Patent ID: 12228851

DETAILED DESCRIPTION OF THE DRAWINGS

In all embodiments, a camera shutter device according to the invention includes an optical opening1, an electromagnetic drive2fixedly arranged with respect thereto and having a linearly guided moving part, and a first shutter blade3forming a unit23fixedly connected to the moving part.

The shutter blade3is movable to an open position exposing the optical opening1(seeFIG.1aandFIG.2a) and to a closed position covering the optical opening1(seeFIG.1bandFIG.2b). In addition, a two-armed lever4is provided, which is divided into an input end4.1and an output end4.2by a pivot point P and can be pivoted about the pivot point P over a pivot angle range α. The pivot point P is located on an axis of rotation4.0fixed relative to the optical opening1. The input end4.1of the two-armed lever4is in communication with the moving part by a rotary joint formed by a pin engaging in an elongated hole, and a counterweight5is provided at the output end4.2of the two-armed lever4.

A first weight force F1acts on the unit23, essentially determined by the mass of the plunger8.2and the first shutter blade3, while a second weight force F2acts on the counterweight5, determined by its mass.

The first weight force F1causes a first torque M1about the axis of rotation4.0, which counteracts a second torque M2about the axis of rotation4.0caused by the second weight force F2. The first and the second torque M1, M2are not necessarily constant and equal in the open and in the closed position and over the movement sequence in between, but they always act in the opposite direction of rotation and compensate each other to a large extent.

The optical opening1may be an area that is not physically confined and through which radiation strikes a detector. It may also be the opening of a diaphragm or the receiving surface of a detector. The optical opening1may have any shape, for example a round shape or preferably a rectangular shape, as shown in the following exemplary embodiments. Only the shape of the first shutter blade3or also of a second shutter blade7, as shown in a second exemplary embodiment, must be adapted to this.

An embodiment of the camera shutter device with only a one-part shutter, which therefore only has the first shutter blade3, is advantageous for the use of the camera shutter device for an offset adjustment in a (particularly thermal) IR camera (NUC, Non-Uniformity Correction), in which it is important that the shutter, which briefly closes the optical opening1for at least one image acquisition cycle, has a temperature on its surface that is as exactly uniform as possible. In the case of a two-part shutter, which thus has the first and the second shutter blades3,7, which inevitably have a different relative position to existing heat sources or heat sinks within the device, a resulting temperature difference between the first and the second shutter blades3,7can already lead to the shutter not being well suited for offset adjustment.

Nevertheless, an embodiment having a first and a second shutter blade3,7may even be advantageous for other applications.

Both for an embodiment of the camera shutter device with only the first shutter blade3as well as with the first shutter blade3and the second shutter blade7as part of the counterweight5, it is advantageous if a first permanent magnet6.1or a first and a second permanent magnet6.1,6.2are arranged in association with the counterweight5in order to hold the counterweight5in the open position and in the closed position by magnetic force when the electromagnetic drive2is in the de-energized state.

The first and second permanent magnets6.1,6.2each have at least one magnetic face14. For the purposes of this description, the magnetic face14is understood to be a surface that has at least one magnetic pole.

In the following five exemplary embodiments, four embodiments are described on the basis of drawings, each of which has only the first shutter blade3, as well as one embodiment which also has a second shutter blade7.

According to a first exemplary embodiment, shown inFIG.1ain an open position and shown inFIG.1bin a closed position, the camera shutter device has only the first shutter blade3.

The counterweight5is made of a ferromagnetic material, and first and second permanent magnets6.1,6.2are provided to hold the counterweight5in the open position and alternatively in the closed position when the electromagnetic drive2is de-energized. The first and second permanent magnets6.1,6.2are advantageously two identical bar magnets with the same holding force and an axis of symmetry, which are aligned with each other on a straight line. The counterweight5has the shape of a round disk, the center of which is on the straight line in the open and closed positions. The magnetic faces14facing the counterweight5, here containing e.g. the north or south pole of the first or second permanent magnet6.1,6.2, respectively, are typically planar surfaces or advantageously cylinder section surfaces with a slightly larger radius than that of the counterweight5.

