Pressure-resistant electric toothbrush

Abstract

Electric toothbrush head (108), comprising: a bristle field (102) with a plurality of bristles (104), wherein the bristles (104) comprise a stimulus-responsive material configured to cause a reversible reduction in stiffness in response to an initial condition indicating excessive brushing pressure; and a mechanical force protection mechanism (112) configured to induce a reversible physical displacement of the bristle field (102) in response to a second condition indicating excessive brushing force, wherein the displacement has at least one of the following properties: rotational slip, linear retraction or angular inclination.

Description

TECHNICAL AREA

[0001] The present disclosure relates to the field of oral care devices, in particular toothbrush heads with safety features that prevent excessive brushing while maintaining plaque removal efficiency.

[0002] The utility models intended to protect and the subject matter of the utility model, in accordance with the requirements of the Utility Model Act, are only devices as defined in the accompanying claims, but not methods. In cases where the description refers to methods, these references serve solely to describe the device or devices for which protection is sought under the accompanying claims. BACKGROUND

[0003] Oral hygiene plays a crucial role in maintaining overall health, with brushing teeth being a fundamental measure for removing plaque and preventing dental diseases. Electric toothbrushes have gained immense popularity since their introduction in the mid-20th century, as they offer advantages over manual brushing by improving plaque removal through the motorized movement of the bristles and simplifying the brushing process for many users.

[0004] Dentists generally recommend brushing your teeth at least twice a day for about two minutes each time. However, the effectiveness of brushing depends not only on frequency and duration but also on proper technique. A major problem in oral hygiene is the use of excessive force while brushing, commonly referred to as "over-brushing."

[0005] Excessive brushing can lead to various dental problems. Applying too much pressure while brushing can damage the gum tissue, potentially causing gum recession. In gum recession, the gum tissue around the teeth wears away or recedes, exposing more of the tooth or tooth root. This exposure can lead to tooth sensitivity and promote tooth decay. Furthermore, aggressive brushing with excessive force can abrasion of the enamel, gradually wearing away the protective outer layer of the teeth, which does not regenerate once damaged.

[0006] Studies have shown that many people use more force than necessary when brushing their teeth. This tendency occurs with both manual and electric toothbrushes, although the motorized movement of electric toothbrushes can sometimes exacerbate the problem if users apply the same amount of force as when brushing manually. Remarkably, most people are unaware that they are applying excessive pressure while brushing, making it difficult to address this issue through education alone.

[0007] The geometry and angle at which users hold the brush can also affect the distribution of pressure on teeth and gums. Incorrect angles can concentrate the force on certain areas, potentially leading to localized damage over time. Users often struggle to maintain a consistent, appropriate angle throughout the brushing process, especially when reaching back molars or other hard-to-reach areas of the mouth.

[0008] A major challenge in toothbrush design is balancing effective plaque removal with the avoidance of excessive pressure. Simply reducing the mechanical action or bristle stiffness might protect gum tissue but compromise cleaning performance. Conversely, designs that prioritize plaque removal can unintentionally encourage harmful brushing habits.

[0009] Several approaches have been investigated to address the problem of over-brushing. Some electric toothbrushes have pressure sensors that issue a warning if too much pressure is applied. Other designs experiment with bristle configurations or ergonomic handle shapes to influence user behavior. Manual toothbrushes sometimes feature a flexible neck or specially designed bristles to mitigate the effects of excessive pressure. However, these approaches have limited effectiveness, particularly for users who have developed an overly aggressive brushing technique over many years.

[0010] The timing and nature of user feedback present a further design challenge. Visual, auditory, or tactile signals could help users recognize when they are applying too much pressure, but the implementation of such feedback mechanisms must be intuitive and perceptible without compromising the brushing experience. Furthermore, feedback that only occurs after pressure has been applied may have limited preventative benefits.

[0011] Despite advances in toothbrush design, the challenge of preventing gum damage and enamel abrasion caused by over-brushing persists. Users often only receive immediate feedback about incorrect brushing technique once damage has already occurred, which may not become visible for months or even years. Furthermore, different users have different brushing habits, apply varying degrees of force to the toothbrush, and have different levels of oral sensitivity, making a one-size-fits-all solution difficult to achieve.

[0012] Challenges remain in the development of toothbrush technologies that effectively prevent overbrushing while maintaining cleaning performance, providing appropriate feedback to the user, and catering to the different needs and habits of individual users. SUMMARY OF THE REVELATION

[0013] The objective of this disclosure is to prevent damage to oral tissues during tooth brushing. A further objective is to provide an electric toothbrush head and a system that can automatically regulate the brushing force through adaptive materials and mechanical mechanisms, thereby increasing user safety and maintaining effective cleaning performance. These objectives are achieved by the subject matter defined in the independent claims. Advantageous modifications of the embodiments of this disclosure are defined in the dependent claims, as well as in the description and drawings.

[0014] In its first aspect, the present disclosure relates to an electric toothbrush head. The electric toothbrush head is intended for attachment to a drive unit, such as is commonly found in electric oral hygiene devices.

