Electromagnetic motor system for driving a pointer

Abstract

The present invention concerns an electromagnetic motor system for driving an indicator (16) in front of a display panel (4). The system comprises: an electromagnetic motor comprising a stator (6) and a rotor (7), the stator being arranged to face a first side of the display panel, and comprising coils, the rotor being arranged to face a second, opposite side of the display panel, and shaped as a ring to allow a readable area on the second side of the display panel (4) to be seen at least through an inner region of the ring, the rotor (7) comprising a set of rotor magnets placed along the ring; a guide arrangement (8) configured to hold the rotor (7) in a given position with respect to the display panel while allowing the rotor to be rotated with respect to a rotor rotation axis; an indicator (16) coupled to, or integrally formed with the rotor (7) such that the indicator is arranged to rotate with respect to the rotor rotation axis when the rotor (7) is rotated as a result of stimulating the coils (13); a sensor system (9) configured to determine rotation-related information of the rotor (7); and a control module (10) configured to feed electrical signals to the coils to stimulate them based on at least the rotation-related information from the sensor system (9).

Description

[0001] ELECTROMAGNETIC MOTOR SYSTEM FOR DRIVING A POINTER

[0002] TECHNICAL FIELD

[0003] The present invention relates to an electromagnetic motor system for driving a pointer of a display or instrument panel. The electromagnetic motor system comprises a stator and a rotor configured to rotate with respect to a rotor rotation axis to thereby rotate the pointer. The stator and rotor are arranged on opposite sides of the display panel. The present invention also relates to a display system comprising the electromagnetic motor system and a display panel. The display panel is arranged between the stator and the rotor.

[0004] BACKGROUND OF THE INVENTION

[0005] Traditional analogue instrument panels equipped with pointers or indicators for displaying information such as speed, temperature, fuel level, and other data have relied on mechanical mechanisms for pointer movement. These conventional systems often employ mechanical linkages, gears, and rotary shafts, which are prone to wear and tear over time, resulting in reduced accuracy, increased maintenance requirements, and decreased overall lifespan.

[0006] In recent years, there has been a growing demand for instrument panels that provide greater precision, durability, and flexibility in their pointer movements. This demand is driven by advancements in technology and the need for more reliable and efficient information display systems across various industries. Electromagnetic motors have emerged as a promising solution to address these challenges by offering precise control, reduced mechanical complexity, and improved longevity.

[0007] Electromagnetic motors, including but not limited to linear motors and rotary motors, have been applied in a variety of applications, such as robotics, manufacturing, and aerospace, to achieve high-precision motion control. However, their adaptation for use in display panels as a means of driving pointers with the required accuracy and responsiveness has been limited.

[0008] The existing electromagnetic motor arrangements used for pointer control in display panels typically lack optimisation for the specific requirements of such applications. For instance, the size of components in front of the display panel is too large thereby obstructing the user’s or driver’s view of large portions of the display panel. Furthermore, these motors often exhibit limitations related to power consumption and size constraints, which may hinder their widespread adoption. Therefore, there is a need for an improved electromagnetic motor system for a display panel, where the pointer is driven by an electromagnetic motor system designed specifically for driving pointers in front of instrument panels. Such a system should be capable of providing precise and reliable pointer movement while addressing the unique challenges associated with display panel applications.

[0009] SUMMARY OF THE INVENTION

[0010] It is an object of the present invention to overcome at least some of the problems identified above related to electromagnetic motor systems. More specifically, the present invention overcomes at least some of the limitations of existing systems by providing an electromagnetic motor system comprising an electromagnetic motor specifically designed for driving a pointer in front of a display panel, and which only minimally obstructs the driver’s or user’s view of the readable area of the display panel.

[0011] According to a first aspect of the invention, there is provided an electromagnetic motor system for driving an indicator in front of a display panel as recited in claim 1 .