Advantageously, the first and second permanent magnets6.1,6.2do not themselves act as stops and a gap12remains between the counterweight5and the first and second permanent magnets6.1,6.2respectively in the open and closed positions. The gap12is advantageous to limit the holding force and in particular prevents wear of the magnetic face14. The gap12is narrower than any distance between the counterweight5and the first and second permanent magnets6.1,6.2, respectively, during movement between the open position and the closed position. This statement advantageously also applies to the further exemplary embodiments described below.

The pivot angle range α is advantageously limited by the stroke length or by mechanical stops against which, for example, the moving part or the two-armed lever4abuts. The electromagnetic drive2is realized here by a solenoid8, with a coil8.1and a ferromagnetic or permanent-magnet armature core8.2.1attached to a plunger8.2, which here represents the moving part of the electromagnetic drive2.

The coil8.1has a bobbin8.1.1which serves not only as a support for the winding8.1.2, but advantageously also as a sliding guide10for the plunger8.2, as shown inFIG.6. For this purpose, the bobbin8.1.1is extended beyond a length intended to accommodate the winding8.1.2and slotted along the extension. The plunger8.2, which is fixedly connected to the first shutter blade3, can thus slide inside the bobbin8.1.1. No additional component is required to guide the plunger8.2.

The first shutter blade3, which is fixedly connected to the plunger8.2, is guided linearly between the open and closed positions, in a direction determined by the direction of movement of the armature core8.2.1, while the two-armed lever4is pivoted about a fixed pivot point P over a pivot angle range α. The movement of the armature core8.2.1takes place over a stroke length which is advantageously greater than half of an overall length of the camera shutter device. The overall length is the maximum extension of the camera shutter device in the direction of movement of the armature core8.2.1. The connection with the two-armed lever4and the unit23is made via a pin/elongated hole connection. Thus, during the motion sequence, the distance of the point of application of the first weight force F1from the pivot point P changes and consequently the length of a first lever arm r1, which also changes the first torque M1. The length of a second lever arm r2remains constant. Moreover, both torques M1, M2change due to the changes of the angles ϕ1, ϕ2. The first and the second torque M1, M2do not have to change equally.

Due to the direct connection of the moving part, which in this first exemplary embodiment is the plunger8.2, with the first shutter blade3, the movement of the armature core8.2.1is transmitted at a transmission ratio of 1:1. In order to be able to dimension a short length on the bobbin8.1.1, compared to the range of movement of the plunger8.2, for accommodating the winding8.1.2, the winding8.1.2is designed as an at least two-phase winding. It can consist of at least two bipolar single windings arranged one behind the other on the bobbin8.1.1or of unipolar pairs of windings whose two halves are wound in opposite directions. A temporally and thus phase-shifted control leads to a comparatively larger stroke length than would be achievable with a coil with only one single winding of the same winding length. A longer stroke length is also obtained when using a permanent-magnet armature core8.2.1and alternating the use of attractive and repulsive forces by reversing the direction of the magnetic field of the coil8.1. In the case of bipolar single windings, the current flow is reversed for this purpose; in the case of unipolar pairs of windings, the current flow is alternately applied to one or the other half of the winding.

Advantageously, the coil8.1is partially or completely enclosed by a ferromagnetic enclosure11, which increases a magnetic flux generated inside the coil8.1and reduces a stray field generated around the coil8.1.

The second exemplary embodiment, shown inFIG.2ain an open position and shown inFIG.2bin a closed position, differs from the first exemplary embodiment or embodiments of the aforementioned modifications in that only a first permanent magnet6.1is present, by its arrangement relative to the counterweight5and the geometric shape of the counterweight5. The shape of the counterweight5here represents a segment of a round disk which has on its outer circumferential surface two planar surface sections which enclose an angle of less than 180° with one another, one of the planar surface sections in each case being parallel opposite an identical magnetic face14of the first permanent magnet6.1in the open or closed position. For this purpose, the first permanent magnet6.1is arranged within the pivot angle range α. Here, the magnetic face14is a planar surface.

