JPS6311084A - Motor drive assembly - Google Patents

Abstract

PURPOSE:To heighten the detecting precision of a rotor by means of a Hall element, by providing a winding around the Hall element to control the conduction of a stator winding, and by generating the flux enough to expunging the flux flowing from stator to Hall element. CONSTITUTION:A fixed pole member 2 has got a stator 2a and a stator winding 3 is wound around the magnetic core member which has got a stator 4a. The shaft of a rotor is fitted into the bearing section of the fixed role member 2. A winding 51a is arranged around a Hall element 21 to control conduction of a stator winding 3. The conduction of this winding 51a is synchronized with that of the stator winding 3, so that the flux is generated to expunge the flux flowing from the stator 4a to the Hall element 21.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a motor drive device that is most suitable for driving a focus ring of a camera, for example.

[Conventional technology]

Conventionally, when using a motor for the focus ring drive device in this type of device as in the case of Utility Model Application No. 58-77310, the outer diameter of the motor is 10 mm or more, and in order to make the lens barrel cylindrical, it is necessary to The diameter is thick (has become).

For this reason, if you try to make a motor with an outer diameter of 10 mm or less, a moving coil type motor will have a small winding space, making it impossible to obtain strong torque. Also in the case of
In conventional motors, the outer diameter is small, so in the case of a ferrous core motor, the windings must be concentrated. Therefore, the rotor must be multi-pole magnetized, and since the rotor's outer diameter is small, anisotropic magnets cannot be used, and strong torque cannot be obtained. In addition, in the case of iron-free core motors, it is possible to use two-pole anisotropic magnets because overlapping winding is possible.
In addition, although it has high efficiency because there is no iron loss, it has the disadvantage that it is difficult to manufacture the coil and the cost is extremely high.

Instead of increasing the overall outer diameter of the lens barrel,
609, it has been proposed to form a lens barrel by protruding a part, but this method spoils the aesthetics, and since the shape is not cylindrical, lathe processing etc. cannot be performed, and it is difficult to match the cover with the main body. Therefore, there was a drawback that it was difficult to completely prevent light leakage.

Furthermore, in order to control the rotation of the rotor made of permanent magnets, it is difficult to control the energization of the coils wound around the stator by having the Hall element receive only the magnetic flux of the permanent magnets of the rotor.
There was a fear that the magnetic flux of the stator would affect the Hall element, resulting in poor S/N ratio and reduced controllability.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and a winding is arranged around a Hall element for controlling the current supply to the stator winding, and the current supply to the stator winding is synchronized with the current supply to the stator winding. By generating magnetic flux that cancels the magnetic flux flowing from the hole to the Hall element, it is aesthetically pleasing and compact.
It is an object of the present invention to provide a motor drive device used for driving a focus ring of a lens barrel that is inexpensive in terms of cost.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the entire motor drive device, where 2 is a motor unit board made of a non-magnetic material and is provided inside the lens barrel, 2 is a first fixed magnetic pole member having a stator 2a,
3 is a first stator winding, 4 is a first magnetic core member having a stator 4a, and 5a is the first magnetic material for forming a first magnetic material.
A screw connecting the fixed magnetic pole member 2 and the first magnetic core member 4 is shown.

6 is a rotor consisting of a permanent magnet magnetized symmetrically into two poles, an N pole and an S pole. A shaft 7a passes through the rotor 6, one end of the shaft 7a is fitted into the bearing portion 8 of the first fixed magnetic pole member 2, and the other end of the shaft 7a passes through the gear 9 and is fixed thereto. ing.

10 is a second 'fixed magnetic pole member having a stator 10a, 1
1 is a second stator winding, 12 is a second magnetic core member having the stator 12a, and 5b is the second fixed magnetic pole member 10 and the second magnetic core to form a second magnetic material. The screws connecting the members 12 are shown. The other end of the shaft 7a is fitted into the bearing portion 19 of the second fixed magnetic pole member IO.

A gear 13 meshes with the gear 9, and the gear shaft 9 fixes a gear 15 via a bearing portion 14 of the second fixed magnetic pole member IO. This gear 15 meshes with a gear 18 via a two-stage gear 17. Also, the mounting hole 2b of the first fixed magnetic pole member 2 and the mounting screw hole 1a of the motor unit board 1 are aligned, and the mounting hole 10b of the second fixed magnetic pole member 10 is aligned with the mounting screw hole 1b of the motor unit board 1. The first fixed magnetic pole member 2 and the second fixed magnetic pole member 10 are matched and fixed to the motor unit board l using screws (not shown), respectively. Further, the gear shaft 13a is fixed to the gear 15, and the second gear 17 fitted to the shaft 16 installed on the second fixed magnetic pole member 10 is connected to the large gear portion 17a of the gear 15 and the second gear 17. The meshing small gear portion 17b meshes with a gear 18 coupled to a focusing portion (not shown), and rotation of the rotor 6 is caused by gear 9. 13.degree.15.17 to the gear 18, and then to a focus section (not shown).

