Musical instrument with key press assembly featuring spring and sensor mechanism

Abstract

A musical instrument comprising a base 108, a keyboard having a key 104 which pivots about a pivot axis 106 between a rest position and a pressed position, and a key press assembly. The key press asse

Description

Technical Field The present disclosure relates to electronic musical instruments having a keyboard, such as electronic keyboards. More particularly, it addresses mechanisms and systems associated with the actuation of keys and the generation of corresponding sound signals. Background Electronic keyboards have undergone extensive development since their early days. Initial designs were predominantly mechanical, utilising physical switches to produce electrical signals. A goal for many electronic keyboards is to design a key press assembly that replicates the tactile feel of an acoustic piano. Variability in key press response can negatively impact user experience and performance. Differences in key actuation force, key travel distance, and the mechanical properties of the materials used can contribute to inconsistent key press response. What is needed is an improved electronic keyboard that provides an improved tactile feel. Summary The present disclosure relates to a musical instrument comprising a keyboard that includes a key configured to pivot about a pivot axis from a rest position to a pressed position. The instrument comprises a base and a key press assembly associated with the key. The key press assembly includes a spring that is arranged between the base and the key and is affixed to at least one of them. The spring is configured to be in a compressed state when the key is in the pressed position. The key press assembly further comprises a sensor associated with the key, which is configured to generate a sound signal associated with movement of the key. The key press assembly is configured such that when the key is in the pressed position, the key contacts the spring at a first location along the length of the spring. The spring then transfers a force to the sensor at a second location along the length of the spring to generate the sound signal. The first and second locations are offset from each other along the length of the spring. The first and second locations are therefore offset by a distance. The key transfers a force to the spring at the first location and the spring then transfers a force to the sensor from the second location along the length of the spring. Existing keyboards may have one or more sensors placed under each key, and the key directly contacts the sensor. Because the key directly applies a force to the sensor via this contact, the user may experience an undesirable tactile feeling / response which is tied to the activation of the sensor at any given point of key press / travel. In such keyboards, each key may be biased towards a rest position by a living hinge or a tension spring arranged at one end of the key. In contrast to those existing keyboards, keyboards according to the present disclosure include a spring arranged between the key and sensor, where the spring itself transfers a force (the force being applied to the key) to the sensor via a lever action. The spring therefore mechanically decouples the sensor activation from the movement of the key. This improves the “feel” of the key press. Coupled with the pivoting nature of the key, the lever action of the spring (by having the first and second locations being offset from each other) provides an improved tactile response when compared to existing musical instruments that include keyboards. Furthermore, as the key is depressed, the deflection of the spring creates a reaction force felt by the sensor. This reaction force changes throughout the stroke of movement of the key, and can be used to provide additional information about the user’s interaction with the key. In examples, the shape of the spring, the position of the sensor(s), and / or any intervening materials located between the spring and sensor can be changed to adjust the tactile response of the key as desired. In examples, the pressed position may be a fully depressed position (for example, the key may not be movable beyond the fully depressed position) or the pressed position may be a position between the rest position and a fully depressed position. In examples, the spring may be in a rest or equilibrium state when the key is at the rest position (or it may be in a lower energy compressed state). The key is urged back to the rest position (and is therefore biased towards the rest position) by the spring being in the compressed state. In one example, a force of about 0.6N must be applied to the key when in the rest position to overcome the force applied by the spring. The pivot axis may be arranged at or towards one end of the key, such as an end of the key opposite to that which is pressed / played by a user (i.e., opposite to the free end of the key). In the pressed position, a free end of the key is closer to the base than when the key is in the rest position. The key therefore pivots towards and away from the base. In examples, the keyboard may have a plurality of keys and a plurality of key press assemblies, each key of the plurality of keys being associated with a key press assembly of the plurality of key press assemblies. The key is therefore one of the plurality of keys. The base may be flat or have one or more raised or protruding portions or recessed portions. The base may be made up of a single element or one or more elements assembled and / or affixed together. In examples, the base may form the bottom of the instrument or keyboard. In examples, the sensor is arranged on the base. In examples, “contacts” may mean “abuts”. In some examples, the spring and key are in contact / abutment at all times (such as when the key is in the rest position and in a pressed position). In one example, the spring contacts the sensor at the second location, or another element (such as a pressing element) arranged between the spring and the sensor contacts the spring at the second location. A “sound signal” is to be understood to mean a signal that is associated with a sound (for example, the keyboard or another device may output a sound associated with the signal). The sound signal may be a MIDI signal, for example. In examples, the sound signal is generated upon application of a force to the sensor. In examples, the signal comprises data indicative of the force applied to the sensor. The sound signal may be an analogue signal or a digital signal. An analogue signal, for example, may change depending on the force applied to the sensor. In examples, the force transferred to the sensor increases as the key is pressed and decreases as the key is depressed. In examples, this occurs without perceivably increasing the force required to press the key down. In a particular example, the spring is a lever