[0012] The proposed electromagnetic motor system is characterised by its ability to deliver highly accurate indicator movement, and which occupies only a minimal space in front of the display or instrument panel, and which is thus particularly well designed to its desired application, for instance in automotive instrument panels. The motor of the system also has a reduced power consumption. Furthermore, the invention offers advantages in terms of reliability, durability, and adaptability, making it suitable for a wide range of display panel applications across different industries.

[0013] According to a second aspect of the invention, there is provided a display system as recited in claim 19.

[0014] In view of the shortcomings in the prior art and the growing demand for improved display panel systems, the present invention provides a novel and inventive solution that advances the state of the art in electromagnetic motor technology for indicator control in display panel systems.

[0015] Other aspects of the invention are recited in the dependent claims attached hereto. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Other features and advantages of the invention will become apparent from the following description of a non-limiting example embodiment, with reference to the appended drawings, in which:

[0017] • Figure 1 is an isometric top view of a display system according to an example embodiment of the present invention;

[0018] • Figure 2 is an isometric bottom view of the display system of Figure 1 ;

[0019] • Figure 3 is a top view of the display system of Figure 1 ;

[0020] • Figure 4 is a side view of the display system of Figure 1 ;

[0021] • Figure 5 is an isometric top view of a motor system used in the display system of Figure 1 ;

[0022] • Figure 6 is an isometric top view of a motor used in the motor system of Figure 5;

[0023] • Figure 7 is an isometric top view of a stator of the motor of Figure 6;

[0024] • Figure 8 is an isometric bottom view of a rotor of the motor of Figure 6;

[0025] • Figure 9 is a top view of the motor of Figure 6;

[0026] • Figure 10 is a top view of an example rotor guide system for guiding the rotor of Figure 8;

[0027] • Figure 11 is a closed-up partial side view of the motor system of Figure 5; and

[0028] • Figure 12 is an isometric top view of a stator of the motor according to a variant of the present invention.

[0029] DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

[0030] An embodiment of the present invention will now be described in detail with reference to the attached figures. The embodiment is described in the context of a display system to be used in an automotive instrument cluster. However, the proposed display system may equally be used in other fields of technology, such as aviation and manufacturing industry, etc. Identical or corresponding functional and structural elements which appear in the different drawings are assigned the same reference numerals. It is to be noted that the use of words “first”, “second” and “third”, etc. may not imply any kind of particular order or hierarchy unless this is explicitly or implicitly made clear in the context. Furthermore, the word ’’between” when used to give a numerical range also includes the end points of the range.

[0031] Figures 1 to 4 show an example display system 1 in different views. The display system 1 comprises an electromagnetic motor system 3 or arrangement, which is better illustrated in Figure 5, and a display or instrument panel 4, which in this example forms a digital display. The motor system 3 comprises the following main components; a first motor part 6, which in this case is a bottom motor part, a second motor part 7, which in this case is a top motor part, a guide arrangement 8, a sensor system 9, and a control module 10 or an electronic circuit. In the present description, the word “top” refers to the side of a readable area or the information-display side of the display panel, and the word bottom refers to the opposite side of the display panel, which is under normal operating conditions not visible to the user. The bottom motor part and the top motor part collectively form an electromagnetic motor 11 , where the bottom motor part is a stator 6 and the top motor part is a rotor 7.

[0032] A first or bottom side of the display panel 4 faces the stator, and the second or top side of the display panel faces the rotor. The rotor is thus arranged on top of the stator so that there is a given spatial separation, i.e., a gap, between the rotor and stator to allow the placement of the display panel between the stator and the rotor. The motor 11 in this example operates using alternating current (AC) electrical power. The stator is a stationary part, which in this example contains a set of coils of wire (armature) 13. The rotor 7 is a rotating part, which contains a set of magnets 14, also referred to as rotor magnets, which in this case are permanent magnets. When an electric current is applied to the armature, it generates a magnetic field that interacts with the rotor’s magnetic field, causing the rotor to spin with respect to a rotor rotation axis 15. The rotor is a ringshaped element or substantially a ring-shaped element forming a closed or open ring. The ring thus has a hollow interior region, which means that the ring has a space inside it that is not filled with material. The rotation axis is perpendicular to the surface of the display panel 4 such that it passes through the centre of the ring. A pointer or an indicator 16, which is coupled to, or integrally formed with the rotor 7 is also provided such that the pointer is arranged to rotate with respect to the rotor rotation axis together with the rotor when it is being rotated as a result of selectively stimulating the coils 13. As shown in Figures 1 , 3, and 5, the pointer is arranged on the inside of the ring pointing towards the centre of the ring. The control module 10 comprises the required hardware and software to control the stimulation of the coils 13 to ensure the exact position of the rotor and / or its demanded rotational speed.

