Sensor array equipped with a soft force sensor

Abstract

A sensor array for measuring a force is provided. The sensor array includes a plurality of soft sensor elements, each of the plurality of soft sensor elements including a sensor, a deformable element configured to be deformable by the force, and at least one element that reacts to the sensor to measure the force by deformation of the deformable element, and at least a part of the deformable element extends between the sensor and the at least one sensor-reacting element. Further, a method for measuring a force using the sensor array is also provided.

Description

Technical Field

[0001] The present invention relates to a sensor array provided with a soft force sensor array and a method for measuring force or position using the same.

Background Art

[0002] A force sensor returns an electronic signal proportional to the mechanical force applied to the sensor. In other words, a force sensor can be said to convert the magnitude of the applied force into an electronic signal correlated therewith. The forces measured by a force sensor can be mechanical quantities such as tension, pressure, mass, torque, strain, and internal stress. Nowadays, force sensors have become essential core components for power equipment, engineering machinery, various machine tools, and industrial automation systems.

[0003] Currently, force sensors are applied in a wide range of fields from the automotive industry to the medical field.

[0004] For example, by using an existing force sensor, it is possible to measure in real time the force applied to a workpiece during an automatic manufacturing process and control the force applied to the workpiece. Using this method, the force load applied to the workpiece during the manufacturing process can be controlled and potentially limited. This is particularly important when the workpiece is delicate.

[0005] However, force measurement can also be important when specifying the hardness of an object. This is because hardness is defined as the degree of resistance that an object can withstand without deforming in response to an applied force.

[0006] A force sensor is often used in conjunction with a multi-axis robotic device to move, position, hold, or sense an object. Examples of multi-axis robotic devices include robotic fingers and gripping devices. A robotic finger resembles a humanoid finger but can move in more directions than a humanoid finger. By attaching a force sensor to the tip of the finger, it becomes possible to sense an object. A gripping device is a mechatronics device that applies a force and the corresponding reaction force to an object. By applying the force and the reaction force, the object is pressed against each part of the gripping device, and the object comes into contact with each part of the gripping device.

[0007] However, the sensors used in the prior art had the problem that they could not measure the force applied to an object with sufficient accuracy. Therefore, there was a risk of damaging the object because the applied force was too strong or too weak.

Summary of the Invention

Problems to be Solved by the Invention

[0008] Therefore, since it is necessary to prevent the applied force from becoming too strong or too weak, there is a need to measure force with high precision.

[0009] In addition, in all application fields, the workpiece, object, or tissue to which force is applied may have an irregular shape. Therefore, there are cases where the force applied to the object also needs to be adapted to such a shape. For this reason, there is a need to measure the force applied to the object not only accurately in terms of time but also with a large measurement surface area. Depending on the application, it may even be necessary to adapt the sensor itself to an irregular shape.

Means for Solving the Problems

[0010] The above needs can be met by a sensor array for measuring force according to the present invention. The sensor array includes a plurality of soft sensor elements. In the present disclosure, "a plurality" includes any number of two or more elements.

[0011] The soft sensor element according to the present invention includes a sensor, a deformable element, and at least one element that reacts to the sensor. The sensor can be a semiconductor die, a bare die, an unpackaged chip, or an unpackaged integrated circuit. The sensor can be wrapped with a deformable element, thereby immobilizing and sealing the sensor, eliminating the need to use a lead frame for the sensor or overmold the sensor. Therefore, it becomes possible to make the sensor array flexible or form it into various shapes. The sensor reaction element may be composed of a single element or a plurality of elements. Also, when composed of a plurality of elements, they may be elements with the same shape and size or elements with different shapes and sizes.

[0012] The deformable element can be configured to be deformable, and at least a part of the deformable element can extend between the sensor and the sensor reaction element. Thereby, it is possible to provide a pocket that forms a kind of empty space where the material of the deformable element does not reach in the deformable element. This empty space can be filled with air, the ambient medium, or an inert gas. Still, it remains that the pocket constitutes a part of the deformable element. Therefore, even when there is an empty space between the sensor reaction element and the sensor, it is included in the state where the deformable element extends between the sensor reaction element and the sensor. In the case of such a configuration, it can also be said that a part or all of the sensor reaction element, the sensor, or both can extend into the empty space of the deformable element. Also, it can be said that a part of the sensor reaction element is embedded or attached to the wall of the formed pocket.

[0013] When an element is "deformable", it means that when an external force acts on it, the shape and volume of the element change. Preferably, "deformable" means that the deformable element undergoes elastic deformation, that is, when the external force no longer acts on the deformable element, the deformable element returns to its original shape and volume. The deformable element can be an elastic element and can include an elastomer. In some cases, the elastomer can be a biocompatible elastomer, which enables the soft sensor array to be used for medical purposes. Also, in some cases, pockets can be formed in the deformable element, and when deformed by an external force, the deformable element can extend into this pocket. For example, when an external force that greatly deforms the deformable element is applied, due to this force, a part of the deformable element can be displaced and extend into one of the pockets. Thus, the pocket becomes a hollow space into which the material of the deformable element can extend when the deformable element is deformed. Forming the pocket not only provides the advantage of enabling the deformable element to extend into the pocket, but also the pocket can give a certain degree of stability to the deformable element.

[0014] Furthermore, due to the deformable element, when a force is applied, not only can the sensor reaction element move to some extent and its position can be changed, but each sensor can also be individually sealed as a sensor chip and electrically insulated, so there is no need to package the sensor chip, and it becomes possible to realize a very thin and flexible sensor array for the sensor array itself. Additionally, since there is no package surrounding each chip, there is also the advantage that the sensor chips of different soft sensor elements can be arranged close to each other, essentially improving the spatial resolution of the sensor array.

[0015] During operation, a force acts on the soft sensor element from an object. Strictly speaking, the operations according to the present disclosure also include cases where a force acts on the object from the soft sensor element pressed against the object. However, in these two cases, since only the same magnitude of force acts in the opposite direction, there is no distinction between them in the present disclosure. When a force acts, either the sensor reaction element or the deformable element comes into contact with the object. This contact may be direct or indirect. Therefore, the sensor reaction element or the deformable element can be in direct or indirect contact with the object. In the case of direct contact, at least one surface of the sensor reaction element or the deformable element is in contact with at least one surface of the object. In the case of indirect contact, at least some other part is interposed between the two contact surfaces. The intervening substance for the sensor reaction element may be a deformable element. In that case, the sensor reaction element is in indirect contact with the object, but the deformable element is in direct contact with the object. In this case, it can also be said that the sensor reaction element is embedded in the deformable element. Therefore, the sensor reaction element can be partially or completely embedded in the deformable element. When the sensor reaction element is completely embedded in the deformable element, all surfaces of the sensor reaction element are in contact with the deformable element. It can also be said that the material of the deformable element surrounds the sensor reaction element. Conversely, when the deformable element is in indirect contact with the object, the sensor reaction element may be in direct contact with the object. However, this also includes cases where the sensor reaction element and the deformable element are only in indirect contact with the object, but some other part is in direct contact with the object. For example, there may be a case where the sensor reaction element is embedded in a plastic piece and this plastic piece is in contact with the deformable element. In another example, although it is the same in that the plastic piece is brought into contact with the deformable element and the object, the sensor reaction element can be embedded in the deformable element, or the sensor reaction element can be brought into contact with the deformable element and the plastic piece. In these three cases, the object is in direct contact with the plastic piece, but not in direct contact with the sensor reaction element or the deformable element.

[0016] At least a part of the deformable element extends between the sensor and the sensor reaction element, or the deformable element surrounds the sensor reaction element, so that the sensor reaction element is held in a specific relative position with respect to the sensor by the deformable element. This position can be defined as the first position of the sensor reaction element with respect to the sensor. It can also be said that the sensor reaction element is held at a specific distance from the sensor by the deformable element. When the deformable element deforms, the sensor reaction element also moves in the direction in which the deformable element deforms in conjunction with this. If this deformation is compression, the distance from the sensor reaction element to the sensor becomes shorter, and conversely, if this deformation is elongation, the distance from the sensor reaction element to the sensor becomes longer.

