Field of the invention

The present invention relates to rotary switches and especially to the construction of a rotary switch which is robust, as defined in the preambles of the independent claims.

Background of the invention

A rotary switch, here refers to a control unit for controlling functions of a device or apparatus by rotation. Rotary switches are often based on rotary encoders which are electro-mechanical devices that convert the angular position or motion of a shaft or axle to an analog or digital code.

Various types of rotary encoder are used for this purpose today. Some examples are optical encoders, magnetic encoders, and capacitive encoders. Rotary encoders are used in many applications that require precise shaft unlimited rotation including industrial controls, robotics, special purpose photographic lenses, computer input devices, such as optomechanical mice and trackballs, controlled stressrheometers, and rotating radar platforms. An optical encoder refers here to a rotary encoder wherein the encoder's disc is made of glass or plastic with transparent and opaque areas. A light source and photo detector array reads the optical pattern that results from the disc's position at any one time. This code can be read by a controlling device, such as a microprocessor or microcontroller to determine the angle of the shaft.

A magnetic encoder refers here to a rotary encoder which uses a series of magnetic poles to represent the encoder position to a magnetic sensor. The magnetic sensor reads the magnetic pole positions. This code can be read by a controlling device, such as a microprocessor or microcontroller to determine the angle of the shaft, similar to an optical encoder. A capacitive encoder refers here to a rotary encoder wherein an asymmetrical shaped disc is rotated within the encoder. This disc will change the capacitance between two electrodes which can be measured and calculated back to an angular value.

One problem with known rotary switches used as controls is that they are due to their construction often not very robust and thus not suited for environments where they might be subjected to impact and spatter. Usually an rotary switch for use as a controller, is constructed such that the axis is connecting a rotary knob with any functional element that are placed inside the device the encoder is controlling some functions of. A disadvantage of this construction is that in case of an impact or strike of some kind to the rotary knob either the knob or the axis connected to the knob may easily break, since it is the weakest part of the construction,

Brief description of the invention The object of the present invention is to provide a rotary switch for use as a controller for controlling for example operations of an industrial device or some other device where robust and durable rotary controls are needed. The objects of the present invention are achieved with a rotary switch according to the characterizing portions of the independent claims.

The preferred embodiments of the invention are disclosed in the dependent claims.

The present invention is directed to a rotary switch comprising a rotary knob for manual operation of the switch and a shaft around which the rotatory knob rotates, the shaft being hollow in order to hold functional elements of the encoder. Shaft here refers to a fixed structure around which the rotary knob may rotate, and which structure is hollow in a manner in which a space inside said structure is formed. In this way sensitive elements of the rotary switch may be fitted inside the rotary switch thus making it less prone to breaking due to impact. Further advantages of the invention are discussed in more detail with description of embodiments of the invention. Brief description of the figures

In the following the invention will be described in greater detail, in connection with preferred embodiments, with reference to the attached drawings, in which

Figure 1 is a cross-section of a rotary switch according to an embodiment according to the invention.

Detailed description of some embodiments

The following embodiments are exemplary. Although the specification may refer to "an", "one", or "some" embodiment(s), this does not necessarily mean that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may be combined to provide further embodiments.

In the following, features of the invention will be described with a simple example of a device structure. Only elements relevant for illustrating the embodiments are described in detail. Various implementations of control units, methods and devices comprise elements that are generally known to a person skilled in the art and may not be specifically described herein.

In the following, embodiments of the invention are described using exemplary terms and elements of rotary switches and control units.

The rotary switch according to the invention is intended as, but not restricted to, being fitted to for example a control unit and functioning as to let a user by rotating or pushing it control functions of the control unit. The rotary switch according to the invention comprises a rotary knob which is a rotary part which may be rotated by a user to select between different settings or steps of a process in order to control a process or the like. Further the rotary switch comprises a shaft around which the rotary knob rotates. The shaft of the rotary switch is hollow in order to hold functional elements of the encoder. The rota ry switch according to the invention may be implemented with a magnetic encoder, an optical encoder, a capacitive encoder or any other type of known encoder. As described before functional elements of a rotary switch may vary depending on which type of encoding is used . When the rotary switch of the invention is implemented with a magnetic encoder the functional elements of the rotary switch may comprise a circuit board, a magnet for creating a magnetic field and a magnetic encoder for sensing the direction of the magnetic field . One option is using a magnet magnetized in the radial direction but other solutions may be available, all well known in the field .

In the case of using an optical encoder the functional elements may comprise a circuit boa rd, an optically readable rotary scale coupled to the rotary knob and an optical sensor for sensing a position of the rotary knob from the portion of the rota ry scale.

In figure 1 a rotary switch 10 according to one embodiment of the invention is depicted as a cross-section. The rotary switch comprises a rota ry knob 11 with a cover 12 preferably made from silicone rubber. The rotary switch comprises a shaft 13. The functional elements comprise a magnet 14 and a magnetic encoder 15. The rotary switch 10 further comprises LED-lights 16 which are placed beside the magnetic encoder 15 for illumination, and a light conductor 17 for bringing the light from the LED-lights through the cover. Protruding lips 18 of the cover and o-rings 19 are preventing dirt from entering the encoder and sealing the cover. A spring clip 20 is pressing inner wings 21 of the rotary knob outward for creating a detent. The outer surface of the shaft comprises threads 22 or the like matching threads 23 on the rotary knob. The rotary switch further comprises a dome switch 24.