[0033] The display panel 4 is in this example non-perforated, i.e., there are no through holes through the panel. More specifically, the display panel 4 is non-perforated at least in the region directly below the ring and directly below the inner region of the ring. In this manner, at least the region of the display panel, which is directly below the inner region of the ring can be fully used to display information. Furthermore, it is easier to manufacture display panels that are not perforated. Moreover, as in this example only the rotor, which is a narrow and thin circular element, is placed in front of the display panel 4, the components in front of the display panel obstruct only a small portion of the display panel. In this manner, the readable area of the display panel 4 can be made large. In this example, the readable area is the area directly below the inner region of the ring. However, in other implementations, the readable area may additionally, or instead be formed by the area which remains outside of the outer periphery of the ring. The mechanical or physical pointer together with the digital display panel thus form a hybrid analogue-digital display or simply a hybrid display combining digital technology for the underlying screen or panel with a mechanical (analogue) pointer to provide a blend of digital and analogue information presentation. In this type of display, the digital panel provides the underlying information or data, while the physical pointer is configured to move (i.e., rotate) to point to specific values or positions on the display panel.

[0034] The stator 6 and rotor 7 are better shown in Figures 6 to 9, where Figure 6 shows the motor 11 composed of the stator and rotor in a top isometric view, Figure 7 shows the stator including the phase diagram of the coils in a top isometric view, Figure 8 shows the rotor in a bottom isometric view, and Figure 9 shows the motor 11 in a top view. The example motor 11 is a three-phase electromagnetic motor is a motor type that operates on a three-phase alternating current (AC) electrical supply. The number of coils 13 on the stator 6 is a multiple of three for three phases. In this example, the stator comprises 24 coils, which are evenly placed on a stator yoke 19. A given coil is connected to one of the three phases of the AC power supply. In this example, the coils 13 on the stator 6 are interconnected as explained below and distributed in this example into groups of eight coils per phase, with 24 coils in total. Coil 1-A belonging to phase A is connected with coils 2-A, 3-A, 4-A, 5-A, 6-A, 7-A, and 8-A. Coil 1-B belonging to phase B is connected with coils 2-B, 3-B, 4-B, 5-B, 6-B, 7-B, and 8-B. Coil 1-C belonging to phase C is connected with coils 2-C, 3-C, 4-C, 5-C, 6-C, 7-C, and 8-C. Furthermore, the rotor magnets 14 of the rotor 7 are placed on a rotor yoke 20. In this example, the rotor comprises 16 magnets. The coils are arranged on the stator yoke so that they face the bottom side of the display panel, and the rotor magnets on the rotor yoke are arranged so that they face the top side of the display panel. The coils 13 and magnets 14 thus face each other but with the display panel placed therebetween, while the stator yoke 19 and the rotor yoke 20 face away from each other. The rotor magnets 14 are thus arranged on a display panel facing side of the rotor yoke 20 such that a south pole (S) or a north pole (N) of a given magnet faces the display panel, while the other pole faces away from the display panel, and such that the rotor magnets are arranged in an alternating fashion on the rotor yoke 20 such that the south pole of every other rotor magnet 14 faces the display panel while the north pole of every other rotor magnet 14 faces away from the display panel. The configuration of the magnets and coils generates a rotating magnetic field with a rotation axis parallel to the rotor rotation axis, which inducts a rotational movement on the rotor equipped with the permanent magnets.

