetic circuit R and the through hole 31. The pair of magnetic resistance portions 233 are provided at 2 locations around the through-hole 31 where the cross-sectional area of the magnetic path R becomes the smallest. The magnetoresistive portion 233 is integrally formed with its periphery by the same member. That is, the magnetic resistance portion 233 is formed of a magnetic material. The pair of magnetoresistive portions 233 are formed: the magnetic flux is not saturated by the magnetic field of the rotor 20, but is saturated when the coil 23 is excited. Thereby, the pair of magnetic resistance portions 233 increase the magnetic resistance against the magnetic field generated by the coil 23, and generate leakage magnetic flux in the through-hole 31, and generate magnetic poles around the through-hole 31.

As described above, according to the stator 21 of the present embodiment, the same operational effects as those of the stator 21 of embodiment 1 can be obtained.

[ 4 th embodiment ]

(Structure of stepping motor)

Fig. 10 is a plan view schematically showing a stepping motor according to embodiment 4. Fig. 11 is a sectional view of a stator according to embodiment 4, where (a) is a sectional view of the stator taken along line Xa-Xa in fig. 10, and (b) is a sectional view of the stator taken along line Xb-Xb in fig. 10.

In embodiment 1 and embodiment 2, the depths of the magnetic resistance portion 33 and the nonmagnetic portions 35 and 135 are not particularly limited. In contrast, in embodiment 4 shown in fig. 10, the magnetic resistance part 333 and the nonmagnetic part 335 have different depths. The configuration other than the following is the same as that of embodiment 1.

As shown in fig. 10 and 11, the magnetic resistance part 333 is formed by: the cross-sectional area of the stator 21 in a cross section orthogonal to the thickness direction gradually decreases from the 1 st main surface 21b to the 2 nd main surface 21c of the stator 21. The magnetic resistance part 333 is provided only partially in the thickness direction of the stator 21. Specifically, the magnetic resistance part 333 is formed so as not to reach the 2 nd main surface 21c from the 1 st main surface 21b of the stator 21, and does not penetrate the magnetic body 30. The magnetic resistance part 333 is formed from the 1 st main surface 21b of the stator 21 (the 1 st surface of the magnetic substance 30) to the 1 st depth D1.

The nonmagnetic section 335 is formed by: the cross-sectional area of the stator 21 in a cross section orthogonal to the thickness direction gradually decreases from the 1 st main surface 21b to the 2 nd main surface 21c of the stator 21. The nonmagnetic section 335 is provided only partially in the thickness direction of the stator 21. Specifically, the non-magnetic portion 335 is formed so as not to reach the 2 nd main surface 21c from the 1 st main surface 21b of the stator 21, and does not penetrate the magnetic body 30. The nonmagnetic section 335 is formed from the 1 st main surface 21b of the stator 21 to the 2 nd depth D2 different from the 1 st depth D1. The 2 nd depth D2 is less than the 1 st depth D1. That is, the nonmagnetic section 335 is formed shallower than the magnetoresistive section 333 with reference to the 1 st main surface 21b of the stator 21.

In the illustrated example, the nonmagnetic section 335 is provided on the inner peripheral surface 31a of the through hole 31, similarly to the nonmagnetic section 35 of embodiment 1. However, as shown in fig. 12, the nonmagnetic section 335 may be provided separately from the through-hole 31, as in the case of the nonmagnetic section 135 according to embodiment 2.

(method of manufacturing stator)

Next, a method for manufacturing a stator according to embodiment 4 will be described with reference to fig. 6 and 12.

Fig. 13 is a flowchart illustrating a method of manufacturing a stator according to embodiment 4.

As shown in fig. 13, in the method of manufacturing the stator 21 according to the present embodiment, the chrome melting step S20A includes the 1 st irradiation step S21 and the 2 nd irradiation step S22. The order of the 1 st irradiation step S21 and the 2 nd irradiation step S22 is not particularly limited.

In the 1 st irradiation step S21, the Cr material is irradiated with a laser beam to form the Cr diffusion region 43 as a part of the magnetoresistive portion 333.

In the 2 nd irradiation step S22, the Cr material is irradiated with laser light to form the Cr diffusion region 44 as at least a part of the nonmagnetic section 335. In the 2 nd irradiation step S22, energy smaller than the energy of the laser beam in the 1 st irradiation step S21 is applied to the Cr material and the magnetic plate material 41. Thus, the depth of the Cr diffusion in the Cr diffusion region 44 is made shallower than the depth of the Cr diffusion in the Cr diffusion region 43.

The energy applied by the laser beam can be changed by adjusting at least one of the output of the laser beam and the irradiation time. The output of the laser beam can be changed by adjusting the pulse energy or the pulse frequency of the pulsed laser beam, the aperture diameter of the laser beam, and the like. In addition, adjustment of the aperture diameter of the laser beam requires changing the mechanical setting of the laser device between the 1 st irradiation step S21 and the 2 nd irradiation step S22, or replacing the laser device with a lens having a different aperture diameter.

Therefore, from the viewpoint of reduction in manufacturing cost such as improvement in productivity, a method that can cope with a change in energy applied by the laser light, by changing only the output condition of the laser light, is preferable. That is, the energy applied by the laser is preferably changed by adjusting the pulse energy, the frequency of the pulse, and the irradiation time.

The stator 21 according to embodiment 4 described above has the following operational advantages in addition to the operational advantages similar to those of embodiment 1 described above.

In the present embodiment, the non-magnetic portion 335 does not penetrate the magnetic body 30. According to this configuration, the range in which the magnetic field of the rotor 20 reaches the nonmagnetic section 335 can be reduced as compared with the case where the nonmagnetic section penetrates the magnetic body. Therefore, the maximum value of the magnetic potential is reduced in relation to the magnetic potential and the rotational position of the rotor 20. Therefore, excessive holding force acting on the rotor 20 can be suppressed.

