JP3193038B2 - Moving coil type linear DC motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a coil movable linear DC motor, for example,
The present invention relates to a moving coil type linear DC motor suitable for application to a drive system such as an image scanner.

The prior art has a field magnet having the magnetic poles of NS alternately in the longitudinal direction, and a driving armature coil group is disposed so as to face the field magnet, and the field magnet is used as a stator, A linear DC motor using a child coil group as a mover is known, for example, in JP-A-59-86473 as a "semiconductor linear DC motor".

Thus, in the conventional coil-movable linear DC motor drive system, the mover moves in or out of the region where the mover reciprocates.
A plurality of detection sensors are provided according to the purpose of use, and the drive state of the linear DC motor is controlled using the detection signals. Therefore, the driving state is usually controlled by the CPU.

When a CPU is used as a control signal for the reciprocating motion of the mover, its driving state is program-controlled by the CPU. However, in program control using a CPU, a malfunction or runaway of a program may occur due to noise or the like.

If the program runs away, the CPU cannot obtain a control signal corresponding to the detection signal from the above-described detection sensor for detecting the overrun position of the linear DC motor drive system. Therefore, the mover jumps out of the reciprocable area, and the mover and the apparatus main body are destroyed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a control circuit that arranges a Hall magnet sensor for overrun detection in opposition to a driving magnet, and instructs a stop of a mover by an output signal thereof. Is provided in parallel with the control signal from the CPU, or by having a movable back yoke wider than the field magnet and a field magnet outside the reciprocating motion area, even if the control program of the CPU runs out of control. The purpose is to stop the mover.

In order to achieve the above object, the present invention provides (1) a stator consisting of a field magnet having NS poles alternately in the longitudinal direction, and a mover consisting of an armature coil group opposed to the field magnet. In the moving coil type linear DC motor having the above, while having a field magnet in the reciprocating motion region, having a plurality of Hall magnetic sensors for overrun detection in a portion facing the field magnet of the mover,
A control circuit for instructing the stop of the mover by an output signal of the Hall magnetic sensor for overrun detection is provided in parallel with a control signal from the CPU. (2) In the above (1), The Hall magnetic sensor for position detection is used as a part or all of the Hall magnetic sensor for overrun detection. Further, (3) a moving coil type linear DC motor having a stator consisting of a field magnet alternately having NS magnetic poles in the longitudinal direction and a mover consisting of an armature coil group opposed to the field magnet, It is characterized by having a movable back yoke wider than the field magnet and a field magnet outside the reciprocating region. (4) In the above (3), the opposing surfaces are opposed to each other in the reciprocating region. Instead, the distance between the field magnet and the movable back yoke in the portion facing each other only outside the reciprocating motion region is always smaller than the distance between the portions facing each other. Hereinafter, a description will be given based on an example of the present invention.

1 to 3 are structural views for explaining an embodiment of a moving coil type linear DC motor according to the present invention. FIG. 1 is a plan view, FIG. 2 is a side view, and FIG. In the drawing, reference numeral 1 denotes a mover, and the mover 1 is fixed to a movable back yoke 2, a coil substrate 3 attached to the movable back yoke 2, and four corners on both sides of the movable back yoke 2. A shaft 4, a roller 5 rotatably mounted on each shaft 4, a coil 6 fixed to the coil substrate 3 and continuously disposed along the longitudinal direction of the coil substrate 3, 6, which is provided at the center in the longitudinal direction of the coil 6 and is provided with Hall magnetic sensors 7u, 7v, 7w for position detection for detecting a magnetic field generated from a permanent magnet 12 described later. I have. A plurality of Hall magnetic sensors 13 a to 13 d for overrun detection are provided on the coil substrate 3 along the traveling direction of the mover 1. At this time, 13a-1
The distance between the 3d Hall magnetic sensors is arbitrary.

Reference numeral 8 denotes a stator.
Elongate base plate 10 having a groove or step-like guide portion 9 for guiding the motor, a fixed back yoke 11 fixed on the base plate 10, and a permanent magnet provided on the upper surface of the fixed back yoke 11. The permanent magnet 12 has a structure in which N poles and S poles are alternately magnetized in the moving direction of the mover 1. At the same time, the permanent magnets 12 are arranged only in the reciprocating region A shown in the figure.