spring. A lever spring is a simple but effective spring mechanism that can amplify an input force to provide a greater output force. A lever spring is a type of mechanical spring that is used to apply force or store energy through the action of a lever. In other examples, the spring may be a leaf spring. In examples, the lever spring is a flat lever spring or a coiled lever spring. Both types of lever spring are compact and can allow the tactile response of the key to be adjusted as desired. The option of using either a flat or coiled lever spring provides flexibility in design and manufacturing. This versatility allows for different mechanical properties to be tailored to specific requirements, such as varying force feedback or durability. Manufacturers can choose the most suitable spring type based on the desired tactile response and production methods. In examples, the flat lever spring has a flat profile (for example, it may be a flat strip of material, such as plastic or metal, which may also be bent or shaped as desired). The flat lever spring may comprise a stepped configuration, with one or more sloped or inclined or vertical sections and / or one or more level / horizontal sections. For example, the lever may be affixed to the base at a first level section. The lever may further comprise a second level section. The first and second level sections may be joined by a first inclined section. A pressing element may be coupled or affixed to the lever spring on the second level section, the pressing element being arranged to press the sensor. A second inclined section may extend from the second level section to a top section. The pressing element may also extend along the spring onto the second inclined section. The key may contact / abut the spring at the top section (the top section therefore includes the first location). The top section may be curved, in some examples. The coiled lever spring may comprise a first leg and a second leg. The first and second legs may separately transfer forces to separate sensors, in the same way as described below for a forked flat lever spring. The coiled lever spring may be used in combination with the pressing element(s) discussed below. In an example, the pressed position is a fully depressed position, the key is configured to pivot about the pivot axis from the rest position to the fully depressed position via an intermediate pressed position, and the key press assembly is further configured such that the spring transfers a force to the sensor when the key is arranged in the intermediate pressed position. Having the sensor activated in the intermediate pressed position and the fully depressed position allows the motion of the key to be monitored / measured throughout the key stroke. For example, one can identify precise and continuous velocity information throughout the stroke of movement of the key. In addition, the capability to detect intermediate pressed positions may allow for nuanced control over the musical instrument and may enable the generation of varied sound outputs based on the degree of key depression. The intermediate pressed position may be a position that is halfway between the rest position and the fully depressed position. The intermediate pressed position may be a partially pressed position. In one example, the spring is affixed to the base. Affixing the spring to the base, rather than the key, can provide an improved tactile response to the key because the key and spring are free to move or pass over each other. In examples, the spring is affixed to the base at a third location along the length of the spring, the second location being between the first and third locations. In an example, the other end of the spring abuts the key but is not affixed to the key, and as the key moves from the rest position to the pressed position, the key may contact the spring at different points along the length of the spring as the key pivots. The spring may be affixed to the base via one or more fixing elements, such as one or more screws or bolts, or via an adhesive, for example. In examples, the spring is forked, and comprises at least a first forked portion and a second forked portion and the first and second forked portions extend at least partially along the length of the spring. Being forked may mean that the spring has two or more portions extending at least partially along the length of the spring, such as partially along the length of the spring. A forked profile can allow lateral (side to side or “rocking”) forces to be applied to the key and transferred to the sensor(s). This can be used for pitch bending, for example, and / or for determining proper finger positioning on a key. In examples, the sensor is a first sensor, and the key press assembly further comprises a second sensor. The second location along the length of the spring is on the first forked portion, such that the force is transferred from the first forked portion to the first sensor, and the key press assembly is configured such that when the key is arranged in the pressed position, the spring transfers a force to the second sensor at an additional location along the length of the spring to generate a second sound signal, wherein the additional location is on the second forked portion, such that the force is transferred from the second forked portion to the second sensor. Separate forces can therefore be applied to separate sensors, thereby allowing the lateral forces to be measured independently. This can be used to control a pitch bend, for example. The first and second forked positions may be separated by a gap and the gap may extend between the first and second forked portions along a width of the spring. The first and second sensors may form a sensor array or at least part of a sensor array. The second sensor is associated with the (same) key and is configured to generate a second sound signal associated with movement of the key, such as upon application of a force to the second sensor. In some examples, the second location and the additional location may not be offset from each other along the length of the spring (i.e., they may be aligned or substantially aligned with each other along the length of the spring). In examples, the key comprises a protruding portion extending from the key, the protruding portion being dimensioned such that: (i) when the key is in the fully depressed position, the protruding portion is configured to transfer a force to the spring, and (ii) when the key is in the rest position and intermediate pressed position, the protruding portion and spring are spaced apart by a gap. The inclusion of a protrusion from an underside of the key, for example, improves the transfer of forces to the sensor(s) (from the first and second forked portions) by providing a second contact point when the key is pressed fully down. The protruding portion can improve the ability to control the pitch bend, for