Motor with print circuit board

Abstract

To provide a motor with a print circuit board, capable of easily attaching a print circuit board to an outside of the motor.SOLUTION: A motor with a print circuit board, comprises: a print circuit board 2 that is attached to an outside of an outer casing of the motor; and four earth fingers 50, 51, 52, and 53 that are soldered to a ground pattern G2 of the print circuit board 2, and are contacted to the outer casing of the motor. Each of the four earth fingers 50, 51, 52, and 53 is arranged along an outer periphery of the print circuit board 2 at roughly equal intervals.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a motor with a printed circuit board, in which the printed circuit board is attached to the outside of the motor.

Background Art

[0002] A brushed motor or a brushless motor is known as a drive source for electronic devices. In a conventional motor, in order to prevent radiation noise from occurring due to an energization phase switching operation by a drive IC or high-frequency switching by PWM control, and to prevent transmission and reception failures in other electronic devices installed nearby, a noise filter capacitor is mounted between the motor output and the ground, and is electrically connected to the case of the motor and grounded.

[0003] For example, Patent Document 1 discloses a motor in which a printed circuit board is disposed in a cylindrical case having an opening on one side. In this Patent Document 1, a coil spring, which is a conductive member having elasticity, is mounted on the substrate and attached to the inside of the case, and a lid (bracket) is fitted into the opening of the case of the motor and caulked and fixed to the case. Then, by attaching a lid (bracket) to the opening of the case of the motor, the coil spring of the printed circuit board is configured to abut against the inside of the case lid (bracket) of the motor with a predetermined pressing force. Thereby, the printed circuit board and the case lid are electrically connected and grounded to prevent the generation of radiation noise.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the case of soldering the terminals protruding from the lid of the case to the printed circuit board and attaching the printed circuit board outside the motor, when trying to make an electrical connection between the printed circuit board, the motor case, and the lid using a coil spring as in Patent Document 1, the printed circuit board tends to tilt with the coil spring as a fulcrum when attaching the printed circuit board to the motor, making it difficult to attach while maintaining parallelism with the surface of the lid, and there is a problem that the attachment is time-consuming.

[0006] An object of the present invention is to provide a motor with a printed circuit board that can easily attach the printed circuit board outside the motor.

Means for Solving the Problems

[0007] In order to achieve the above object, a first invention provides a motor with a printed circuit board including a rotor, a stator that interacts with the rotor to generate a rotational moment, a conductive exterior case that houses the rotor and the stator, a printed circuit board provided with a power pattern, a ground pattern, and an opening through which the rotation axis of the rotor passes, and attached outside the exterior case. In the motor with a printed circuit board, three or more conductive elastic members that contact the exterior case are attached to the ground pattern of the printed circuit board, and the printed circuit board is evenly divided into the same number as the three or more elastic members in a line or in the vicinity of the line in the rotational direction of the rotation axis of the rotor, and the three or more conductive elastic members are respectively arranged at substantially equal distances from the center of the opening of the printed circuit board.

[0008] The second invention is a motor with a printed circuit board, comprising a rotor, a stator that interacts with the rotor to generate a rotational moment, a conductive outer casing that houses the rotor and the stator, a printed circuit board provided with an opening through which the rotation axis of the rotor passes, and a power supply pattern, a ground pattern, and the printed circuit board is attached to the outside of the outer casing. In the motor with a printed circuit board, the printed circuit board has a conductive elastic member attached to the ground pattern and contacting the outer casing, and a regulating member contacting the outer casing and regulating the distance between the printed circuit board and the casing. The conductive elastic member and the regulating member are provided in such a way that the combined number thereof is three or more. The conductive elastic member and the regulating member are respectively arranged on a line or in the vicinity of the line that evenly divides the printed circuit board in the rotational direction of the rotation axis of the rotor by the combined number of the conductive elastic member and the regulating member, and at a substantially equal distance from the center of the opening of the printed circuit board.