When a focus section (not shown) rotates, the focus lens is moved in the optical axis direction by a helicoid screw or a cam, similar to the focus section of a known lens, and focus adjustment is performed. The rising portion of the first fixed magnetic pole member 2, the tip portion of the first magnetic core member 4, the tip portion of the second magnetic core member 12, and the falling portion of the second fixed magnetic pole member IO are fixed to the rotor 6. Children 2a, 4a.

However, depending on the direction of the current flowing in the stator winding 3 and the stator winding 11, for example, when the stator 4a is the N pole, the stator 2a is the S pole, and the stator 12a is the N pole. When it is a pole, the stator becomes 10altS pole.

And stators 4a and 12a, 12a and 2a,
The angles formed between 2a and 10a and between IOa and 4a are approximately 90'.

In addition, the first fixed magnetic pole member 2 includes a Hall element 21 for timing the drive current flowing through the stator winding 3 and the stator winding 11. 22 and 90″ apart, respectively, stator 4
The Hall element 21 is arranged in the same phase as the stator 12a, and the Hall element 22 is arranged in the same phase as the stator 12a. The first fixed magnetic pole member 2 has a first
As shown in Figure (b), the erasing winding 5'Oa is wound around the iron core 51a, and the Hall element 21 is arranged thereon.

The erasing winding 50a is connected in series with the stator winding 3.

A current is caused to flow through the erasing winding so that the magnetic flux flowing from the stator 4a to the stator 2 through the Hall element 21 is canceled by the magnetic flux of the erasing winding 50a. Therefore, the magnetic flux from the stator 4a does not affect the output of the Hall element 21. FIG. 1(C) shows the winding 50a viewed from the Hall element 21 side.

Note that even if the sheet winding 52 is wound around the Hall element 21 as shown in FIG. 1('d) (FIG. 1(b)).

This has the same effect as (C).

In addition, other Hall elements 22 are also shown in FIG. 1(b), <c)
Similarly, an erasing winding 50b is wound around an iron core 51b.

FIGS. 2(a) and 2(b) show cross-sectional views of a lens barrel in which a motor drive device is disposed within the lens barrel.

That is, 20 indicates an end surface of a certain part of the lens barrel; end surface 2
The motor unit explained in FIG.

Here, FIG. 3 shows the energization control circuit of the motor drive device shown in FIG. 1, and 21 and 22 are the aforementioned Hall elements,
21a and 21b are output terminals of the Hall element 21, and 22a
, 22b are output terminals of the Hall element 22. 23 is an energization control circuit, 11, 3 is the stator winding described above, 50a,
50b is an erasure winding, lla and llb are terminals of the stator winding 11, and 3a and 3b are terminals of the stator winding 3. This energization control circuit 23 includes a differential amplifier section 23a.

23e, comparator sections 23b, 23f, logic circuit section 23c.

23g1 is composed of drive circuit sections 23d and 23h.

This energization control circuit 23 controls the energization of the stator winding '11 by the output of the Hall element 21, and controls the energization of the stator winding 3 by the output of the Hall element 22. Hall element 21
When facing the S pole (N pole), for example, the output voltages of 21a and 21b become 21a>21b, and the energization control circuit 23 energizes the coil 11 in the direction of lla→llb, for example.

Next, when the Hall element 21 faces the N pole (S pole),
The output voltages of the outputs 21a and 21b of the Hall element 21 are inverted so that 21a<21b, and the energization control circuit 23 inverts the energization of the coil 11 and energizes the coil 11 in the direction of 1 l b -'' 11 a. The comparator section 23b (23f) in the energization control circuit 23 is used to prevent oscillation when the magnetic poles are opposed to the boundary between the N and S magnetic poles.
has a predetermined hysteresis characteristic. Further, the operation of the energization control circuit for the Hall element 22 and the stator winding 3 is completely (same) as the operation for the Hall element 21 and the stator winding 11 described above.

Reference numeral 24 denotes a control circuit, which has the function of sending command signals for the rotational direction of the rotor 6 and for starting and stopping the rotor 6 to the energization control circuit 23.

The erasing windings 50a and 50b are the stator windings 11, respectively.
Since it is connected in series with the stator windings 11 and 3, it can be synchronized with the energization control of the stator windings 11 and 3, and as mentioned earlier, the magnetic flux from the stator windings 11 and 3 enters the Hall elements 21 and 22. Windings 50a and 50b for erasing magnetic flux so as to cancel the
can be generated.

Next, the operation of the above configuration will be explained with reference to FIGS. 4, 5, and 6.

Figure 4 shows the state of rotation of the rotor 6 as shown in Figures 4 (a) to (h).
In addition, the voltages applied to the stator winding 3 and the stator winding 11 are shown in FIG. The output voltage is shown in FIG. 6 with reference to the output voltages of the Hall element output terminal 21a and the Hall element output terminal 22a.