The third exemplary embodiment, shown inFIG.3ain an open position and inFIG.3bin a closed position, differs from the second exemplary embodiment in the shape of the counterweight5. Here, the counterweight5has the shape of an open-end wrench, with an inner circumferential surface showing two flat surface areas. Said flat surface areas are each opposite one of the planar magnetic faces14in the open or closed position, with an equal gap12of equal thickness and equal width. The first permanent magnet6.1is arranged within the pivot angle range α and within the counterweight5.

According to the fourth exemplary embodiment, shown inFIG.4ain an open position and inFIG.4bin a closed position, the first permanent magnet6.1is fixedly attached to the counterweight5within the pivot angle range α and radially aligned with the pivot point P, so the counterweight5itself need not be made of a ferromagnetic material in this case. A ferromagnetic armature13, with two flat end faces13.1facing the pivot point P, is also statically fixed within the pivot angle range α. In the open position and the closed position, one of the end faces13.1faces an identical one of the magnetic faces14in each case, forming an equal gap12.

The magnetic faces14, the end faces13.1or the surface sections on an inner or outer circumferential surface of the counterweight5have been described as planar surfaces in the exemplary embodiments; they may also take other surface shapes, such as cylindrical, conical or spherical surface sections. It is known to the skilled person that the concrete course of the magnetic force during the movement over the pivot angle range α can be specifically influenced by the design of the magnetic faces14.

According to a fifth exemplary embodiment, shown inFIG.5aandFIG.5b, the counterweight5includes a second shutter blade7. This exemplary embodiment differs from the first exemplary embodiment only in the design of the counterweight5.

The counterweight5, which in the first exemplary embodiment is fixedly connected to the output end4.2of the two-armed lever4and thus moves on a circular path, moves here, like the unit23, in a straight line and orthogonally to the axis of rotation4.0. For this purpose, comparable to the unit23, which is connected to the input end4.1of the two-armed lever4via a pin/elongated hole connection, it is rotatably connected to the output end4.2of the two-armed lever4via a pin/elongated hole connection, whereby the length of the second lever arm r2also changes here during the movement sequence. Advantageously, the second shutter blade7is attached to a connecting rod9, comparable to the connection of the first shutter blade3to the plunger8.2. The connecting rod9is made of a ferromagnetic material and can thus be held by the first or the second permanent magnet6.1,6.2. As with the plunger8.2, there is a pin on the connecting rod9, which is guided in an elongated hole formed on the two-armed lever4.

A sliding guide10is provided for linear guidance of the connecting rod9. The first and second shutter blades3,7are moved simultaneously in opposite directions by only one electromagnetic drive2.

In particular, an advantageous embodiment of the camera shutter device with only a first shutter blade3is significantly more compact compared to the prior art. Advantageously, the first and second permanent magnets6.1,6.2exerting a holding force in the direction of movement of the first shutter blade3in the position covering the optical opening1or in the position uncovering the optical opening1ensures that the first shutter blade3is held in a stable position even when shocks or vibrations act on the camera shutter device in the direction of movement.

LIST OF REFERENCE NUMERALS

1optical opening2electromagnetic drive3first shutter blade23unit4two-armed lever4.0axis of rotation4.1input end4.2output end5counterweight6.1first permanent magnet6.2second permanent magnet7second shutter blade8solenoid8.1coil8.1.1bobbin8.1.2winding8.2plunger8.2.1armature core9connecting rod10sliding guide11enclosure12gap13armature13.1end face of the armature14magnetic faceP pivot pointα pivot angle rangeM1first torqueM2second torqueF1first weight forceF2second weight forceϕ1first angleϕ2second angler1first lever armr2second lever arm