JP3139626B2 - Linear DC motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a linear DC motor, and is suitably applied to, for example, an image scanner or the like.

Prior art A field magnet having NS magnetic poles alternately arranged in the longitudinal direction, a driving armature coil group is arranged opposite to the field magnet, and the field magnet is used as a stator. A linear DC motor having a movable element is known, for example, from Japanese Patent Laid-Open No. 59-86473.

Thus, in the drive system of the conventional moving coil type linear DC motor, a plurality of detection sensors according to the intended use are provided before and after the area where the mover reciprocates or outside the area, and the detection signals of the detection sensors are provided. The control of the driving state of the linear DC motor is performed by using this. 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 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 cannot be obtained from the CPU. Therefore, the mover jumps out of the reciprocable area, and the mover and the apparatus main body are destroyed.

Object The present invention has been made in view of the above-described circumstances, and has been described in view of the fact that the field magnet outside the reciprocating motion area is made stronger than the field magnet in the reciprocating motion area to thereby increase the CPU.
The control program of the CPU can run out of control by stopping the mover surely even if the control program of The purpose is to stop the mover surely even when it is done.

Furthermore, by setting the guide portion to a curved surface having an arbitrary curvature outside the reciprocating motion region, when the control program of the CPU runs away, the movable member is surely stopped, and the distance to the stop is shortened. It is another object of the present invention to prevent the vibration and impact at the boundary by making the radius of curvature of the guide portion infinite at the boundary inside and outside the reciprocating motion region.

To achieve the above object, the present invention provides (1) a stator consisting of a field magnet having NS magnetic poles alternately in the longitudinal direction, an armature coil group and a back yoke opposed to the field magnet. In a moving coil type linear DC motor driven by a CPU having a mover composed of a moving element, the field magnet outside the reciprocating motion area is made stronger than the field magnet in the reciprocating motion area, and (2) NS
A field magnet having a magnetic pole alternately in the longitudinal direction, and an armature coil opposed to the field magnet, one of which is a movable element and the other is a linear driven by a CPU having a stator. In the DC motor, the mover guide portion has an arbitrary angle with respect to the inside of the reciprocating motion region outside the reciprocating motion region. Hereinafter, a description will be given based on an example of the present invention.

FIG. 1 is a plan view for explaining one embodiment of a moving coil type linear motor according to the present invention, FIG. 2 is a side view, FIG. 3 is a front view, and in FIG. The movable element 1 includes a movable back yoke 2, a coil substrate 3 mounted on the movable back yoke, shafts 4 fixed to four corners on both sides of the movable back yoke 2, and rollers rotatably mounted on each shaft 4. 5, a coil 6 fixed to the coil substrate 3 and continuously disposed along the longitudinal direction of the coil substrate 3, and a center located in the coil 6 and in the longitudinal direction of the coil. And a hole detection magnetic sensor 7 for detecting a magnetic field generated from a permanent magnet 12 described later.

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. Further, the permanent magnets 12a and 12b (the hatched magnets) outside the reciprocating motion region (L) of the mover 1 are made of a material (having a larger maximum energy product than the permanent magnet 12 in the reciprocating motion region (L)). Therefore, the magnetic flux density in the gap between the permanent magnet and the movable back yoke outside the reciprocating region is larger than that in the reciprocating region.

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 sensor 7 are connected to the external drive control circuit via the connector 13 attached to the coil board 3. (Not shown).

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

Now, it is assumed that the mover 1 runs out of control due to a malfunction of the CPU or the like and comes out of the reciprocating motion area (L). Then, the magnetic flux density in the gap between the permanent magnets 12a, 12b and the movable back yoke 2 becomes larger than that in the reciprocating region (L) by the action of the permanent magnets 12a, 12b stronger than in the reciprocating region (L). . The thrust F _{1 of the} mover 1 is (However, B: magnetic flux density in the gap, l: conductor length in the magnetic field, I: drive current, K ₁ : constant), and the thrust of the mover 1 increases in proportion to the magnetic flux density B. Become. However, the attractive force F2 between the permanent magnets 12a and 12b and the movable back yoke ₂ is (Where B is the magnetic flux density in the gap, Am is the cross-sectional area facing each other, and K _{2 is a} constant). It increases in proportion to the square. Since this attractive force acts as a normal force on the support system, it can be considered that the frictional force of the support system increases in proportion to the square of the magnetic flux density outside the reciprocation region. That is, by this, the frictional force strikes the thrust outside the reciprocating motion region of the mover 1 to stop the mover. That is, even if the mover runs away due to the CPU runaway or the like, the mover surely stops.

