JP3623672B2 - Ultra high vacuum pulse current driver - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pulse current driver suitable for use in ultra-high vacuum.
[0002]
[Prior art]
As a method for performing mechanical operation in an ultra-high vacuum,
(1) Rotation using magnetic coupling and bellows seal, and a method of transmitting and converting the movement outside the ultra-high vacuum chamber by combining a linear advance introducer and multiple gears (2) Internally equipped with a motor for ultra-high vacuum (3) A method using a combination of a solenoid magnet and a spring is used.
[0003]
[Problems to be solved by the invention]
The method (1) has a complicated mechanism, occupies a large space in the ultra-high vacuum chamber, increases its weight, results in high costs, and requires labor for maintenance and inspection. In addition, since many bearings are used, the seizure phenomenon associated with baking becomes a problem.
The method {circle around (2)} has a problem that an ultra-high vacuum-compatible motor is expensive, baking is difficult, and a large amount of degassing causes a reduction in vacuum quality.
In the method (3), it is necessary to flow a large current through the solenoid coil in order to obtain a sufficient driving force. Since it is difficult to dissipate heat in a vacuum, the reliability is poor for long-term use, and the deterioration of the quality of the vacuum accompanying heat generation becomes a major problem.
[0004]
An object of the present invention is to solve the above-mentioned problems, and it is an object of the present invention to eliminate the generation of heat and burn-in, to affect the quality of the vacuum, and to enable mechanical operation in an ultra-high vacuum that can be miniaturized and highly reliable. And
[0005]
[Means for Solving the Problems]
The present invention includes a solenoid magnet having a ferromagnetic core, a permanent magnet that is disposed opposite to the magnetic core and connected to a movable member that engages with an object to be driven, and a magnetic force between the magnetic core and the permanent magnet. A spring member that acts to separate the permanent magnet from the magnetic core against the magnetic field, attracts the permanent magnet to the magnetic core by the magnetic field generated by the solenoid magnet by flowing a pulse current, and moves the movable member 1 by the permanent magnetic force. It is held in one stable state, and a permanent magnet is separated from the magnetic core by a magnetic field generated from a solenoid magnet by flowing a pulse current, and the movable member is held in another stable state by the force of the spring member. A vacuum pulse current driver,
The permanent magnet is disposed in a housing having an opening at one end, and a movable member connected to the permanent magnet and extending to the outside through the opening is guided by a linear guide provided on the inner surface of the housing to reciprocate between two stable positions. It is characterized by that.
Further, the present invention is characterized in that the linear guide is made of a permanent magnet, and the movable member is magnetically levitated.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating an example of an ultrahigh vacuum pulse current driver according to the present invention.
The housing 9 that holds the entire drive unit is, for example, a tubular body (of course, may be a box) having an open front portion, and is connected to a pulse power source (not shown) for supplying current at the innermost portion. A magnetic core 5 made of a ferromagnetic material around which a solenoid coil 6 is wound is disposed to constitute a solenoid magnet. The magnetic core 5 is held between a front spacer 7 provided on the inner surface of the housing and a bottom surface of the housing 9. ing. A movable permanent magnet 4 to which the movable rod 1 is connected is arranged so as to be opposed to the magnetic core 5 and move in the housing under the force of a magnetic field generated from a solenoid magnet. The movable permanent magnet 4 holds the movable rod 1 against the force of a spring, which will be described later, by a permanent magnetic force acting between the ferromagnetic core 5.