[0017] When the deformable element "deforms", it means that at least one spatial extension range of the deformable element in at least one spatial dimension changes. Therefore, the deformable element of the sensor mechanism can have "softness" in the sense of being deformable. Such deformability, specifically, how much the deformable element can deform depends on the material used for the deformable element. For example, the deformable element can be made of a flexible material. A flexible material is a material that returns to its initial shape when an external force is removed. Therefore, when the external force is removed, the deformable element can return to its initial shape. Therefore, the deformable element can also be called a flexible element or an elastic element. In another example, the deformable element can be an elastomer. Usually, an elastomer is formed by monomers bonded by weak intermolecular forces. Since the intermolecular forces of the chemical elements of the elastomer are weak, the structure of the compound can be changed without causing damage to the covalent bond or only by damaging a part of the covalent bond. And this property makes the elastomer a material with both viscosity and elasticity. Therefore, the elastomer can be deformed by an external force.

[0018] When the deformable element deforms, the sensor reaction element moves to a second position different from the first position. When the deformable element is compressed, the second position of the sensor reaction element is closer to the sensor than the first position of the sensor reaction element. On the other hand, when a tensile force is applied, the second position of the sensor reaction element is farther from the sensor than the first position. Then, the sensor of the sensor mechanism can detect such a change in position by reacting to the sensor reaction element. When the sensor reaction element reacts to the sensor, the measurement value of the sensor is affected by the sensor reaction element. It can also be said that a coupling is generated between the sensor reaction element and the sensor due to a physical action peculiar to the sensor and the sensor reaction element. This coupling between the sensor reaction element and the sensor changes depending on the relative position of the sensor reaction element with respect to the sensor. Also, since such a coupling changes depending on the position, it can also be said that the measurement value of the sensor is a unique function of the relative position of the sensor reaction element with respect to the sensor. In this sense, the sensor used for the soft sensor element can be said to be a distance measuring sensor. Such a sensor returns an electronic signal proportional to the relative position of the sensor reaction element with respect to the sensor.

[0019] In a state where no external force is applied to the soft sensor element, the deformable element does not deform, and the sensor reaction element is located at a first position with respect to the sensor. Therefore, the sensor can return a first signal corresponding to a measured value indicating that the force is zero. On the other hand, when a finite external force is applied to the sensor reaction element, the deformable element deforms, and the sensor reaction element moves to a second position different from the first position. Due to the relative position of the sensor reaction element with respect to the sensor becoming the second position, the signal of the sensor also becomes a second signal corresponding to the applied external force. Therefore, the spatial difference between the first position and the second position can be uniquely associated with the applied external force respectively by mapping. This spatial difference is a difference that includes the axial difference, the rotational difference, or both between the two positions. This spatial difference can also be called the displacement of the sensor reaction element. Such mapping can be performed using a non-linear model. This is because the applied force does not change in proportion to the displacement of the sensor reaction element but can change according to a non-linear function. Since the change in the interaction between the sensor reaction element and the sensor can be measured with high precision, it becomes possible to reliably perform high-precision measurement, derivation, calculation, or estimation of the applied force. In other words, it becomes possible to infer the external stimulus that caused the variation, that is, the applied external force, from the variation in the influence exerted by the sensor reaction element on the sensor. For example, as described above, the displacement of the sensor reaction element with respect to the sensor can be sensed by the sensor.

[0020] The soft sensor element can be configured to measure the position change of the sensor reaction element using a magnetic field. This magnetic field can be the magnetic field created by a permanent magnet (for example, the sensor reaction element can be a permanent magnet), or it can also be a magnetic field induced by a change in an electric field (for example, the sensor can be configured to generate a magnetic field that couples with the element by generating eddy currents in the sensor reaction element).

[0021] According to the present invention, a plurality of soft sensor elements are arranged to form a sensor array. By adopting such a configuration, not only can the force acting on one sensor be accurately measured, but also how the force acts on a plurality of sensors can be measured. For example, since it has spatial sensitivity, the sensor array can measure the spatial distribution of the applied force with high precision. As a result, not only can the position where the force exceeding the threshold is applied be specified, but also when continuous measurement is performed with the sensor array, or when repeated measurement is performed at individual time instances with the sensor array, how the applied force changes over time, or how the applied force propagates over time can be specified by the sensor array. Further, since the inactivation and encapsulation of the sensor can be performed by the deformable element, adjacent soft sensor elements can be arranged close to each other, so that the force can be specified with high resolution and the position where the force is applied can even be specified.

[0022] One of the advantages of the present invention is that the sensor array can be bent or rounded thanks to the deformable element, so that the sensor array can be adapted to any surface.

[0023] The sensor array according to the present invention is deformable and thus particularly useful for measuring the force applied to an object having any shape. Such usefulness can be demonstrated not only in the automotive industry but also in medical applications. For example, by using the sensor array according to the present invention in palpation in minimally invasive surgery, the absolute or relative hardness of an object or each part of the object can be specified, because the hardness is obtained as the tolerance that the object can withstand without being deformed against the applied force. Further, based on the measured values, abnormal tissue formation can also be identified. In this case, a high resolution is required to identify even minor abnormalities. Since the sensor array according to the present invention is configured to be bendable or roundable, the sensor array can be adapted to any surface such as the outer surface of a diagnostic device or instrument, or the surface of a glove used by a surgeon.

[0024] To further improve the spatial sensitivity of the sensor array, a plurality of soft sensor elements can be spatially distributed in a predetermined manner. In a preferred embodiment of the present invention, the plurality of soft sensor elements are arranged in a row. For example, the sensor array can be spatially extended along a certain spatial direction, and the soft sensor elements can be arranged in a row in a direction parallel to this spatial direction. Thereby, it becomes possible to measure how the applied force acts along the straight line defined by the row of the plurality of soft sensor elements, or how the applied force propagates along this straight line.

[0025] In another preferred embodiment of the present invention, the plurality of soft sensor elements are arranged in a grid pattern. This grid can be a two-dimensional grid. Also, this grid can be a so-called regular grid having a structured topology. A regular grid is a grid formed by orthogonal parallel lines, and an example thereof is a Cartesian grid in which the intersecting lines form a 90-degree angle. As other examples of regular grids, grids in which the intersecting lines form other angles, such as a hexagonal grid or a rhombic grid, are also possible. Alternatively, an irregular grid pattern can also be used.

[0026] When arranged in a grid pattern, the soft sensor elements can be arranged on a plane. Alternatively, a curved grid, for example, a grid curved in a convex or concave shape, can also be used. Also, it is possible to configure such that the soft sensor elements of the sensor array can be bent into a curved shape after being arranged in a planar grid pattern. In this case, it can also be said that the grid spreads (occupies the surface) along the surface to which the sensor array is attached.

[0027] Compared with the above-described embodiment in which a plurality of soft sensor elements are arranged in a row, by arranging them in a grid pattern, it becomes possible to measure the distribution and propagation of the applied force along two spatial directions (two spatial directions as the directions in which the grid spreads). Also, a more complex arrangement corresponding to a three-dimensional array can be adopted. For example, the sensor array can be set on a curved surface. Such a curved surface may be a convex surface or a concave surface. An example thereof is a spherical arrangement. For example, the sensor array can be arranged at the fingertip of a robotic gripping device, adapted to smoothly follow the shape of the fingertip, form an outer layer with a deformable element, and configure the gripping force of the gripping device to be recorded by this outer layer. Also, the arrangement of the sensors can be adapted to cover at least a part of the surface of the glove. Furthermore, it is also possible to wrap some element with a sensor array having a shape such as a sphere so that the element is located inside the wrapped surface, and apply a force to the deformable element according to the movement of the element wrapped by the sensor array.

