JPH025666Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a DC servo motor in which rotation of a rotor is optically detected.

(Prior art) In a conventional DC servo motor, a rotor having a structure in which a cylindrical part is connected to the periphery of a disc is rotatably held in a motor housing, and the rotor is rotatably held on the inner surface of the cylindrical part of the rotor at equal pitches in the circumferential direction. A magnet is installed, and the stator placed inside the cylindrical part of the rotor is fixed to the motor housing.A magnetic leakage hole is bored in the cylindrical part of the rotor, and a magnetic detection coil is placed near the outer periphery of this cylindrical part. There is a device that detects the rotation of the rotor based on the pulse signal from this magnetic detection coil and controls the rotation of the rotor.

(Problems to be Solved by the Invention) However, in this type of DC servo motor, the detection means such as the magnetic detection coil was disposed outside the rotor, so the overall size tended to increase. Moreover, since the magnetic detection coil for detecting slight magnetic leakage is expensive, a DC servo motor using this coil has the problem of high cost.

Therefore, the purpose of this invention is to provide a DC servo motor that is more compact and lower in cost than conventional ones.

(Means for Solving the Problem) In order to achieve this object, this invention allows a cup-shaped rotor 13 to be rotatably held in a plate-shaped motor housing 1 by a rotor shaft 6, and a stator 16 is connected to the rotor 13. A printed circuit board 17 is disposed concentrically with the rotor shaft 6 in a space 14 formed between the stator 16 and the motor housing 1, and is fixed to the motor housing 1. an optical pulse generator 18 which is a DC servo motor and is used to detect the rotation of the rotor 13 and control the rotation of the rotor 13;
is attached to the stator 16, and a cylindrical light-shielding wall 4 is integrally provided to the motor housing 1 concentrically with the rotor 13, and the cup-shaped rotor 1 is attached to the stator 16.
3 loosely inserted into the cylindrical light-shielding wall 4 and covering the space 14 with the light-shielding wall 4, the stator 16 and printed circuit board 17 are protected by the light-shielding wall 4 and the rotor 13. The DC servo motor is characterized in that a wiring outlet 26 is provided at a position away from a portion of the light shielding wall 4 that corresponds to the optical pulse generator 18.

(Example) This invention will be explained below based on the drawings.

FIGS. 1 and 2 show an example of a DC servo motor used in a magnetic disk recording/reproducing device. In FIGS. 1 and 2, a motor housing 1 includes a plate body 2 with a portion cut away. A cylindrical light shielding wall 4 is integrally formed on the peripheral edge of one side of the disc body 2 and is concentric with the bearing sleeve 3, and a cylinder portion 5 for sealing that communicates with the bearing sleeve 3 is formed in the center of the other surface of the disc body 2. It is formed in one piece.

The rotor shaft 6 passing through the bearing cylinder 3 and the cylinder part 5 is
It is rotatably held in the bearing sleeve 3 via a bearing 7. A hub 8 on which a floppy disk is mounted is attached to the upper end of the rotor shaft 6, and an exclusion seal, ie, a magnetic seal 9, is interposed between the cylindrical portion 5 and the rotor shaft 6. This magnetic sticker 9
In this example, magnetic pole pieces 11 and 12 are magnetized to each pole of a magnet 10, and a magnetic fluid is interposed between these pieces and the rotor shaft 6.

A rotor 13 is attached to the lower end of the rotor shaft 6. The rotor 13 has a cylindrical portion 13b connected to the periphery of a disc 13a, and the upper end of the cylindrical portion 13b is fitted into the light shielding wall 4. This light blocking wall 4
closes the space 14 formed between the rotor 13 and the motor housing 1. A plurality of magnets 15 are provided on the inner peripheral surface of the cylindrical portion 13b.
are fixed at equal pitches in the circumferential direction, and a stator 16 fixed to the bearing sleeve 3 of the motor housing 1 is disposed inside the cylindrical portion 13b.
A printed circuit board 17 disposed inside is fixed.

There is a rotor 1 between the rotor 13 and the stator 16.
An optical pulse generator 18 is interposed for detecting the rotation of the rotor 3 and controlling the rotation of the rotor 13. The optical pulse generator 18 includes a light emitting diode 19 attached to the stator 16 and a phototransistor 20 attached to the printed circuit board 17 in opposition thereto. The light shielding plate 21 fixed to the cylindrical portion 13b of the rotor 13
As the light emitting diode 19 rotates, light emitted from the light emitting diode 19 to the phototransistor 20 is blocked. In the figure, 22 is a Hall element attached to the stator 16, 23 is a stator yoke of the stator 16, and 24 is a winding wound around the stator yoke.

The Hall element 22, the winding 24, the generating diode 19, the phototransistor 20, etc. are connected to the printed wiring of the printed circuit board 17, and the lead wire 25 connected to the printed wiring of the printed circuit board 17
is wired to the outside from a wire outlet 26 formed in the light shielding wall 4. This wiring outlet 26 is provided at a position offset by 180 degrees with respect to the optical pulse generator 18.

Next, the operation of the DC servo motor having such a configuration will be explained together with other setting conditions. When the rotor 13 is rotated by energizing the winding 24 and exciting the stator yoke 23, the light shielding plate 21
rotates together with the rotor 13 and the light emitting diode 1
The light irradiated from 9 to the phototransistor 20 is cut off every rotation. As a result, the phototransistor 20 outputs a pulse signal every time the rotor 13 rotates once. Then, this pulse signal is counted by a counter (not shown), and the output signal of this counter is inputted to an arithmetic circuit.
The rotation per unit time of rotor 13 is calculated.
determine whether the rotation is at a predetermined rotation speed,
The rotation speed of the rotor 13 is maintained at a predetermined value by controlling the field current to the winding 24 by the motor control circuit so that the rotor 13 has a predetermined rotation speed.