Advantages of the Invention

[0009] It becomes possible to easily attach the printed circuit board to the outside of the motor.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiment for Carrying Out the Invention

[0011] Hereinafter, embodiments of the motor with a substrate according to the present invention will be described in detail. The motor with a substrate described below is incorporated and used, for example, in a drive unit of an electronic device such as a printer, a copier, and peripheral devices thereof.

[0012] Fig. 1 is a perspective view showing the appearance of a brush motor with a printed circuit board, and Fig. 2 is a schematic view showing the mounting state of the brush motor with a printed circuit board. Fig. 3 is a cross-sectional view showing the internal configuration of the brush motor. The brush motor with a printed circuit board of the present embodiment includes a brush motor 1 and a printed circuit board 2 attached to the brush motor 1 as shown in Fig. 1. For convenience, the brush motor 1 will be referred to as the motor 1 hereinafter.

[0013] In the present embodiment, as shown in Fig. 2, the case 10 of the motor 1 is attached to the motor mounting bracket 3 with screws, and the motor mounting bracket 3 is attached to the device frame 4 of the device on which the motor 1 is mounted with screws. The motor mounting bracket 3 and the device frame 4 are made of sheet metal, and the above-mentioned screws are made of metal.

[0014] The motor 1 of the present embodiment includes a cylindrical case 10 with one end closed and the other end open as shown in Fig. 3, a stator 13 and a rotor 14 disposed in the case 10, a rotating shaft (shaft) 12 to which the rotor 14 is attached, and a bracket 11 that closes the open portion of the case 10 and constitutes an outer case together with the case 10.

[0015] The rotor 13 is composed of a laminated core 15 fixedly attached to the shaft 12, a coil 16 wound around the laminated core 15, and an insulating layer (not shown) using an epoxy resin that insulates the laminated core 15 and the coil 16. Also, a pair of commutators 23a and 23b for switching the phase of the current flowing through the coil 16 of the laminated core 15 are fixed to the shaft 12.

[0016] The stator 14 is a permanent magnet 17 disposed opposite to each other so as to surround the rotor 14 composed of the laminated core 15 and the coil 16. The permanent magnet 17 has an S pole and an N pole magnetized on its front and back surfaces, and is fixedly attached to the inner peripheral side of the case 10 at equal intervals. In this embodiment, it is composed of three coils 16 and two permanent magnets 17, and the magnetic force generated by passing a current through the coil 16 by the pair of commutators 23a and 23b repels the permanent magnet 17 to rotate the shaft 12. Note that the surfaces of the two permanent magnets 17 facing each other are magnetized with different poles.

[0017] The case 10 is formed in a bottomed cylindrical shape by performing deep drawing on a steel plate. A round hole for passing the shaft 12 is formed at the center of the bottom side of the case 10, and a bearing 18 for rotatably supporting the shaft 12 is provided in the round hole. The open portion side of the case 10 is closed by a disk-shaped bracket 11. In this embodiment, the appearance of the brush motor 1 is constituted by the case 10 and the bracket 11.

[0018] A holder member 19 is attached to the bracket 11. The holder member 19 is formed of resin, and a bearing 20 for supporting the shaft 12 is provided at the central portion thereof. Thus, the shaft 12 rotates while being supported at both ends by the bearing 18 provided at the central portion on the bottom side of the case 10 and the bearing 20 formed in the holder member 19. Further, the holder member 19 holds a pair of brushes 21a, 21b and a pair of springs 22a, 22b. One of the springs 22a elastically contacts the corresponding one of the brushes 21a with the first commutator 23a, and the other spring 22a elastically contacts the corresponding other one of the brushes 21a with the other commutator 23a. Each of the brushes 21a, 21b is mainly made of graphite (carbon), and one end surface (contact surface) thereof is provided so as to abut orthogonally against the circumferential surfaces of the respective commutators 23a, 23b. Both ends of the coil 16 are connected to the respective commutators 23a, 23b, and the respective commutators 23a, 23b contact the respective brushes 21a, 21b which are electrodes to pass current through the coil 16. Thus, the coil 16 and the shaft 12 rotate.