In the above configuration, a fixed gap is always interposed between the permanent magnet 12 and the coil 6, and the coil 6 and the Hall magnetic sensors 7u, 7v, 7w are described later via a connector 13 attached to the coil board 3. Connected to an external drive control circuit.

FIG. 4 is a diagram for explaining an outline of the drive control circuit. In the figure, reference numeral 21 denotes a general three-phase motor drive IC, which is a signal from Hall magnetic sensors 7u, 7v, 7w for position detection. Outputs an output signal to the motor drive circuit 22 in response to the control signal to drive the coil 6. At this time, the START / STOP signal and CW / CCW
The signals are controlled by the CPU 23 (start at Hi level, stop at Lo level, CW at Hi level,
Set to CCW at Lo level. ).

The signals from the Hall magnetic sensors 13a to 13d for overrun detection and the signal from the reference voltage generator 24 are input to comparators 25a to 25d, respectively, and the TTL level Hi and Lo signals are output according to the state of both input signals. Output. Now, assuming that the signal from the reference voltage generator 24 is A and the signals from the Hall magnetic sensors 13a to 13d for overrun detection are B, B <A
At this time, the comparators 25a to 25d output Lo level signals, and when B ≧ A, output Hi level signals.

The output voltage of the reference voltage generator 24 is desirably 0, but is not actually possible.For example, on an actual machine, when a Hall magnet sensor for overrun detection faces a driving magnet, the output voltage is 1/10 to 1/1 of the maximum output. Set to 20th place.

The outputs of the comparators 25a to 25d are divided according to the direction of overrun detection (13a and 13b, 13c and 13d), and
The signals are input to the R circuits 26a and 26b.

Output signals of two OR circuits 26a and 26b and STAR from CPU 23
The T / STOP signal is input to a three-input AND circuit 27, and the output signal is input to the motor drive IC 21 as a final START / STOP signal. The control signal of the moving direction of the mover is directly input to the motor drive IC 21 by the CPU 23.

 Next, the actual operation will be described.

First, the mover 1 is moved in the reciprocating motion area A shown in FIG.
Will be described. At this time, the output signals of the hall magnetic sensors 13a and 13b and 13c and 13d for overrun detection do not become 0 at the same time, so that the comparators become Hi level by the operation of the reference voltage generator 24 and comparators 25a to 25d. Signal is continuously output. Then, since the output signals of the two OR circuits 26a and 26b also become Hi level, the operation of the AND circuit 27 causes the start / stop signal of the motor to depend on the output of the CPU 23.

Next, a case where the mover 1 advances to the left in FIG. 1 and comes out of the reciprocating region A will be described.

The mover 1 moves out of the reciprocating motion area A, and both of the Hall magnetic sensors 13a and 13b for detecting the overrun
Let's say you come to a part without. At this time, the outputs of the hall magnetic sensors 13a and 13b for overrun detection become 0 at the same time, and the outputs of the comparators 25a and 25b both become Lo by the operation of the reference voltage generator 24 and the comparators 25a to 25d.
Therefore, the output of the OR circuit 26a also becomes Lo.

Therefore, regardless of the drive signals of the other Hall magnetic sensors 13c and 13d for overrun detection and the CPU 23, the AND circuit 2
By the operation of 7, a stop signal is input to the motor driving IC 21. The same applies when the mover 1 has advanced in the opposite direction to that described above. That is, by this, outside the reciprocating motion area A
The mover 1 can be stopped reliably without depending on the instruction of the CPU (that is, even when the CPU goes out of control).

5 to 7 are configuration diagrams for explaining another embodiment of the present invention. FIG. 5 is a plan view, FIG. 6 is a side view, FIG. 7 is a front view, and FIG. 1 to 3 are denoted by the same reference numerals as those in FIGS. 1 to 3. In this embodiment, the number of parts is reduced by using the hole magnetic sensors 7u, 7v, 7w for position detection as the hole magnetic sensors for overrun detection in the embodiment shown in FIGS. 1 to 3. Therefore, in this embodiment,
The overrun detection Hall sensors 13a to 13d required in the embodiment shown in FIGS. 1 to 3 are unnecessary.