[0035] The number of rotor magnets may depend on many factors. One factor is the aim to keep the physical dimension of the rotor 7 as small as possible for the purpose of the application. Another factor is the gap between the stator and the rotor. It is advantageous to keep the spatial separation between the stator and rotor constant or substantially constant in order to keep the dynamics of the system substantially unchanged during the operation of the motor. One more factor is the strength of the magnetic field to reach the dynamics and speed required for the application. The weight of the rotor yoke 20 also influences the dynamics. The weight of the rotor is advantageously comprised between 50 grams and 300 grams, or more specifically between 70 grams and 250 grams.

[0036] Figures 10 and 11 illustrate the rotor guide arrangement 8 or guide system in more detail. In this example, the rotor guide arrangement comprises three guide elements or wheel arrangements or systems 3, where each wheel arrangement comprises a rotating element 25, wheel or a washer and a bearing 26, which in this example is a ball bearing. According to this example, one of the wheel arrangements further comprises an elastic or flexible arm 27 for lateral play compensation. The arm is in this case configured as a spring. The wheels are preferably evenly or substantially evenly distributed along the periphery of the rotor 7. The rotor comprises a rail 29, which in this example is configured as a groove extending along the periphery of the rotor 7. Alternatively, the rail 29 could be configured as a ridge. The outer surface of the rail 29 is advantageously shaped to be complementary in form to the exterior surface of the wheels 25. The rail 29 may be integrally formed on the periphery of the rotor yoke, but as shown in the present example, it is formed in a rim 30 having a ring shape, which is coupled to the rotor yoke 20. Thus, the rotor yoke 20 and the rim are modular elements.

[0037] Furthermore, the rotation axis of the wheels 25 may be angled with respect to the surface normal of the plane defined by the top surface of the rotor or the top surface of the display panel (i.e. , the surface of the readable area). A surface normal to a surface at point P is a vector perpendicular to the tangent plane of the surface at point P. The wheels are thus arranged to rotate with respect to a respective wheel rotation axis, and wherein at least one of the wheels 25 is angled such that its / their wheel rotation axis / axes is / are non-parallel to a surface normal of a plane defined by a bottom or top surface of the rotor 7. This angle, which is shown as angle a in Figure 11 is a non-zero angle, i.e., the surface normal and the rotation axis of at least one of the wheels are not parallel to each other. Angle a is advantageously comprised between 0.5 degrees and 20 degrees, or more specifically between 1 degree and 10 degrees. An angled wheel helps to counteract the vertical (attraction) forces between the stator and the rotor. These forces are depicted in Figure 11 by the double-headed arrow. The angled wheel thus exerts a force to the rotor 7 when in contact with it such that at least one force component of the force is directed away from the stator 6.

[0038] The sensor system 9 comprises in this example two sensors, namely a first sensor 31 and a second sensor 32. The two sensors are used to ensure the exact position and demanded rotational speed of the rotor, and by consequence the pointer on the readable area (information). The first sensor 31 is in this example an optical sensor and it is used to determine by using an optical sensing method whether or not the rotor is at a rotational reference position, which in this case is a unique position. For this purpose, the rotor may comprise a marking along the rotor circumference indicating the location of the reference position. Thus, this unique position can be detected thanks to the marking on the rotor. The second sensor 32 is in this example a Hall effect sensor configured to use Hall effect physics to read the magnetic field emitted by the rotor magnets 14. A Hall effect sensor is a device that measures the magnitude of a magnetic field. It relies on the Hall effect, which is a phenomenon where a voltage difference (Hall voltage) is generated across a conductor or semiconductor material when it is subjected to a magnetic field perpendicular to the current flow. This voltage difference is proportional to the strength of the magnetic field. This allows the second sensor to detect whether or not the rotor is rotating, and also the rotation direction. The sensitivity of the sensor defines the resolution / accuracy of the positioning of the rotor. The rotation or rotation-related information detected by these two sensors is then fed into the control module 10, which is configured to combine the information from these two sensors (if this information has not been combined earlier by the sensors for example) to determine the rotation angle of the rotor (position) with an absolute and accurate value. The control module is also configured to determine the rotation speed of the rotor by using the signal generated by the Hall effect sensor. The rotation-related information is then taken into account by the control module 10 when selectively stimulating the coils by feeding electrical signals to the coils 13 to control the rotation of the rotor in dynamic mode of the motor. Dynamic mode is the mode during which the rotor is driven by the stator to rotate it according to the instructions from the control module 10. The control module is thus configured to stimulate the coils based on the rotation-related information, and further based on information about the desired position of the pointer at a given point in time. The latter information may be received by the control module from another module, which is not shown in the figures. It is to be noted that the sensor system 9 may optionally comprise more than two sensors to detect rotation information of the rotor (and which are also in data communication with the control module 10), namely at least a third sensor, which may optionally also be a Hall effect sensor.