[0015] In embodiments, the toothbrush head comprises a bristle field with a plurality of bristles, wherein the bristles comprise a stimulus-responsive material. Accordingly, the bristle field includes multiple bristles, each of which is at least partially formed from a stimulus-responsive material. The stimulus-responsive material can be configured to undergo a reversible reduction in stiffness in response to an initial condition indicating excessive brushing pressure. Accordingly, the stimulus-responsive material is selected and designed to experience a reversible reduction in stiffness when subjected to an initial condition signaling excessive brushing pressure.Such an initial state could, for example, include a threshold for mechanical stress, temperature change, or another physical parameter associated with the application of excessive force during brushing. The reversible reduction in bristle stiffness serves to mitigate the risk of gum or enamel damage by decreasing the effective hardness of the bristles upon detection of excessive pressure, thus providing a protective response that is automatically reversed when normal brushing conditions are restored.

[0016] A common solution for brushing too hard with electric toothbrushes is not to change the bristle stiffness, but to send a signal via pressure sensors or interrupt the power supply. For manual toothbrushes, manufacturers simply recommend softer bristles for sensitive gums. The responsive bristles of the embodiment described above therefore represent a significant departure: they are made of an advanced material (shape-memory polymer or piezoelectric composite) that bends or relaxes on its own when a certain force threshold is exceeded. This self-regulating behavior has no direct equivalent in toothbrush technology to date. The closest analogues are either passive designs with soft bristles or electronic feedback systems – however, neither of these achieves the proposed direct adjustment at the material level.Thus, the use of "smart" bristle filaments for automatic gum cushioning represents a completely new approach in oral care. The difference lies in the fact that external feedback or static softness is replaced by an active, material-based response to user behavior, which is a subtle but significant leap forward.

[0017] Furthermore, the stimuli-responsive bristles combine dynamic action (through adjustable elements) with a clever modification of material properties to achieve an unconventional combination. Instead of simply warning the user, the brush adapts itself in real time – a subtle approach influenced by intelligent material technology. This cross-domain leap goes beyond incremental pressure sensors, offering a self-regulating mechanism.

[0018] In some embodiments, the toothbrush head includes a mechanical force protection mechanism. This mechanism can be configured to induce a reversible physical displacement of the bristle field in response to a second condition indicating excessive brushing force. This displacement can occur relative to a drive unit. The second condition indicating excessive brushing force may differ from the first condition or overlap in certain operating scenarios. The displacement can take at least one of the following forms: rotational slippage, linear retraction, or angular tilting. These displacement modes serve to absorb or redirect excessive forces, thereby reducing the risk of injury to oral tissues and extending the service life of the toothbrush head.

[0019] The combination of responsive bristles and a mechanical force-protection mechanism offers a two-pronged approach to user safety and oral care effectiveness. The responsive material allows the bristles to dynamically adapt to brushing conditions, while the mechanical mechanism provides additional safety by physically repositioning the bristle field in case of excessive force.

[0020] In various embodiments, the toothbrush head can be manufactured using conventional injection molding or overmolding techniques, with the stimulus-responsive material integrated into the bristle matrix or applied as a coating. The mechanical force-protection mechanism can employ springs, friction clutches, elastomeric couplings, or other suitable components to achieve the desired displacement behavior.

[0021] In various configurations, the electric toothbrush head is compatible with standard drive units and can be attached via a conventional coupling interface. The design ensures that, under normal brushing conditions, the bristle field remains firmly connected to the drive unit, efficiently transferring movement for effective cleaning. Only when excessive pressure or force is detected are the safety features activated, after which the system returns to its original configuration once safe operating conditions are restored. This reversible functionality ensures both user safety and consistent cleaning performance throughout the toothbrush head's lifespan.

[0022] In some embodiments, the first condition can be a rise in the temperature of the bristles to mouth temperature. This allows the bristles to automatically adapt to the oral environment without requiring user intervention.

[0023] In some embodiments, the first condition can be a mechanical force exerted on the bristles that exceeds a first pressure threshold. This ensures an immediate response to excessive force and protects the gums from damage caused by aggressive brushing.

[0024] In some embodiments, the stimulus-responsive material can be a shape-memory polymer. Shape-memory polymers offer reliable and repeatable changes in stiffness in response to temperature or force, thus ensuring consistent protection.

[0025] In some embodiments, the stimuli-responsive material can be a piezoelectric composite. Piezoelectric composites can actively respond to applied forces, thus providing dynamic protection against excessive pressure.

[0026] In embodiments, the stimulus-responsive material can be a magnetorheological elastomer, the head further comprising a magnetic field generator configured to modify a magnetic field applied to the bristles to effect the reversible reduction in stiffness. This enables precise electronic control of bristle stiffness based on real-time pressure conditions.

[0027] In embodiments, the reversible reduction in stiffness can result in a reduction of the effective tip stiffness by at least 40 percent, measured between 22 °C and 37 °C. This significant reduction ensures effective protection while maintaining cleaning performance.

[0028] In some embodiments, the mechanical force protection mechanism can be activated when the second condition corresponds to a force of more than 150 grams applied to the tip. This specific threshold provides protection at clinically relevant force levels known to potentially cause gingival damage.

[0029] In some embodiments, the physical displacement can be rotational slippage, and the mechanical force protection mechanism includes a clutch mechanism. A rotational slippage mechanism provides the user with intuitive tactile feedback while preventing excessive force transmission.

[0030] In some embodiments, the coupling mechanism can be a magnetic torque micro-coupling calibrated to slip at a peak force between 160 and 200 grams. This precise calibration ensures consistent protection while allowing effective cleaning at safe pressure levels.