[0028] In some preferred embodiments of the present invention, a plurality of soft sensor elements can be arranged on a substrate. The substrate can be a carrier substrate such as a printed circuit board (PCB), for example. The sensors of the plurality of soft sensor elements can be mounted on the substrate. Thereby, a flip-chip design can be adopted in which the sensors are constituted by dies and the active surfaces of the dies are arranged on the substrate. Here, the active surface refers to the surface of the sensor provided with the circuit and the connection portion to the external circuit. Further, this active surface can be configured to record the displacement of the sensor reaction element. However, the configuration in which the surface other than the active surface is arranged on the substrate to mount the sensor and the sensor is connected to the circuit of the substrate by wire bonding is also included in this specification. Also, it is possible to adopt a configuration in which the active surface does not record the displacement of the sensor reaction element, that is, a configuration in which the sensor has a surface for connection to the substrate and a surface for recording displacement on opposite surfaces. Also in this case, a flip-chip design in which the active surface is directly connected to the substrate can be adopted, or the active surface can be connected to the substrate by wiring with the active surface facing the opposite side of the substrate.

[0029] In some cases, for example, in order to adapt the surface of the sensor array to smoothly follow the surface of an object of an arbitrary shape, or to wrap and grip an object with the sensor array, or to attach the sensor array to a device (for example, a medical instrument) or a (non-flat) gripping device, it may be desired to make the sensor array bendable or rollable. In such a case, a thin sensor array may be desired. Therefore, in that case, the thickness of the substrate can be about 60 to 600 μm, and the thickness of the deformable element can be about 4 mm. Preferably, the ratio of the thickness of the substrate to the thickness of the deformable element is 0.1% to 15%, more preferably 1% to 5%.

[0030] In some preferred embodiments of the present invention, the pitch between two adjacent elements of a plurality of soft sensor elements can be made equal. The pitch can be measured, for example, as the distance from the center point of a certain soft sensor element to the center point of the adjacent soft sensor element. Alternatively, it can also be measured as the distance from the edge of a certain soft sensor element to the corresponding edge of the adjacent soft sensor element. This point will be described in detail in the description regarding the drawings (especially FIG. 4). By making the pitch equal, it becomes possible to measure the spatial characteristics of the applied force with a specific resolution associated with the pitch of the equal intervals.

[0031] Furthermore, each soft sensor element can have a specific size represented by, for example, the edge length or diameter of the sensor. It is preferable that the size of each sensor of the soft sensor element is the same. By using the same or similar types of soft sensor elements, the spatial resolution of the measurement by the sensor array is improved. The size of the sensor can be represented by L. And the pitch p between two adjacent soft sensor elements of a plurality of soft sensor elements can be p≦3L, preferably p≦2L, or p≦1.5L. Therefore, in some examples, the pitch can be 1.1 times, 1.5 times, 2 times, or 3 times the size of the soft sensor element. In other words, the array pitch of the soft sensor elements is on the same scale as the size of the soft sensor elements, thereby making it possible to manufacture a high-resolution sensor array (the resolution is inversely proportional to the pitch). Since the deformable element can be used to immobilize and seal the sensor, adjacent soft sensor elements can be arranged closely, which enables the realization of high resolution.

[0032] In still other embodiments of the present invention, the sensor of each soft sensor element of a plurality of soft sensor elements can be a multi-pixel sensor. The multi-pixel sensor can have two or more sensitive elements having a function of recording a change in the position of a sensor reaction element. For example, the multi-pixel sensor can have two sensitive elements (hereinafter also referred to as pixels). Preferably, the multi-pixel sensor can have four sensitive elements arranged in a 2×2 grid, but configurations having other numbers of sensitive elements (for example, but not limited to, 1×2, 2×3, or 3×3 grid arrangements) are also included in this specification. In the multi-pixel sensor, two or more sensitive elements can be arranged on the same die. By using the multi-pixel sensor, the spatial resolution of the sensor array can be improved, and it is also possible to suppress the influence from external factors other than the applied force. For example, when the soft sensor element measures the change in the position of the sensor reaction element using a magnetic field, the differential magnetic field can be measured by using the multi-pixel sensor, thereby suppressing the influence from the external magnetic field.

[0033] Thus, each sensitive element of the multi-pixel sensor can be configured to identify the force acting on the deformable element, the position of the force, or both. The identification of the position of the force can be performed based on the gradient or difference of the data obtained from two or more sensitive elements of one or more multi-pixel sensors. This has the advantage that it can suppress and even cancel out the influence of the external stray magnetic field.

[0034] Adjacent pixels of the multi-pixel sensor can have a first interval s1. In that case, the second interval s2, which is the interval between the last pixel of the multi-pixel sensor of the first sensor element and the first pixel of the multi-pixel sensor of the second sensor element, can be an interval smaller than or equal to the first interval s1. In this way, a uniform arrangement of the sensing elements can be realized. For example, when using a plurality of 1×2 multi-pixel sensors, the first interval s1 refers to the interval between two adjacent sensing elements within one 1×2 multi-pixel sensor. On the other hand, the second interval s2 refers to the interval between the second sensing element of the first 1×2 multi-pixel sensor and the first sensing element of the second 1×2 multi-pixel sensor. The same applies to other lattice-array multi-pixel sensors such as 2×2 multi-pixel sensors. In this case, the first interval and the second interval can be applied to both of the two lattice directions in which (2×2) sensing elements extend. Also, if the first interval s1 and the second interval s2 are made the same, the uniformity of the resolution of the sensor array can be ensured.

[0035] In some preferred embodiments, the pitch p between adjacent sensors can be correlated with the interval s1 between the sensing elements of the multi-pixel sensor. For example, the pitch p can be set such that p≦3s1.

[0036] In other preferred embodiments of the present invention, a plurality of soft sensor elements can be embedded in a common deformable element. In other words, a plurality of soft sensor elements can share a common deformable element.

[0037] However, when adopting common deformable elements, it may happen that the deformation of the deformable elements caused by the force applied at the first position extends to the second position close to the first position in terms of distance. Therefore, in some cases, so-called crosstalk may occur between adjacent soft sensor elements. This type of crosstalk is caused by the fact that adjacent soft sensor elements are mechanically coupled by common deformable elements. Therefore, in the sensor arrays of some preferred embodiments, mechanically separated portions can be provided. For example, a plurality of subsets of a plurality of soft sensor elements can be arranged in at least two portions of the sensor array, and these at least two portions can be mechanically separated. The step of mechanically separating the plurality of portions of the sensor array can be performed, for example, by separating the sensor array into a plurality of portions by the recesses of the common deformable element. Thereby, when the deformation of the deformable element occurs in the first portion, the situation where the deformation of the deformable element is also caused in the adjacent second portion due to the deformation does not occur. Therefore, each portion of the deformable element can be configured such that the portion deforms only when an external force is applied to a certain portion. The recesses act as an obstacle, and the propagation of deformation through the common deformable element does not occur beyond the recesses. Since the deformable element is separated into a plurality of portions by the recesses, it can also be said that the common deformable element includes a plurality of pillars (each pillar corresponds to a portion separated from other portions by one or more recesses). When two or more recesses are arranged substantially parallel to each other, the pillars can form a linear arrangement. In another example where two or more recesses are arranged in a grid pattern, the pillars can also form a grid pattern arrangement.

[0038] In a preferred embodiment, the soft sensor array can be composed of a plurality of portions, and each portion can be configured to include only one soft sensor element. In this case, high spatial resolution can be achieved while minimizing crosstalk.