[0039] Figure 12 shows a variant of the stator 6. According to this variant, the motor optionally provides a powerless position holding mode or steady or static mode during which the rotor is not allowed to rotate. In the event the motor is powered off, an embedded system ensures that the motor will keep the position of the rotor without consuming energy. In this case, the embedded system comprises a set of stator magnets 35. More specifically, additional permanent magnets, in this example eight magnets, are placed on the stator, on the side facing the display panel 4, to generate a holding force (magnetic attraction force) to keep the rotor, and consequently the pointer, in place when the motor is powered off. The magnets are placed in the coil cores, optionally at equal or substantially equal intervals. These additional magnets 35 do not have any significant effect on the dynamics of the motor during the dynamic operation of the motor. In this example, the stator magnets are all oriented in the same direction. In other words, either the north pole or the south pole of the magnets is facing the rotor (with the display panel placed therebetween), while the other pole is facing in the opposite direction, i.e. , facing away from the rotor. The principle is that during the static mode, the stator magnets 35 in the middle of the coils lock the rotor 7 in place thanks to the opposite attraction force generated by the magnetic fields from the stator and rotor magnets. The magnetic field intensity generated collectively by the stator magnets is smaller or significantly smaller than the magnetic field intensity generated collectively by the coils 13 when they are stimulated.

[0040] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive, the invention being not limited to the disclosed embodiment. Other embodiments and variants are understood, and can be achieved by those skilled in the art when carrying out the claimed invention, based on a study of the drawings, the disclosure and the appended claims. Further variants may be obtained by combining the teachings of any of the examples explained above. In the claims, the word ’’comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that different features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be advantageously used. Any reference signs in the claims should not be construed as limiting the scope of the invention.

Claims

CLAIMS1. An electromagnetic motor system (3) for driving an indicator (16) in front of a display panel (4), the electromagnetic motor system (3) comprising:- an electromagnetic motor (11 ) comprising a stator (6) and a rotor (7), the stator (6) being arranged to face a first side of the display panel (4), and comprising a set of coils (13), the rotor (7) being arranged to face a second, opposite side of the display panel (4), and shaped as a closed or an open ring to allow a readable area on the second side of the display panel (4) to be seen at least through an inner region of the ring, the rotor (7) comprising a set of rotor magnets (14) placed along the ring;- a guide arrangement (8) configured to hold the rotor (7) in a given position with respect to the display panel (4) while allowing the rotor (7) to be rotated with respect to a rotor rotation axis (15);- an indicator (16) coupled to, or integrally formed with the rotor (7) such that the indicator (16) is arranged to rotate with respect to the rotor rotation axis (15) when the rotor (7) is rotated as a result of stimulating the coils (13);- a sensor system (9) configured to determine rotation-related information of the rotor (7); and- a control module (10) configured to feed electrical signals to the coils (13) to stimulate the coils (13) based on at least the rotation-related information from the sensor system (9).

2. The electromagnetic motor system (3) according to claim 1 , wherein the indicator (16) is arranged on the inside of the ring pointing towards the centre of the ring.