FIG. 8 is a diagram for explaining the drive control circuit of the moving coil type linear DC motor shown in FIGS. 5 to 7, in which the same operation as the control circuit shown in FIG. 4 is performed. Parts are given the same reference numbers as in FIG.
In other words, the circuit shown in FIG. 8 uses the 7w signal of the position detection Hall magnetic sensor instead of the overrun detection Hall magnetic sensor 13a of the circuit shown in FIG.
A signal of 7v is used in place of 13b and 13c, and a signal of 7u is used in place of 13d. Thus, when the mover 1 is moving to the left in FIG. When the hall magnetic sensors 7w and 7v exceed the reciprocating motion area A, the circuit shown in FIG. 8 can be reliably operated regardless of the start / stop signal from the CPU 23 even if the control program of the CPU 23 runs away. The child stops.

When the mover is moving to the right in FIG.
Reciprocating motion area A
Is exceeded, the mover 1 is reliably stopped regardless of the start / stop signal from the CPU 23.

At other times, that is, when the Hall magnetic sensors 7u, 7v, 7w for position detection (that is, the mover) are located within the reciprocating motion area A, the start / stop of the mover 1 is performed by the CPU 23.
Depending on the control signal from

9 to 11 are configuration diagrams for explaining another embodiment of the present invention. FIG. 9 is a plan view, FIG. 10 is a side view, and FIG.
FIG. 11 is a front view, in which 1 is a mover. This mover 1 has a movable back yoke 2, a coil substrate 3 attached to the movable back yoke, The shafts 4 are fixed at the four corners on both sides of the roller, the rollers 5 are rotatably mounted on the shafts 4, and are fixed to the coil substrate 3 and are continuously disposed along the longitudinal direction of the coil substrate. It comprises a coil 6 and a Hall magnetic sensor 7 for position detection, which is located inside the coil and is provided at the center in the longitudinal direction of the coil and detects a magnetic field generated from a permanent magnet 12 described later. However, in the present embodiment, the width of the movable back yoke 2 in the direction perpendicular to the moving direction of the mover 1 is wider than the width of the field magnet (permanent magnet 12) in the reciprocating motion region.

Reference numeral 8 denotes a stator, which is a long base plate 10 having a groove or a stepped guide portion 9 for guiding the roller 5 as in the above-described embodiment.
The fixed back yoke 11 is fixed on the fixed back yoke 11 and a permanent magnet 12 is provided on the upper surface of the fixed back yoke 11. The permanent magnet 12 has an N-pole and an S-pole.
Are alternately magnetized in the moving direction.

Thus, in the present embodiment, the width of the permanent magnet 14 outside the reciprocating region is the same as the width of the movable back yoke 2 described above.

In the above configuration, a constant gap is always interposed between the permanent magnet 12 and the coil 6, and the coil 6 and the Hall magnetic sensor 7 are connected to the external drive control circuit (via the connector 13 attached to the coil substrate 3). (Not shown).

 Next, the operation of the present embodiment will be described.

Now, it is assumed that the mover runs out of control due to a malfunction of the CPU program or the like and comes out of the reciprocating motion area. At this time, the facing area between the field magnet (permanent magnet) and the movable back yoke 2 increases. Then, the attractive force F between the permanent magnet and the movable back yoke 2 becomes (Where B is the magnetic flux density in the air gap, Am is the cross-sectional area facing each other), and the attractive force (F) between the permanent magnet and the back yoke increases.

Since the suction force F acts as a vertical force on the support system, the frictional force of the support system increases, and the frictional force strikes the thrust of the movable force to stop the mover. That is, even if the mover runs away due to runaway of the CPU or the like, the mover is securely locked by the operation of the present embodiment.

FIG. 12 is a front view for explaining a modified embodiment of the embodiment shown in FIGS. 9 to 11, wherein FIG. 9 to FIG.
Parts having the same functions as those in the embodiment shown in the figures are denoted by the same reference numerals as those in FIGS. 9 to 11. Thus, in this embodiment, the distance between the field magnet and the movable back yoke in a portion facing each other only outside the reciprocating motion region does not oppose each other in the reciprocating motion region than the distance between the portions always facing each other. This is a structure in which the thickness of the portion of the movable back yoke 2 that is not in contact with the coil is increased, in other words, the thickness of the portion that is not in contact with the coil.