[0031] In some embodiments, the physical displacement can be the linear retraction movement, and the mechanical force protection mechanism includes a spring-mounted subassembly. The linear retraction provides a shock-absorbing effect that effectively cushions excessive forces while also giving the user clear visual feedback.

[0032] In some embodiments, the linear retraction can occur over a distance between 1.0 mm and 2.0 mm. This specific retraction range ensures noticeable feedback to the user while maintaining brush stability.

[0033] In embodiments, the spring-mounted subassembly can further include a viscoelastic dashpot cartridge configured to provide velocity-dependent damping. This velocity-dependent damping differentiates between slow and fast force applications and offers improved protection against sudden pressure spikes.

[0034] In some embodiments, the physical displacement can be the angular tilt, and the mechanical force protection mechanism is located in a neck section of the toothbrush head. The angular tilt automatically adjusts the brush orientation to the optimal tooth cleaning angle, thus reducing gum irritation.

[0035] In some embodiments, the angle of inclination can be between 10 and 15 degrees relative to a longitudinal axis of the neck section. This specific angle range ensures optimal adaptation to the tooth surfaces while simultaneously preventing gum damage.

[0036] In some embodiments, the mechanical force protection mechanism can include an eccentric cam and a compliant joint. This mechanism ensures a smooth, controlled tilting movement that automatically returns to its starting position when the pressure is released.

[0037] In some embodiments, the eccentric cam mechanism may include at least one detent configured to provide tactile feedback when engaged. This tactile feedback helps the user learn the correct pressure for brushing their teeth through immediate physical signals.

[0038] In some embodiments, the electric toothbrush head can further include a feedback generator configured to provide a user-perceived signal when the physical movement is triggered. Additional feedback reinforces proper brushing technique through multiple sensory channels.

[0039] In various embodiments, the user-perceived signal can be at least one of the following: a visual signal from an LED, a tactile signal including a click or patterned vibration, or an acoustic signal. Multimodal feedback ensures that users with different sensory preferences receive effective guidance.

[0040] In some embodiments, the multiple bristles may further include hydrogel cap ends configured to swell under pressure. Swelling hydrogel caps reduce abrasion to teeth and gums when brushing with high pressure.

[0041] In some embodiments, the multiple bristles can be mounted on telescopic, spiral root anchors configured to expand reversibly under pressure. This feature increases the contact area under pressure and effectively distributes the force to prevent localized damage.

[0042] In some embodiments, the electric toothbrush head may also include a transparent window configured to allow at least a portion of the mechanical force-protection mechanism to be seen. Visual confirmation of the mechanism's function improves the user's understanding and confidence in the protective features.

[0043] In a second aspect, the present disclosure relates to an electric toothbrush. The electric toothbrush may include a handle. The handle may include a drive unit. The electric toothbrush may include the electric toothbrush head of the first aspect, which may be functionally coupled to the drive unit. The handle may optionally house a power source, such as a rechargeable battery or replaceable batteries, and include an electronic circuit for controlling the operation of the drive unit. The drive unit itself may be implemented as an electric motor, a piezoelectric actuator, or any other suitable mechanism capable of setting the toothbrush head in motion.

[0044] The electric toothbrush head, which may be removable or permanently attached to the handle, can be configured according to one of the embodiments described above. For example, the head may optionally include a bristle field with a plurality of bristles, wherein the bristles may comprise a stimulus-responsive material designed to cause a reversible reduction in stiffness in response to a first condition, such as excessive brushing pressure. Additionally, the head may optionally include a mechanical force-protection mechanism, which may be arranged to cause a reversible physical displacement of the bristle field relative to the drive unit in response to a second condition, such as excessive brushing force. The physical displacement may include, among other things, rotational slippage, a linear retraction movement, or an angular tilt.

[0045] In some possible configurations, the connection between the toothbrush head and the drive unit can be achieved via a mechanical interface, such as a snap-fit, bayonet, or threaded connection, allowing for easy head replacement or interchangeability. Alternatively, the head can be permanently attached to the handle, creating an integrated assembly. Depending on the specific design and intended cleaning effect, the drive unit can be positioned to transmit an oscillating, rotating, or reciprocating motion to the bristle field.

[0046] It is also conceivable that the handle could include user interface elements such as buttons, switches, or touch-sensitive controls to select operating modes, adjust intensity, or activate additional functions. In some designs, the handle may also include indicators such as LEDs or screens to provide feedback on battery status, cleaning time, or the activation of safety mechanisms. Depending on the intended application and user requirements, wireless charging capabilities or a waterproof design may also be included.

[0047] The electric toothbrush can be designed to be compatible with a range of brush heads, including those with adaptive or protective features, as described here. In certain models, the system can be configured to detect the presence or type of attached head and adjust the operating parameters accordingly. The combination of a handle with a drive unit and a brush head with stimulation-sensitive bristles and / or a mechanical force-protection mechanism can offer the user increased safety, comfort, and cleaning effectiveness.

[0048] Overall, the electric toothbrush can be implemented in numerous forms, with the specific arrangement and features of the handle, drive unit, and toothbrush head being selected according to performance objectives, manufacturing considerations, and user preferences. The embodiments described herein serve to illustrate possible configurations and are not to be understood as limiting the scope of disclosure.

[0049] In some embodiments, the drive unit can be configured to temporarily reduce its operating intensity in response to the physical displacement of the toothbrush head. This coordinated response between mechanical protection and motor function offers increased safety while maintaining consistent cleaning performance.

