JPH0145254Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a brushless motor with a frequency generator that has an improved structure of a substrate on which a rotation control circuit and the like are disposed.

[Technical background of the invention]

Conventionally, a brushless motor with a frequency generator has been used, for example, as a motor for driving a polygon mirror of a laser printer. The configuration of this type of motor that has recently been considered is as follows based on FIG. 1. 1 is a motor bracket with a bearing tube 2 erected in the center, 3 is an armature coil 4
A stator 5 is rotatably supported by a bearing sleeve 2, and a field permanent magnet 6 and a frequency power generation permanent magnet 7 are fixed to the rotor 5. 8 is a printed circuit board arranged so as to fit into the bearing sleeve 2 and extend outward from the motor bracket 1;
This includes a frequency power generation coil (not shown) disposed in an annular region facing the frequency power generation permanent magnet 7, and a position detection element 9 located within this annular region to detect the rotational position of the rotor 5. is installed. Further, on the outer side of the motor bracket 1 of the printed circuit board 8, a group of electronic components ( (not shown) is provided.

[Problems with background technology]

Incidentally, particularly in the case of the polygon mirror driving motor of the laser printer as described above, extremely high rotational speed stability is required in order to obtain good image quality.

However, in the above configuration, since the position detection element 9 is arranged on the same printed circuit board 8 as the rotation control circuit, the output line of the position detection element 9 is connected along the printed circuit board 8, that is, the frequency power generation permanent magnet 7
It must be extended in the radial direction and connected to the rotation control circuit. Therefore, the output line is interlinked with the magnetic flux from the frequency power generation permanent magnet 7, and the resulting electromotive force is superimposed on the output signal of the position detection element 9, resulting in a decrease in the S/N ratio of the output signal. A problem arises in that the speed control of the rotor 5 becomes unstable. Furthermore, when the electronic components constituting the rotation control circuit are soldered using the solder dip method, for example, the heat causes the printed circuit board 8 to warp slightly, but the frequency generating coil is attached to the same printed circuit board 8 as the rotation control circuit. Because of this, warpage inevitably occurs in the frequency generation coil as well. Therefore, the deceleration detection signal of the frequency generator coil becomes unstable,
As a result, speed control of the rotor 5 becomes unstable.

[Purpose of invention]

Therefore, an object of the present invention is to provide a brushless motor with a frequency generator that can obtain excellent speed stability.

(Means for solving the problem) The brushless motor with a frequency generator of the present invention is
A container-shaped motor bracket having a bearing sleeve erected on the inner bottom, a stator arranged concentrically around the outer periphery of the bearing sleeve, and a rotating shaft rotatably supported by a bearing provided inside the bearing sleeve. The rotor is equipped with a permanent magnet for the field and is attached to the rotating shaft and is arranged so that the permanent magnet for the field exists in a gap in the radial direction of the stator relative to the armature coil. A permanent magnet for frequency power generation provided,
A first board provided below the rotor in the motor bracket, and position detection that detects the rotational position of the rotor by receiving the leakage magnetic flux of the field permanent magnet of the rotor, which is provided on the first board. A frequency generating coil provided to face the frequency generating permanent magnet of the rotor, and the first board provided outside the motor bracket so as to sandwich the bottom part of the motor bracket. A second board on which a rotation control circuit is arranged, and a first and second board extending through the bottom of the motor bracket in the axial direction of the rotor are connected to each other to detect the position detection element and the frequency. It is characterized by a configuration including a conductive member that transmits a signal from the power generation coil to the rotation control circuit.

(Function) A first board on which a position detection element and a frequency power generation coil are arranged, and a second board on which a rotor rotation control circuit is arranged are arranged in two stages, upper and lower, with a line between them in the axial direction of the rotor. The structure is such that they are connected by a conductive member that extends to. Therefore, compared to a structure in which a position detection element and a rotation control circuit are mounted on the same board and connected by a conductor pattern extending in the radial direction of the rotor, it is less affected by the magnetic flux of the permanent magnet for frequency power generation. Therefore, it is possible to prevent noise from being superimposed on the output signal from the position detection element as much as possible, thereby making it possible to stabilize rotation control. Also, when soldering the parts that make up the rotation control circuit, the second
Even if the substrate is warped due to heat acting on it, the first substrate on which the frequency power generation coil is disposed is not affected at all, so there is no possibility that the speed detection signal from the frequency power generation coil will be distorted.