4 to 6 are configuration diagrams for explaining another embodiment of the present invention. FIG. 4 is a plan view, FIG. 5 is a side view, and FIG. 6 is a front view. 1 to 3 are denoted by the same reference numerals as those in FIGS. 1 to 3. Thus, in the present embodiment, the guide groove or the stepped guide portion 9 is
As shown in FIG. 5, the mover 1
Is designed so as to make an arbitrary angle (θ) with the traveling direction (horizontal direction in the figure) in the reciprocating motion region of FIG.

 Next, the operation will be described.

Now, it is assumed that the mover runs out of control due to a malfunction of the CPU or the like and comes out of the reciprocating motion area. Then, since the stepped guide portion 9 is inclined with respect to the horizontal direction in the figure, the component force of the own weight (including the magnetic attraction force) in the inclined direction acts as a friction force as it is. That is, the frictional force increases. On the other hand, since the gap between the movable back yoke 2 and the field magnet increases due to the inclination of the guide portion 9, the magnetic flux density between the gaps decreases, and the thrust of the mover decreases. That is, as a result, the frictional force exceeds the thrust force outside the reciprocating motion region of the mover 1, and the mover stops. That is, even if the mover runs away due to runaway of the CPU or the like, the mover surely stops.

FIG. 7 is a side view for explaining a modified embodiment of the embodiment shown in FIGS. 4 to 6, in which the same operation as the embodiment shown in FIGS. 4 to 6 is performed. Are denoted by the same reference numerals as in FIGS. 4 to 6.
Thus, in this embodiment, the stepped guide portion 9 is formed of a curved surface having an arbitrary curvature outside the reciprocating motion region of the mover 1, and has a boundary (A) with the reciprocating motion region. In (point), the curvature of the guide portion 9 is designed to be Δ.

Therefore, since the step-shaped guide portion 9 has a curved surface, it is possible to rapidly increase the frictional force and decrease the thrust, and therefore, it is possible to reduce the distance to the stop during the runaway. Also, the boundary with the reciprocating motion area (point A)
Since the radius of curvature of the guide portion 9 is represented by ∞, the mover also moves smoothly in this portion, and therefore, vibration and impact at this boundary can be prevented. Although the moving coil type linear DC motor has been described above, the present invention can be applied to a moving magnet type linear DC motor in the same manner.

Effect As apparent from the above description, according to the first aspect of the present invention, the field magnet outside the reciprocating region is made stronger than the field magnet in the reciprocating region.
Outside the reciprocating range, the frictional force is greater than the thrust.
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.

According to the second aspect of the present invention, since the guide portion has an arbitrary angle with respect to the inside of the reciprocating motion region outside the reciprocating motion region, the frictional force is larger than the thrust outside the reciprocating motion region. Become. Therefore, even if the mover runs away, there is an advantage that the mover can be stopped without fail and the mover and the apparatus main body are not destroyed.

[Brief description of the drawings]

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

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) H02K 41/02-41/035 H02P 5/00 101 H02P 7/00 101 B60L 13/03-13/10

Claims (2)

(57) [Claims] The present invention is driven by a CPU having a stator composed of a field magnet alternately having NS magnetic poles in the longitudinal direction, and a mover composed of an armature coil group and a back yoke opposed to the field magnet. A linear DC motor in which a field magnet outside a reciprocating motion region is made stronger than a field magnet in a reciprocating motion region in a moving coil type linear DC motor. 2. A field magnet having a magnetic pole of NS alternately in a longitudinal direction, and an armature coil opposed to the field magnet, one of which is a movable element and the other is a stator. In linear DC motor driven by CPU,
A linear DC motor, wherein the mover guide section has an arbitrary angle with respect to the inside of the reciprocating motion area outside the reciprocating motion area.