[0039] In another preferred embodiment of the present invention, the sensor of the soft sensor element can be a passive magnetic sensor, and the sensor reaction element can be an element that generates a magnetic field (for example, a permanent magnet). The magnetic sensor is a sensor that measures at least one characteristic of the magnetic field generated from the sensor reaction element. A passive magnetic sensor means a sensor that detects at least one characteristic of the magnetic field generated by the sensor reaction element but does not generate the measured magnetic field itself. Generally, a magnetic field is a vector field. That is, the characteristics of the magnetic field at each point in space can be represented by a three-dimensional vector representing the magnetic field strength. The passive magnetic sensor can measure one or more magnetic fluxes obtained by projecting the magnetic vector field onto one or more surfaces associated with the passive magnetic sensor. Thus, in this case, it can be said that at least one characteristic to be measured is the magnetic flux passing through each surface. The measured magnetic flux is proportional to the density of the magnetic field lines penetrating each surface at an angle perpendicular to each surface. And when the magnetic flux passes through each surface, the passive magnetic sensor outputs a signal corresponding to each magnetic flux (for example, a current signal or a corresponding voltage signal). Specifically, the output signal can be proportional to the distance from the sensor reaction element to the sensor. When the position of the sensor reaction element changes, the position of the magnetic field lines also changes. Thus, the change in the position of the sensor reaction element is directly linked to the change in the magnetic flux measured by the passive magnetic sensor. The output signal can directly indicate how the position of the sensor reaction element has changed, and in addition to that, or instead of that, by further processing and synthesizing the output signal, it can also be configured to identify the relative position of the sensor reaction element with respect to the sensor. Therefore, an algorithm for identifying the position of the sensor reaction element from the magnetic flux measurement value signal can be configured to rely on the difference value between the signals. In addition to or instead of this, based on the signal measured for the displaced sensor reaction element after the deformable element has deformed and the signal measured for the sensor reaction element at the initial position before the deformable element deforms, it can be configured to calculate the gradient. And another algorithm can be used to estimate the applied external force from the position identified by the above algorithm.However, instead of obtaining the position of the sensor reaction element as the median value, the externally applied force can also be directly estimated from the magnetic flux measurement signal. That is, generally speaking, a change in the interaction between the sensor reaction element and the passive magnetic sensor causes a change in at least one characteristic of the magnetic field, which is measured by the passive magnetic sensor, and then, using an algorithm, the externally applied force that caused the change in such interaction can be estimated from at least one characteristic of the measured magnetic field.

[0040] In addition to or instead of this, the magnetic flux gradient can also be directly measured using a transducer that senses the magnetic field gradient. When the measurement signals are subtracted from each other, the influence of the static levitation magnetic field is canceled out. Therefore, by using the difference value or the gradient, it is possible to identify the position without being affected by the levitation magnetic field. In addition, the passive magnetic sensor can also measure the direction of the magnetic field intensity vector in addition to or instead of the magnetic flux. By measuring the direction of the magnetic field intensity vector, one or more angles representing the direction of the magnetic field in space can be obtained. Based on this direction, the force applied to the deformable element can be derived. Also, by utilizing the change in the direction of the sensor reaction element with respect to the sensor, it is also possible to derive at what angle the object deformed the deformable element. That is, it becomes possible to identify whether the applied force was a uniform force or a non-uniform force.

[0041] The passive magnetic sensor can be provided with at least one sensor element that measures at least one physical characteristic of the magnetic field. The at least one sensor element can be any of all devices suitable for measuring at least one characteristic of the magnetic field generated from the sensor reaction element, such as a magnetoresistive sensor or a Hall sensor.

[0042] In another preferred embodiment of the present invention, the sensor of the soft sensor element can be an active magnetic sensor, and the sensor reaction element can be targeted. An active magnetic sensor measures at least one physical property of a magnetic field. However, unlike the passive magnetic sensor described above, in the case of an active magnetic sensor, at least one magnetic field is generated by itself. In other words, an active magnetic sensor is a sensor that generates a magnetic field by itself. The active magnetic sensor observes the magnetic interaction between the magnetic field generated by the sensor itself and the target. The active magnetic sensor can be composed of one sensor element configured to perform both the generation of a magnetic field and the measurement of magnetic field fluctuations by a target. For example, the one sensor element can be adapted to operate as a magnetic field generator during a first period and as a detector of magnetic field fluctuations by a target during a second period. Alternatively, the active magnetic sensor can also be composed of at least two sensor elements. In that case, the at least two sensor elements can be separate sensor elements or can be the sensitive elements of a multi-pixel sensor as described above. And at least one of the at least two sensor elements can be configured to generate a magnetic field, and at least one of the other sensor elements of the at least two sensor elements can be configured to measure magnetic field fluctuations by a target. Note that the sensor element configured to measure the at least one physical property can be the same as the sensor element of the passive magnetic sensor described above. Thereby, the sensor element can be configured to measure the properties of a magnetic field, a magnetic field gradient, a differential magnetic field, or any combination thereof.

[0043] The generated magnetic field is affected by the target, and at least one physical property of the magnetic field affected in this way is measured by a sensor element configured to measure at least one physical property. The shape of the target can be a shape that is not rotationally invariant. Specifically, the target can be planar or substantially planar. Thereby, the target can have a shape that preferentially affects the magnetic field in a preferred direction. Such a direction can be substantially the same direction throughout the target. For example, by making the target have a structure in which induced current tends to preferentially flow in a specific linear direction, the influence of the target on the generated magnetic field can also be made directional. To have such a structure, the target can include at least one slit extending from one end of the target to the other end. However, different target designs are equally possible as well.

[0044] Alternatively, it can also be said that the target affects the magnetic flux coupling between the magnetic field generator and the detector that measures at least one physical property of the generated magnetic field. The target can include a soft magnetic material or a non-magnetic conductive material. Here, the soft magnetic material means that the magnetic material constituting the target is a material that is easily magnetized and easily loses magnetization. Also, it can be said that the soft magnetic material is a material characterized by rapidly losing magnetization when the external magnetic field is removed. The soft magnetic material is a material with a high relative permeability and / or a low coercive force. Coercivity (coercive field) may sometimes also be called magnetic coercivity or coercive force, and it is a measure indicating how well a ferromagnetic material can maintain magnetization without demagnetizing against an external magnetic field. A ferromagnetic material with a high coercive force is called a hard magnetic material and is used, for example, as a material for permanent magnets. On the other hand, a material with a low coercive force can be called a soft magnetic material. Also, it can be said that the soft magnetic material is a material with a small residual magnetization. Although not limited, generally, a magnetic material with a coercive force below 1000 A / m is called a soft magnetic material. However, this is only an example and should not be understood as an intention to limit.

[0045] When the target is made of a soft magnetic material, the target can affect magnetic flux coupling by concentrating the magnetic field lines of the generated magnetic field. The soft magnetic material can be made of an isotropic material having no preferred direction. On the other hand, when the target is made of a non-magnetic conductive material, energy can be dissipated by the induced current flowing in the conductive material of the target. The induced current can flow as an eddy current. In this case, the target affects magnetic flux coupling by causing losses in the generated magnetic field due to energy dissipation. Optionally, the target can be shaped to align the magnetic field lines of the generated magnetic field in a preferred direction. Additionally or alternatively, it can be said that the target functions as a magnetic field line rectifier that aligns the magnetic field lines in a preferred direction. When setting the position and orientation of the target such that the preferred direction of the magnetic field lines is the direction of the sensor element for measuring at least one physical property, the measured value of the at least one physical property takes a maximum value.

[0046] In another preferred embodiment of the present invention, the sensor array can further include a plurality of additional elements that respond to the sensors. The additional elements can be, for example, additional magnets or additional targets. The additional elements can be arranged between the sensor response elements of two adjacent soft sensor elements. For example, when a plurality of soft sensor elements are arranged in the sensor array, the additional elements can be arranged at positions between adjacent soft sensor elements. When using the additional elements, it is preferable to arrange the additional elements for any pair of two adjacent soft sensor elements. However, a configuration in which the additional elements are provided only for a part of the pairs of adjacent soft sensor elements is also included in this specification. In this case, regularity can be provided between the pairs of soft sensor elements with the additional elements provided therebetween and the pairs of soft sensor elements without the additional elements provided therebetween.

[0047] When the additional element is a magnetic element, the magnetization of the additional element can be different from the magnetization of the sensor reaction element of the soft sensor element. Alternatively, instead of this, the additional element can be made of a magnetic material different from the sensor reaction element of the soft sensor element. This different magnetic material can be a material having magnetic properties (for example, magnetic permeability) different from the magnetic properties of the sensor reaction element.

[0048] On the other hand, when the additional element is a target, the additional element can have electrical or magnetic properties different from those of the target used for the soft sensor element.

[0049] In another preferred embodiment of the present invention, the sensor array can include one or more evaluation circuits. The one or more evaluation circuits can be configured to receive at least one signal from one or more sensors and evaluate this signal to derive, calculate, or estimate the applied force. In that case, for each soft sensor element, an individual evaluation circuit that outputs the force applied to itself can be provided. In some embodiments, the signals supplied from these multiple evaluation circuits can be transferred to a common evaluation circuit of the sensor array for further processing, or can be directly transferred to an external circuit.