[0019] Reference numerals 24 and 25 in FIGS. 2 and 3 are electrode terminals (positive electrode terminal 24, negative electrode terminal 25) electrically connected to the respective brushes 21a, 21b to pass current through the coil 17. These electrode terminals 24, 25 are provided so as to protrude outside the motor 1 through the bracket 11 from the inside of the case 10. By soldering the electrode terminals 24, 25 to the printed circuit board 2, the printed circuit board 2 is attached to the motor 1. A resin material is interposed between the bracket 11 and the electrode terminals 24, 25 so that the bracket 11 and the electrode terminals 24, 25 do not contact each other.

[0020] Next, the printed circuit board 2 will be described with reference to FIGS. 4(a) and 4(b). FIG. 4(a) is a diagram showing the front surface 2a of the printed circuit board 2, and FIG. 4(b) is a diagram showing the back surface 2b of the printed circuit board 2. The printed circuit board 2 is a double-sided printed circuit board in which patterns of copper foil printed on both sides of a base material are formed. The printed circuit board 2 of the present embodiment is formed in a circular shape having substantially the same outer peripheral surface as the disk-shaped bracket 11, and an opening 43 for the shaft 12 to penetrate is formed at the center thereof. Further, a slit 38 into which the positive electrode terminal 24 is inserted and a slit 39 into which the negative electrode terminal 30b is inserted are formed.

[0021] On the front surface 2a of the printed circuit board 2 that is exposed to the outside, a power supply circuit for passing current through the brushes 21a and 21b is formed. Specifically, on the front surface 2a, positive electrode patterns 30a, 30b, 30c, negative electrode patterns 31a, 31b, 31c, and a ground pattern G1 are formed. Further, a capacitor 32 mounted between the positive electrode pattern 30a and the negative electrode pattern 31a, a capacitor 33 mounted between the positive electrode pattern 30c and the negative electrode pattern 31c, a capacitor 34 mounted between the positive electrode pattern 30b and the ground G1, and a capacitor 35 mounted between the negative electrode pattern 31b and the ground G1 are provided on the front surface 2a. Furthermore, a plurality of ferrite beads 40a, 40b, 41a, 41b that function as noise removal filters are mounted. Also, power is supplied from an external power source by a pair of connectors. One of the pair of connectors, connector 37, is mounted on the printed circuit board 2, and the other connector (not shown) attached to the power source via a harness is fitted to supply power.

[0022] Note that one end side of the positive electrode pattern 30c is formed so as to surround the area around the slit 38. By soldering the positive electrode terminal 24 inserted into the slit 38, the positive electrode terminal 24 and the positive electrode pattern 30c are electrically connected (energized). Also, one end side of the negative electrode pattern 31c is formed so as to surround the area around the slit 39. By soldering the negative electrode terminal 25 inserted into the slit 39, the negative electrode terminal 25 and the negative electrode pattern 31c are electrically connected (energized).

[0023] The current supplied from the connector 37 flows from the positive electrode pattern 30a through the ferrite bead 40a to the positive electrode pattern 30b, then from the positive electrode pattern 30b through the ferrite bead 40b to the positive electrode pattern 30c, and is supplied from the positive electrode terminal 24 to the motor 1. The current supplied to the motor 1 is passed through the coil 16 via one brush 21a and one commutator 23b, and flows through the other commutator 23b and the other brush 21b to the negative electrode terminal 25. The current from the negative electrode terminal 25 flows from the negative electrode pattern 31c through the ferrite bead 41b to the negative electrode pattern 31b, then from the negative electrode pattern 31b through the ferrite bead 41a and the negative electrode pattern 31a to the connector 37.