3. The electromagnetic motor system (3) according to claim 1 or 2, wherein the guide arrangement (8) comprises at least a first guide element comprising a first rotating element (25) and a first bearing (26), a second guide element comprising a second rotating element (25) and a second bearing (26), and a third guide element comprising a third rotating element (25) and a third bearing (26), and wherein the first, second, and third rotating elements (25) are arranged along the periphery of the rotor (7).

4. The electromagnetic motor system (3) according to claim 3, wherein the rotating elements (25) are arranged substantially evenly along the periphery of the rotor (7).

5. The electromagnetic motor system (3) according to claim 3 or 4, wherein the rotating elements (25) are wheels (25) arranged to rotate with respect to a respective wheel rotation axis, and wherein at least one of the wheels (25) is angled such that its / their wheel rotation axis / axes is / are non-parallel to a surface normal of a plane defined by a bottom or top surface of the rotor (7).

6. The electromagnetic motor system (3) according to claim 5, wherein the respective angled wheel (25) is angled such that it exerts a force to the rotor (7) when in contact with the rotor (7) such that at least one force component of the force is directed away from the stator (6).

7. The electromagnetic motor system (3) according to any one of the preceding claims, wherein the rotor (7) comprises on its periphery a rail (29) having a groove or ridge configured to be in contact with the guide arrangement (8).

8. The electromagnetic motor system (3) according to claim 7, wherein the rail (29) is shaped to be complementary in form to the exterior surface of rotating element (25) of the guide arrangement (8).

9. The electromagnetic motor system (3) according to any one of the preceding claims, wherein the guide arrangement (8) comprises a lateral play arrangement (27) configured to allow controlled movement of the rotor (7) in a direction which is substantially parallel to the plane defined a bottom or top surface of the rotor (7).

10. The electromagnetic motor system (3) according to any one of the preceding claims, wherein the sensor system (9) comprises a first sensor (31 ) configured to determine whether or not the rotor (7) is at a reference position, and a second sensor (32) configured to determine whether or not the rotor (7) is rotating, and the rotation direction of the rotor (7).11 . The electromagnetic motor system (3) according to claim 10, wherein the first sensor (31 ) is an optical sensor, and the second sensor (32) is a Hall effect sensor.

12. The electromagnetic motor system (3) according to any one of the preceding claims, wherein the stator (6) comprises a set of stator magnets (35) to generate a force of attraction between the stator magnets (35) and at least some of the rotormagnets (14) to ensure that the rotor (7) remains immobile when the coils (13) are not stimulated.

13. The electromagnetic motor system (3) according to claim 12, wherein the stator magnets (35) are placed at equal or substantially equal intervals along the stator (6).

14. The electromagnetic motor system (3) according to claim 12 or 13, wherein the stator magnets (35) are placed at coil cores.

15. The electromagnetic motor system (3) according to any one of claims 12 to 14, wherein the magnetic field intensity generated by the stator magnets (35) is smaller than the magnetic field intensity generated by the coils (13) when they are stimulated.

16. The electromagnetic motor system (3) according to any one of claims 12 to 15, wherein the stator magnets (35) are oriented mutually in the same direction such that either the north or south pole of the stator magnets (35) faces the rotor (7), and the other pole faces in the opposite direction facing away from the rotor (7).

17. The electromagnetic motor system (3) according to any one of the preceding claims, wherein the rotor magnets (14) are arranged on a stator-facing side of a rotor yoke (20) such that a south pole or a north pole of a given magnet faces the stator (6), while the other pole faces away from the stator (6), and such that the rotor magnets (14) are arranged in an alternating fashion on the rotor yoke (20) such that the south pole of every other rotor magnet (14) faces the stator (6) while the north pole of the other rotor magnets (14) faces the stator (6).

18. The electromagnetic motor system (3) according to any one of the preceding claims, wherein the coils (13) are placed on a rotor-facing side of a stator yoke (19).

19. A display system (1 ) comprising the electromagnetic motor system (3) according to any one of the preceding claims, and further comprising the display panel (4) placed between the stator (6) and the rotor (6).

20. The display system (1 ) according to claim 19, wherein the display panel (4) is non-perforated in the region directly below the ring and the inner region of the ring.

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