[0050] In some embodiments, the handle can include a power source that is functionally coupled to a feedback generator located on the toothbrush head. This integration enables energy-efficient feedback that reinforces proper brushing technique.

[0051] In a third aspect, the present disclosure relates to a method for automatically regulating the brushing force exerted by an electric toothbrush.

[0052] In embodiments, the method comprises detecting a first state indicating excessive brushing pressure on a bristle field. This first state can be identified by a sensor, a change in a physical property of the bristles, or by the inherent response of the stimuli-responsive material itself. For example, the first state can correspond to a threshold value for the pressure, temperature, or mechanical stress to which the bristles are subjected during brushing.

[0053] In embodiments, the method comprises, in response to the first condition, automatically inducing a reversible reduction in the stiffness of a plurality of bristles within the bristle field. The bristles may comprise a stimulus-responsive material. The stimulus-responsive material is selected such that, when exposed to the first condition, it undergoes a physical or chemical change resulting in a reduction of its modulus or stiffness. This reversible reduction in stiffness allows the bristles to bend more easily under load, thereby reducing the risk of excessive force being transmitted to the teeth and gums. The reduction in stiffness is automatically reversed when the first condition ceases, restoring the bristles to their original state to ensure continued effective cleaning.

[0054] In embodiments, the method includes detecting a second condition indicating excessive brushing force on the bristle field. This second state can be determined by monitoring the force exerted on the bristle field, for example, by integrated force sensors, mechanical triggers, or by activating a mechanical force protection mechanism. The second state may differ from the first state or overlap in certain operating scenarios, depending on the toothbrush design and the properties of the stimuli-responsive material.

[0055] In embodiments, the method comprises, in response to the second state, the automatic induction of a reversible physical displacement of the bristle field. The displacement can take at least one of the following forms: rotational slippage, linear retraction, or angular tilting. The physical displacement can occur as rotational slippage, in which the bristle field rotates relative to the drive shaft; as linear retraction, in which the bristle field moves axially away from the drive unit; or as angular tilting, in which the bristle field rotates relative to its normal orientation. The specific type of displacement can be determined by the configuration of the mechanical force-protection mechanism integrated into the toothbrush head.

[0056] The reversibility of both the reduction in bristle stiffness and the physical displacement ensures that the protective reactions are only active under excessive pressure or force, and that normal operation is restored as soon as safe brushing conditions are re-established. This method offers a two-stage approach to regulating brushing force, combining adaptive bristle properties with mechanical displacement to enhance user safety and comfort while ensuring effective oral hygiene.

[0057] The method can be implemented in electric toothbrushes equipped with suitable, sensitive bristle materials and mechanical force-protection mechanisms. Detection of the first and second conditions, and activation of the corresponding protective responses, can be achieved through passive material properties, integrated sensors, or a combination of both. The method is compatible with a range of toothbrush head and handle designs and can be adapted to different user preferences or oral care needs.

[0058] In some embodiments, the first condition can involve raising the temperature of the bristles to mouth temperature. This temperature-based adjustment provides automatic protection without requiring any user action or electronic systems.

[0059] In some embodiments, the first condition can involve applying a mechanical force to the bristles that exceeds a first pressure threshold. The force-based adaptation reacts immediately to aggressive brushing, thus preventing damage before it occurs.

[0060] In some embodiments, the second condition may include the application of a peak force exceeding 150 grams. This specific threshold ensures that the protection is activated at clinically relevant force levels associated with potential gum damage.

[0061] In embodiments, the step of bringing about the reversible physical displacement can include slipping a magnetic coupling about its axis of rotation.

[0062] The slippage of the magnetic coupling ensures precise, consistent force limitation with tactile feedback.

[0063] In some embodiments, the step of bringing about the reversible physical displacement can include the linear retraction of the bristle field by a distance between 1.0 mm and 2.0 mm. This specific retraction path provides noticeable feedback while maintaining brush stability.

[0064] In some embodiments, the step of bringing about the reversible physical displacement can include tilting the bristle field by an angle between 10 and 15 degrees. This controlled tilt automatically optimizes the brush's alignment with the teeth while simultaneously protecting the gums.

[0065] In some embodiments, the method can further include the step of generating a feedback signal perceptible to the user in response to the second condition. Additional feedback reinforces the learning of the correct cleaning technique.

[0066] In some embodiments, generating the user-perceived feedback signal can involve emitting a light pulse from an LED. The visual feedback provides a clear, unambiguous indication of excessive pressure, complementing tactile cues.

[0067] In embodiments, the method can further include the release of a fluid or air blast from the electric toothbrush head in response to the second condition. This function ensures a consistent cleaning effect, even when mechanical movement is restricted due to excessive pressure.

[0068] In a fourth aspect, the present disclosure relates to a method for manufacturing an electric toothbrush head.