[0024] The back surface 2b of the printed circuit board 2 facing the outer surface 11a of the bracket 11 has a ground pattern G2 formed thereon except for the peripheral areas 38a and 39a of the slit 38 for the positive electrode terminal and the slit 39 for the negative electrode terminal. The ground pattern G2 and the ground pattern G1 on the surface 2a are electrically connected by a plurality of through holes 42 whose interiors are barrel-plated. In this embodiment, as shown in FIG. 2b, by using a wide area other than the peripheral areas 38a and 39a of the two slits 38 and 39 on the back surface 2a of the printed circuit board 2 as the ground G2, the radiation noise is reduced.

[0025] On the ground pattern G2 of the back surface 2b, four ground fingers 50, 51, 52, and 53 are mounted. These four ground fingers 50, 51, 52, and 53 are elastic deformable leaf springs made of a conductive member (metal). The four ground fingers 50, 51, 52, and 53 are in contact with the outer surface 11a of the bracket 11 of the motor 1 to electrically connect the ground patterns G1 and G2 of the printed circuit board 2, the bracket 11 of the motor 1, and the case 10. Here, in the present embodiment, the motor 1 is attached to the device frame 4 via the motor mounting bracket 3 as described above, and the device frame 4 is grounded (earthed) to the ground (see FIG. 2). Therefore, by energizing the ground pattern G2 of the printed circuit board 2 and the bracket 11 of the motor 1 with the four ground fingers 50, 51, 52, and 53, the ground patterns G1 and G2 of the printed circuit board 2, the bracket 11 of the motor 1, and the case 10 are grounded (earthed) to the ground via the motor mounting bracket 3 and the device frame 4. By using the ground fingers 50, 51, 52, and 53 as described above, it is not necessary to provide a ground wire on the printed circuit board, and it is not necessary to perform processing such as screw holes for attaching the ground wire to the case 10 or the bracket 11 of the motor 1, and the grounds G1 and G2 of the printed circuit board 2 can be easily grounded (earthed). In addition, since it is not necessary to process screw holes in the case 10 or the bracket 11 of the motor 1, the handling of the motor becomes easy.

[0026] FIG. 5 is a state diagram showing the configuration and attachment state of the ground fingers. FIG. 5(a) is a state diagram showing the state of the ground fingers before attaching the printed circuit board 2 to the motor 1, and FIG. 5(b) is a state diagram showing the state of the ground fingers when the printed circuit board is attached to the motor. FIG. 6 is a state diagram showing the attachment state of the printed circuit board 2. FIG. 6(a) is a state diagram showing the state before attaching the printed circuit board 2 to the motor 1, and FIG. 6(b) is a state diagram showing the state before attaching the printed circuit board 2 to the motor 1. In the present embodiment, since the configurations of the four ground fingers 50, 51, 52, and 53 are all the same, for convenience, only the ground finger 50 will be described here.

[0027] As shown in FIG. 5, the ground finger 50 is an elastically deformable metallic leaf spring, and has a contact portion 46 that abuts against the outer surface 11a of the bracket 11 of the motor 1 and bends toward the printed circuit board 2 with respect to the outer surface 11a of the bracket 11, and a mounting portion 47 that is bonded to the ground pattern G2 on the back surface 2b of the printed circuit board 2 with solder 48.

[0028] As shown in FIG. 5(a), the ground finger 50 has no elastic force applied when it is separated from the outer surface 11a of the bracket 11. When the printed circuit board 2 is brought closer to the bracket 11 from a state of being separated from the outer surface 11a of the bracket 11, the ground finger 50 is brought into contact with the outer surface 11a of the bracket 11, and further, when a pressing force F directed toward the bracket 11 is applied to the printed circuit board 2, the contact portion 46 of the ground finger 50 is configured to elastically deform as shown in FIG. 5(b). By elastically deforming the contact portion 46 of the ground finger 50, a biasing force on the bracket 11 side is always applied to the contact portion 46 of the ground finger 50, so that the contact portion 46 of the ground finger 50 reliably abuts against the outer surface 11a of the printed circuit board 2 and the contact state can be maintained.