In the embodiment described above, the light emitting diode 1
9. Although an example using the optical pulse generator 18 composed of a phototransistor 20 and the like has been shown, it is not necessarily necessary to use the optical pulse generator 18 having such a configuration. For example, a light reflection type can also be used as the optical pulse generator. That is, as this optical pulse generator, an element in which a generating element and a light receiving element are arranged side by side is attached to the stator 16,
When a light reflecting surface is provided on the rotor 13 and the light reflecting surface faces the light emitting element as the rotor 13 rotates,
By setting the light emitted from the light-emitting element to reflect on the light-reflecting surface and enter the light-receiving element,
It may be configured such that a pulse signal is output from the light receiving element.

Furthermore, in the embodiment described above, the lead wire 25
Although an example is shown in which the lead wire is wired to the outside from the wire outlet 26, as shown in FIG. 3 and FIG.
7a may be provided, and the lead wire 25 may be connected to the printed wiring of this lead wire wiring portion 17a outside the light shielding wall 4.

(Effects) As explained above, this invention allows the cup-shaped rotor 13 to be rotatably held in the plate-shaped motor housing 1 by the rotor shaft 6, and the stator 16 is placed between the rotor 13 and the motor housing 1. A DC servo motor is arranged concentrically with the rotor shaft 6 in a formed space 14 and fixed to the motor housing 1, and a printed circuit board 17 is arranged between the stator 16 and the motor housing 1, An optical pulse generator 18 used to detect the rotation of the rotor 13 and control the rotation of the rotor 13 is attached to the stator 16, and a cylindrical light shielding wall 4 is integrated into the motor housing 1 concentrically with the rotor 13. and the cup-shaped rotor 13
By loosely inserting a part of the opening side into the cylindrical light shielding wall 4 and covering the space 14 with the light shielding wall 4, the stator 16 and the printed circuit board 17 are covered with the light shielding wall 4 and the rotor 13. Since the wiring outlet 26 is provided at a position away from the portion of the light shielding wall 4 corresponding to the optical pulse generator 18, the magnetic detection coil is not disposed outside the rotor as in the conventional case. The entire structure can be made more compact by not using a magnetic detection coil, and costs can be reduced by not using a magnetic detection coil. Furthermore, since the space in which the optical pulse generator is housed is covered with the light shielding wall of the motor housing, it is possible to prevent the optical pulse generator from malfunctioning due to external light.

Furthermore, in the case of a DC servo motor in which the wiring exit from the stator side is located 180 degrees away from the optical pulse generator of the motor housing, even if external light enters the light-shielding wall from the wiring exit, this It is possible to prevent the optical pulse generator from malfunctioning due to external light.

Furthermore, a printed circuit board is attached to the stator, and this printed circuit board is integrally equipped with a lead wire wiring section that protrudes to the outside through a wiring outlet provided in the light-shielding wall of the motor housing. In this case, the amount of light leaking into the light shielding wall can be sufficiently reduced, and the lead wire can be reliably prevented from coming into contact with the rotor.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a DC servo motor according to this invention, FIG. 2 is a bottom view of the motor housing shown in FIG. 1, and FIG. 3 is a bottom view of the motor housing showing another embodiment of this invention. FIG. 4 is a partial sectional view showing the relationship between the motor housing and printed circuit board of FIG. 3 and the rotor. 1...Motor housing, 4...Shading wall, 13
... Rotor, 13a ... Disk, 13b ... Cylinder part,
14... Space, 16... Stator, 17... Printed circuit board, 18... Optical pulse generator, 19...
Light emitting diode, 20...Phototransistor, 2
1... Light shielding plate, 25... Lead wire, 26... Wiring exit.

Claims (1)

[Claims for Utility Model Registration] (1) A cup-shaped rotor 13 is rotatably held in a plate-shaped motor housing 1 by a rotor shaft 6, and a stator 16 is formed between the rotor 13 and the motor housing 1. A DC servo motor is arranged concentrically with the rotor shaft 6 in a space 14 and fixed to the motor housing 1, and a printed circuit board 17 is arranged between the stator 16 and the motor housing 1, wherein the rotor an optical pulse generator 18 used to control the rotation of the rotor 13 by detecting the rotation of the rotor 13;
is attached to the stator 16, and a cylindrical light-shielding wall 4 is integrally provided to the motor housing 1 concentrically with the rotor 13, and a part of the opening side of the cup-shaped rotor 13 is attached to the cylindrical light-shielding wall. 4
The stator 16 and the printed circuit board 17 are covered by the light shielding wall 4 and the rotor 13 by inserting the light shielding wall 4 loosely into the space 14 and covering the space 14 with the light shielding wall 4, and the optical pulse generator 18 of the light shielding wall 4 A DC servo motor characterized in that a wiring outlet 26 is provided at a position away from a portion corresponding to the servo motor. (2) The DC servo motor according to claim 1, characterized in that the wiring outlet 26 from the stator 16 side is provided at a position offset by 180 degrees from the optical pulse generator 18 of the motor housing 1. (3) Registration of a utility model characterized in that the printed circuit board 17 is integrally provided with a lead wiring portion 17a that penetrates the wiring outlet 26 provided in the light shielding wall 4 of the motor housing 1 and projects to the outside. A DC servo motor according to claim 1 or 2.