[0069] In embodiments, the method comprises forming a plurality of bristles from a stimulus-responsive material. The material can be selected to exhibit a reversible reduction in stiffness in response to a first condition indicating excessive brushing pressure. Accordingly, the method begins with the selection and preparation of a stimulus-responsive material suitable for bristle formation. The stimulus-responsive material is selected to undergo a reversible reduction in stiffness when subjected to a first condition, which may be, for example, excessive brushing pressure. Suitable materials may include, among others, shape-memory polymers, thermoreactive polymers, piezoelectric composites, or magnetorheological elastomers. The material can be selected based on its ability to respond to a particular stimulus, such as...A rise in temperature to oral temperature, the application of a mechanical force exceeding a threshold, or exposure to a magnetic field can cause a temporary reduction in modulus or stiffness. Once the appropriate material has been selected, the multiple bristles are formed using conventional bristle manufacturing techniques. These may include extrusion, forming, or cutting processes, depending on the type of stimuli-responsive material and the desired bristle geometry. The bristles can be produced in various lengths, diameters, and cross-sectional shapes to meet the intended cleaning performance and user comfort. In some embodiments, the bristles can be further processed to incorporate features such as tapered tips, hydrogel cap tips, or surface texturing.

[0070] The process can involve attaching multiple bristles to form a bristle field on a head chassis. The head chassis serves as the structural base for the bristle field and provides the interface for attachment to the rest of the toothbrush head assembly. Bristle attachment can be achieved by inserting the bristle tufts into openings in the chassis and by hot pressing, ultrasonic welding, gluing, or mechanical anchoring. The arrangement of the bristle field can be customized to provide optimal cleaning coverage for the teeth and an adaptive response of the bristles under varying brushing conditions.

[0071] The method may involve integrating the head chassis with a mechanical force protection mechanism configured to induce a reversible physical displacement of the bristle field in response to a second condition indicating excessive brushing force. The displacement includes at least one of the following: rotational slip, linear retraction, or angular tilt. The integration of the force protection mechanism may involve assembling components such as a clutch (for rotational slip), a spring-mounted subassembly (for linear retraction), or a compliant joint or hinge (for angular tilt) into the head housing. The mechanism may be designed to be activated when a second condition, such as...Excessive brushing force is detected, allowing the bristle field to move in such a way as to reduce the transmission of excessive force to the user's teeth and gums.

[0072] The assembly process may include aligning and securing the mechanical force guard mechanism within the head housing, ensuring that the bristle field is functionally coupled to the mechanism and that the intended displacement modes are achievable under the specified force conditions. Quality control steps may be performed to verify the bristle responsiveness to the first condition and the correct function of the force guard mechanism under simulated brushing forces.

[0073] The electric toothbrush head manufactured using this process is able to provide adaptive protection against excessive brushing pressure and force, thereby increasing user safety and comfort while maintaining effective cleaning performance. The process is compatible with a range of toothbrush head designs and can be adapted to include additional features such as feedback generators, hydrogel cap tips, or telescopic bristle anchors, depending on the desired functionality and application.

[0074] In some embodiments, the step of forming the multiple bristles can involve forming the bristles from a shape-memory polymer. Shape-memory polymers offer reliable, repeatable stiffness changes with minimal manufacturing complexity.

[0075] In embodiments, the step of forming the multiple bristles can include embedding ferromagnetic particles in an elastomeric polymer and further integrating a magnetic field generator into the head housing near the bristle field. This approach enables precise electronic control of the bristle stiffness in response to real-time conditions.

[0076] In some embodiments, the step of integrating the mechanical force protection mechanism may include assembling a magnetic torque micro-coupling configured for rotational slip. This mechanism provides precise, calibrated force limitation with minimal wear over time.

[0077] In embodiments, the method can further include calibrating the magnetic torque micro-coupling so that it slips at an equivalent peak force between 160 grams and 200 grams. This specific calibration range ensures consistent protection at clinically relevant force thresholds.

[0078] In some embodiments, the step of integrating the mechanical force protection mechanism may involve assembling a spring-mounted subassembly configured for linear return. This approach provides clear tactile and visual feedback with reliable mechanical function.

[0079] In embodiments, the step of integrating the mechanical force protection mechanism may involve assembling an eccentric cam and a compliant joint in a neck section of the toothbrush head configured for an angled tilt. This mechanism allows for automatic adjustment to optimal brushing angles while protecting against excessive force.

[0080] In further embodiments, the method may include integrating a feedback generator into the toothbrush head, wherein the feedback generator is configured to be activated by the mechanical force protection mechanism. Direct mechanical activation ensures reliable feedback without the need for complex sensors.

[0081] In some embodiments, the feedback generator can include an LED and a microswitch or a Hall-effect sensor, positioned to detect the physical displacement. This combination provides reliable electronic feedback with minimal components and power requirements.

[0082] In further embodiments, the method may include forming a transparent window in the head housing to allow a view of at least part of the mechanical force protection mechanism. This visual confirmation improves the user's understanding of and confidence in the toothbrush's protective functions.

[0083] In the aspects and embodiments described above, the stimulus-responsive bristles and the mechanical force-protection mechanism are advantageously combined. However, in alternative aspects and embodiments, a toothbrush head may be provided with only one of these safety features, such as: In another aspect, the present disclosure relates to an electric toothbrush head for coupling with a drive unit, comprising the following: a bristle field with a plurality of bristles. The bristles may comprise a stimulus-responsive material configured to cause a reversible reduction in stiffness in response to a condition indicating excessive brushing pressure.

[0084] In another aspect, the present disclosure relates to an electric toothbrush head for attachment to a drive unit, comprising the following: a mechanical force protection mechanism. The force protection mechanism can be configured to cause a reversible physical displacement of the bristle field relative to the drive unit in response to a condition indicating excessive brushing force. The displacement can have at least one of the following characteristics: a rotational slip, a linear retraction movement, or an angular tilt.