[0007]
The movable rod 1 extends from the opening of the housing 9 and has a pin 10 formed at the tip thereof. The pin 1 is fitted into a holding hole of a sample holder or a sensing lever holder such as an STM (scanning tunnel microscope) or AFM (atomic force microscope) However, this is for giving a predetermined movement. The portion of the movable rod 1 that is a predetermined distance from the connecting portion with the movable permanent magnet 4 has a large-diameter portion 1a. Correspondingly, the housing inner diameter is larger in the front portion than the region where the movable permanent magnet 4 moves. Yes. A spring 3 is arranged between the large-diameter portion 1a of the movable permanent magnet 4 and the step portion where the diameter of the housing has changed, and the movable rod 1 is urged forward, and the front portion of the large-diameter portion 1a is directed to the inner surface of the housing. It acts against the formed stopper 8, that is, against the magnetic force acting between the magnetic fields generated by the movable permanent magnet 4 and the solenoid magnet. The spacer 7 prevents the movable permanent magnet 4 and the magnetic core 5 from coming into close contact with each other, determines the position in which the movable bar 1 is contracted, and the stopper 8 determines the position in which the movable bar 1 is extended. Yes. The magnetic core 5 strengthens the magnetic field induced by the current flowing through the solenoid coil 6, and also acts to hold the movable rod 1 against the force of the spring 3 by the permanent magnetic force with the movable permanent magnet 4. Yes. Therefore, the movable rod 1 is driven by the movable permanent magnet 4 that receives the force of the magnetic field generated from the solenoid coil 6 by the pulse current, and reciprocates between two stable positions. In order to stabilize the reciprocating motion of the movable rod 1, a linear guide 2 is provided on the inner surface of the housing so that the movable rod 1 can move smoothly using, for example, a bearing or the like.
[0008]
Next, the operation of the pulse current driver having such a configuration will be described with reference to FIG.
In the pulse current driver, the movable rod 1 reciprocates between the state 1 (FIG. 2 (a)) and the state 2 (FIG. 2 (b)) due to the pulse current, and is 0.1 during the transition between the states. It operates with a pulse current of about a second and enters a self-holding state at each stable position.
[0009]
State 1
The movable rod 1 is kept in the state 1 pressed to the foremost position defined by the stopper 8 by the repulsive force of the spring 3. At this time, the movable permanent magnet 4 is separated from the magnetic core 5, and the attractive force acting between them is smaller than the repulsive force of the spring.
[0010]
Transition state (state 1 → state 2)
When a current in a direction that exerts an attractive force on the movable permanent magnet 4 is passed through the solenoid coil 6, the force acting between the movable permanent magnet 4 and the magnetic core 5 exceeds the repulsive force of the spring 3, and the movable rod 1 moves toward the state 2. To exercise.
[0011]
State 2
The movable rod 1 is kept in the state 2 attracted to the rearmost position defined by the spacer 7 by the attractive force between the movable permanent magnet 4 and the magnetic core 5. At this time, since the movable permanent magnet 4 and the magnetic core 5 are close to each other, it is no longer necessary to supply current to the solenoid 6, and the repulsive force of the spring is exceeded only by the permanent magnetic force of the movable permanent magnet 4, and the stable state is maintained. Is done.
[0012]
Transition state (state 2 → state 1)
When a current in a direction that exerts a repulsive force on the movable permanent magnet 4 is passed through the solenoid coil 6, the permanent magnetic force and the electromagnetic force cancel each other, the repulsive force of the spring 3 becomes stronger, and the movable rod 1 moves toward the state 1. To do.
[0013]
In the above example, the movable rod 1 is mechanically guided by the linear guide 2 to give a stable movement. However, a permanent magnet is used as the linear guide, and the movable rod is magnetically levitated by a magnetic force. Also good. By adopting such a configuration, a driver having no mechanical contact such as a bearing can be realized, so that seizure can be avoided even when baking is performed in an ultra-high vacuum. Moreover, since there is no mechanical friction, there is almost no outgas at the time of a drive, and it can apply to an ultra clean system.
[0014]
FIG. 3 is a diagram showing another example of the present invention applied to the lever movement.
A lever 22 is pivotally mounted at a fulcrum 21 at the end of the support base 20, and a spring 23 is provided between the root portion and an appropriate position on the lower surface of the support base 20 to urge the lever clockwise, It is pressed against the cradle 29. In addition, a permanent magnet 24 is attached to the base of the lever, and a ferromagnetic coil in which a solenoid coil 26 connected to a pulse power source is wound around an attachment member 27 attached to the lower surface side of the support base. A magnetic core 25 made of a body is attached to constitute a solenoid magnet. When a pulse current is passed through the solenoid coil 26, the lever 22 rotates counterclockwise to the position defined by the stopper 28 and stabilizes in that state by the generated magnetic field and the attractive force of the permanent magnet. The pin 30 at the tip of the lever 22 is for engaging with the operation target.