Further, the magnetic resistance part 333 is formed from the 1 st main surface 21b of the stator 21 to the 1 st depth D1, and the nonmagnetic part 335 is formed from the 1 st main surface 21b of the stator 21 to the 2 nd depth D2 different from the 1 st depth D1. In this structure, the magnetoresistive portion 333 and the nonmagnetic portion 335 are formed at different depths from each other. Here, it is preferable to appropriately set the depth of the magnetic resistance portion 333 from the viewpoint of suppressing an excessive magnetic flux required for magnetic saturation when a magnetic pole is generated. In addition, from the viewpoint of suppressing an excessive holding force acting on the rotor 20, it is preferable to appropriately set the depth of the nonmagnetic section 335. By forming the magnetic resistance portions 333 and the nonmagnetic portions 335 at different depths from each other, it is possible to suppress an excessive magnetic flux when a magnetic pole is generated and an excessive holding force acting on the rotor 20. Therefore, the current flowing through the coil 23 when the rotor 20 rotates can be reduced.

Further, the 2 nd depth D2 is less than the 1 st depth D1. According to this configuration, the depth of the nonmagnetic section 335 is set to obtain a desired holding force acting on the rotor 20, and the magnetoresistive section 333 can be formed deeper than the nonmagnetic section 335 to reduce the magnetic flux required for magnetic saturation. Therefore, excessive magnetic flux generated when the magnetic poles are generated and excessive holding force acting on the rotor 20 can be suppressed. Therefore, the current flowing through the coil 23 when the rotor 20 rotates can be reduced.

In the present embodiment, the chrome melting step S20A includes: a 1 st irradiation step S21 of irradiating the Cr material with laser light to form at least a part of the magnetoresistive portion 333; and a 2 nd irradiation step S22 of irradiating the Cr material with a laser beam and applying energy smaller than the energy of the laser beam in the 1 st irradiation step S21 to form at least a part of the nonmagnetic section 335. According to this configuration, the larger the energy applied, the deeper the Cr melt diffusion depth, so the nonmagnetic section 335 can be formed shallower than the magnetoresistive section 333. Therefore, it is possible to suppress an excessive magnetic flux generated in the vicinity of the magnetic resistance unit 333 when the magnetic poles are generated, and to suppress an excessive holding force acting on the rotor 20. Thus, it is possible to provide a stator capable of reducing the current flowing through the coil 23 when the rotor 20 rotates.

In embodiment 4, the magnetoresistive portion 333 and the nonmagnetic portion 335 are formed at different depths from each other by changing the energy applied by the laser beam, but the present invention is not limited to this. For example, the position of the cut position of the Cr diffusion region 44 with respect to the through hole 31 may be adjusted so that the depth of the nonmagnetic section 335 is different from the depth of the magnetoresistive section 333.

The present invention is not limited to the above-described embodiments described with reference to the drawings, and various modifications are conceivable within the technical scope.

For example, in the above embodiment, the stepping motor 7 is a single coil motor including 1 coil 23, but is not limited thereto. The stepping motor may be a double coil motor having two coils.

In the above embodiment, the non-magnetic portions 35 and 135 are formed in a circular shape in a plan view, but the present invention is not limited thereto. The shape of the nonmagnetic portion in a plan view may be appropriately adjusted to control the holding torque acting on the rotor 20 in accordance with the irradiation range of the laser beam. That is, the non-magnetic portion may have, for example, an elliptical shape or an oval shape (rounded rectangular shape) in a plan view.

In the above embodiment, the magnetic resistance part 33 is formed of a non-magnetic material and is provided continuously from the through hole 31 to the outer edge 21a of the stator 21, but the present invention is not limited thereto. When the magnetic resistance portion is formed of a non-magnetic material, the magnetic resistance portion may be provided at least partially between the through hole 31 and the outer edge 21a of the stator 21.

In the above embodiment, the nonmagnetic portions 35 and 135 are provided only partially in the penetrating direction of the through hole 31, but the present invention is not limited to this. The nonmagnetic portion may be provided over the entire region in the penetrating direction of the through hole 31, and may extend from the 1 st main surface 21b to the 2 nd main surface 21c of the stator 21.

In the above embodiment, the pair of nonmagnetic sections 35 and 135 is provided, but the present invention is not limited to this. Only one nonmagnetic portion may be provided, or 3 or more may be provided.

The through-hole of the magnetic material 30 may be formed not by the entire through-hole 31 but by the magnetic material 30. That is, at least a part of the through-hole may be formed in the magnetic body. For example, the magnetic body may be divided by the magnetic resistance portion 33 to form only a part of the inner peripheral surface of the through hole. In this case, the same operational effects as those of the above-described embodiment are obtained.

Further, the components in the above embodiments may be replaced with well-known components as appropriate without departing from the spirit of the present invention, and the above embodiments may be combined as appropriate.

Description of the reference symbols

1 … clock and watch; 11 … gear set; 17 … movement (movement for clock); 20 … a rotor; 21 … stator; 21a … outer edge; 23 … coil; 30 … magnetic body; 31 … through holes; 31a … inner peripheral surface; 33. 233, 333 … magnetic resistance parts; 35. 135, 335 … non-magnetic portions; 41 … magnetic plate material (magnetic material); d1 … depth No. 1; d2 … depth No. 2; s10 … preparing chromium; s20, S20A … chromium melting process; s21 … item 1 irradiation step; s22 … item 2 irradiation step; and S30 … through hole forming step.