DE2305362A1 - ELECTROMAGNETIC ACTUATION DEVICE FOR A PEN OF A DOT PRINT DEVICE - Google Patents

Description

PafenicmwSIfe

. Wilhelm Eoichel W.

feg H3icl

6 Frankfurt a. M. 1
Parkstrasse 13

7297

BURROUGHS CORPORATION, Detroit, Michigan, V.St.A.

Electromagnetic actuator for a pen of a dot printing device

The invention relates to an electromagnetic actuator for a pen of a dot printing device to which a movable core is attached, with one with one Magnetic circuit cooperating drive coil »which is to move the movable core. Such dot printing devices or matrix printers are used as output devices for electronic calculating machines or for computing systems.

In such dot printing devices or matrix printers, the individual characters are to be printed by a certain number of Points formed. Each point is thereby printed on a medium, for example on paper, in the form of a piece of sewing or a pin, actuated by an electromagnet, strikes through an ink-wetted tape and leaves a printed dot on the bracket part.

Even if the word »piece of wire ^{11 is} a common expression for a scrolling element actuated in this way, since it has an elongated shape, the term" pin "is used in the following description and in the claims because

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this term better adapts to the general operation of a writing element. The term "matrix printer" becomes but retained unchanged in the following.

As mentioned above, the invention is concerned with an electromagnetic actuator for a matrix printer. Such a matrix printer usually has several actuating devices which ^:! n are suitably arranged so that they enable simultaneous printing according to a predetermined point distribution.

The electromagnetic actuators for pens known embodiment contain one or more control coils that are used for the printing movement. she usually use trigger springs to retrieve the pen.

Γ te control devices for the pens must meet two technical requirements that actually correspond to each other opposing are:

On the one hand, the mass of the movable part must be reduced as much as possible, and the electrical energy consumption for the actuation is necessary must also as far as possible be reduced. On the other hand, for correct printing, it is necessary that the movable parts have a certain Achieve speed when the pen hits. This speed increases with the number of amp turns in the coil and thus with the mass of the movable arrangement, also taking into account a certain movement sequence will.

In order for the magnetic flux generated by the coil to run in a suitable manner to the movable core, it is necessary that the size and consequently the mass of the core are related to the size and mass of the coil.

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Further, it is necessary to increase the output movement of the movable electromagnetic core as much as possible in order to the smallest possible fourth for the consumption of electrical Energy and for the mass of the movable part.

The use of return springs means that the return force is greatest when the spring is as far as possible is stretched out, i.e. that during the printing time the electrical energy used to operate the coil, is used in part to overcome the retraction force, thereby increasing the electrical power consumption of the device will.

On the other hand, the retraction force of the spring is lowest when the core is in the rest position, which leads to a considerable Rebound leads.

The known retraction devices and in particular the spring retraction devices work only at frequencies that of the mechanical coupling between the pen and the movable part on the one hand and the electromagnetic device depend on the other hand for actuation. These frequencies are either very low or they include higher nominal frequencies, for which a next energization of the actuating coil is in phase with the kickback on retraction. This leads to, that the device cannot operate at relatively large variable frequencies.

The invention is based on the object of providing an electromagnetic actuating device for a pen which has a greater output power than the known devices of this type.

According to the invention an actuating device further seeks to provide that the low or even no-check occurs. 309835/0863

Also for the invention is an electromagnetic actuator provide in which the retraction of the movable part is carried out such that the restoring force at the time of Pressing is zero.

The electromagnetic actuator for matrix printers according to the invention is not intended to have any resonance effects at nominal high frequencies exhibit.

The underlying of the invention. The task is solved by that a device of the type described above is characterized in that the magnetic circuit at the ends of the Coil has a fixed core and an annular part, both along the axis of the coil in its interior up to protrude from its center, and that the movable core is arranged substantially in the center of the coil, being partially from is surrounded by an annular part. The. Arrangement of the movable * Core in the middle of the coil allows for the most extensive Reduction of the leakage flow. The ring-shaped part provides a guide for the movable core under favorable conditions represent.

According to a further development of the arrangement according to the invention, the electromagnetic actuating device has a second movable core, which is connected to the pen, and a permanent magnet, which is connected to a second magnetic circuit cooperates in such a way that it exerts a restoring force on the second movable core, which is then transmitted to the pen will.

This type of arrangement provides a restoring force, which is greatest in the rest position of the pen and which significantly reduces the effect of the kickback.

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The electromagnetic actuating device can also have an auxiliary coil which is activated at the same time, like the drive coil and which is designed so that it has the restoring force by the permanent magnet at the time when a Print command comes, suppressed. This auxiliary coil has a magnetic circuit in which the permanent magnet is located, with the magnetic circuit is constructed similarly to the magnetic circuit that belongs to the drive coil.