[0015]
Next, the operation will be described.
The lever 22 is rotated clockwise to a position defined by the cradle 29 by the repulsive force of the spring 23, and is maintained in that state. At this time, the permanent magnet 24 is separated from the magnetic core 25, and the attractive force acting between them is smaller than the repulsive force of the spring.
[0016]
Next, when a current in a direction that exerts an attractive force on the permanent magnet 24 is passed through the solenoid coil 26, the force acting between the permanent magnet 24 and the magnetic core 25 exceeds the repulsive force of the spring 23, and the lever 22 rotates counterclockwise. To do.
[0017]
The lever 22 rotates counterclockwise to the position defined by the stopper 28 by the attractive force between the permanent magnet 24 and the magnetic core 25 and is maintained in that state. At this time, since the permanent magnet 24 and the magnetic core 25 are close to each other, it is not necessary to supply current to the solenoid 26, and the repulsive force of the spring is exceeded only by the permanent magnetic force of the permanent magnet 24, and the stable state is maintained. In this state, if a current in a direction that exerts a repulsive force on the permanent magnet 24 is passed through the solenoid coil 26, the permanent magnetic force and the electromagnetic force cancel each other, the repulsive force of the spring 23 becomes stronger, and the lever 22 rotates clockwise. , Held in another stable state.
[0018]
【The invention's effect】
As described above, according to the present invention, the following effects can be achieved.
(1) Since it is driven by a pulse current, it hardly generates heat and does not adversely affect the quality of vacuum when used in an ultra-high vacuum apparatus.
{Circle around (2)} Since the pulse current drive is used, a thin lead wire for introducing the current is sufficient, and the degree of freedom in designing the device is large.
{Circle around (3)} Since pulse current driving is used, a large current can be flowed instantaneously, and a sufficient driving force can be obtained with a small solenoid coil. Compared to a conventional magnetic driver using a steady current, the size can be significantly reduced.
(4) A stable position is maintained by a self-holding function based on a balance between magnetic force and spring force.
Since the mechanism that holds the stable position has no mechanical friction, there is no seizure and the reliability is high.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an example of an ultra-high vacuum pulse current driver according to the present invention.
FIG. 2 is a diagram illustrating the operation of a pulse current driver.
FIG. 3 is a diagram showing an example applied to a lever movement.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Movable rod, 2 ... Linear guide, 3 ... Spring, 4 ... Movable permanent magnet, 5 ... Magnetic core, 6 ... Solenoid coil, 7 ... Spacer, 8 ... Stopper, 9 ... Housing, 10 ... Pin, 20 ... Support stand , 21 ... fulcrum, 22 ... leverage, 23 ... spring, 24 ... permanent magnet, 25 ... magnetic core, 26 ... solenoid coil, 27 ... mounting member, 28 ... stopper, 29 ... cradle, 30 ... pin.

Claims (2)

A solenoid magnet having a ferromagnetic core, a permanent magnet disposed opposite to the magnetic core and connected to a movable member that engages with the driven object, and a magnetic force between the magnetic core and the permanent magnet And a spring member that acts to move the permanent magnet away from the magnetic core. By applying a pulse current, the permanent magnet is attracted to the magnetic core by a magnetic field generated from the solenoid magnet, and the movable member is brought into one stable state by the permanent magnetic force. An ultra-high vacuum pulse current drive that keeps the movable member in another stable state by the force of the spring member by holding the pulse magnet and separating the permanent magnet from the magnetic core by the magnetic field generated from the solenoid magnet. A vessel ,
The permanent magnet is disposed in a housing having an opening at one end, and a movable member connected to the permanent magnet and extending to the outside through the opening is guided by a linear guide provided on the inner surface of the housing to reciprocate between two stable positions. An ultra-high vacuum pulse current driver characterized by that. The linear guide is made of a permanent magnet, an ultra-high vacuum pulse current driver according to claim 1, characterized in that magnetically levitate the movable member.

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