example. Having the gap ensures that the presence of the protruding portion does not negatively affect the tactile response of the key when the key is traveling (i.e., between the rest position and the fully depressed position). When the key is in the fully depressed position, the protruding portion transfers a force to the spring at a fourth location along the length of the spring, the fourth location being closer to the second location than the first location is to the second location. In one example, the second and fourth locations are not offset from each other along the length of the spring (i.e., they may be aligned or substantially aligned, just on different sides of the spring (such as a bottom side and top side)). In the fully depressed position, the protruding portion is configured to abut or contact the spring or one or more pressing elements affixed to the spring. In examples, when the key is in the rest position and intermediate pressed position, the protruding portion does not transfer a force to the spring (for example, there is a gap between the spring and / or the one or more pressing elements). The protruding portion may extend from an underside of the key and towards the spring, such as the one or more pressing elements. In a particular configuration, the protruding portion comprises a first leg and a second leg, the first leg being configured to transfer a force to the first forked portion and the second leg being configured to transfer a force to the second forked portion. Having two legs further improves the transfer of forces from the first and second forked portions, thereby allowing a more precise measurement of the lateral forces applied to the key. The first leg may contact or abut the first forked portion or a pressing element, such as a first pressing element. Similarly, the second leg may contact or abut the second forked portion or a pressing element, such as a second pressing element. The key press assembly may comprise a pressing element extending from the spring at the second location and the pressing element is moveable with the spring. The pressing element is positioned along the spring such that the spring transfers the force to the sensor via the pressing element. A separate element that transfers the force to the sensor can allow the application of the force to be controlled as desired. For example, the pressing element may be formed with a particular shape to precisely control where the force is applied, or the pressing element may be formed from a particular material so as to further allow the tactile response of the key press to be tailored as desired. In examples, the pressing element comprises a protrusion, such as a dome-shaped protrusion, which contacts the sensor. In examples, the pressing element may form part of the spring (for example, it may be a protruding portion of the spring) or it may be coupled / affixed to the spring, and may therefore be formed from a different material to the spring. The pressing element may be formed of silicone. The pressing element may be formed from a resilient material (rather than be rigid) to provide an improved tactile response. In a first arrangement, when the key is arranged in the rest position, the pressing element and sensor are spaced apart by a gap. In a second arrangement, when the key is arranged in the rest position, the pressing element abuts the sensor and applies a force to the sensor that is less than a threshold force required to cause the sensor to generate the sound signal. Both arrangements ensure that the sensor generates the sound signal only when a desired force is applied. The second arrangement can allow the force to be transferred quickly to the senor and may also ensure the “feel” of the key press remains relatively smooth by avoiding transitioning from no contact to a point of contact. In an example, the gap is less than or equal to around 0.3mm (for example, so that when the key is moved by around 3mm at the front, the pressing element will move 0.3mm). The threshold force may be around 0.2N, for example. The pressing element may be a first pressing element extending from the first forked portion and may be moveable with the first forked portion. The key press assembly may further comprise a second pressing element extending from the second forked portion and being moveable with the second forked portion. The first pressing element is positioned along the first forked portion such that the spring transfers the force to the first sensor via the first pressing element and the second pressing element is positioned along the second forked portion such that the spring transfers the force to the second sensor via the second pressing element. In this configuration, two pressing elements (each being on separate forked portions of the spring) can allow the application of the forces to be different when bending the key or pressing it on one side and then the other, thus creating two different signals on the two sensors, which can be used to create a pitch bend sound effect. For example, the pressing elements may be formed with a particular shape to control where the forces are applied, or the pressing elements may be formed from a particular material so as to further allow the tactile response of the key press to be tailored as desired. In examples, the second pressing element comprises a protrusion, such as a domeshaped protrusion, which contacts the second sensor. The first and second pressing elements are separate from each other. The pressing elements may form part of the spring or they may be coupled / affixed to the spring, and may therefore be formed from a different material to the spring. The pressing elements may both be formed of the same material, such as silicone. Each pressing element may contact their respective sensors at the rest position, or may be spaced apart by a gap. The sensor may be a pressure sensor configured to generate a sound signal indicative of a magnitude of the force applied to the sensor. The pressure sensor may be a force sensitive resistor (FSR), which changes its resistance when a force or pressure is applied. A pressure sensor allows the magnitude of the force to be determined via a single sensor, which can provide increased control of the keyboard. As the key is pressed, the deflection of the spring creates a reaction force felt by the pressure sensor. This reaction force changes throughout the stroke of movement of the key, and can be used to provide additional information about the user’s interaction with the key. For example, the speed of movement of the key, both up and down, can be determined from the rate of change of force felt by the pressure sensor. Furthermore, to create a pitchbend like functionality, aperiodic variation in force felt by the pressure sensor could be detected, to identify that the user is wobbling the key. In addition, the pressure sensor's ability to generate sound signals based