[0050] Alternatively or in addition, the sensor array can also include a common evaluation circuit. The common evaluation circuit can be configured to connect to and communicate with a plurality of soft sensor elements. Here, "communication" means that the evaluation circuit is configured to receive signals or read data from the plurality of soft sensor elements. This data can be data that has been converted into the force applied to each individual soft sensor element (when an individual evaluation circuit is provided for each soft sensor element), or raw data that means the data in the state provided by the sensor. Also, the common evaluation circuit can be adapted to simply transfer the data collected from the plurality of soft sensor elements, or can be adapted to derive the force applied to the sensor array by evaluating the data collected from the plurality of soft sensor elements. Therefore, the common evaluation circuit can execute the calculations necessary to identify the distance, position, etc. of the sensor reaction elements, thereby enabling the measurement of force. Furthermore, the evaluation circuit can also perform differential measurements between adjacent soft sensor elements or between adjacent sensitive elements of a multi-pixel sensor. For example, when an active magnetic sensor is used, the evaluation circuit can also be used for driving the sensor.

[0051] When a multi-pixel sensor is used, based on a plurality of signals from the multi-pixel sensor, for example, based on the difference, sum, or combination of the signals, the evaluation circuit can be configured to calculate the force. As described above, based on the gradient or difference of the data provided by two or more sensitive elements of two or more multi-pixel sensors, one or more evaluation circuits can be configured to identify the position of the applied force.

[0052] In any case, the plurality of sensors can be connected to a digital bus for data communication. Each sensor can have a unique ID and can be configured to transmit the unique ID.

[0053] In another preferred embodiment of the present invention, another deformable element is brought into contact with the deformable element, the sensor reaction element, or both. And at least a part of the other deformable element can be extended between the deformable element and the object. In this case, the deformable element can be rephrased as the first deformable element, and the other deformable element as the second deformable element. When the object moves toward the second deformable element, the second deformable element may come into contact with the object. When the object exerts a force on the second deformable element during such contact, the second deformable element exerts a force on the first deformable element, the sensor reaction element, or both, causing the first deformable element to deform as described above. Also, thereby, deformation may occur in the second deformable element as well. However, the second deformable element can be configured to be less deformable than the first deformable element, and in some cases, the second deformable element may not deform at all. In a state where no force is applied, the thickness of the second deformable element in a direction perpendicular to the surface of the sensor can be configured to be smaller than the thickness of the first deformable element. The bulk modulus and / or shear modulus of the second deformable element can be different from those of the first deformable element. Specifically, the bulk modulus of the second deformable element can be set to a bulk modulus higher than that of the first deformable element. In that case, it might be said that the second deformable element is more rigid and / or less flexible than the first deformable element. Therefore, since the second deformable element is more rigid than the first deformable element, the possibility of being damaged by contact with the object is lower than that of the first deformable element. Also, it can be rephrased that by the second deformable element serving as a protective layer for the first deformable element, the first deformable element is prevented from directly contacting the object, thereby preventing damage to the first deformable element. That is, the second deformable element protects the deformation characteristics of the first deformable element. Furthermore, the second deformable element can also function as a converter for the force applied by the object to the second deformable element. This can also be rephrased as the second deformable element evenly and uniformly dispersing the force applied from the object and transmitting it to the first deformable element.For example, if the surface of the object that contacts the second deformable element is defined as the first contact surface, and the surface of the sensor reaction element, the first deformable element, or both that contact the second deformable element is defined as the second contact surface, then the second deformable element disperses and transmits the force received at the first contact surface to the second contact surface. Note that depending on the shape of the object, the first contact surface may be smaller than the second contact surface. In this case, compared to the case where the object directly contacts the first deformable element, the sensor reaction element, or both, the second deformable element reduces the force or pressure applied to the first deformable element and the sensor reaction element. As a result, the risk of damaging the first deformable element is reduced. In other words, the second deformable element can prevent the stress of the object from being applied pointwise to the first deformable element, the sensor reaction element, or both. In addition to or instead of this, the second deformable element can have a specific friction coefficient adapted to the object. In this case, the surface roughness of the second deformable element can be adjusted according to the surface roughness of the object that contacts the second deformable element. For example, when the friction coefficient of the object surface is low, the friction coefficient of the second deformable element can be increased to maintain a stable contact state between the object and the second deformable element. On the other hand, when the friction coefficient of the object surface is high, even if the friction coefficient of the second deformable element is decreased, a stable contact state between the object and the second deformable element can be maintained. In this way, even when the type of the object changes, the grip between the object and the second deformable element can be stabilized. Therefore, according to the type of the object, the second deformable element can be adjusted without changing the first deformable element. As a result, this soft sensor element can be made versatile for a wide variety of objects using the same deformable element. Note that this also includes the ability to reversibly attach the second deformable element to the first deformable element. In other words, the second deformable element can be made replaceable. In this way, different second deformable elements can be selected according to the application and the object.

[0054] In a further preferred embodiment of the present invention, the characteristics of the deformable element can be indicated by the shape, bulk modulus, shear modulus, or any combination thereof that the deformable element has. The shape of the deformable element in the undeformed state can be at least one of a cylinder, a cube, a cone, and a dome shape. The shape and other selected characteristics of the deformable element can be adapted to the implementation conditions.

[0055] In a further preferred embodiment of the present invention, the deformable element can be attached to the sensor. For example, the deformable element can be adhered to the sensor. In this case, a single layer of adhesive layer (such as tape, etc.) can be used. Also, instead of stably attaching the deformable element to the sensor, the deformable element can be in a state where it only contacts the sensor. In a further example, the deformable element can be in a state where it does not contact the sensor at all. In this case, there is a free space between the deformable element and the sensor, and holding means can be provided to hold the deformable element in a state separated from the sensor. Although several examples have been given above, these examples should not be understood as being intended to be limiting.

[0056] In a further preferred embodiment of the present invention, the soft sensor element can further include a mechanical stopper that restricts the deformation of the deformable element. Thus, the mechanical stopper functions as a physical barrier that restricts the amount of deformation, that is, a physical barrier that restricts the amount of force acting on the deformable element. Thus, the mechanical stopper generates a reaction force against the force applied to the deformable element. As a result, the force and the reaction force at least partially cancel each other out. It can also be said that the mechanical stopper functions as a force absorber that absorbs at least a part of the force applied to the deformable element. The mechanical stopper can be a rigid element whose occupied range with respect to the sensor is shorter than the range occupied by the deformable element in the undeformed state with respect to the sensor. As a result, the deformable element can be at least partially deformed by an amount equal to the difference between the range occupied by the mechanical stopper and the range occupied by the deformable element in the undeformed state. Note that the mechanical stopper can be an element made of a material with lower elasticity than the deformable element itself, rather than a rigid element. In this case, the mechanical stopper functions not as an emergency stop stopper but as a damper that suppresses the deformation of the deformable element. This is because a greater force needs to be applied to compress both the deformable element and the mechanical stopper.

[0057] The above-described preferred embodiments are not exclusive. Rather, combinations of two or more aspects of the above-described preferred embodiments are also included within the scope of the present invention. Thus, all of the above aspects or embodiments can be combined.

[0058] Furthermore, the above needs can also be solved by a method of measuring force using a sensor array. According to this method, a sensor array including a plurality of soft sensor elements is provided. Each of the plurality of soft sensor elements includes a sensor, a deformable element, and at least one element (sensor reaction element) that reacts to the sensor. And at least a part of the deformable element extends between the sensor and at least one sensor reaction element.

[0059] In this method, furthermore, a plurality of signals are received from the sensor. The signals are received when the deformable element is deformed by an external force. In other words, this signal can be a feedback signal that gives feedback indicating the applied external force.

[0060] Then, based on a predefined correlation between the value of the applied force and the value of the signal, the strength of the force is derived.

[0061] The sensor array used in the method according to the present invention can have any of the characteristics described in the above description regarding the sensor array according to the present invention.

Brief Description of the Drawings

[0062] In the following description and the accompanying drawings, specific exemplary embodiments of the above-described sensor array and method will be described in detail. However, these embodiments merely show a part of various ways of using the principles of various embodiments, and the embodiments described herein are intended to include all such embodiments and their equivalents.