[0029] In the present embodiment, as shown in FIG. 4(b), a plurality of four ground fingers 50, 51, 52, 53 are arranged on the back surface 2a of the printed circuit board 2 at substantially equal intervals in the circumferential direction of the printed circuit board 2. Thereby, when the printed circuit board 2 is attached to the motor 1, the parallelism of the printed circuit board 2 with respect to the outer surface 11a of the bracket 11 can be maintained, and the attachment of the printed circuit board 2 described later becomes easy. In the present embodiment, as shown in FIG. 4(b), the four ground fingers 50, 51, 52, 53 are arranged at intervals of approximately 90° and at substantially equal distances from the center of the circular printed circuit board 2. That is, the four ground fingers 50, 51, 52, 53 are respectively arranged on or near the lines that divide the printed circuit board into four equal parts in the rotational direction of the shaft 12 of the rotor 14.

[0030] In addition, in the present embodiment, one of the four ground fingers 50, 51, 52, 53, i.e., the ground finger 50, is disposed at a position close to both the capacitor 34 mounted between the positive electrode pattern 30b and the ground G1 and the capacitor 35 mounted between the negative electrode pattern 31b and the ground G1. Thereby, the radiation noise can be efficiently reduced.

[0031] Next, the attachment of the printed circuit board 2 to the motor 1 will be described. With the motor 1 fixed, the slits 38 and 39 of the motor board 1 are inserted through the electrode terminals 24 and 25 protruding through the bracket 11 of the motor 1 (see Fig. 6(a)). At this time, since the back surface 2b of the printed circuit board 2 is attached so as to face the outer surface 11a of the bracket 11, the four ground fingers 50, 51, 52, 53 come into contact with the outer surface 11a of the bracket 11. Thereafter, the printed circuit board 2 is pressed from the surface 2a side using a jig (not shown), and the positive electrode terminal 24 and the negative electrode terminal 25 are soldered and attached to the positive electrode pattern 30c and the negative electrode pattern 31c of the printed circuit board 2 in a state where the contact portions 46 of the four ground fingers 50, 51, 52, 53 are bent toward the back surface 2b side (see Fig. 6(b)).

[0032] Note that the position on the surface 2a of the printed circuit board 2 pressed by the jig is set as the area inside the straight line connecting the four ground fingers 50, 51, 52, 53. Thereby, while maintaining the parallelism of the printed circuit board 2 with respect to the outer surface 11a of the bracket 11, the contact portions 46 of the four ground fingers 50, 51, 52, 53 can be bent.

[0033] According to the above embodiment, the four ground fingers 50, 51, 52, 53 are used. However, if there are three or more ground fingers, it is possible to maintain the parallelism of the printed circuit board 2 with respect to the outer surface 11a of the bracket 11, and there may be three or more than four ground fingers. When there are three or more than four ground fingers, when attaching the printed circuit board 2 to the motor 1, the area inside the straight line connecting adjacent ground fingers is pressed.

[0034] In the above embodiment, the ground fingers 50, 51, 52, 53 made of an elastically deformable leaf spring composed of four conductive members (metals) are provided. However, if there is at least one ground finger, an elastic member formed of resin or a regulating member that regulates the distance between the bracket 11 and the printed circuit board 2 and has the same configuration as the ground finger may be attached to the printed circuit board 2 in place of some of the other ground fingers. In this case, the arrangement shall be the same as that in the above embodiment. Further, it is preferable that at least one conductive ground finger be arranged at a position close to the capacitors 34, 35 mounted between the electrode patterns 30b, 31b and the ground G1. Of course, if the total number of the ground finger and the regulating member is three or more, any number of ground fingers and the regulating member may be provided.

[0035] Furthermore, in the above embodiment, a brushed motor is described as the motor, but it is also applicable to a brushless motor.

