JP3608261B2 - Watch manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a structure of a timepiece position detecting mechanism for a timepiece using magnetism and a manufacturing method thereof.
[0002]
[Prior art]
Conventional position detection devices using magnetism are bulk permanent magnet materials on which digitally encoded patterns and analog patterns are formed, as disclosed in Japanese Patent Laid-Open Nos. 4-262502 and 4-262501. Connect the object to be measured to make the magnetic sensor recognize the movement and position of the magnet as the object to be measured, or use a thin film magnetic medium such as HDD or FDD, and magnetic information (data position) ).
[0003]
Conventional watch position detecting devices for watches have a contact energization method, a magnetic method, an optical method, and an electrostatic method.
[0004]
In the contact energization method, as shown in Japanese Patent Application Laid-Open No. 61-111484, a part of a grounded pointer is rotated and swept while being in contact with an electrode formed on a dial, and a current is supplied from both ends of the electrode. Therefore, the pointer position was detected.
[0005]
As shown in Japanese Patent Application Laid-Open No. 54-118870, the magnetic system includes a magnetic sensitive element such as an MR element at a position to be detected on a dial, and a magnetic flux generated when a magnetized pointer crosses the magnetic sensitive element. An increase was detected.
[0006]
As shown in JP-A-55-154485 and JP-A-61-17317, the light system is arranged with a photosensitive element such as a CCD or a solar cell on a dial, and a pointer is provided on the element. As shown in Japanese Patent Application Laid-Open No. 3-239963, a method of detecting a change in the amount of light when crossing, a small hole is formed outside the shaft center of the gear, and the light passing through the small hole is measured by a plurality of optical sensors, The rotation of the pointer was detected.
[0007]
As disclosed in Japanese Patent Application Laid-Open No. 62-222183, the electrostatic method measures the capacitance generated when the pointer crosses over the single electrode dial set on the dial as a time constant, and detects the position of the pointer. I was doing.
[0008]
In addition, the manufacturing method of the magnetic pointer position detecting device is as follows. First, as shown in Japanese Patent Application Laid-Open No. 4-262501, a magnetized bulk permanent magnet is partially heated and magnetized using a laser to form a magnetized pattern. A magnetized pattern is formed by applying a magnetic field necessary to magnetize a part of a bulk permanent magnet material which is not magnetized as in Kaihei 4-262502, while partially heating the laser. Position information is recorded by an array of magnetization patterns. Next, a magnetic sensor such as an MR element that performs relative operation facing the magnetized pattern array is installed. A magnetic sensor detects a change in magnetic flux to recognize position information and specify a position. In addition, a part of a magnetic medium is magnetized by using a magnetic head or the like as found in an FDD or HDD, and position information is recorded with an array pattern of the magnetization. Further, although the manufacturing method of the timepiece position detecting device of the timepiece disclosed in Japanese Patent Laid-Open No. 54-118870 is not described in detail, the timepiece movement is the same as the method of manufacturing a normal timepiece, and an MR sensor is installed on the dial, It is thought that the magnetized pointer is assembled in the final assembly process.
[0009]
[Problems to be solved by the invention]
However, the conventional magnetic method position detection method as disclosed in JP-A-4-262502 has the following problems.
[0010]
1) The position of the bulk permanent magnet connected to the object to be measured is detected, and since the position of the object to be measured is not directly detected, there is a large error in position detection accuracy.
[0011]
2) Connecting a heavy bulk permanent magnet to the object to be measured affects the operation and position of the object to be measured. In particular, if it is installed in a mechanical system with a small driving torque such as a wristwatch, the pointer cannot be moved.
[0012]
3) Since a position detection device such as a bulk permanent magnet or a magnetic sensor is connected to the object to be measured, the system becomes large. In many cases, it cannot be installed with a limited space such as a wristwatch.
[0013]
4) As a countermeasure against the problems 1, 2, and 3, the measured object itself may be made from a bulk permanent magnet manufactured by casting or sintering, but the permanent magnet itself is very difficult to process. Although it is a material and the shape of a bonded magnet is easy to make, there are many restrictions such as being often unsuitable as a mechanical element.
[0014]
Further, in the HDD and FDD, the magnetic media is a thin film, so that the leakage magnetic field of magnetic information is small, and the magnetic head must be within 1 micron of or in contact with the magnetic media. In order to keep the distance below 1 micron in a non-contact manner, the magnetic medium had to be rotated at high speed and the shape of the magnetic head had to be specially processed to fly. Also, in order to increase the magnetic information detection electromotive force of the magnetic head, the magnetic medium has to be rotated at high speed. For this reason, this method is not suitable for detecting the position of an object moving at low speed, and the magnetic head is made to fly or contact with the magnetic media, so that the special processing of the magnetic head and the protection against increased wear resistance are protected. There is a problem that the cost of the magnetic head, such as film formation, is high. Further, a method in which a magnetic head is brought into contact with a magnetic medium like FDD is not suitable for a driving system with a small driving torque like a watch.