[0063] Throughout the plurality of drawings, similar parts are denoted by similar reference numerals. Note that the drawings are not necessarily drawn to scale. Rather, generally, the focus is on the description of the general principles of the present invention.

[0064] In the following description, various embodiments of the present invention will be described with reference to the following drawings.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0065] Hereinafter, a detailed description will be given with reference to the accompanying drawings. The accompanying drawings exemplarily show specific details and embodiments in which the present invention can be implemented

[0066] As used herein, the term "exemplary" means "being given as an example or illustration". Therefore, embodiments or designs described as "exemplary" in this specification should not necessarily be construed as being more preferred or advantageous than other embodiments or designs.

[0067] FIG. 1 is a cross-sectional view showing a soft sensor element 100 according to an embodiment of the present invention. The soft sensor element 100 includes a sensor 110, a deformable element 120, and an element 130 (a "sensor reaction element") that reacts to the sensor 110. The deformable element 120 can include, for example, at least one of an elastomer, a polymer, a rubber, and a vulcanized product. Further, the deformable element 120 can be composed of a flexible element, an elastic element, or a flexible structure. The flexible element or the flexible structure can be made of metal. For example, the flexible element or the flexible structure can be composed of a flexible metal beam. In the illustrated embodiment, the element 130 is completely embedded in the deformable element 120. "Completely embedded" means a state in which the deformable element 120 completely surrounds the element 130 and all surfaces of the element 130 are in contact with the deformable element 120. It can also be said that the element 130 is wrapped in the material of the deformable element 120. The deformable element 120 is configured to be deformable by applying an external force. When an external force is applied, the deformable element 120 may be compressed, thereby changing the distance between the element 130 and the sensor 110. The sensor 110 can detect this change in distance. For example, when the element 130 is a magnet and the sensor 110 is a magnetic sensor, as the distance between the element 130 and the sensor 110 decreases, the sensor detects a magnetic field (e.g., a different magnetic field strength, magnetic field orientation, or both) different from that before deformation. Therefore, it is possible to estimate how much the deformable element 120 has deformed from the change in the value of the physical unit used for the measurement. However, those skilled in the art will recognize that it is also possible to measure the compression distance of the deformable element 120 using other combinations of the sensor 110 and the element 130.

[0068] The deformation that occurs in the deformable element 120 will vary depending on the applied external force. Therefore, conversely, it means that the applied external force is related to the physical measurement value obtained from the sensor 110. Accordingly, there is a correlation between the value of the applied external force and the measurement value of the sensor 110 corresponding thereto. Such a correlation can be specified at the time of initial calibration of the sensor 110, and can also be obtained in advance if the bulk modulus or shear modulus of the deformable element 120 is known. In addition, the correlation can be defined, for example, in the form of a look-up table including a plurality of external force values and sensor indication values associated therewith. The correlation between the applied external force value and the measurement value of the sensor 110 corresponding thereto can be clarified using a model trained by machine learning. Those skilled in the art will recognize other methods for clarifying individual correlations, but all such other methods are also included in this specification. If the actual measurement value of the sensor 110 is obtained, the external force can be estimated using the look-up table. In addition, when the bulk modulus, shear modulus, or both of the deformable element 120 are known, an algorithm can be used to output the actually applied force from the deformation amount by simple calculation. The algorithm can be a non-linear model that defines the actual force as a non-linear function of the measurement value of the sensor 110. The algorithm or correlation can be implemented either inside the integrated circuit (IC) in which the sensor 110 is incorporated, outside the integrated circuit in which the sensor 110 is incorporated, or a part (for example, the part that calculates the position of the element 130 from the sensor signal) is implemented inside the integrated circuit in which the sensor 110 is incorporated, and a part (for example, the part that estimates the force from the displacement of the element 130) is implemented outside the integrated circuit in which the sensor 110 is incorporated. The sensor 110 can also be configured to perform dual sensing capable of detecting linear force and shear force. For example, it can be configured to sense a linear force that travels straight in the direction of the external force and a shear force in one direction in the plane perpendicular to the direction of the external force or two directions perpendicular to each other. The correlation or algorithm can directly link the value of the applied external force and the measurement value of the sensor 110.Optionally, the displacement amount of element 130 can also be calculated as an intermediate step by a correlation or an algorithm. In that case, the position of element 130 is identified from the measurement value of sensor 110 by a first correlation or a first algorithm, and the value of the external force applied from the position of element 130 is identified by a second correlation or a second algorithm. Therefore, in this case, as an intermediate step, the step of determining the position of element 130 is performed.

[0069] Element 130 embedded in deformable element 120 is, in the illustrated embodiment, at a position at a distance d1 from sensor 110. The distance d1 from sensor 110 to element 130 is smaller than the distance d2 from sensor 110 to the second end of deformable element 120.

[0070] Although not intended to be limiting, the distance d1 from sensor 110 to element 130 can be 3 mm, and the distance d2 from the sensor to the second end of deformable element 120 can be 4 mm. It should be recognized by those skilled in the art that the names of the above dimensions are only defined for the convenience of explanation and should not be understood as being intended to be limiting unless otherwise explicitly stated.

[0071] FIG. 2 is a cross-sectional view showing a state in which an external force ("pressure" in the figure) is applied to the soft sensor element 200 shown in FIG. 1. The external force can be a uniform force, that is, a force applied with a constant force over the force application surface. However, there are cases where a non-uniform force, that is, a force with variations on the force application surface, is applied as the external force. Such variations in the force on the application surface may be linearly varying variations or non-linearly varying variations. That is, in this case, different values of force can be assigned to each point on the force application surface, but the force value at each point and the force value at the adjacent point may show a linear relationship or a non-linear relationship. In the example of FIG. 2, the external force is a uniform force with respect to the surface of the deformable element 120 and is applied perpendicular to the surface of the sensor 110. When the external force is applied, the deformable element 120 is compressed. As a result, the distance d2 from the sensor 110 to the second end of the deformable element is reduced to a distance d2 smaller than the distance d2 ’ up to. Also, since the element 130 is embedded in the deformable element 120, the distance d1 from the element 130 to the sensor 110 is also reduced to a distance d1 smaller than the distance d1 ’ up to.

[0072] The sensor 110 reacts with the element 130, so that from d1 to d1 ’configured to detect a change in the distance thereto. When the sensor 110 is a magnetic sensor and the element 130 is a magnet, since the magnetic field strength detected by the sensor 110 is proportional to the distance from the sensor 110 to the element 130, the sensor 110 detects a stronger magnetic field strength as the distance from the sensor 110 to the element 130 becomes shorter. Such a change in the magnetic field strength can be used to estimate the force applied to the deformable element 120. In some cases, when the sensor 110 is a magnetic sensor, the sensor 110 can detect a change in the direction of the magnetic field strength vector, i.e., a change in one or more angles assigned to the magnetic field vector, in addition to or instead of the magnetic field strength. In this case, the magnetic sensor can be arranged offset with respect to the axis of the magnet. Although an example of measuring the distance in only one dimension, and thus an example where the force is applied perpendicularly, is described, those skilled in the art will recognize that the element 130 may be tilted at an angle as shown in FIG. 3.

[0073] In FIG. 3, an external force (labeled "pressure" in the figure) is applied in a direction that is uniform but not perpendicular to the surface of the sensor 110. Therefore, when this external force is applied, the deformable element 120 deforms in a direction that is not perpendicular to the surface of the sensor 110. This causes a non-uniform change in the distance d1 from the element 130 to the sensor 110. For example, the upper end of the element 130 moves to a relatively large distance d1 ’ while the lower end of the element 130 moves to a relatively small distance d1 ’’ When a non-linear force is applied, d1 ’ and d1 ’’Since they are at different distances, element 130 is inclined at an angle α other than zero with respect to sensor 110. Therefore, when an external force is applied in a non - vertical direction, element 130 undergoes not only translational movement but also rotational movement. Sensor 110 is adapted to detect a change in angle α by reacting with element 130. When sensor 110 is a magnetic sensor and element 130 is a magnet, when the angle α between sensor 110 and element 130 changes, the direction of the magnetic field lines of magnet 130 changes with respect to sensor 110, so sensor 110 detects this change in the magnetic field. It can also be said that when element 130 rotates by angle α, sensor 110 senses the rotation of the three - dimensional magnetic field generated by element 130. When rotating, the absolute intensity of the magnetic field does not change, but the direction of the magnetic field vector in space changes. As a result, the projection of the magnetic field vector onto the magnetic flux measurement plane of sensor 110 changes, so sensor 110 senses a magnetic flux different from the state where element 130 is not rotating. From the measured change in magnetic flux, the position change of element 130 can be estimated. The position change of element 130 is uniquely associated with the force acting on deformable element 120. Therefore, when a force non - perpendicular to deformable element 120 is applied, the rotation of element 130 can be used to identify the force applied to deformable element 120.