on the magnitude of the applied force enables a dynamic sound response. This can allow the musical instrument to produce varying sound intensities depending on how hard or soft a key is pressed. As a result, users can achieve a more expressive and nuanced performance, which may be similar to an acoustic instrument, for example. In some examples, the keyboard further comprises an additional sensor associated with the key and the additional sensor is configured to generate an additional sound signal associated with movement of the key, wherein the key press assembly is configured such that the sensor is activated before the additional sensor, and when the key is arranged in a further pressed position, different to the pressed position, the spring transfers a force to the additional sensor at a further location along the length of the spring to generate the additional sound signal, the second and further locations being offset from each other along the length of the spring. A pair of sensors (such as switches) can be placed underneath the key, in an orientation / arrangement such that when pressing down the key, one sensor is pressed before the other. By doing so, a measure of ‘velocity’ can be calculated, based on the time delay between sensor activation. This may be particularly useful if the sensors are not pressure sensors. In examples, “the sensor is activated before the additional sensor” may mean that the sound signal is generated before the additional sound signal (such as at an earlier time). The pressed position may be between the rest position and the further pressed position (i.e., the key pivots from the rest position to the further pressed position via the pressed position). In an example, the further pressed position is the fully depressed position. In a particular example, the musical instrument is an electronic keyboard. For example, the electronic keyboard is a MIDI keyboard. Brief Description of the Figures Examples of the present disclosure will now be described with reference to the accompanying drawings: Figure 1 is a perspective view showing a key in a rest position on an electronic keyboard; Figure 2 is a perspective view showing the key of Figure 1 in a fully depressed position on an electronic keyboard; Figure 3 is a perspective view showing a key with two sensors on an electronic keyboard; Figure 4 is a perspective view showing the key of Figure 3 in a fully depressed position with two sensors on an electronic keyboard; Figure 5 is a cross-sectional view showing a key in a rest position with a protruding portion on an electronic keyboard; Figure 6 is a cross-sectional view showing a key in a fully depressed position with a protruding portion on an electronic keyboard; Figure 7 is a plan view showing a spring with first and second forked portions; Figure 8 is a plan view showing the underside of the spring of Figure 7; Figure 9 is an elevation view of the spring of Figures 7 and 8; and Figure 10 is a perspective view showing a key in a rest position with a protruding portion having two legs. Detailed Description Rest Position and Pivot Mechanism of Key Assembly Figure 1 is a perspective view illustrating a key 104 in a rest position on an electronic keyboard 102. The electronic keyboard is a musical instrument, specifically a MIDI keyboard. Although this example relates to a MIDI keyboard, the aspects described can be applied to other musical instruments having keyboards, such as other types of electronic keyboards, synthesizers, or digital pianos. The key 104 is configured to pivot about a pivot axis 106 from the rest position (shown in Figure 1) to a pressed position (shown in Figure 2). The keyboard 102 comprises a key press assembly associated with the key 104. There may be a plurality of keys on the electronic keyboard (not shown in Figure 1), each associated with a corresponding key press assembly. The key press assembly comprises at least a spring 110 and a sensor 112. In the rest position, the spring 110 may be in an equilibrium state or a slightly compressed state, requiring a force of approximately 0.6N to move the key from the rest position. As shown in Figure 2, when the key is in the pressed position, the free end 124 of the key is closer to the base 108 than when in the rest position. When the key is in the pressed position, the spring 110 is in a compressed state, urging the key 104 back to the rest position. In this example, the pivot axis 106 is defined by an axle 118, which forms part of the key 104. The pivot axis may be positioned towards one end of the key, opposite to a free end 124 that is pressed by the user. The axle 118 is received within a through hole 120 of another component of the keyboard 102. Together, the axle 118 and through hole 120 form a pivoting mechanism. The base 108 of the electronic keyboard in this example is flat, and extends underneath the key 104. The spring 110 is arranged between the base 108 and the key 104 and is affixed to at least one of these components. In this example, the spring 110 is not affixed to the key 104 and is affixed to the base 104 at one end of the spring 110. The key 104 contacts or abuts the spring 110 at a first location 114 along a length of the spring 110. Applying a force to the key 104 means that the force is transferred to the spring 110 at the first location 114. As the key pivots about the pivot axis 106, the point of contact along the key and spring 110 can change. The spring 110 is a flat lever spring in this example. The spring transfers a force to the sensor 112 from a second location 116 along its length. The first location 114 is offset from the second location 116 by a distance. The sensor 112 is associated with the key 104 and is configured to generate a sound signal corresponding to the key's movement. In this example, the sensor 112 is a force-sensitive resistor (FSR) arranged on the base 108, which changes its resistance when force or pressure is applied. The sound signal generated in this example is an analog signal, indicative of the force applied to the sensor 112. The spring 110 may contact the sensor directly at the second location 116 or through a pressing element 126, as in this example. The pressing element 126 comprises a protrusion, such as a dome-shaped projection, which contacts the sensor 112. The pressing element 126 of this example is coupled to the spring 110 and is made from silicone. In this example, when the key is in the rest position, the pressing element 126 abuts the sensor with a force less than a threshold force required to generate the sound signal. The spring 110 is fixed to the base 108 at a third location 122 along its length, with the second location 116 situated between the first and third locations 114, 122. The spring 110 may be secured to the base using fixing elements like screws or bolts, or with an adhesive. The configuration of the key press assembly allows for a responsive key press experience. The