[0085] Both aspects can be combined with the corresponding features and embodiments disclosed above and elsewhere in the disclosure. Furthermore, corresponding electric toothbrushes, methods for automatically regulating the brushing force exerted by an electric toothbrush, and methods for manufacturing an electric toothbrush head can be provided.

[0086] Finally, the present disclosure is not limited to electric toothbrushes and electric toothbrush heads. Rather, the disclosed concepts can also be provided in embodiments that include a manual toothbrush, or simply a "toothbrush," a corresponding toothbrush head, and, if applicable, corresponding operating and manufacturing processes.

[0087] Unless explicitly stated otherwise, the terms used herein are generally to be understood as they would be understood by an average person skilled in the art. The following explanations may aid understanding: Unless otherwise specified, the term "electric toothbrush head" refers to the part of an electric toothbrush configured to connect to a handle or similar housing containing a drive unit and which carries the bristles or cleaning elements. Examples of specific designs include interchangeable heads that snap onto a suitable drive shaft, integrated one-piece heads, and variants with a swivel or rotary interface. It should be noted that the toothbrush head itself need not be electric, but must be designed to interact with an electric toothbrush.

[0088] Unless otherwise specified herein, the term "bristle field" refers to an arrangement or grouping of individual bristles or cleaning filaments mounted on a head chassis. Examples of specific embodiments include bristles arranged in concentric rings, bristles arranged in linear rows, or multi-zone combinations of angled and straight filaments.

[0089] Unless otherwise specified herein, the term "bristle" refers to a single strand or filament of bristles suitable for cleaning teeth or gums. Examples of specific embodiments include nylon filaments, polymer filaments impregnated with active ingredients, or microfiber filaments with specially structured tips.

[0090] Unless otherwise specified, the term "stimulus-sensitive material" in this description refers to a category of materials that undergo a reversible change in their mechanical or physical properties when subjected to a specific stimulus, such as temperature, force, magnetic field, or electric field. Examples of specific embodiments include shape-memory polymers that soften above a certain temperature, piezoelectric composites that change their stiffness under an electric field, or magnetorheological elastomers that change their stiffness in the presence of a magnetic field.

[0091] Unless otherwise specified herein, the term "excessive brushing pressure" refers to a force or pressure exerted on the bristles that exceeds the level desirable or recommended for safe and effective tooth cleaning. Examples of specific embodiments include a threshold that triggers a softening response at a certain temperature caused by frictional heating or at a certain pressure measured by a pressure-sensitive element.

[0092] Unless otherwise specified herein, the term “reversible reduction in stiffness” refers to a change in the stiffness of a material or structure that can be reversed or undone when the inducing stimulus is removed or reduced. Examples of specific embodiments include a polymer that softens above a certain temperature but returns to a stiffer state upon cooling, and an elastomer that increases in flexibility during compressive loading but becomes stiff again after the loading is removed.

[0093] Unless otherwise specified herein, the term "mechanical force protection mechanism" refers to any mechanical arrangement or feature incorporated into a toothbrush head to prevent or mitigate damage or excessive forces by enabling or causing a structural response when a force threshold is exceeded. Examples of specific embodiments include clutch mechanisms that slip under high torque, tensioned spring subassemblies that retract, or joints configured to oscillate or tilt.

[0094] Unless otherwise specified herein, the term "excessive brushing force" refers to a force applied to the toothbrush head that exceeds a recommended limit and may lead to undesirable results such as gum irritation or damage to the toothbrush. Examples of specific embodiments include forces exceeding a specified load threshold, e.g., 150 grams, 180 grams, or other calibrated force values ​​selected based on safety guidelines.

[0095] Unless otherwise specified herein, the term “reversible physical displacement” refers to a movement or displacement of the bristle field or assembly that can return to its original position once the excessive force is reduced or removed. Examples of specific embodiments include rotary slip facilitated by a clutch, linear retraction enabled by a spring mechanism, or angular tilt facilitated by a pivot joint.

[0096] Unless otherwise specified herein, the term “rotational slippage” refers to a partial or complete rotation of a brush head or subassembly relative to its drive shaft or anchoring point, triggered by a threshold torque or force, which returns to its original rotational orientation after the force is reduced. Examples of specific embodiments include friction-based couplings, magnetic torque micro-couplings, and ratchet locks that permit limited rotation.

[0097] Unless otherwise specified herein, the term “linear retraction” refers to an essentially rectilinear movement of the bristle field or assembly away from the user’s teeth or gums in response to an applied force, with the ability to return to its original position once the force is released. Examples of specific embodiments include springs, elastomeric couplings, and telescopic guides that allow travel within a defined range, for example, 1.0 mm to 2.0 mm.

[0098] Unless otherwise specified, the term "angular tilt" refers to a pivoting or bending movement of the toothbrush head, or a part thereof, around an axis, allowing the bristle field to assume a new angular position and return to its original orientation when the excessive force is released. Examples of specific embodiments include swivel joints in the neck region, bend-based pivoting mechanisms, and eccentric cam systems with elastic couplings.

[0099] Unless otherwise specified herein, the term "shape memory polymer" refers to a polymer material that can be deformed under certain conditions (e.g., temperature) and then returns to its original shape when those conditions are changed. Examples of specific embodiments include polyurethane-based shape memory resins, thermoplastic polyurethane elastomers, polycaprolactone-based blends, and other formulations designed to transition between different stiffness states in response to temperature changes.