[Example of idea]

The following is a second example of an example in which the present invention is applied to a motor for driving a polygon mirror of a laser printer.
This will be explained with reference to FIGS. 4 to 4. Reference numeral 11 designates a container-shaped motor bracket having a bearing sleeve 12 erected in the center thereof, and bearings 13, 13 are fitted into both upper and lower ends of the bearing sleeve 12. A stator 14 is formed by winding a plurality of armature coils 16 around a bobbin 15, and is fixed to the motor bracket 11 by fitting the bobbin 15 into the bearing sleeve 12. Reference numeral 17 denotes an outer rotor, to which a rotor yoke 20 is screwed to a boss 19 fitted on a rotating shaft 18, and a field permanent magnet 21 having a substantially cylindrical shape is fixed to the inner circumference of the rotor yoke 20. In addition, a ring-shaped permanent magnet 22 for frequency power generation is fixed to the lower peripheral edge of the rotor yoke 20. A rotating shaft 18 of the rotor 17 is rotatably supported by a bearing 13, and a field permanent magnet 21 is connected to the armature coil 1 of the stator 14.
A cap is provided at 6 in the radial direction of the stator 14 and faces the stator 14. Note that 23 is a pressurized boss attached to the lower end of the rotating shaft 18.

Now, 24 is a first board located in the motor bracket 11, and this board is attached to the lower end of the bobbin 15 fitted to the bearing sleeve 12 with a predetermined gap below the rotor 17. A frequency power generation coil (not shown) is provided in an annular region facing the frequency power generation permanent magnet 22 of the rotor 17 on its upper surface.
is formed by printed wiring means. As the rotor 17 rotates, magnetic flux from the frequency power generation permanent magnet 22 interlinks with this frequency power generation coil, and a speed detection signal having a frequency corresponding to the rotational speed of the rotor 17 is induced. Reference numeral 25 denotes a position detection element disposed on the first substrate 24, which is located on the inner circumferential side of the frequency power generation coil and fixed via a mounting seat 26, and outputs a position detection signal according to the rotational position of the rotor 17. Output. A number of conductive pins 27 are conductive members, which are provided on the first substrate 24 to extend in the axial direction of the rotor 17 and protrude downward, and are connected to the motor bracket 1.
1 and protrudes below the motor bracket 11 through a long hole 11a (see FIG. 3) formed at the bottom of the motor bracket 11. The position detection element 25 and the frequency power generation coil arranged on the first substrate 24 and each armature coil 16 of the stator 14 are connected to the conductive pin 27 . Reference numeral 28 denotes a second board, which includes a well-known rotation control circuit that turns off current to each armature coil 16 based on the position detection signal from the position detection element 25 and the speed detection signal from the frequency power generation coil. A group of electronic parts is arranged. This second substrate 28 is separate from the first substrate 24, and
The motor bracket 11 is screwed to a stud 29 protruding downward from the bottom of the motor bracket 11, and in this attached state, the first and second boards 24 and 28 are spaced apart from each other in the axial direction of the rotor 17 and positioned in two stages, upper and lower. I'm starting to do that. 30 is a receiving terminal fixed to the second board 28 in correspondence with the conductive pin 27;
By attaching it to the motor bracket 11 of the board 28, the receiving terminal 30 and the conductive pin 27 are electrically connected. is connected,
Signals from the position detection element 25 and the frequency power generation coil are transmitted to the rotation control circuit of the second board 28.