spring 110, positioned between the base 108 and the key 104, ensures that the key 104 returns to its rest position promptly after being pressed and then released. This setup provides tactile feedback that enhances the user's interaction with the electronic keyboard. Depressed Position and Fully Depressed Key State As mentioned, Figure 2 shows the keyboard 102 and key 104 of Figure 1 at a later time after a user has fully pressed down the key 104. The features in Figure 2 are therefore the same as previously described. Figure 2 therefore illustrates the key 104 in a fully depressed position, although in other examples, the pressed position shown in Figure 2 may not be a fully depressed position. The key 104 is configured to pivot about the pivot axis 106 from the rest position to the fully depressed position via an intermediate pressed position. As the key pivots, the user applies a force to the free end 124, causing the key to move through these positions. When the key is in the intermediate pressed position, such as halfway between the rest position and the fully depressed position, a force greater than approximately 0.60N is required to overcome the restoring force of the spring. For example, to move the key to the intermediate pressed position, a force of around 0.65N may be necessary, whereas a force of approximately 0.70N might be needed to fully depress the key. Due to the form of the spring 110 and the offset arrangement of the first and second locations 114, 116, when the key 104 is pressed, the spring 110 compresses, creating a sensation that mimics the feel of an acoustic piano. This tactile feedback is beneficial for musicians / users seeking a realistic playing experience on an electronic keyboard. Dual Sensor Configuration and Key Assembly Components Figure 3 shows a variation of the keyboard shown in Figures 1 and 2, and in particular the keyboard 102 includes two sensors 112, 302 instead of a single sensor. Figure 3 is a perspective view of the key 102 in a rest position. Other than there being two sensors, the features shown in Figure 3 are the same as those illustrated in Figures 1 and 2. As mentioned, in this example, rather than a single pressure sensor, there are two switch type sensors, those being the sensor 112 and additional sensor 302. Both sensors are configured to be activated in a binary manner, and are either on or off. The sensor 112 generates a sound signal upon activation, while the additional sensor 302 generates an additional sound signal upon activation. As above, the key 104 itself does not directly contact the sensor 112 or the additional sensor 302. Figure 4 shows the keyboard 102 and key 104 of Figure 3 at a later time after a user has fully pressed down the key 104. The user applies a force to the free end 124 of the key 104, causing it to pivot through various positions, including an intermediate pressed position before reaching the fully depressed position shown in Figure 4. As mentioned above, in some examples, the pressed position shown in Figure 4 may not be a fully depressed position. The key 104 pivots from the rest position to the fully depressed position via the intermediate pressed position. When the key 104 is in the intermediate pressed position (not shown in either Figures 3 or 4), the spring 110 transfers a force to the sensor 112 at a second location 116 along its length. When the key 104 is in the fully depressed position, the spring 110 transfers a force to the sensor 112 at the second location 116 along its length and transfers a force to the additional sensor 302 at a further location 304 along its length. Accordingly, initially, sensor 112 is activated, producing the sound signal and as the key 104 is further pressed, additional sensor 302 is subsequently activated, generating an additional sound signal. This sequential activation provides another means for determining a key press velocity, without needing pressure sensors, for example. In this configuration, the spring 110 directly contacts the sensors, as there is no pressing element depicted in Figures 3 and 4. However, in other examples, one or more pressing elements could be used to transfer force from the spring 110 to either or both of the sensors 112, 302. Protruding Key Portion and Rest Position Configuration Figure 5 includes the features discussed in relation to Figures 1 and 2, but in contrast to Figures 1 and 2, the spring 110 has a slightly different form / shape, and the key 104 also includes the protruding portion 502. The spring 110 and / or the protruding portion and / or the pressing element(s) of Figure 5 may be included in any of the other examples described previously or herein. The key press assembly further comprises a pressing element 126 extending from the spring 110 at the second location 116. The pressing element 126 is moveable with the spring 110 and is positioned along the spring 110 such that the spring transfers the force to the sensor 112 via the pressing element 126. The pressing element 126 comprises a protrusion, such as a dome-shaped protrusion, which contacts the sensor 112. In some examples, the pressing element may form part of the spring (for instance, it may be a protruding portion of the spring), or it may be coupled to the spring, as in this example, and is made from a different material to the spring, such as silicone. The pressing element may be formed from a resilient material to provide an improved tactile response. In this example, when the key 104 is in the rest position, the pressing element 126 abuts the sensor 112 and applies a force to the sensor that is less than a threshold force required to cause the sensor to generate a sound signal. The threshold force may be around 0.2N, for example. In alternative examples, however, there may be a gap or space between the sensor(s) and pressing element(s). The key 104 comprises a protruding portion 502 extending from the key. The protruding portion 502 is dimensioned such that when the key is in the fully depressed position (to be discussed below, with reference to Figure 6), the protruding portion 502 is configured to transfer a force to the spring 110. In particular, the protruding portion 502 contacts the spring 110 or the pressing element 126, when the key is in the fully depressed position. When the key is in the rest position (shown in Figure 5), the protruding portion 502 and spring 110 are spaced apart by a gap 506. Figure 6 is a cross-sectional view showing the key 104 in the fully depressed position with the protruding portion 502 on the key 104. In this view, when the key 104 is fully depressed, the protruding portion 502 contacts the pressing element 126 or the spring 110 near, or at, the second location 116 along the spring 110. The point of contact between the pressing element 126 or the spring and the protruding portion 502 is referred to as the fourth location 604. As mentioned, the key 104 comprises a protruding