[0015]
Further, the conventional method for detecting the hand position of a timepiece has the following problems.
[0016]
1) The contact energization method has poor position detection reliability due to intrusion of foreign matter between electrical contacts or electrical corrosion of the contacts.
[0017]
2) In the conventional magnetic system, multipoint detection, for example, detection of the second hand every second is very difficult and the manufacturing cost is high. Further, since a magnet or a high-permeability material is used for the pointer, it is weak against an external magnetic field and easily causes an error.
[0018]
3) Multi-point detection is also difficult for the optical method, and the cost is high. Detection errors are also likely to occur due to external light.
[0019]
4) The electrostatic method is likely to cause detection errors due to environmental changes such as humidity changes.
[0020]
Further, conventional methods for manufacturing a position detecting device using a magnetic method, such as Japanese Patent Application Laid-Open Nos. 4-262501 and 4-262502, are not compatible with timepiece manufacturing. That is, the watch is manufactured by first assembling a non-magnetized rotor, stator, gears, etc., and in terms of structure, the movement is completed, and then a 20 K Oersted magnetic field is applied to the entire movement parallel to the gear rotation surface. The rotor is magnetized. If the rotor is magnetized before assembly, the rotor cannot be assembled because the rotor is joined to the stator that is a soft magnetic material during assembly. Therefore, if a permanent magnet whose position is recorded is connected to a gear in the movement as in JP-A-4-262501, the position information is erased or erroneous information is generated by magnetization after assembly. Have. In order to avoid this, Japanese Patent Application Laid-Open No. 4-262502 is applied, and a permanent magnet that is not magnetized is connected to a gear in the movement, and the movement is not affected by the rotor after the rotor is magnetized after the movement is assembled. Although it is conceivable to write magnetization information to the permanent magnet with a laser while applying a magnetic field, there are three permanent magnets installed in the movement that correspond to the maximum, hour, minute, and second, and the structure is centered on the movement and gears. Therefore, writing position information in each of them has a problem that there is no mass productivity. Magnetizing position information on a permanent magnet with a magnetic head used in an HDD or FDD has the same problem, and also has the problem that the leakage magnetic flux density varies depending on the pitch of the magnetization pattern, making it difficult to recognize the information.
[0021]
Therefore, the present invention solves such a problem, and the object is as follows.
1) The position of a moving object moving at a very low to high speed can be directly recognized, its position detection pitch is about 100 microns, and the watch pointer position can be recognized stably every second. 2) The entire detection system Is ultra-compact and does not need to change the shape of the device to be incorporated, and does not affect the movement or function of the device 3) Low effective current consumption and low manufacturing cost 4) Currently widely used It is an object of the present invention to provide a magnetic hand position detecting device for a timepiece that can be adapted to a manufacturing process of a timepiece and a method for manufacturing the same.
[0022]
[Means for Solving the Problems]
The present invention is for achieving the above-described object, and the contents thereof will be described below.
[0026]
The manufacturing method of the timepiece of the present invention includes:
In a timepiece manufacturing method including a pointer, a gear that rotationally drives the pointer, and a rotor that rotationally drives the gear,
A first step of printing a hard magnetic film pattern in which the rotation position of the pointer is digitally encoded radially from the center of the gear on the rotation surface of the gear, and perpendicularly magnetizing the hard magnetic film pattern;
A second step of assembling a hall element facing the gear, the rotor, and the hard magnetic film pattern;
A third step of magnetizing the rotor by applying a magnetic field parallel to the gear rotation plane,
And having a fourth step of magnetizing the hard magnetic film pattern by applying the third step is smaller than a magnetic field perpendicular to said gear rotating surface.
[0027]
By adopting this manufacturing method, it is possible to incorporate the pointer position detection device without greatly changing the timepiece manufacturing method currently in wide use. That is, in the case of a normal timepiece manufacturing method, a magnetizing operation is performed by applying a magnetic field in a state where a rotor, which is a main component of a motor for driving a pointer, is incorporated in a timepiece drive unit (movement). However, the hard magnetic film pattern of the present invention uses the perpendicular magnetization method, and by adjusting the magnitude of the applied magnetic field and performing remagnetization, both the rotor and the gear on which the hard magnetic film pattern is formed are provided. Even when the movement is magnetized in a state in which the rotor is incorporated, the rotor and the hard magnetic film pattern can be distinguished and correctly magnetized.
