JP3455090B2 - Motor coil unit with detection coil - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor coil unit incorporated in a so-called axial gap type brushless DC motor (brushless DC motor), and more particularly to a motor driving coil. A rotational speed detection coil and / or
Alternatively, the present invention relates to noise reduction of a motor coil unit having a detection coil provided with a rotor position detection coil. 2. Description of the Related Art For example, a brushless DC is used as an actuator for audio equipment, visual equipment, OA equipment and the like.
Although motors are frequently used, recently, thinner motors have been demanded in response to the demand for smaller and lighter devices. To meet this demand,
Motor driving coil, frequency generator coil (hereinafter referred to as FG coil) and rotor position detecting coil (hereinafter referred to as PG coil) used for detecting the number of rotations of the motor.
Are manufactured in a thin, flat shape by printed wiring technology,
There is a tendency to widely use a motor in which a product obtained by laminating them is integrated into a motor. FIG. 4A shows a conventional flat-type motor driving coil unit (hereinafter, referred to as a coil unit) using this type of printed wiring technology.
FIG. 1 is a plan view showing an example of a printed coil unit (1), in which a motor coil pattern 2 in which conductors are formed in a spiral shape one by one is arranged on the front and back surfaces of an annular insulating substrate 3 at equal intervals. I have. Front and back motor coil pattern 2
Are connected via a through hole 2h. The thin printed coil unit 1 formed as described above is sandwiched between a plurality of magnetized rotor magnets 4 and a stator yoke 5 as shown in FIG. And an axial gap type brushless small motor having the following characteristics. [0004] Incidentally, an axial gap type brushless small motor in which such a thin print coil unit 1 is sandwiched between a rotor magnet 4 and a stator yoke 5 is lightweight and has a low moment of inertia. It is difficult to expect the effect of suppressing the unevenness of rotation due to the moment of inertia, so that the control of the rotation speed and the rotation position of the motor and the sensor therefor are important. As a means for detecting the rotational speed, for example, as shown in FIG. 5A, an FG coil 6 which is a frequency generating sensor formed in a rectangular pattern on an annular sheet is generally used. ing. That is, when the motor starts and the rotor magnet 4 moves on the FG coil 6 of the print coil unit 1, the FG coil 6 receives a voltage having a half wave number of the number of poles of the rotor magnet 4 for each rotation of the motor. appear.
This FG output is converted into a DC voltage proportional to the frequency using an FV converter, compared with a reference voltage, and controlled by a FG servo method that controls the voltage applied to the motor according to the differential output. Can be kept constant. [0005] Video (analog, digital) and D
When the print coil unit 1 is used for a cylinder motor of an AT (digital audio tape) or a DDS (digital data streamer), a PG coil 7 as shown in FIG. Is used. When this PG coil 7 is used, in addition to the driving magnetic pole of the rotor magnet 4 in which a plurality of magnetic poles are formed, one or more magnetic poles are additionally provided on the circumference thereof. Coil 7
A pulse is generated each time it passes over the sensor, and is used to detect that the rotor magnet 4 has passed a predetermined position. The FG coil 6 and the PG coil 7 may be formed mainly on one side of one sheet (layer), for example, as shown in FIG. This sheet is overlaid and adhered to another sheet (layer) on which the motor driving coil pattern 2 is formed as shown in FIGS. 5B and 5C.
One printed coil unit 1 is formed by laminating three layers via an insulating layer. Also, for example, as shown in FIG.
An FG coil 6 is formed together with the motor coil pattern 2 on one sheet (one layer), and the motor coil pattern is formed on another sheet (another layer) as shown in FIG. 2, a PG coil 7 may be formed, and both sheets may be overlapped and adhered to each other to form a single printed coil unit 1 having two layers laminated via an insulating layer. The connection of the detection coil (PG coil 7) between the layers is made through a through hole (7h). The through-hole is formed in the through-hole land, but a certain size and size are required in consideration of maintaining the reliability of the connection, responding to the stress acting on the inner wall of the through-hole, and tolerance for drilling errors. It is said. [0008] The magnetic poles for applying a magnetic field to the detection coils 6 and 7 are respectively provided to the rotor magnets. As for the FG coil, there is a method in which the magnetic field of the motor driving coil is diverted as it is, as in the print coil unit in FIG.
Is the same as that of the FG coil 6. On the other hand, a magnetic field dedicated to the FG coil may be provided inside or outside the magnetic field of the motor driving coil. Since the purpose of the magnetic field of the PG coil is to generate about one pulse during one rotation of the rotor magnet, the magnetic field is usually different from the magnetic pole for the FG coil or the motor drive coil. A magnetic field is passed through the magnetic poles N and S once per rotation of the magnet.