[0074] Figure 4 is a cross - sectional view showing an embodiment of a sensor array according to the present invention. Sensor array 400 includes a plurality of soft sensor elements. The configuration of each soft sensor element can be the same as or identical to the soft sensor elements shown in the embodiments of FIGS. 1, 2, and 3.

[0075] The plurality of soft sensor elements are arranged on substrate 410. Substrate 410 can provide mechanical support and / or electrical support. Further, substrate 410 can also be used as a connection part to the circuit to connect the sensor array to other electrical devices.

[0076] Each of the plurality of soft sensor elements includes a sensor 440, a deformable element 420, and an element 430 (a "sensor reaction element") that reacts to the sensor 440. In the embodiment shown in FIG. 4, the deformable element 420 is shown as a deformable element common to the plurality of soft sensor elements, and a plurality of sensors 440 of the plurality of soft sensor elements and a plurality of elements 430 that react to the sensor 440 are embedded therein.

[0077] In the illustrated embodiment, the sensor 440 of each soft sensor element of the plurality of soft sensor elements can be configured as, for example, a semiconductor die, a bare die, an unpackaged chip, or an unpackaged integrated circuit. The die is flip-chip mounted on the substrate 410. The die includes a sensing element 450 and an electrical connection portion 445 that connects the die to the circuit of the substrate 410. In some embodiments, the electrical connection portion to the substrate can be configured not to exceed the outer periphery of the sensor, and in addition to or instead of this, it can also be configured to directly contact the active surface of the sensor.

[0078] The substrate 410 has a thickness h s and the deformable element 420 has a thickness h de Thus, the sensor array has a thickness h = h s + h de As shown in FIG. 4, the thickness h s of the substrate 410 is preferably smaller than the thickness h de of the deformable element 420. The thickness of the sensor array is preferably kept as small as possible. However, when a force is applied to the element 430 that reacts to each sensor 440 of the plurality of soft sensor elements, since the element 430 moves relative to the sensor 440, a specific thickness is required to ensure normal operation. On the other hand, the thickness of the substrate 410 can be made quite small. Therefore, preferably, the thickness h s of the deformable element 420 is larger than the thickness h de of the substrate 410. Preferably, the thickness h sis set to be about 60 to 600 μm, and the thickness h of the deformable element 420 de can be set to be about 4 mm. Preferably, the thickness h of the deformable element 420 de to the thickness h of the substrate 410 s is in the range of 0.1% to 15%, more preferably 1% to 5%.

[0079] The sensor 440 has a one-dimensional width (which may also be referred to as size), and this width is represented by the length L in FIG. 4. Preferably, the plurality of soft sensor elements are made homogeneous with each other, and all the sensors 440 have the same size. On the other hand, the element 430 that reacts to the sensor 440 is illustrated as having a size (i.e., length l) smaller than that of the sensor 440. However, although this is preferable, it is not necessarily essential. A configuration in which the element 430 that reacts to the sensor 440 has the same size as the sensor 440 or a size larger than that of the sensor 440 is also possible. In some embodiments, the sensor is not a sealed die or a packaged die, but is sealed by a deformable element. In that case, the length L corresponds to the length of the die of the sensor, rather than the length of the packaged chip.

[0080] Preferably, the pitch p between two adjacent elements of the plurality of soft sensor elements is made uniform. This means that the arrangement of the plurality of soft sensor elements is equally spaced as shown in FIG. 4. The pitch p can be measured as the distance from the center of a soft sensor element to the center of an adjacent soft sensor element, or the distance from an edge of a soft sensor element (e.g., the edge of the sensor 440) to the same edge of an adjacent soft sensor element.

[0081] Figure 4 shows a cross-sectional view of the sensor array 400. In this cross-sectional view, a plurality of soft sensor elements are arranged in a row along the illustrated cross-section. The sensor array 400 can be composed of such a plurality of soft sensor elements arranged in a row, and in addition, a plurality of soft sensor elements can be arranged in a two-dimensional lattice (however, the remaining soft sensor elements arranged in the other spatial dimension are located in a direction perpendicular to the image plane shown in Figure 4 and are not shown).

[0082] In the following, with respect to further embodiments shown in FIGS. 5 to 10, the differences from the embodiment shown in FIG. 4 will be described while indicating them. For the further embodiments shown in FIGS. 5 to 10, parts that are not explicitly different from the description regarding FIG. 4 can have the same features as the sensor array shown in FIG. 4.

[0083] FIG. 5 is a cross-sectional view showing another embodiment of the sensor array according to the present invention. In this embodiment, a plurality of recesses are formed in the deformable element in order to mechanically separate a plurality of parts of the sensor array from each other.

[0084] Similar to the embodiment shown in FIG. 4, the sensor array 500 also includes a substrate 510 and a plurality of soft sensor elements. The plurality of soft sensor elements include a deformable element 520, a plurality of sensors 540, and a plurality of elements 530 that react to the sensors 540.

[0085] Compared with the embodiment shown in FIG. 4, the sensor array is the same in that it includes a common deformable element 520, but is different in that a plurality of recesses 560 are provided in the common deformable element 520. The recesses 560 separate the common deformable element 520 into a plurality of parts 550. This separation is a mechanical separation, and thereby, the force applied only to a certain part does not affect the adjacent parts, so that the crosstalk between adjacent soft sensor elements is reduced.

[0086] Similar to FIG. 4, FIG. 5 also shows a cross-sectional view in which a plurality of soft sensor elements are arranged in a row. As described above, the plurality of soft sensor elements can also be arranged in a two-dimensional lattice. In this case, recesses orthogonal to the recess 560 shown in FIG. 5 are further provided. These additional recesses can further separate the soft sensor elements divided into a plurality of subsets into a plurality of parts.

[0087] FIG. 6 is a cross-sectional view showing another embodiment of the sensor array according to the present invention. In this embodiment, a plurality of recesses are formed in the deformable element in order to mechanically separate a plurality of parts of the sensor array from each other. However, unlike FIG. 5, the soft sensor elements shown in FIG. 6 are not configured to include a part of a common deformable element.

[0088] Similar to the embodiment shown in FIG. 4, the sensor array 600 also includes a substrate 610 and a plurality of soft sensor elements. The plurality of soft sensor elements include a plurality of deformable elements 620, a plurality of sensors 640, and a plurality of elements 630 that react to the sensors 640. Further, similar to the embodiment shown in FIG. 5, the plurality of soft sensor elements are separated into a plurality of parts. However, in the example shown in FIG. 6, the depth of the recess 660 is deeper, and the deformable elements 620 of adjacent soft sensor elements are separated to a state where they can be regarded as completely separated, so crosstalk is further reduced. In this example, it can be said that the plurality of soft sensor elements do not include a common deformable element.

[0089] FIG. 7 is a cross-sectional view showing another embodiment of the sensor array according to the present invention. In this embodiment, a plurality of sensors of a plurality of soft sensor elements are embedded in a passivation layer, and a plurality of elements that react to the sensors of the plurality of soft sensor elements are embedded in a common deformable element.

[0090] Similar to the embodiment shown in FIG. 4, the sensor array 700 also includes a substrate 710 and a plurality of soft sensor elements. The plurality of soft sensor elements include a deformable element 720, a plurality of sensors 740, and a plurality of elements 730 that react to the sensors 740.