Embodiments of the invention are described below by way of example with reference to the drawings. Show:

Fig. 1 is a longitudinal section through a known electromagnetic Actuator j

FIG. 2 shows a longitudinal section through an electromagnetic actuating device for pens according to FIG Invention, wherein the arrangement of the magnetic circuit and the drive coil is shown;

Fig. 3 is a longitudinal section through which a preferred possibility of the structure of the electromagnetic device according to the invention is shown, and

4a and 4B are longitudinal sections through a device according to FIG. 3, in which the course of the magnetic flux is shown when the pen is in the rest position and during the forward pressure movement.

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In Fig. 1 is the known structure of an electromagnetic arrangement shown:

A coil 10 is coupled to a magnetic circuit 11 which has a solid core 12 extending substantially through Coil 10 passes and which is closed by an outer part 13 which at the free end of the coil 10 has a movable core 14 surrounds, which is connected to a pen. When the coil 10 is energized, the solid core 12 pulls the movable core 14 so that the electromagnetic circuit C- £ c closed as much as possible.

A return spring (not shown) pulls the movable core 14 returns to its original position as soon as the coil is no longer supplied with current.

According to the schematic section of FIG. 2, which shows a device according to shows the invention, a coil 20 is arranged in a magnetic circuit 21 having an axial core 22 of the one end of the coil protrudes into this, and which has an annular part 23 which also extends from the other end of the coil into the inside of the coil protrudes. The fixed axial core and the annular part 23 are located on both sides of the Center of the coil 20 and are at a certain distance from it Arranged in the middle, so that the magnetic circuit between these two parts is not closed.

A movable core 24 connected to a pen 25 is movable near the center of the spool while he is at the same time partially protrudes into the annular part. The pen 25 is coaxial with the fixed core 22 and also runs through the adjacent part of the magnetic circuit at the lower end of FIG. 2. To carry out the printing process, the pen moved downward in the figure. When not printing, the core 24 takes the one shown in FIG Location a.

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When the coil 20 is fed with a current, then forms a magnetic flux in the magnetic circuit 21 through the annular member 23, the movable core 24 and the fixed core 22 passes through.

The annular air gap between the movable core 24 and the annular part 23 of the magnetic circuit is controlled by the magnetic flux interspersed, which balances the radial forces with each other; hence the resulting radial forces are in Height of the annular air gap on the movable core 24 zero.

On the other hand, the axial air gap between the fixed core 22 and the movable core 24 is affected by an axial magnetic flux through which an axial force is exerted in a direction below the movable core 24.

The device shown in Fig. 2 reduces the leakage flow compared to the known devices and in particular in comparison with the device shown in FIG. If the masses of the movable cores 24 and 14 are equal, then will As a result of the decrease in leakage flow achieved according to the invention, there is a better transfer of energy to the pen let reach.

For better results, the one shown in Fig. 2 has an annular shape Part 23 has a beveled tip on the end that protrudes into the spool. This arrangement enables the the Leak flow generating /. Air gap between the annular part and the fixed core 22 is reduced as much as possible is, in that the magnetic field lines run through the movable core 24 on a preferred path. Naturally the coil 20 is wound around the fixed core 22 and the annular member 23 in an appropriate shape so that the maximum flux through these two parts of the magnetic circuit

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passes through it, but the movable core is still free can move.

In Fig. 3 is a preferred modified embodiment of the Invention shown, in which the pen returns to its normal position with the help of a permanent magnet.

In Fig. 3 an apparatus is shown which is similar to that The device according to FIG. 2 is one coil 30, a magnetic circuit housing 31 surrounding the coil 30, one on the housing 31 attached .axial core 32 and a movable core 34 which runs through the center of the coil for this purpose.

Of course, a central opening is provided in the spool for this purpose.

The magnetic circuit also has an annular part 33, the is located in the coil 30 in an axial opening provided for this purpose and that is almost to the middle extends, then facing the fixed core 32. Outside the coil 30 and on the same side is the magnetic circuit closed by a radial extension 36 of the annular part 33, this extension being in the form of a flange having.

A first movable core 34 is axially near the center of the Coil 30 arranged and it is partially from the annular Surround part 33, the diameter of which has a suitable value for this purpose. This becomes the ring-shaped part 33 is also used to guide the movable core 34.

The core 34 is connected to the pen 35, which is through the core 34 protrudes completely and which runs freely movable in the axis of the stationary core 32.

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A shoulder 37 is used to hold the mounting part (the permanent magnet and the backward magnetic circuit) to fix.

As already mentioned above, the annular part 33 points in the direction the center of the coil 30 has a part 38 which tapers towards the inside.

There is an annular permanent magnet 39 coaxial with the flange and on the opposite side of the housing in Contact with this arranged, the diameter of which is more or less the same as the outer diameter of the flange 36. A second movable core is connected to the pen 35 and this core 40 is movable with respect to the first Core 34 arranged so that it lies on the opposite side as the fixed core 32. The distance between the first and second movable core is chosen so that the laterally movable core is near the center of the permanent magnet 39 is located.