 Next, the operation of the present embodiment will be described.

Now, it is assumed that the mover runs out of control and goes out of the reciprocating motion area.
Thus, the portion of the movable back yoke that is not in contact with the coil is closer to the permanent magnet 14 than the movable coil type linear DC motor shown in FIGS. 9 to 11. Then, the magnetic flux density of the air gap in that portion increases, and as a result, the attractive force between the permanent magnet 14 and the movable back yoke 2 increases. Since this suction force acts as a normal force on the support system, the frictional force of the support system increases, and the frictional force strikes the thrust of the mover, and the mover stops. At this time, in the moving coil type linear DC motor shown in FIG. 12, the frictional force for stopping the mover is not only increased by the cross-sectional area of the permanent magnet and the back yoke facing each other, but also by the increase in the hourly speed density in the air gap. Therefore, the area opposed to the moving coil type linear DC motor shown in FIGS. 9 to 11 can be smaller than that of the moving coil type linear DC motor. Can be reduced in size, so that cost reduction can be achieved.

Advantages As is apparent from the above description, in the moving coil linear DC motor according to claim 1, a plurality of Hall magnetic sensors for overrun detection are provided in a portion of the movable element facing the field magnet. In addition, a control circuit that instructs the stop of the mover based on the output signal of the Hall magnetic sensor for overrun detection is provided in parallel with the control signal from the CPU. Can be stopped, and the mover and the apparatus main body are not destroyed. Further, since the Hall magnetic sensor for position detection is used as the Hall magnetic sensor for overrun detection, the number of components can be reduced, and there is an advantage that cost can be reduced. Further, in the moving coil type linear DC motor according to the second aspect of the present invention, since the moving back yoke is wider than the field magnet and the field magnet is outside the reciprocating motion region, the reciprocating motion is achieved. Friction increases outside the region. Therefore, even when the mover runs away, the mover can be stopped without fail, and the mover and the apparatus main body are not destroyed. Furthermore, by making the distance between the field magnet and the movable back yoke of the part facing each other only outside the reciprocating movement area smaller than the distance between the parts always facing each other, not facing each other in the reciprocating movement area, The magnetic flux density in the air gap increases and the frictional force increases outside the reciprocating region, thereby reducing the area where the field magnet and the movable back yoke oppose each other. Since the size of the magnet can be reduced, the cost can be reduced.

[Brief description of the drawings]

FIGS. 1 to 4, FIGS. 5 to 8, and FIGS. 9 to 11 are configuration diagrams for explaining an embodiment of the present invention. 9 is a plan view, FIG. 2, FIG. 6, and FIG. 10 are side views, respectively.
FIG. 3, FIG. 7, and FIG.
FIG. 8 and FIG. 8 are front views for explaining a drive control circuit, and FIG. 12 is a front view for explaining still another embodiment of the present invention. 1 ... mover, 2 ... movable back yoke, 3 ... coil substrate, 4 ... axis, 5 ... roller, 6 ... coil, 7 ...
Hall magnetic sensor, 8 ... stator, 9 ... guide, 10 ...
… Base plate, 11… fixed back yoke, 12… permanent magnet, 13… connector, 14… permanent magnet.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02P 5/00 101 H02P 7/00 101 H02K 41/02-41/035 G05D 3/00-3/20

Claims (2)

(57) [Claims] A moving coil type linear DC motor having a stator comprising field magnets having NS magnetic poles alternately in the longitudinal direction and a movable element comprising an armature coil group opposed to the field magnet. While having a field magnet in the reciprocating motion area, a plurality of Hall magnetic sensors for overrun detection are provided in a portion opposed to the field magnet of the mover, and an output signal of the Hall magnetic sensor for overrun detection is provided. A moving coil type linear DC motor, comprising: a control circuit for commanding a stop of a mover in parallel with a control signal circuit from a CPU. 2. A moving coil type linear DC motor having a stator consisting of a field magnet having NS magnetic poles alternately in the longitudinal direction and a mover consisting of an armature coil group opposed to the field magnet. A moving coil type linear DC motor having a movable back yoke wider than a field magnet and a field magnet outside a reciprocating region.