Therefore, the region of the magnetic field of the PG coil is set outside or inside the region of the magnetic field of the motor drive coil or the region of the magnetic field for the FG coil. [0010] Recently, brushless D
While the miniaturization of devices equipped with C motors is progressing rapidly, and the size of motors is also progressing accordingly, the performance required for motors, such as torque and rotational accuracy, is the same as before miniaturization. It has become difficult to obtain sufficient characteristics with the print coil units described above. By the way, the size of the motor itself was about 40 mm in diameter in a video cylinder motor.
The current digital video has a diameter of 19 mm.
Even with such a small-diameter motor, in order to obtain the same torque as a large motor, the magnetic gap must be increased by narrowing the magnetic gap of the rotor magnet. Therefore, the thickness of the printed coil unit is also 2 to 5
However, the diameter is 0.2 mm to 1.5 mm including the FG coil and the PG coil, and the diameter is 17 mm, which is almost the same as that of the motor. As described above, in the presently required print coil unit, the motor coil pattern and the FG coil and / or the PG coil are arranged in an extremely small area, and a strong magnetic field must be used. is there. Furthermore, since the sizes of the FG coil and the PG coil are small, it is necessary to efficiently arrange conductor wiring patterns for obtaining necessary signals in places where the magnetic field is as strong as possible. The FG coil and the PG coil generate a signal in each effective coil area in accordance with the rotation of the rotor magnet, and the signal is led to each external connection terminal using a connection line. However, in the case of a print coil motor, the magnetic field region sandwiching the print coil unit is extremely thin. Moreover, each coil is arranged in a plane. For this purpose, the connection line must pass through the magnetic field region of another coil before reaching the external connection terminal. Thus, in the conventional print coil unit, the generation of noise due to the interference of the magnetic field between the coils inevitably occurs at the connection line portion, which may hinder the rotation speed control and the rotation position control of the motor. There is a problem that there is no. Therefore, the present invention has been made in view of such an unsolved problem in the related art, and by improving the wiring pattern of connection lines in a detection coil used for rotation control and position control, noise is reduced. It is an object of the present invention to provide a motor coil unit with a detection coil capable of suppressing the occurrence of the above. [0015] In order to achieve the above object, the invention according to claim 1 is a combination with a motor driving coil.
Rotation speed detection coil or rotor position used in combination
At least one of the position detection coils is provided
In the motor coil unit with a detection coil, the detection
Of the connection through-hole land connected to the coil
In addition, dummy through-hole lands that are not involved in the connection
It is provided on the connection line of the detection coil.
You. The present inventors have repeatedly studied the structure of a motor coil unit with a detection coil, and in particular, to reduce noise generated in the detection coil. As a result, the present inventors have found the following facts and reached the present invention. It is a thing. That is, in both the FG coil and the PG coil which are the detection coils, the magnetic field for generating an electromotive force in those coils may be the same as the magnetic field of the motor driving coil, but is often different. Further, even if the magnetic field is the same, there is always a connection line for connecting the conductor circuit portion for generating a signal to the detection coil to the external connection terminal, and the connection line is connected to another coil (for example, a motor driving coil). ) Must pass through the magnetic field region. In any case, by passing through a magnetic field unrelated to the connection line,
Noise occurs at the connection line. At this time, the generated noise is not limited to the connection line. That is, noise is generated in the through-holes that are actually connecting the conductor layers on the front and back of the sheet or the conductor pattern of the conductor layer of another sheet, and the inner walls of the through-holes that contribute to the connection between the conductor layers. Conductors are no exception. Therefore, for example, as shown in FIG. 5A, the PG in the magnetic field region of the motor driving coil 2
Noise is generated even through-hole 7h ₁ of the coil 7.
However, FIG. 5, through-holes 7h ₂ just below the external connection terminals 7t of PG coil 7 shown in (a), contains in the magnetic field region for PG coil to the magnetic field in the region of the motor driving coil No noise is generated. The present inventors have studied a method for eliminating this noise, and as a result, have found that dummy through-hole run, which is not necessary for connection, is provided on the connection line of the detection coil exposed to the same magnetic field.
It was found to be to prevent noise by installing a de. If the dummy through-hole land has the same shape and size as the through-hole land of the original through-hole 7h necessary for connection, the effect of removing noise is greater. Also, a dummy through hole is located in the dummy through hole land.