The annular part 33 also protrudes on the other side of the flange 36 as a further annular part 41, which extends almost to the center of the permanent magnet 39. In the direction of this center, this annular part 41 has a part which is inclined towards the inside 42. The _f ^ second movable core 40 is partially surrounded by the second annular member 41, whereby a radial ^ air gap between the two parts and an axial guidance of the second movable core 48 is formed.

The second magnetic circuit, which is formed by the second annular part 41, the flange 36 and the permanent magnet 39, lot by oin Toll with oinom rndinlon Voroprung, dor as oino Type disc 43 is formed, closed, which has an axial, inwardly protruding shoulder 44.

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The second movable one is thus located in the second magnetic circuit Core 40, similar to how the first movable core 34 is located in the first magnetic circuit. The distance between the first and the second movable core is slightly less than the distance between the centers of the coil 30 and the permanent magnet 39, so that when the pen is (only very briefly) in ·; the writing position or is in the rest position, only the first movable core 34 or the second movable core 40 one are exposed to significant magnetic attraction.

In order to achieve better working conditions, the device has an auxiliary coil 45, which is in the second., Magnetic circuit is arranged and works with this together. The auxiliary coil 45 is preferably electrically connected to the drive coil 30 in FIG Connected in series and constructed so that when the two coils are supplied with current, the auxiliary coil 45 Flux generated in the second magnetic circuit cancels the flux formed by the permanent magnet 39, so that the retracting force is canceled by the permanent magnet. It is then advantageous, but not necessary, that the inner wall of the two annular parts 33 and 41 is cylindrical, the diameter being slightly larger than the outer diameter of the two movable cores 34 and 40. On the other hand, the inner wall of the ring-shaped parts and the outer wall of the movable Cores do not necessarily have to be cylindrical. The same goes for the fixed cores.

In connection with the reference to the annular part and the fixed cores "that they extend almost to the center of the coil or the permanent magnet" must be taken into account that the fixed core is arranged so that the movable core can be engaged with it when the movable core is attracted by the stationary core or the magnet and that it is then essentially in the center " and that further the annular part is arranged so that the radial air gap, which together with the movable part in de *

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attracted position is formed, one in the axial direction Has a size sufficient that the magnetic flux formed by the core and the magnet can pass through.

The parts that make up the electromagnetic devices in FIG. 1 are provided with fastening devices that are not shown are connected, which sit on the one hand on the paragraph 37 and on the other hand on the radial and outer projection of the end part 43. This contact is necessary in order to achieve a good closing of the outer parts of the magnetic circuit.

Simplified sections of the device according to FIG. 3 are shown in FIGS. 4A and 4B, in which the magnetic flux is drawn which arises in the normal position of the pen or during the forward movement of the pen.

In the normal position, the magnetic flux of the permanent magnet 39 (which is represented by a dotted line at short intervals and whose direction of magnetization is indicated by an arrow in the axial direction) runs through the end part 43 and the second fixed core 44 to the second movable core 40, the second annular part 41 and the flange 36. This leads to the fact that in the radial air gap which separates the second movable core 40 from the second annular part 41, radial forces F 1 and F ₂ occur, the components of which cancel each other out.

On the other hand, generated by the axial air gap, the second movable part 40 and the second fixed core 44 separates, an axial force F ,, which the movable core 40 pulls towards the stationary core 44 and holds it there.

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Referring to Fig. 4B, the drive coil 30 and the auxiliary coil are shown 45 fed in series with a current pulse. The one flowing through the coil 45. Current is directed so that the through this coil generated flux (shown by a dash-dotted line) through the permanent magnet generated flux (which is shown by a dotted line) is substantially compensated. The second movable core is then no longer attracted to the second stationary core. Of course, the same applies to the first movable one Core 34 and for the pen 35 too.

The same current pulse that passes through the drive coil 30 forms a magnetic flux (indicated by a dashed line Line is shown) which passes through the first movable core 34. The radial components of the Forces are directed towards the movable core 34 because this magnetic flux is canceled. The axial components, which pass through the first core 32, however, generate an axial attractive force towards the left side of the core 34, which leads to a movement of the pen 35 and 'the movable cores 34 and 40 until the pen touches the paper or touches a ribbon (not shown) and prints a dot.

When a dot is printed out, the power is turned off. This can be achieved by following the above mentioned current provided for printing has a predetermined length or in which a control signal is provided for switching off will. At this point in time, the magnetic flux again has the course that is shown in Fig. 4A. The second movable one The core and thus the entire movable device are attracted by the magnet 39 generated flow is attracted upwards. The movable device then returns to its rest position.