[0100] Unless otherwise specified, the term "piezoelectric composite" refers to a composite material containing one or more piezoelectric phases—for example, piezoceramic particles—embedded in a polymer or other matrix, such that the composite changes its mechanical properties in response to an electric field or mechanical stress. Examples of specific embodiments include polyvinylidene fluoride (PVDF) mixtures with ceramic inclusions, flexible transducer films, and layered laminate structures.

[0101] Unless otherwise specified herein, the term “magnetorheological elastomer” refers to an elastomer matrix embedded or loaded with magnetic particles that, under an applied magnetic field, cause reversible changes in the stiffness or viscosity of the material. Examples of specific embodiments include silicone rubber loaded with iron microparticles, natural rubber doped with neodymium powder, and hybrid polymer-metal suspensions formulated to produce controllable stiffening in response to an external magnetic field.

[0102] Unless otherwise specified herein, the term "magnetic field generator" refers to any device or arrangement that generates a magnetic field near the bristles and thereby affects a magnetorheological elastomer or other magnetically reactive material. Examples of specific embodiments include small permanent magnets, electromagnets powered by the toothbrush's power source, and adjustable solenoid systems.

[0103] Unless otherwise specified, the term "effective tip stiffness" refers to the overall stiffness or resistance to deflection exhibited by the bristle tips under specific conditions, such as temperature or applied field, as a functional measure. Examples of specific embodiments include measured values ​​within a range of stiffness reduction percentages, such as a decrease of at least 40 percent between 22 °C and 37 °C.

[0104] Unless otherwise specified herein, the term "clutch mechanism" refers to an assembly that enables the selective transmission of torque or rotary motion and automatically disengages under excessive load to protect components. Examples of specific embodiments include friction-based rotary clutches, magnetic clutches, and ratchet spring clutches designed to slip when a certain torque threshold is exceeded.

[0105] Unless otherwise specified herein, the term "magnetic torque micro-coupling" refers to a compact coupling mechanism that uses magnetic coupling elements to control torque transmission and allows a slip or disengagement condition when a specified torque level is exceeded. Examples of specific embodiments include magnet pairs with calibrated gaps, multipole magnet arrays, or embedded magnetic particles arranged to slip within a specific load range, for example, between 160 grams and 200 grams equivalent peak force.

[0106] Unless otherwise specified herein, the term "spring-mounted subassembly" refers to a loosely or rigidly guided structural arrangement in which a spring or other elastic element controls and assists the movement of the bristle field or an associated component. Examples of specific embodiments include coil springs, leaf springs, elastomer rings, and compression assemblies that provide variable travel distances to enable linear return.

[0107] Unless otherwise specified herein, the term "viscoelastic dashpot cartridge" refers to a damping component that provides resistance proportional to the displacement rate and is typically used in conjunction with a spring to control sudden or rapid movements. Examples of specific embodiments include small oil-filled cylinders, silicone fluid-based dashpots, and polymeric shock absorbers integrated into a subassembly to produce progressively increasing resistance.

[0108] Unless otherwise specified herein, the term "eccentric cam" refers to a cam device in which the axis of rotation deviates from the geometric center, resulting in a controlled variable displacement as it rotates or engages. Examples of specific embodiments include eccentric circular cams, cams with cam projections, and multi-part cam profiles used to create an angular inclination or to achieve a specific mechanical advantage.

[0109] Unless otherwise specified herein, the term "flexible connection" refers to a flexible or semi-flexible connection that allows relative movement between connected components under load. Examples of specific embodiments include polymer hinges, elastomeric couplings, or pivot elements with integrated spring characteristics.

[0110] Unless otherwise specified herein, the term "detent" refers to a feature or projection that engages in a corresponding recess or stop to produce tactile feedback or temporary locking when engaged. Examples of specific embodiments include ball-and-spring detent mechanisms, cam-drive detents, or small notches that produce an audible click when engaged.

[0111] Unless otherwise specified herein, the term "feedback generator" refers to any component or system that provides a user-perceived signal in response to a specific threshold or event, such as a physical displacement or force detection. Examples of specific implementations include LEDs that light up, miniature speakers or buzzers that emit an audible tone, vibration motors that produce a tactile alarm, or mechanical clickers that generate a perceptible noise.

[0112] Unless otherwise specified herein, the term "hydrogel cap tips" refers to bristle caps that are partially or entirely composed of a hydrogel material that may swell or change its consistency under certain conditions, such as increased humidity, heat, or pressure. Examples of specific embodiments include polyacrylamide caps, polyethylene glycol-based gels, and hybrid polymer tips that expand or soften in an aqueous environment.

[0113] Unless otherwise specified herein, the term “telescopic spiral root anchor” refers to bristle fastening structures designed to expand or contract spirally or helically under compressive or tensile stress and to return to their original position when the stress is removed. Examples of specific embodiments include interlocking spiral tubes, threaded anchor rods capable of slight axial expansion, and spiral spring-loaded connectors.

[0114] Unless otherwise specified herein, the term "transparent window" refers to a portion of the toothbrush head or housing made of a clear or transparent material that allows a view of internal components or mechanisms. Examples of specific embodiments include polycarbonate windows, acrylic inserts, or special glass or ceramic parts integrated into the head assembly.