[0028]
A method of manufacturing a timepiece of the invention, said applied magnetic field of the fourth step is 1/2 or less of the rotor coercivity, and is at least 3 times the hard magnetic Makuho magnetic force of the first step It is characterized by.
[0029]
Thus, the fourth step does not adversely affect the characteristics of the rotor, and the hard magnetic film pattern can be magnetized correctly.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings.
[0031]
A basic diagram showing a configuration of one embodiment of the present invention is shown in FIGS. FIG. 1 is a cross-sectional view of a movement, which is a small timepiece drive unit represented by a wristwatch, and FIG. 2 is a cross-sectional view taken along line AA ′ of FIG. In the figure, a gear 2 on which a hard magnetic film pattern 8 that is perpendicularly magnetized is formed is directly connected to a pointer shaft 5 that supports a pointer 1 that displays time. The gear 2 is connected to a gear 22 that is directly connected to the rotor 9 and a gear 21 that is connected to the gear 22, and rotates according to the rotation of the rotor 9. The rotor 9 constitutes a step motor together with the stator 10, and is rotated every 180 degrees in one step. For this reason, the gear 2 is configured to rotate stepwise at a constant angle corresponding to the reduction ratio of the gears 21 and 22. The gear 2, the gear 21, the gear 22, and the rotor 9 are rotatably supported and fixed by the watch substrates 4a and 4b. On the upper part of the watch substrate 4b, there is provided a dial plate 3 on which the time letters, symbols, numbers and the like are formed on the surface so as to cover the entire watch substrate 4b. This movement is suppressed to a thickness of about several mm as a whole. In this example, a second hand is assumed as the pointer 1, but in the case of a normal timepiece, a minute hand and an hour hand are also provided. However, in FIG. 1, the minute hand and the hour hand are not shown in order to simplify the drawing and make the explanation easy to understand.
[0032]
A Hall element 7 is installed on the watch substrate 4 a facing the hard magnetic film pattern 8 and detects magnetization information from the hard magnetic film pattern 8. A Hall element control current is passed through the Hall element 7 through the bonding wire 6 and the Hall element electromotive force is measured. The Hall element 7 and the hard magnetic film pattern 8 are not in contact with each other, thereby eliminating the influence on the hand movement. In addition, the GaAs Hall element is a non-packaged product and is very small with a thickness of 300 μm * 300 μm * 150 μm.
[0033]
The hard magnetic film pattern 8 is arranged radially from the center of the gear 2 as shown in FIG. In the figure, the frame portion indicated by the formation angles θ ₁ and θ ₃ is a portion where the hard magnetic film pattern 8 is formed, and the hard magnetic film pattern 8 is not formed in the other region. The formation angles θ ₁ , θ ₃ and the gap angle θ ₂ are appropriately controlled so that the rotational position of the gear 2 can be recognized as an absolute position (absolute position). Although only a part of the gear 2 is shown in FIG. 2, actually, the remaining gear portion has the hard magnetic film pattern 8, and the formation angle and gap angle to be controlled are not limited to this. That is, the hard magnetic film pattern 8 differs depending on the rotational position of the gear 2.
[0034]
Here, in FIG. 2, an example of the position of the gear 2 where the Hall element 7 detector is stationaryly opposed for each hand movement (step rotation of the gear 2) is indicated by X (A to K). As described above, since the gear 2 rotates stepwise, the stationary position x of the gear 2 becomes discontinuous. Magnetization information can be detected by causing a Hall element control current of 10 mA to flow through the Hall element 7 in a pulsed manner (intermittently) every time step rotation is performed. Since the pulse width may be on the order of microseconds, even with a relatively large amount of current of 10 mA, the current consumption is almost the same as the current required to rotate the rotor 9 during hand movement, which is very high. Low current consumption. In accordance with the rotation of the gear 2, the position detected by the Hall element 7 moves step by step, such as a, b, and so on in FIG. 2, and the Hall element electromotive force V _H changes as shown in FIG. To do. A, b, and c are opposed to the perpendicularly magnetized hard magnetic film pattern 8, so that a positive electromotive force is generated. However, in D, O, F, and K, the direction of the magnetic flux deviates from the hard magnetic film pattern 8 and is reversed. It becomes-because it becomes. Since the distance between the Hall element detection part and the hard magnetic film pattern is about 100 μm, even if a GaAs Hall element is used as the Hall element 7, an electromotive force of several mV can be secured with a Hall element control current of 10 mA, which is sufficiently detectable. . Further, the point where the Hall element detection position deviates from the hard magnetic film pattern 8 can be clearly detected as shown in FIG. Then, while the gear 2 rotates 6 steps from A to F, +++ --- magnetization information is detected, and the position of the F in the series of 6-step magnetization information groups is, for example, 35 seconds. Recognize absolute position information. This correspondence is coded and stored in advance. In the second and minute recognition, since recognition of 60 divisions is generally required, 6-bit position recognition is required, and the magnetization information group is formed by rotating at least 6 steps (because at least 2 ⁶ = 64 ways). Because a combination is required). In this example, the second hand is described as an example. However, for example, in the time recognition for the hour hand, since it is divided into 12 rounds, it may be rotated at least 4 steps. Next, rotate further one step to obtain-information at the position of key, and the 6 magnetization information from A becomes a magnetization information group of ++ ----, which is coded and stored so as to be recognized as 36 seconds. Keep it. Thus, θ ₁ , θ _2, etc. of the hard magnetic film pattern 8 are controlled so that the position information groups do not overlap.