According to the above configuration, the first substrate 24 is provided with the position detection element 25, and the second substrate 24 is provided with the rotation control circuit.
Since the electrically conductive pin 27 extending in the axial direction of the rotor 17 is used to connect the substrate 28 of the It can be input to the rotation control circuit. Furthermore, since the conductive pin 27 is provided to extend in the axial direction of the rotor 17, no electromotive force is induced in the conductive pin 27 by the magnetic flux from the frequency power generation permanent magnet 22 when the rotor 17 rotates. Therefore, since noise does not occur in the position detection signal, the S/N ratio can be improved, and the rotational position of the rotor 17 can be detected with high precision. Moreover, since both the first and second boards 24 and 28 are separate bodies, even if the electronic components constituting the rotation control circuit are soldered to the second board 28 using the solder dip method, the first board 24 does not warp. Therefore, the positional accuracy between the frequency power generation coil and the frequency power generation permanent magnet 22 can be improved, and the rotational speed of the rotor 17 can be detected with high precision. It can be done. In this way, both the rotational position and rotational speed of the rotor 17 can be detected stably with high precision, so that the speed stability of the rotor 17 can be sufficiently increased and the image quality of the laser printer can be improved. Furthermore, in the conventional one constructed from a single printed circuit board 8 as shown in FIG.
In order to fit the printed circuit board 8 into the bearing sleeve 12, the motor bracket 1 has to be divided into upper and lower halves, but according to this embodiment, the first board 24 can be stored in the motor bracket 11. The motor bracket 11 can be constructed as an integral piece.

In the above embodiment, the present invention is applied to a motor for driving a polygon mirror of a laser printer, but the present invention is not limited to this, and it goes without saying that the present invention can be implemented with various modifications without departing from the scope of the invention.

[Effect of idea]

As described above, in the present invention, the first substrate on which the position detection element and the frequency generating coil are arranged, and the second substrate on which the rotation control circuit is arranged are separated in the axial direction of the rotor and arranged in two stages. The structure is characterized in that the two boards are connected by a conductive member extending in the axial direction of the rotor, and as a result, the electromotive force due to the magnetic flux of the permanent magnet for frequency power generation is superimposed on the position detection signal. This has the effect that it is possible to prevent the S/N ratio from decreasing, and also to prevent the accuracy of the speed detection signal from decreasing due to warpage of the frequency power generation coil, thereby achieving excellent speed stability.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of an example of a polygon mirror driving motor shown for comparison, FIGS. 2 to 4 show an embodiment of the present invention, and FIG. 2 is an overall longitudinal sectional view, Figure 3 is a plan view of the motor bracket.
FIG. 4 is a plan view of the second substrate. In the figure, 11 is the motor bracket, 12 is the bearing sleeve,
13 is a bearing, 14 is a stator, 16 is an armature coil, 17 is a rotor, 21 is a permanent magnet for field, 22
is a permanent magnet for frequency power generation, 24 is a first substrate, 2
5 is a position detection element, 27 is a conductive pin (conductive member),
28 is a second substrate.

Claims (1)

[Scope of utility model registration request] a container-shaped motor bracket having a bearing sleeve erected on its inner bottom; a stator comprising an armature coil and disposed concentrically around the outer periphery of the bearing sleeve;
A rotating shaft is rotatably supported by a bearing provided in the bearing sleeve, and a field permanent magnet is attached to the rotating shaft, and the field permanent magnet is attached to the armature coil with a diameter of the stator. a rotor of an epidermal shape arranged so as to have a gap in the direction; a permanent magnet for frequency power generation provided at the lower end of the rotor; and a permanent magnet provided below the rotor in the motor bracket. 1 board and this first board.
a position detection element that is provided on the substrate and detects the rotational position of the field permanent magnet of the rotor by receiving leakage magnetic flux; and a position detection element that is provided on the first substrate so as to face the frequency power generation permanent magnet. a frequency generating coil, and a first coil disposed outside the motor bracket.
a second board which is provided so as to sandwich the bottom part of the motor bracket between the second board and the rotation control circuit for the rotor; A brushless motor with a frequency generator, comprising: a conductive member that extends and connects the first and second substrates to transmit signals from the position detection element and the frequency power generation coil to the rotation control circuit. .