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During the forward movement until a dot is printed out, the first movable core 34 does not become necessary touch the first stationary core 32. There are then the current pulse length and / or the distance between the movable Cores 34 and 40 selected.

During the restoring movement of the movable part, a permanent magnet then generates a maximum restoring force generated when the core is in its initial position (with minimal air gap). The spring return device the known arrangements then shows the maximum restoring force when the pen is moving forward is at the stop, and it then shows the slightest Resetting force when the pen is in its rest position. The release with the help of a permanent magnet reduces or suppresses the rebound of the movable device completely when the second b € .regbaren Core 40 abuts against the first stationary core 44. Furthermore, in order to achieve a certain impact energy, the necessary electrical energy is less important, since that of the movable device supplied by the drive coil Force is not counteracted by a release force which gradually increases, as is the case with the use of springs the case is. On the contrary, when using an auxiliary coil according to the invention, the restoring force is then canceled, when the command is to be printed, regardless of the position occupied by the movable device .

On the other hand, reducing rebound has two technical consequences:

The risk of double pressure (the first being desirable and the second occurring due to the rebound) is reduced for the same course of the movable device. This allows the movement process of the

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Shorten the pen;

- if no rebound occurs and if the restoring force is canceled for every command to druden, then · "·· work with varying frequencies, while when a restoring force, such as that caused by Springs is provided, is present and then if significant rebound phenomena occur, the device can only work accurately at a very low frequency or at the setpoint frequency when each new print command is in phase with the rebound phenomenon.

The magnetic circuits are made of magnetic, soft materials, in particular the housing 31, the first fixed core 32, the two annular parts 33 and 41 with their flange 36, the second end piece 43 with the second fixed core 44, as well as the first and the second movable core and 44.

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Claims (3)

Claims Electromagnetic actuator for a ^ _(pen on which a movable core is mounted, cooperating with a magnetic circuit driving coil to move the movable core ,, characterized in that the magnetic circuit (21, 22) at the ends of the coil (20) a fixed core (22) and an annular part (23), both of which protrude along the axis of the coil (20) in its interior to its center, and that the movable core (24) is substantially in the center of the .Spule ( 20) is arranged, wherein it is partially surrounded by an annular part (23). 2. Electromagnetic actuator according to claim 1y characterized in that the annular part (23) is chamfered in a Section ends that is beveled towards the center of the spool (20). 3. Electromagnetic actuator according to claim 1 _# and 2, characterized in that the annular part (33) radially acts as a flange (36) protrudes from the coil (30) so that the stationary core (32) protrudes from the axis of the coil (30) and that the magnetic circuit between the flange (36) and the fixed core (32) through a housing (31) »the surrounds the drive coil (30) is closed. 309835/0863 Electromagnetic actuator according to one of Claims 1 to 3, characterized in that it has a second movable core (40), which is connected to the pen (35) used for printing, and that a permanent magnet (39) with a second magnetic circuit cooperates to cause a second movable core (40) to move in a direction that movement caused by the drive coil (30) is in the opposite direction. Electromagnetic actuator according to one of Claims 1 to 3, characterized, that an auxiliary coil (45) is arranged in such a way that it is at the same time as the drive coil (30) is controlled so that the effect of the "permanent magnet (39) on the movable core (40) is balanced will. An electromagnetic actuator according to claim characterized in that the second magnetic circuit (43, 44, 40, 42, 36) both is provided for the permanent magnet (39) as well as for the auxiliary coil (45). Electromagnetic actuator according to claim 6, characterized, that the second magnetic circuit (43, 44, 40, 42, 41, 36) at the ends of the auxiliary coil (40) has a second fixed Core (44) and a second annular part (41) on - · - *, both coaxially into the interior of the auxiliary coil (40) protrude to the middle, and that the second movable 309835/08 6 3 Core (40) is slidably arranged in the middle of the coil (45), being partially surrounded by the second annular part (44) _e S. Electromagnetic actuator according to claim 7 _S. characterized in that the second annular part (41) ends in a beveled section ₉ whose bevel extends into the interior of the auxiliary coil up to its center, 9 "o electromagnetic actuator performing according to claim 7 and S the ring-shaped part which is connected to the drive coil _{r 5} extends in the radially as a flange outwardly, characterized gekennse rest", "> that it is also in the axial direction over Car . flange (36) extends _f so that it forms the z-site: ^v Ring-shaped part (41) _t is connected to the auxiliary coil (45), Electromagnetic actuator according to one of Claims 6 to 9, characterized in that the permanent magnet (39) is annular and that it forms part of the second magnetic circuit which represents the outside of the auxiliary coil (45). 11 _β electromagnetic actuator according to one of claims 5 to 10, characterized in that the drive coil (30) and the auxiliary coil (45) are electrically connected in series. Rei / Pi. 30983 57 0863