[0035]
Next, a method for manufacturing a magnetic pointer position detection device will be described. First, the brass gear 21, gear 22, and gear 2 are produced by hob gear cutting. The gear material is not limited to brass, and any nonmagnetic material may be used. However, it is not preferable to use a magnetic material. This is because, when a magnetic material such as a soft magnetic material is used, there is a drawback that the perpendicular magnetization of a hard magnetic film pattern 8 to be described later becomes difficult.
[0036]
Next, Ba ferrite powder having a particle size of 0.7 microns is kneaded with 85 wt% of a one-component epoxy resin to prepare a Ba ferrite printing paste. At this time, it is sufficiently kneaded so that the Ba ferrite powder is dispersed individually. The magnetic properties of the Ba ferrite powder were coercive force: 900 oersted and remanent magnetization: 3KG. Here, the particle size of the Ba ferrite powder is preferably about 5 microns or less. This is because if the particle size is too large, the magnetic efficiency of the hard magnetic film is deteriorated, and the surface roughness of the printed pattern is increased, so that the substantial gap between the hard magnetic film pattern and the Hall element is enlarged. Moreover, although it is the kneading ratio of Ba ferrite, the larger the magnetic property of the hard magnetic film pattern 8 is, the more suitable it is. Furthermore, the coercive force of Ba ferrite greatly affects the degree of mutual influence when performing rotor magnetization and hard magnetic film pattern magnetization described later. That is, to sufficiently magnetize a hard magnetic film, it is necessary to apply a magnetic field that is three times or more of the coercive force. This is because it cannot be said that the movement of the clock will be hindered. Since SmCo is generally used as the material of the rotor 9, the coercive force of Ba ferrite is generally about 1K Oersted.
[0037]
Next, Ba ferrite paste was printed on the gear 2 using a metal mask to form a hard magnetic film pattern 8 having a thickness of 50 microns. Here, metal mask printing has been presented as a method of forming the hard magnetic film pattern 8, but there are various other methods. Screen printing with a mesh may be used, or a method in which a Ba ferrite paste is embedded by forming a through-hole in a gear and pressing a hole or the like in advance. Further, the thickness is basically any thickness as long as it is 10 microns or more. However, when it is formed on a gear by printing, it cannot be made too thick due to restrictions on the design of the movement, and it becomes about 50 microns. If it is the method of embedding in the said gearwheel, 200 micron or more is possible, and since the leakage magnetic flux density is large, it is suitable.
[0038]
Immediately after the formation of the hard magnetic film pattern 8, a vertical magnetic field of 5KG was applied to the hard magnetic film pattern 8 to align the Ba ferrite powder and fired. By this step, the perpendicular residual magnetization of the hard magnetic film pattern 8 is increased from 700 G to 1500 G, the detected electromotive force of the Hall element 7 is increased, and resistance to environmental disturbances such as temperature is enhanced. As described above, the coercive force of Ba ferrite powder is 900 Oersted, and a magnetic field of about 3 KG more than three times that is necessary for magnetization, but here the orientation of the magnetic powder is aligned (magnetic powder in the paste Therefore, a larger magnetic field was required, and the actual value was 5 KG or more. However, since a corner is generated in the paste when the magnetic field is too large, the limit is about twice the minimum required magnetic field (about 3 KG) (about 6 KG).