In the state shown in FIG. 4(a), the aforementioned energization control circuit 23 applies an N pole to the stator 12a, an S pole to the stator 10a, and an S pole to the stator 4 according to the outputs of the Hall elements 21 and 22.
It is assumed that the energization of the stator winding 3 and the stator winding 11 is controlled so that the N pole is excited at a and the S pole is excited at the stator 2a.

At this time, the north pole of the rotor 6 is separated from the north pole of the stator 4a, and the south pole of the rotor 6 is separated from the south pole of the stator 2a. Since the stator 12a is the north pole, the south pole of the rotor 6 is the stator 12a.
Since the stator 10a is the S pole, the N pole of the rotor 6 is the N pole of the rotor 6.
Rotate in the direction in which the poles are attracted, ie, counterclockwise.

Next, when the rotor 6 rotates 45 degrees counterclockwise from the state shown in FIG. 4(a) and comes to the position shown in FIG. 4(b), the output of the Hall element 21 is reversed and the energization control is performed. Circuit 23 reverses the energization of stator winding 11 . As a result, stator 12
a changes from the north pole to the south pole, and the stator 10a changes from the south pole to the north pole. At this time, the south pole of the rotor 6 is separated from the south pole of the stator 12a and the stator 2a, and is attracted to the north pole of the stator 4a. Similarly, the N pole of the rotor 6 is the stator 4a and the stator 1.
It continues to rotate counterclockwise so that it is separated by the north pole of stator 0a and attracted to the south pole of stator 2a.

Similarly, at the position shown in FIG. 4(a), the output of the Hall element 22 is reversed, the energization of the stator winding 3 is reversed, and the rotation continues in the counterclockwise direction, and further as shown in FIG. 4(f). At the position, the output of the Hall element 21 is reversed, the energization of the stator winding 11 is reversed, and the rotation continues in the counterclockwise direction.

Further, in order to rotate the motor unit according to the present invention in the opposite direction from the counterclockwise direction described above in FIG. 4, that is, in the clockwise direction, the voltages applied to the stator windings 3 and 11 shown in FIG.
Between each terminal (3a, 3b and 11a.

11b), and a phase inversion circuit for this purpose is included in the energization control circuit 23.

〔Effect of the invention〕

As explained above, when the motor drive device according to the present invention is arranged in an arc shape and assembled into a lens barrel, the radial dimension of the arc shape is approximately equal to the diameter of the rotor made of permanent magnets plus the plate thickness of the stator. Since the lens barrel can be constructed with the dimensions of Therefore, in terms of manufacturing costs, the lens barrel can be manufactured by lathe processing, which is advantageous in terms of cost, and since there is no need for external protrusions, the aesthetic appearance is not compromised. Furthermore, since the rotor is bipolar magnetized, strong anisotropic permanent magnets can be used even in a small-diameter rotor, which has the excellent advantage of being able to obtain strong torque.

A coil is placed around the Hall element on the fixed magnetic pole member,
By controlling the energization in synchronization with the stator energization control,
Since it is possible to generate a magnetic field in the opposite direction to the magnetic field that affects the Hall element from the stator, it is possible to cancel the effect of the magnetic field from the stator on the Hall element. Therefore, since the Hall element can detect only the magnetic field of the rotor, the S/N ratio can be improved, accurate energization control can be realized, and efficiency can be increased.

Furthermore, since a cylindrical lens barrel can be implemented, it has the effect of being able to take measures against light ray leakage in the same way as conventional cylindrical lens barrels.

[Brief explanation of drawings]

FIG. 1(a) is an exploded perspective view of a motor drive device according to an embodiment of the present invention, FIG. 1(b) is a schematic diagram of the main part of FIG. 1(a), and FIG. 1(c) is a schematic diagram of the main part of FIG. 1(a). FIG. 1(b) is a top view of the Hall element, FIG. 1(d) is a diagram showing a modification of FIG. 1(c), and FIG. 2(a) is the device shown in FIG. 2(b) is a detailed view of the device shown in FIG. 1 installed in the lens barrel, FIG. 3 is a power supply control circuit diagram of the device shown in FIG. Diagram for explaining the rotational operation of the device shown in Figure 5.
This figure is a waveform diagram of the voltage applied to the stator winding in the circuit of FIG. 3, and FIG. 6 is a diagram of the output voltage waveform of the Hall element of the circuit of FIG. 3. 1...Motor unit board 2...
...First fixed magnetic pole member 3.11...
・Stator winding 4...First magnetic core member 6...Rotor

Claims (1)

[Claims] A rotor made of a permanent magnet, a plurality of magnetic materials formed by opposing fixed magnetic poles provided at both ends with the rotor interposed therebetween, and a plurality of magnetic materials wrapped around each magnetic material so that the opposing fixed magnetic poles are different magnetic poles. A stator winding that is wound around each magnetic material, a Hall element that controls the energization of the stator windings that are wound around each magnetic material, a winding that is provided around the Hall element, and a stator that controls the energization of the winding. A motor drive device comprising: an energization control circuit that generates magnetic flux that cancels magnetic flux flowing from a stator to a Hall element in synchronization with energization of a winding.