It was also clarified that a higher noise removal effect could be obtained if the dummy through hole was formed and the inner wall of the dummy through hole could be installed as a dummy covered with a metal not connected to the conductor. Embodiments of the present invention will be described below with reference to the drawings. The same or corresponding parts as those in the related art are denoted by the same reference numerals, and detailed description thereof will be omitted. FIG. 1 is a plan view of a sheet on which an FG coil 6 and a PG coil 7 constituting a motor coil unit with a detection coil according to the present invention are arranged. FIGS. 2 (a) and 2 (b) are superimposed thereon. It is a top view of the sheet | seat in which the motor drive coil combined is formed. The sheet shown in FIG. 1 has an FG coil 6 formed by connecting four rectangular detection patterns in a circle, its outer connection terminals 6t, 6t, and a PG composed of one and a half rectangular detection patterns. through hole land 7h ₁ of three of the coil 7 for the connection line 7s and PG coil, 7h _D, and the 7h ₂ and PG Yogaibu connection terminals 7t are disposed. On the other hand, the two motor coil sheets of FIG. 2 are provided with a six-pole spiral motor coil pattern 2 and through holes 2h for connection thereof on both front and back surfaces. Then, the sheet (FIG. 2A) that is to be overlapped with the sheet of FIG. 1 has a part 7p of the effective portion of the PG coil on the surface on the overlap side (the surface without the PG external connection terminal 7t). the connection line 7s and the through hole land 7h ₁ in two places, 7h ₂ and are disposed. The motor coil patterns 2 on the front and back surfaces of each sheet are connected via motor coil through holes 2h. [0024] towards the PG coil 7 in FIG. 1, the connecting lines 7s entering from one PG Yogaibu connection terminals 7t progresses circumferentially after traveling radially free Da relevant here in connection
Pass through Meadow Hole Land 7h _D. This dummy
Through hole land 7h _D are those not required for the conduction of PG coil circuit functions exclusively as for noise prevention. Thereafter, PG coil 7 after tortuous periphery of the sheet, the circumference are connected to the through hole land 7h _1. The connection line 7s of PG coil entered from the other PG Yogaibu connection terminal 7t is connected to the through hole land 7h ₂ in the sheet outside and serpentine. P contrast, PG coil 7 towards the seat motor coil of Figure 2, which enters the through hole land 7h _2, transverse to the connecting line 7s and sheet through the sheet periphery to the radially
After a part 7p of the effective portion of the G coil, are connected to the through hole land 7h ₁ in the inner periphery of the sheet. Thus, by overlapping the detection coil sheet of FIG. 1 on the motor coil sheet of FIG. 2A, the former PG coil 7 and a part 7p of the effective portion of the latter PG coil are formed. , is coupled via a through hole land 7h ₁ and 7h _2. But dummy through hole
Land 7h _D is still not at all involved in the connection. The above-described motor coil pattern 2, FG coil 6, PG coil 7 and the like may be manufactured by etching, plating, or a combination thereof, as in the prior art.
In particular, when it is intended to improve the characteristics of the actuator and the accuracy of the FG and PG coils, it is most effective to form them by plating. For example, taking the motor coil sheet of FIG. 2A as an example, a photomask of the motor coil pattern 2, the PG coil 7p, and the connection line 7s on the front side is designed by a conventional method, and the photomask is used for conducting. A photoresist pattern corresponding to each coil pattern is formed on the surface of the conductive substrate on which a conductor pattern is to be formed, by a technique of printed wiring technology. Next, electrolytic copper plating is performed while energizing the conductive substrate on which the pattern is formed to form a predetermined conductor pattern (copper pattern). In addition, the conductor pattern of the motor coil on the back side (not shown) is formed on another conductive substrate surface in the same procedure. An insulating varnish is applied and cured on the surface of each conductive substrate on the side where the conductive pattern is formed. The two conductive substrates are bonded to each other with an epoxy-based adhesive sandwiching a glass cloth or a sheet of an insulating film therebetween, with the surface coated with the insulating varnish facing inward. Next, if necessary, a hole is made in a portion to be connected to the through hole, and a catalyst treatment for chemical plating is performed. Next, the conductive substrate is removed by etching, and chemical plating is performed. Electrolytic copper plating is performed using the thus obtained sheet having the coil pattern 2 on both sides as electrodes. Through these steps, the sheet shown in FIG. 2A having the motor coil pattern 2 on both front and rear surfaces and the pattern of the effective portion 7p of the PG coil 7 on one side is formed. The sheet of FIG. 2B is manufactured through the same process. Note that the sheet of FIG. 2A and the sheet of FIG. 2B are laminated with a two-layer structure by bonding with an insulating resin. Also,
The conductor pattern (copper pattern) of the detection coil in FIG. 1 can also be formed on the conductive substrate surface in substantially the same manner. These are laminated as follows via an insulating resin to complete the motor coil unit 1 with the detection coil. That is, the sheet having the motor coil pattern 2 on both the front and back surfaces prepared in the above process (FIG. 2A)
A conductive substrate having the copper pattern of the FG coil 6 and the PG coil 7 of FIG. 1 formed on the surface on which the part 7p of the effective portion of the PG coil is formed is overlapped with an insulating resin. Glue with Next, the conductive substrate is removed by etching. Thereafter, a layer of the motor coil pattern 2 and a layer on which the FG coil 6 and the PG coil 7 are formed are punched, and solder is poured into the layer to connect the layers via an insulating layer. The printed coil unit 1 of the present invention thus obtained is fixed on the stator yoke plate 5 and is opposed to the rotor magnet 4 with a slight gap therebetween to produce an axial gap type brushless DC motor. And an operation test. 6 generated by the PG coil 7 when the motor is started and the rotor magnet is turned
And the PG coil 7 generates one wave per rotation of the rotor magnet.