[0039]
Next, as shown in FIG. 1, the GaAs Hall sensor was bonded to the watch substrate 4b and mounted by wire bonding, so that the Hall element control current could be applied and the Hall element electromotive force could be detected. The GaAs Hall sensor is used because its characteristic change with respect to temperature is very small (that is, the characteristic is stable with respect to environmental temperature). In addition, Hall sensors such as InSb and InAs were also tried, but a hard magnetic film pattern could be detected satisfactorily using any Hall element. However, since all sensors other than the GaAs Hall sensor are sensitive to temperature, the detection output is likely to fluctuate, and the phenomenon that the recognition of + − changes may be observed.
[0040]
Next, a rotating shaft was press-fitted into the manufactured gear. The gear 22 was press-fitted into the rotation shaft of the non-magnetized SmCo rotor 9. Then, it assembled so that it might be in the movement state like FIG. 1 using the assembly robot. The reason why the rotor 9 is assembled in a non-magnetized state is to prevent the rotors 9 from aggregating and joining when supplying the rotor 9 to the assembly robot with a parts feeder or the like.
[0041]
Next, a horizontal magnetic field of 20 KG was applied to the assembled movement (state shown in FIG. 1), and the SmCo rotor 9 was magnetized. At this time, since the hard magnetic film pattern 8 is also magnetized in the horizontal direction, it is necessary to remagnetize only the hard magnetic pattern 8 in the vertical direction. Therefore, a perpendicular magnetic field of 3 KG is further applied to remagnetize only the hard magnetic film pattern 8. The 3KG magnetic field had little effect on the SmCo rotor, and the effect on the rotor rotation characteristics could be ignored.
[0042]
The pointer position detection device according to the present invention has no expensive and special items such as material costs for Hall elements, Ba ferrite printing paste, etc., screen printing, wire bonding, etc., and the rotor is magnetized after the movement is assembled. Because it follows the conventional watch manufacturing process, it can be manufactured at low cost.
[0043]
Disadvantages of magnetic system pointer position detection include disturbance due to strong magnetic fields, but even if the magnetization of the hard magnetic film is demagnetized, it can be easily restored by applying a vertical magnetic field to the entire movement again. is there.
[0044]
【The invention's effect】
According to the present invention, it is possible to obtain a position detection device having the following effects that were impossible in the past.
[0045]
1) Directly recognizes the position of the hand of a watch that moves step by step at an extremely low speed. 2) Since the entire detection system is ultra-compact, there is no need to change the watch movement to be thick and the system is non-contact with the hand movement. Does not affect movement or function 3) Low effective current consumption and low manufacturing cost 4) Assemble the movement in the state of a non-magnetized rotor, and then apply a strong magnetic field to the entire movement to magnetize the rotor By adapting to the general manufacturing process of a timepiece, it was possible to achieve the extremely low-speed position detection, low current consumption, low cost, ultra-compact, and high-accuracy functions desired for a timepiece position detection device. At present, an automatic current time return function has been added to watches. This catches the radio wave including the current time information and automatically corrects the hands to the correct time. For this purpose, a hand position detection function for detecting where the watch hand is currently located is indispensable, but until now there was only the conventional technology without the accuracy and reliability described above, and the commercial value was small. However, according to the present invention, the pointer position can be corrected with high accuracy, for example, every 6 degrees (every second of the second hand). That is, the accuracy of the atomic clock can be achieved at a low cost, and the magnitude of the effect can be understood.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a pointer position detection device according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along the line AA ′ in FIG.
FIG. 3 is a change diagram of the Hall element electromotive force with respect to the movement of the gear according to the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pointer 2 Gear 3 Dial 4a, 4b Clock board 5 Pointer shaft 6 Bonding wire 7 Hall element 8 Hard magnetic film pattern 9 Rotor 10 Stator 21 Gear 22 Gear

Claims (2)

In a timepiece manufacturing method including a pointer, a gear that rotationally drives the pointer, and a rotor that rotationally drives the gear,
A first step of printing a hard magnetic film pattern in which the rotation position of the pointer is digitally encoded radially from the center of the gear on the rotation surface of the gear, and perpendicularly magnetizing the hard magnetic film pattern;
A second step of assembling a hall element facing the gear, the rotor, and the hard magnetic film pattern;
A third step of magnetizing the rotor by applying a magnetic field parallel to the gear rotation plane,
Method for manufacturing a timepiece and having a fourth step of magnetizing the hard magnetic film pattern by applying the third step is smaller than a magnetic field perpendicular to said gear rotating surface. According to claim 1, wherein the applied magnetic field of the fourth step is 1/2 or less of the rotor coercivity, and the clock, characterized in that said at first hard magnetic Makuho force step 3 times Production method.

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