1. Field of the Invention
The present invention relates to improvements on motors, and more particularly, to a motor provided with a flexible circuit board having land portions that are electrically connected to the terminal portions of stator coils extending from the motor.
2. Related Art
In typical motors, a shaft member and a bearing member are rotatably supported by each other using a base frame to which a stator core is fixed. A stator coil is wound around each of a plurality of salient pole sections of the stator core. The terminal portion of the stator coil is, for example, soldered to a land portion located on a sheet-shaped flexible circuit board. The flexible circuit board is provided with a wiring pattern and is arranged to extend out radially from the soldered land portion and protrude from the motor.
In an example shown in FIG. 18, the terminal portion of the stator coil 1, which is, for example, a power feeding lead wire 1a, extends from the motor through a hole 3 which penetrates the base frame 2. An insulator member (an insulating paper) 4 is provided on an inside surface (the upper surface of FIG. 18) of the base frame 2. The insulator member 4 includes a hole for accommodating the lead wire 1a. Lead wire 1a also passes through the hole of the insulator member 4 and the hole 3 of the base frame 2. A flexible circuit board 5 for signal transmission is provided on the outside surface (the underside surface of FIG. 18) of the base frame 2. Flexible circuit board 5 covers an opening portion of the hole 3 (the under surface in FIG. 18). The power feeding lead wire 1a extends outside from the motor by protruding through holes which are provided in the flexible circuit board 5 and the base frame 2. The power feeding lead wire 1a is electrically connected to the printed circuit board by soldering the feeding lead wire 1a to land portion 6 located on the flexible circuit board 5.
Motors configured in the manner, wherein the lead wire 1a is soldered to land portion 6 of the flexible circuit board 5, cannot be manufactured such that the thickness of the motor thin. For example, with a motor having a thickness along an axial direction of 4 mm or less, the thickness ratio of soldering the feed lead wire to the land portion increases considerably with respect to the thickness of the entire motor even when the lead wire used is 0.1 mm in diameter. The soldered thickness of the lead wire of size 0.1 mm usually increase the size of the wire to about 0.5 mm. Therefore, the electrical connecting portion of the terminal portion of the stator coil 1 and the flexible circuit board 5 creates a large problem when trying to reduce the thickness of the motor.
To solve this problem, attempts have been made to absorb the thickness of the soldered land portion 6 by cutting out a part of the base frame 2 so as to put the soldered land portion 6 in the cutting part or by forming an opening portion at the corresponding area of the soldered land portion 6 so as to put the soldered land portion 6 in the opening portion. Since the thickness of the base frame 2 is often thin to make the motor thinner, however, these solutions are inadequate because the thin base frame 2 provided with the cutting part or opening portion lacks rigidity.
Alternatively, a motor is provided with a flexible circuit board that includes a main body portion and terminal portions. The terminal portion is formed extending from the main body portion and bent in a slanted direction towards a slot space between the salient pole sections of a stator core. A coil end portion is soldered to a land portion provided on each of the terminal portions. However, in this structure described above, both side sections of each terminal portion are engaged with neighboring salient pole sections respectively so that the terminal portion does not move up in the slot space only by way of the elastic engagement of its both side sections with the neighboring salient pole sections. Thus, the bending state of the terminal portion is extremely unstable in this example. Furthermore, when the terminal portions are disengaged from the salient pole sections, the land portion move in an axial direction and come into contact with other metal parts, which may result in a short-circuit.
Thus, there exists a need to provide a motor that is configured in a simple and thinner construction with high reliability, wherein the soldering section in a land portion of a flexible circuit board is held in an extremely stable condition.
In according with one embodiment of the present invention, a motor includes a stator core mounted to a base frame and includes salient pole sections extending radially from the stator core and each of the plurality of salient pole sections is provided with stator coils wound around each of the salient pole sections. The motor also includes a sheet-shaped flexible circuit board that has a flexible main body portion provided with land portions to which each of the terminal portions of the stator coils is electrically connected. The flexible main body portion of the flexible circuit board is provided with elastic extending portions extending between the salient pole sections, the land portion is formed on each of the elastic extending portions, the elastic extending portion is bent by the flexible main body portion being mounted to the fixed member, and each of the land portions of the elastic extending portions is pushed against the fixed member by the elastic force due to the bending.
According to one embodiment of the present invention, a cut portion assisting for bending of the elastic extending portion is provided in a connecting portion between the flexible main body portion and the elastic extending portion of the flexible circuit board. Thus, the bending of the elastic extending portion is easy and productivity of the motor is improved.
According to one embodiment of the present invention, an insulation member is provided on the surface of the fixed member to which a land portion is pushed. Thus, electric reliability of the motor is attained.
In addition, according to one embodiment of the present invention, a rotor magnet is attached to a rotor, a magnetic attraction member is provided on the base frame such that the rotor magnet can be attracted in an axial direction for regulating a thrust position of the rotor, and the flexible main body portion of the flexible circuit board is retained to the base frame by the magnetic attraction member. Thus, extra fixing members for the flexible circuit board are unnecessary, a satisfactory fixed state is obtained with low cost, and the construction of the motor is simplified.
Further, according to one embodiment of the present invention, a guide groove is provided in the magnetic attraction member or the base frame such that the flexible main body portion of the flexible circuit board can be easily drawn toward the outside of the motor, and thus, the flexible circuit board can be disposed along the guide groove with ease and precision.
Also, according to one embodiment of the present invention, a guide groove is provided in the fixing member of the stator core or the base frame such that the flexible main body portion of the flexible circuit board can be easily drawn towards the outside of the motor.
Also, according to one embodiment of the present invention, the position of the drawing out from inside of the motor for the flexible circuit board is arranged in a circumferential direction except the range of the scanning zone for the head and the head actuator. Consequently, the height dimension of the drive device may not be increased. Also, according to one embodiment of the present invention, a plate is attached to the base frame and the land portions of the elastic extending portions are firmly held against the plate instead of the base frame. Other features and advantages of the invention will be apparent from the following detailed description, taken in conjunction with the accompanying drawings that illustrates, by way of example, various features of embodiments of the present invention.