portion 502 extending from its underside. When the key 104 is in the fully depressed position, the protruding portion 502 transfers the force to the spring 110 at the fourth location 604, which is closer to the second location 116 than the first location 114. As shown, in this example, the second and fourth locations 116, 604 are not offset from each other along the length 602 of the spring and are aligned or substantially aligned, situated on different sides of the spring, such as a bottom side and a top side of the spring 110. In the fully depressed position, the protruding portion 502 is configured to abut or contact the spring 110 or the pressing element 126 affixed to the spring. As mentioned, the protruding portion 502 can improve the transfer of force to the spring, which is useful for pitch bending. When the key 104 is in the rest position or the intermediate pressed position, the protruding portion 502 and the spring 110 are spaced apart by a gap. This gap ensures that no force is transferred to the spring 110 when the key is not fully depressed. The protruding portion 502 may extend from the underside of the key towards the spring and / or a pressing element. Figure 6 also illustrates the length 602 of the spring, which could be measured along the spring itself or as a projected length onto the base 108. Although not visible in this view, the protruding portion 502 may comprise a first leg and a second leg, which will be described below. As shown in Figures 5 and 6, a sensor support 504 is arranged on the base 108, and the sensor 112 is coupled to the sensor support. In other examples, such as the example of Figures 1 and 2, the sensor is coupled directly to the base 108. Although not visible in Figures 5 and 6, there may be first and second sensors associated with the key 104. Each may be activated separately, as will be discussed below. Isolated Spring Configuration and Forked Portions Figure 7 is a plan view of the spring 110 of Figures 5 and 6 shown in isolation. Figure 8 shows the spring of Figure 7, but from an underside of the spring. As shown, the spring 110 is forked and has a first forked portion 702 and a second forked portion 704. The spring 110 may be used in any of the musical instruments described above or herein. In this example, the spring 110 is a flat lever spring. The first and second forked portions 702, 704, extend at least partially along the length 602 of the spring 110. The forked profile allows separate lateral forces, such as side-to-side or rocking forces, to be applied to the key 104 and transferred to first and second sensors 112, 708. This can be used for pitch bending or determining proper finger positioning on a key. The sensors 112, 708 in Figure 7 are shown with dashed outlines because they are arranged underneath / behind the spring 110, and are therefore obscured from view. The first and second sensors 112, 708 may form a sensor array or part of a sensor array. Figure 7 illustrates a gap 712, which separates the first forked portion 702 from the second forked portion 704. This separation allows for independent movement of the forked portions, facilitating the transfer of force to the respective sensors 112, 708. The gap 712 may extend along the width of the spring 110, ensuring proper alignment and functionality of the parts. The spring 110 is configured such that the first forked portion 702 transfers a force to the first sensor 112 via a first pressing element 126. Similarly, the second forked portion 704 transfers force to the second sensor 708 via a second pressing element 706. The first pressing element 126 extends from the first forked portion 702 and is moveable with it, and is positioned to transfer a force to the first sensor 112. The second pressing element 706 extends from the second forked portion 704 and is moveable with it, and is positioned to transfer a force to the second sensor 708. Although not shown in Figures 7 and 8, the key 104 may include a protruding portion with a first leg and a second leg. The first leg can transfer a force to the first forked portion 702, such as via the first pressing element 126, while the second leg can transfer a force to the second forked portion 704, such as via the second pressing element 706. The pressing elements 126 and 706 may be optional and may form part of a single pressing element rather than being separate elements. They can be made of silicone and may either contact their respective sensors in the rest position or be spaced apart by a gap. The key press assembly is configured such that when the key is arranged in the pressed position (such as an intermediate or fully depressed position), the spring 110 transfers a force to the second sensor 708 at an additional location 710 along the length of the spring. This additional location 710 is on the second forked portion 704, such that the force is transferred from the second forked portion to the second sensor 708. Similarly, the second location 116 is on the first forked portion 702, such that a force is transferred from the first forked portion 702 to the first sensor 112. In this example, the second location 116 and the additional location 710 are not offset from each other along the length 602 of the spring 110 (i.e., they are aligned or substantially aligned with each other along the length 602 of the spring 110). Both the first sensor 112 and the second sensor 708 are pressure sensors, such as force-sensitive resistor (FSR) sensors. As shown most clearly in Figure 8, the pressing elements 126, 706 include domed portions that contact the first and second sensors 112, 708, respectively. Figure 9 is a side view of the spring 110 shown in Figures 7 and 8. As shown, the spring 110 has a stepped configuration. The stepped configuration of the lever spring includes one or more sloped or inclined sections and one or more level or horizontal sections. In particular, the spring 110 includes a first level section 902, a first inclined section 906, a second level section 904, a second inclined section 904 and a top section 910. In this example, the lever spring 110 is affixed to the base 108 at the first level section 902. The first level section 910 therefore provides stability and support for the spring 110 when forces are applied. The first level section 902 is connected to the second level section 904 by the first inclined section 906. The first inclined section 906 allows for a change in elevation between the two level sections, facilitating a smoother transfer of forces through the spring. The pressing element(s) 126, 706 are coupled or affixed to the lever spring 110 on the second level section 904. In this example, the pressing element(s) 126, 706 also extend along the spring 110 onto the second inclined section 908. Extending from the second level section 904 is the second inclined section 908, which leads to a top section 910. The top section 910 is the area where the key 104 may contact