In one embodiment of the invention the functional elements of the rotary encoder comprise LED-lights for illumination . The LED-lights may be placed around the encoder for illumination. A light conductor may be used for leading the light from the LED-lights to the top of the rotary knob.

The rotary knob may comprise a cover, preferably made from silicone rubber. A cover made from an elastic material protects the rota ry switch from impact, i.e. due to a drop or ca reless handling . Further a cover made from silicone rubber also protects the rotary switch from spatter and welding spa rks and the like in industrial environments. The cover may also be shaped in order to absorb impact e.g. by rounding of corners. This may also be achieved by choice of material. A cover made from rubber, silicone rubber or the like will absorb impact better than a harder material. A shape without any sharp corners or rims is also beneficial in this sense and better absorption of shock also has the advantage of spreading of the energy resulting of an impact.

The cover may also be grooved or patterned for better grip, which may be useful when wearing working gloves. Better grip may also be enhanced by choice of material, e.g. a softer material gives better grip than a hard.

Another advantage of the rotary switch according to the invention is that the size of the rotary knob is due to the axis being hollow, larger than in conventional encoders. This has several benefits for the user, some of them being better grip and being easier to use while wearing protecting glows. Another advantage of the hollow axis is that all functional parts of the switch can be situated inside the switch, thus protected by the cover of the switch. This is especially advantageous as the functional elements will thus be protected and there are no week points. In conventional rotary switches such a weak point is e.g. the axis, at the point where it is fastened, and often penetrates a surface of for example the device it is to control. This is avoided by the encoder according to the invention as the axis does not extend outside the cover of the rotary knob and is thus protected from breaking.

In one embodiment of the invention the cover functions both as a push-button for selecting a function and a rotary switch for scrolling between functions. In case a magnetic encoder is used, a push of the button is detected as a change of the strength of the magnetic field and is detected by a magnetic encoder and interpreted as a selection of a function. A change in the direction of the magnetic field detected by the magnetic encoder is interpreted as rotational movement by the rotary button.

According to a preferred embodiment the press button functions only when pressed in the middle or in other words in the centre of the top surface of the cover or top concentric. This is advantageous as impact to the cover of the rotary encoder due to a fall or careless handling will not erroneously be interpreted as a selection of a function. This is especially advantageous in industrial environments or while working with protective gloves which may more easily be the cause of dropping of the control device controlled by the rotary switch. According to one embodiment of the invention the rotary switch may comprise a dome switch for providing mechanical response for the push-button functionality. This is advantageous as this will give the user feedback and confirm when the button has been properly pushed and a function selected.

According to one embodiment the rotary knob further comprises a spring clip and wings, where the spring clip is arranged to press the wings outward for causing a detent of the rotary switch.

In one embodiment the cover comprises a silicone rubber lip for preventing dirt from entering and o-rings for sealing of the cover.

In one embodiment of the invention, where a magnetic encoder is used, a light conductor may be used for holding the magnet in place as well as for transmitting motion from the push button to the magnet.

One advantage of the present invention is that due to the construction of the rotary switch, i.e. the shaft being hollow and that the functional elements may be fitted therein, is the possibility of fitting of the rotary switch on a flat surface or plane, without any parts penetrating said surface or plane. The rotary switch according to a preferred embodiment of the invention comprises a flat cable extending from the rotary switch for connection of the switch to the device it is to control. This cable may either penetrate the surface of the device such as a screen, or be coupled without penetrating the surface. The rotary encoder may attached by the edges. If the rotary switch due to impact or the like is detached from the surface or plane it is attached to, this will not damage either the rotary switch due to its robust construction and cover, or the device it is attached to as no fixed parts, such as an axis is penetrating the surface of the device. The advantage of this is a more robust structure, as the shaft or axis is conventionally the part that is most prone to breaking. In the case of a switch constructed according to the invention the shaft is protected by the cover and will not easily break, and an impact will likely not break the switch. More over the construction of the rotary switch enables installation of the rotary switch in such a manner that the rotary switch and the screen it is attached to may be overlapping. This means that the rotary switch may be installed on a screen in a manner where the edges of the rotary switch are extending over a part of the screen and thus covering it. This allows for a solution where e.g. the scale of the value controlled by the rotary switch may be displayed on the display around the switch thus making the process of scrolling to scales and functions more visualized. This manner of installation is also advantageous as the rotary encoder may be easily reinstalled if it comes off during use.

Thus, the invention provides an apparatus and a method by which a significant improvement can be achieved in the area of rotary switches for controlling of industrial applications. The arrangement according to the present invention is easy and economical to realize by per se known components and reliable in use. It should be noted that the foregoing examples of the embodiments of the invention are not intended to restrict the scope of the invention to the specific forms presented above but the present invention is meant rather to cover all modifications, similarities and alternatives which are included in the spirit and scope of the present invention, as defined by the appended claims. All additional embodiments, modifications and applications obvious to those skilled in the art are thus included within the spirit and scope of the invention as set forth by the claims appended hereto.

It is apparent to a person skilled in the art that as technology advances, the basic idea of the i nvention ca n be i mplemented i n va rious ways. The i nvention a nd its embodiments are therefore not restricted to the above examples, but they may vary within the scope of the claims.