[0036] According to the present embodiment, at least three or more ground fingers 50, 51, 52, 53 that abut against the bracket 11 of the motor 1 are attached to the ground pattern G2 of the printed circuit board 2, and the three or more ground fingers 50, 51, 52, 53 are arranged on or near the lines obtained by equally dividing the printed circuit board 2 in the number of the ground fingers 50, 51, 52, 53 in the rotational direction of the shaft 12 of the rotor 14. Therefore, it becomes easy to attach the printed circuit board outside the motor. Also, even if the total number of the ground finger and the regulating member is three or more, and the ground finger and the regulating member are arranged on or near the lines obtained by equally dividing the printed circuit board along the outer periphery of the opening in the number of the total of the number of the ground fingers and the number of the regulating members, the printed circuit board can be easily attached.

Explanation of Reference Numerals

[0037] 1 Motor 2 Printed Circuit Board 10 Case 11 Bracket 11a Exterior surface 13 Stator 14 Rotor 30a, 30b, 30c Positive electrode patterns 31a, 31b, 31c Negative electrode patterns 32, 33, 34, 35 Capacitors 50, 51, 52, 53 Ground fingers G1 Ground pattern G2 Ground pattern

Claims

1. A motor with a printed circuit board, comprising: a rotor; a stator that interacts with the rotor to generate a rotational moment; a conductive outer casing that houses the rotor and the stator; a printed circuit board provided with a power pattern, a ground pattern, and an opening through which the rotation axis of the rotor passes, and attached to the outside of the outer casing. In the motor with a printed circuit board, three or more conductive elastic members that contact the outer casing are attached to the ground pattern of the printed circuit board, and the printed circuit board is evenly divided into as many lines or near the lines as the number of the three or more elastic members in the rotational direction of the rotation axis of the rotor, and the three or more conductive elastic members are respectively arranged at substantially equal distances from the center of the opening of the printed circuit board.

2. Connected to the power pattern and the ground pattern, and comprising a capacitor for removing noise, and at least one of the three or more conductive elastic members is arranged near the capacitor. The motor with a printed circuit board according to claim 1.

3. The power pattern is formed on one surface of the printed circuit board. The ground pattern is formed on one surface and the other surface of the printed circuit board, and a through hole for connecting the ground pattern on one surface and the ground pattern on the other surface is provided on the printed circuit board. The three or more conductive elastic members are provided on the other surface of the printed circuit board. The motor with a printed circuit board according to claim 1.

4. Connected to the power pattern and the ground pattern, and a capacitor for removing noise is provided on one surface of the printed circuit board. At least one of the three or more conductive elastic members is arranged near the other surface of the position where the capacitor is arranged. The motor with a printed circuit board according to claim 3.

5. Comprising power terminals provided so as to protrude outward from the outer casing, and in a state where the three or more conductive elastic members are in contact with the outer casing, the power terminals are soldered to the power pattern, and the printed circuit board is attached to the outside of the outer casing. The motor with a printed circuit board according to claim 1.

6. A motor with a printed circuit board, comprising: a rotor; a stator that interacts with the rotor to generate a rotational moment; a conductive exterior case that houses the rotor and the stator; a printed circuit board provided with a power pattern, a ground pattern, and an opening through which the rotation axis of the rotor passes, and attached to the outside of the exterior case. The printed circuit board has a conductive elastic member attached to the ground pattern and contacting the exterior case, and a regulating member contacting the exterior case and regulating the distance between the printed circuit board and the case. The conductive elastic member and the regulating member are provided such that the combined number thereof is three or more. A motor with a printed circuit board, characterized in that the conductive elastic member and the regulating member are respectively arranged on or near a line that evenly divides the printed circuit board in the rotational direction of the rotation axis of the rotor by the combined number of the conductive elastic member and the regulating member, and at a substantially equal distance from the center of the opening of the printed circuit board.

7. The motor with a printed circuit board according to claim 1, further comprising a capacitor connected to the power pattern and the ground pattern for removing noise, and one of the conductive elastic members is arranged near the capacitor.

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