or abut the spring. The top section 910 includes the first location 114, where a force is transferred to the spring 110 from the key 104. This configuration ensures that the applied forces are effectively transferred through the spring to the sensors. The first forked portion 702 is hidden behind the second forked portion 704 in this view. Similarly, the first pressing element 126 is also hidden behind the second pressing element 706. Figure 10 shows a perspective view of the keyboard 102 and key 104 shown in Figures 5 and 6. In this example, the key 104 is in a rest position. In this example, the forked nature of the spring 110 is more clearly visible. In addition, Figure 10 also illustrates the protruding portion 502, which includes a first leg 1002 and a second leg 1004. Other features shown in Figure 10 are the same as those previously described, so will not be described again. The first leg 1002 is configured to transfer a force to the first forked portion 702, while the second leg 1004 is configured to transfer a force to the second forked portion 704. When the key 104 is pressed, such as fully depressed, the first leg 1002 may contact or abut the first forked portion 702 or a pressing element, such as first pressing element 126. Similarly, the second leg 1004 may contact or abut the second forked portion 704 or a pressing element, such as second pressing element 706. As mentioned, the configuration of the first and second legs allow for differentiated force application to the corresponding forked portions of the spring. This arrangement enhances the sensitivity of the key press detection by distributing the force more precisely. As a result, the accuracy of the key press detection is improved, providing a more responsive user experience. This is particularly useful for pitch bending, as mentioned. Unlike the example pivoting mechanism shown in Figures 1 to 4, the key 104 of this example has a through hole 120 formed in one end. The through hole 120 can receive an axle formed on another component of the keyboard 102. However, in other examples, the pivoting mechanism may be the same as in Figures 1 to 4. Additional Details and Variations In one example, the spring 110 may be configured as a flat lever spring having a stepped configuration. This configuration may include one or more sloped or inclined sections and / or one or more level or horizontal sections. The flat lever spring may be affixed to the base 108 at a first level section, and it may further comprise a second level section. These sections can be joined by an inclined portion. A pressing element 126 may be coupled or affixed to the lever spring on the second level section, arranged to press the sensor 112. The second inclined portion may extend from the second level section to a top portion, with the pressing element extending along the spring onto the second inclined portion. The key 104 may contact or abut the spring at the top portion, which includes the first location. Alternatively, the spring 110 may be a coiled lever spring comprising a first leg and a second leg. These legs can separately transfer forces to separate sensors, in the same manner as described for the flat lever spring. The coiled lever spring can be used in combination with the pressing element(s), which may be positioned along the spring to transfer forces to the sensors. In another example, the spring 110 may be a forked flat lever spring, comprising at least a first forked portion and a second forked portion. A forked profile can allow lateral forces to be applied to the key and transferred to the sensors. This configuration may be useful for pitch bending or determining proper finger positioning on a key. Separate forces can be applied to separate sensors, allowing lateral forces to be measured independently and potentially used to control a pitch bend. The sensor 112 in these examples may be a pressure sensor, such as a forcesensitive resistor (FSR), which changes its resistance when a force or pressure is applied. The sensor may be arranged on the base 108 and configured to generate a sound signal indicative of the magnitude of the force applied. There may be one or more sensors associated with each key 104, and the sound signal can be either an analogue or digital signal. In some examples, the pressing element 126 may comprise a protrusion, such as a dome-shaped protrusion, which contacts the sensor. This pressing element can be formed from a resilient material, such as silicone, to provide an improved tactile response. The pressing element may be part of the spring 110 or coupled to it, and it is positioned such that the spring transfers the force to the sensor via the pressing element. Additionally, when the key 104 is in the rest position, the pressing element 126 may either abut the sensor 112 and apply a force that is less than a threshold force required to generate the sound signal or be spaced apart by a gap. This gap, if present, may be less than or equal to around 0.3mm. When the key 104 is moved, the pressing element 126 moves accordingly, transferring the necessary force to the sensor 112 to generate the sound signal. The option of using either a flat or coiled lever spring provides flexibility in design and manufacturing. This versatility allows for different mechanical properties to be tailored to specific requirements, such as varying force feedback or durability. Manufacturers can choose the most suitable spring type based on the desired tactile response and production methods. The capability to detect intermediate pressed positions allows for nuanced control over the musical instrument. This feature enables the generation of varied sound outputs based on the degree of key depression. Musicians can achieve greater expressiveness and dynamic range in their performances. Multiple key press sensitivity is facilitated by the configuration of the spring and sensor system. This setup ensures that each key press, whether partial or full, is accurately detected. The result is a more responsive and versatile keyboard that can accommodate complex playing techniques. The pressure sensor's ability to generate sound signals based on the magnitude of the applied force enables a dynamic sound response. This allows the musical instrument to produce varying sound intensities depending on how hard or soft a key is pressed. As a result, users can achieve a more expressive and nuanced performance. The configuration of the pressure sensor to respond to different force magnitudes enhances the expressive capabilities of the keyboard. This feature allows musicians to convey subtle variations in their playing style, similar to an acoustic instrument. Consequently, it provides a more authentic and engaging playing experience. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications may also be employed without departing from the scope of the disclosure, which is defined in the accompanying claims.