Noise waveform P _F to the output waveform P regular PG coil 7 four waves coil 6 is generated is riding output. However, the output voltage of the noise waveform P _F by the action of the dummy through hole land 7h _D is extremely small, the function of PG coil 7 is not at all impaired. On the other hand, the dummy through shown in FIG.
The operational test of the brushless DC motor of the conventional axial gap type using a print coil unit incorporating no detection coil sheet hole lands 7h _D, PG coil output voltage as shown in FIG. 3 (b), P
G are very large noise waveform P _F to the output waveform P regular coil 7 ride, it can not perform sufficiently function as PG coil 7. [0031] In the above embodiments, the dummy through hole land for suppressing noise has been described the case of providing one for PG coil, the dummy through hole run
The number of coils is not limited to this, and may be provided on the FG coil, or one or more coils may be provided. The number of turns of the motor coil pattern 2 in the motor coil unit with a detection coil to which the present invention can be applied and the method of connecting the spirals to each other are not limited to those in the above-described embodiment. The shape is not limited, and any shape may be used as long as it generates a magnetic field when energized. Also, through holes for connecting the conductor patterns of the respective coils on the insulating sheet surface may be appropriately provided in portions other than the center of the spiral. Furthermore, it is not necessary to limit the number of sheets on which the motor coil pattern is formed on both the front and back surfaces, and the number may be arbitrary. As described above, in the motor coil unit with the detection coil according to the first aspect, in addition to the through holes for pattern connection, the dummy through holes for connection are not provided.
Because the hole land is provided on the connection line of the detection coil,
Noise generation when the connection line of the detection coil passes through the magnetic field region of another coil can be suppressed, and as a result,
There is an effect that an axial gap type brushless DC motor capable of high-precision rotation speed control and position control can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a pattern diagram of a layer on which a detection coil of a print coil unit with a detection coil of the present invention is arranged. 2A and 2B are pattern diagrams of a layer in which a motor driving coil to be combined with a detection coil layer of FIG. 1 is arranged. FIG.
(B) is a layer further superimposed thereunder. 3A and 3B are diagrams showing an output voltage waveform of a PG coil when a rotor magnet is rotated, wherein FIG. 3A shows an output voltage of a PG coil of the present invention, and FIG. 3B shows a PG coil of a comparative example (conventional example). 5 shows an output voltage waveform of the first embodiment. 4A and 4B are examples of a flat brushless motor using a conventional print coil unit. FIG. 4A is a plan view of the print coil unit, and FIG. 4B is an exploded view of the motor. 5A and 5B are exploded views of a conventional print coil unit with a detection coil, in which FIG. 5A is a pattern diagram of a layer on which an FG coil and a PG coil are disposed, and FIGS. FIG. 5 is a pattern diagram of a layer formed. 6A and 6B are exploded views of another conventional printed coil unit with a detection coil, in which FIG. 6A is a pattern diagram of a layer on which an FG coil and a motor coil are arranged, and FIG. FIG. 4 is a pattern diagram of a layer in which is disposed. [Description of Signs] 1 Print coil unit 2 Motor coil pattern 4 Rotor magnet 5 Stator yoke plate 6 FG coil 6t FG external connection terminal 7 PG coil 7t PG external connection terminal 7h PG connection through hole 7h _D (PG) Dummy through hole land 7s (PG) connection line

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Claims (1)

(57) [Claims] [Claim 1] Used in combination with a motor drive coil
Rotation speed detection coil or rotor position detection coil
A motor with a detection coil provided with at least one of
In the data coil unit, a connection through hole connected to the detection coil
In addition to lands, dummy through holes that are not involved in connection
The land is provided on the connection line of the detection coil.
Motor coil unit with detection coil.