[0091] Unlike the above-described embodiment, in this embodiment, only the elements 730 that react to the sensors 740 are embedded in the common deformable element 720. On the other hand, the sensors 740 are embedded in another layer (so-called passivation layer) 750. The passivation layer 750 may also be called a sealing layer and can be composed of a thermoplastic material, epoxy, profile, or photoresist such as SU-8. By using such a sealing layer, the sensors of the plurality of soft sensor elements can be sealed. In some of the above embodiments, the sensors are sealed by the deformable element to protect the sensors from moisture, contamination, and damage, and to electrically insulate the sensors from each other. On the other hand, in the embodiment of FIG. 7, a sealing layer for sealing is provided. This embodiment is suitable for specific applications where the deformable element is required to have high flexibility, but the protective layer of the sensor is required to be more robust.

[0092] FIG. 8 is a cross-sectional view showing another embodiment of the sensor array according to the present invention. In this embodiment, additional elements are further arranged in the space between the sensor reaction elements of the plurality of soft sensor elements.

[0093] Similar to the embodiment shown in FIG. 4, the sensor array 800 also includes a substrate 810 and a plurality of soft sensor elements. The plurality of soft sensor elements include a deformable element 820, a plurality of sensors 840, and a plurality of elements 830 that react to the sensors 840.

[0094] In addition to this, the sensor array 800 further includes additional elements 850. These additional elements 850 are arranged at intervals between elements 830 that react to the sensors 840 of a plurality of soft sensor elements. The additional elements 850 can be, for example, magnets or targets having characteristics different from those of the elements 830. For example, the additional elements 850 can apply a magnetic field in a direction different from that of the elements 830 of the soft sensor elements. In one example, the magnetic field of the additional elements 850 can be a magnetic field rotated 90° from the magnetic field of the elements 830 that react to the sensor 840. The additional elements 850 can be arranged at positions equidistant from adjacent elements 830.

[0095] FIG. 9 is a top view showing another embodiment of the sensor array according to the present invention. In this embodiment, the sensors of a plurality of soft sensor elements are configured as multi-pixel sensors.

[0096] The sensor array 900 includes sensors having a so-called multi-pixel configuration. That is, each sensor 940 includes a plurality of sensitive elements 950. In FIG. 9, each multi-pixel sensor includes four sensitive elements 950. The four sensitive elements 950 are symmetrically arranged at the four corners or on the diagonals of the sensor 940. The interval s1 between adjacent sensitive elements 950 within the sensor 940 is preferably uniform for all sensors 940. Further, the interval s2 between adjacent sensitive elements 950 between adjacent sensors 940 is also preferably uniform throughout the sensor array 900 in order to provide a uniform resolution. Moreover, it is more preferable if the interval s1 between the sensitive elements 950 of the same sensor 940 and the interval s2 between the adjacent sensitive elements 950 between adjacent sensors 940 can be made equal.

[0097] In the case of the multi-pixel sensor shown in FIG. 9, each pixel can be a magnetic field sensor. In that case, each pixel can measure at least one component of the magnetic field.

[0098] FIG. 10 is a cross-sectional view showing another embodiment of the sensor array according to the present invention. In this embodiment, the sensor reaction elements of a plurality of soft sensor elements are configured as a powder material.

[0099] Similar to the embodiment shown in FIG. 4, the sensor array 1000 also includes a substrate 1010 and a plurality of soft sensor elements. The plurality of soft sensor elements include a deformable element 1020, a plurality of sensors 1040, and a plurality of elements 1030 that react to the sensors 1040.

[0100] Different from the above-described embodiment, in this embodiment, the element 1030 that reacts to the sensor 1040 is formed of a powder material. The powder material can be, for example, a magnetic material or a magnetizable material. By using such a powder material, the bending behavior of the sensor array is improved, and thus it becomes possible to bend and round the sensor array better.

[0101] Using any of the above-described embodiments, the intensity of the applied external force can be specified. Furthermore, using each embodiment, the application point of the external force can also be specified. Also, by performing continuous measurement or repeatedly performing individual measurements at regular intervals using each of the above-described embodiments, it becomes possible to specify the propagation of the external force, that is, to record the movement. For example, if used in a gripping device, there is a possibility of detecting a gripping failure at an early stage.

[0102] Although the description has been made while giving a plurality of examples of one or more embodiments, it is of course impossible to describe all possible combinations of components or methods in the description of the above embodiments. However, those skilled in the art will recognize that many more various embodiments with different combinations and orders are possible. Therefore, the embodiments described in this specification are intended to include all such changes, corrections, and modifications within the spirit and scope of the appended claims.

Description of Reference Numerals

[0103] 100, 200 Soft sensor elements 110, 440, 540, 640, 740, 840, 940, 1040 Sensors Deformable elements 120, 420, 520, 620, 720, 820, 1020 Elements 130, 430, 530, 630, 730, 830, 1030 (sensor reaction elements) Sensor arrays 400, 500, 600, 700, 800, 900, 1000 Substrates 410, 510, 610, 710, 810, 1010 Sensing elements 450, 950 Recesses 560, 660 Electrical connection part 445 Portion of deformable element 550 Passivation layer 750 Additional element 850

Claims

1. A sensor array for measuring a force, the sensor array comprising: a plurality of soft sensor elements (100), each of the plurality of soft sensor elements (100) comprising: a sensor (110, 440); a deformable element (120, 420) configured to be deformable by the force; at least one element (130, 430) responsive to the sensor (110, 440) for measuring the force by deformation of the deformable element (120, 420); and at least a portion of the deformable element (120, 420) extends between the sensor (110, 440) and the at least one element (130, 430), the sensor array.

2. The sensor array according to claim 1, wherein the at least one element (130, 430) is embedded in the deformable element (120, 420).

3. The sensor array according to claim 1 or 2, wherein the plurality of soft sensor elements are arranged in a row or a grid.

4. The sensor array according to any one of claims 1 to 3, wherein the pitch (p) between two adjacent elements of the plurality of soft sensor elements is equally spaced.

5. The sensor (110, 440) of each soft sensor element has a size (L), The sensor array according to any one of claims 1 to 4, wherein the pitch (p) between two adjacent elements of the plurality of soft sensor elements satisfies p ≦ 3L.

6. The sensor array according to any one of claims 1 to 5, wherein the sensor of each soft sensor element of the plurality of soft sensor elements is a multi-pixel sensor (940).

7. Two adjacent pixels of the multi-pixel sensor have a first interval (s １ ), and A second interval (s), which is the interval between the last pixel of the multi-pixel sensor of the first sensor element and the first pixel of the multi-pixel sensor of the second sensor element adjacent thereto ２ ), is smaller than or equal to the first interval (s １ ), The sensor array according to claim 6.

8. The sensor array according to any one of claims 1 to 7, wherein the plurality of soft sensor elements are embedded in a common deformable element (120, 420).

9. The sensor array according to claim 8, wherein a plurality of subsets of the plurality of soft sensor elements are arranged in at least two portions of the sensor array, and the at least two portions are mechanically separated.

10. The sensor array according to claim 9, wherein the sensor array is separated into a plurality of portions by recesses (560, 660) of the common deformable element (120, 420).

11. The sensor array according to any one of claims 1 to 10, wherein the sensor (110, 440) is a passive magnetic sensor and the at least one element (130, 430) is an element that generates a magnetic field.

12. The sensor array according to any one of claims 1 to 10, wherein the sensor (110, 440) is an active magnetic sensor and the at least one element (130, 430) is a target.

13. The sensor array further comprises a plurality of additional elements (850), and at least one of the plurality of additional elements (850) is disposed between at least one element (130, 430, 830) of each of two adjacent soft sensor elements. The sensor array according to any one of claims 1 to 12.

14. One or more evaluation circuits configured to derive the applied force by receiving at least one signal from one or more sensors and evaluating the at least one signal The sensor array according to any one of claims 1 to 13, further comprising.

15. A method of measuring a force using a sensor array, the method comprising: Providing a sensor array comprising a plurality of soft sensor elements, each of the plurality of soft sensor elements comprising a sensor (110, 440), a deformable element (120, 420), and at least one element (130, 430) that reacts to the sensor, and at least a portion of the deformable element (120, 420) extending between the sensor (110, 440) and the at least one element (130, 430); Receiving one or more signals from one or more sensors when the deformable element (120, 420) is deformed by a force; Deriving the applied force from the received one or more signals; A method comprising.

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