Claims

1. A musical instrument, comprising:a keyboard having a key configured to pivot about a pivot axis from a rest position to a pressed position;a base;a key press assembly associated with the key, and comprising:a spring arranged between the base and the key and being affixed to at least one of the key and base, the spring being configured to be in a compressed state when the key is arranged in the pressed position;a sensor associated with the key and configured to generate a sound signal associated with movement of the key;wherein the key press assembly is configured such that when the key is arranged in the pressed position:the key contacts the spring at a first location along a length of the spring; andthe spring transfers a force to the sensor at a second location along the length of the spring to generate the sound signal, the first and second locations being offset from each other along the length of the spring.

2. A musical instrument according to claim 1, wherein the spring is a lever spring.

3. A musical instrument according to claim 2, wherein the lever spring is a flat leverspring or a coiled lever spring.

4. A musical instrument according to any preceding claim, wherein:the pressed position is a fully depressed position;the key is configured to pivot about the pivot axis from the rest position to the fully depressed position via an intermediate pressed position; andthe key press assembly is further configured such that the spring transfers a force to the sensor when the key is arranged in the intermediate pressed position.

5. A musical instrument according to any preceding claim, wherein:the spring is forked, and comprises at least a first forked portion and a second forked portion; andthe first and second forked portions extend at least partially along the length of the spring.

6. A musical instrument according to claim 5, wherein:the sensor is a first sensor, and the key press assembly further comprises a second sensor;the second location along the length of the spring is on the first forked portion, such that the force is transferred from the first forked portion to the first sensor; andthe key press assembly is configured such that when the key is arranged in the pressed position, the spring transfers a force to the second sensor at a third location along the length of the spring to the generate a second sound signal, wherein the third location is on the second forked portion, such that the force is transferred from the second forked portion to the second sensor.

7. A musical instrument according to claims 5 or 6, when appendant to claim 4, wherein the key comprises a protruding portion extending from the key, the protruding portion being dimensioned such that:when the key is in the fully depressed position, the protruding portion is configured to transfer a force to the spring; andwhen the key is in the rest position and intermediate pressed position, the protruding portion and spring are spaced apart by a gap.

8. A musical instrument according to claim 7, wherein the protruding portion comprises a first leg and a second leg, the first leg being configured to transfer a force to the first forked portion and the second leg being configured to transfer a force to the second forked portion.

9. A musical instrument according to any preceding claim, wherein:the key press assembly comprises a pressing element extending from the spring at the second location;the pressing element is moveable with the spring; andthe pressing element is positioned along the spring such that the spring transfers the force to the sensor via the pressing element.

10. A musical instrument according to claim 9, wherein one of:when the key is arranged in the rest position, the pressing element and sensor are spaced apart by a gap; andwhen the key is arranged in the rest position, the pressing element abuts the sensor and applies a force to the sensor that is less than a threshold force required cause the sensor to generate the sound signal.

11. A musical instrument according to claims 9 or 10, when appendant to claim 6, wherein:the pressing element is a first pressing element extending from the first forked portion and being moveable with the first forked portion, and the key press assembly further comprises a second pressing element extending from the second forked portion and being moveable with the second forked portion;the first pressing element is positioned along the first forked portion such that the spring transfers the force to the first sensor via the first pressing element; andthe second pressing element is positioned along the second forked portion such that the spring transfers the force to the second sensor via the second pressing element.

12. A musical instrument according to any preceding claim, wherein the sensor is a pressure sensor configured to generate a sound signal indicative of a magnitude of the force applied to the sensor.

13. A musical instrument according to any of claims 1 to 12, further comprising an additional sensor associated with the key and configured to generate an additional sound signal associated with movement of the key, wherein the key press assembly is configured such that:the sensor is activated before the additional sensor; andwhen the key is arranged in a further pressed position, different to the pressed position, the spring transfers a force to the additional sensor at a further location along the length of the spring to generate the additional sound signal, the second and further 5 locations being offset from each other along the length of the spring.

14. A musical instrument according to any preceding claim, wherein the spring is affixed to the base.10 15. A musical instrument according to any preceding claim, wherein the musicalinstrument is an electronic keyboard.s

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