[0115] Unless otherwise specified herein, the term "electric toothbrush" refers to a toothbrush assembly comprising a motor-driven drive or drive unit in a handle section and a removable or fixed toothbrush head section configured for cleaning teeth. Examples of specific embodiments include rechargeable cordless toothbrushes, corded systems with external transformers, and battery-powered travel units.

[0116] Unless otherwise specified herein, the term "handle" refers to the grippable body part of an electric toothbrush or similar device that houses or carries a power source, motor, control electronics, or other functional systems. Examples of specific embodiments include cylindrical housings with an internal battery, ergonomic handles with textured grip areas, and contoured housings that also contain a charging module.

[0117] Unless otherwise specified herein, the term "drive unit" refers to the power transmission assembly within an electric toothbrush handle that generates the movement or rotating oscillation of the brush head. Examples of specific embodiments include small DC motors, magnet-based vibration drives, linear actuators, or sonic vibration generators.

[0118] Unless otherwise specified herein, the term "power source" refers to any device or component that supplies electrical energy to operate the toothbrush. Examples of specific embodiments include rechargeable lithium-ion batteries, replaceable alkaline batteries, and inductively powered modules that receive energy from a charging station.

[0119] Unless otherwise specified herein, the term "liquid or air burst" refers to a controlled release of liquid or gas from a reservoir or channel within a toothbrush head or handle, often triggered by a sensor or mechanical event. Examples of specific embodiments include a short burst of water from a mini-pump, a release of compressed air from an internal reservoir, or a controlled spray of mouthwash solution from an integrated chamber.

[0120] Particular and preferred aspects of the present disclosure are set forth in the attached independent and dependent claims. Features from the dependent claims may be combined with features of the independent claims and with features of other dependent claims, to the extent appropriate and not merely expressly set forth in the claims.

[0121] The aforementioned and other features, characteristics, and benefits of the present revelation will become apparent from the following detailed description in conjunction with the accompanying drawings, which exemplify the principles of the revelation. This description serves only as an example and does not limit the scope of the revelation. BRIEF DESCRIPTION OF THE DRAWINGS

[0122] The present revelation can be better understood with the help of the following drawing: Fig. Figure 1 is a schematic view of an electric toothbrush with a handle and a toothbrush head according to embodiments of the present disclosure. DETAILED DESCRIPTION

[0123] The following section describes representative embodiments, which are illustrated in the accompanying drawing. It is understood that the illustrated embodiments and the following descriptions are examples and do not serve to limit the embodiments to a preferred embodiment.

[0124] Embodiments relate to an electric toothbrush and a corresponding brush head designed to prevent overbrushing while maintaining plaque removal through material-level adaptation, mechanical force limitation, automatic geometric alignment, or combinations thereof. Certain embodiments combine adaptive bristles, a calibrated magnetic slip clutch with LED coaching, an automatically tilting cam, and a spring / damper head to physically implement the principle: the harder the user presses, the more the brush protects, without compromising cleaning performance.

[0125] Embodiments of the electric toothbrush and toothbrush head disclosed herein may, individually or in combination, provide one or more of the following protective measures: • Stage 1 - Material adaptation: Bristle stiffness and contact softness change under load and at mouth temperature. • Stage 2 - Mechanical Limitation: The magnetic micro-coupling slips at a calibrated peak force, the head assembly retracts by 1-2 mm to absorb peaks. • Level 3 - Geometric alignment and coaching: The head automatically tilts downwards by 10-15° under torque; tactile "click" + short LED pulse guidance for easier technique. System overview

[0126] Fig. Figure 1 shows an electric toothbrush 100 with a handle 114 and a toothbrush head 108 according to embodiments of the present disclosure. The handle 114 houses a drive unit 110. The toothbrush head 108 comprises a neck section 106 and a bristle field 102 with bristles 104.

[0127] In certain embodiments, the bristles 104 comprise a stimulus-responsive material configured to cause a reversible reduction in stiffness in response to an initial condition indicating excessive brushing pressure.

[0128] In certain embodiments, the toothbrush head 108 includes a mechanical force protection mechanism configured to cause a reversible physical displacement of the bristle field 102 relative to the drive unit 110 in response to a second condition indicating excessive brushing force.

[0129] These features, individually or in combination, help the toothbrush to adapt to excessive brushing force, thereby increasing user comfort and protecting oral tissue. sensitive bristles

[0130] In certain embodiments, the first condition that triggers the reversible reduction in bristle stiffness can be an increase in the bristle temperature to oral temperature. For example, the reactive material incorporated into the bristles can be selected to undergo a change in its mechanical properties, such as softening, at temperatures typically encountered in the oral cavity during tooth brushing. This temperature-sensitive behavior can be achieved by using polymers or composite materials that exhibit a modulus transition at or near human body temperature, for example, in the range of approximately 30°C to 40°C.

[0131] The bristles may remain relatively stiff at ambient temperatures, such as those encountered during storage or handling, and become more flexible once the toothbrush head is inserted into the mouth and the bristles are exposed to the increased oral temperature. This reversible adaptation can offer the user greater comfort and protection, as the bristles yield more easily under pressure when softened by the warmth of the oral cavity, thus reducing the risk of excessive force being applied to teeth and gums.

[0132] Alternatively, the stimulus-responsive material can be designed to react to a specific temperature threshold, so that the reduction in stiffness only occurs when the bristles reach a predetermined temperature associated with oral use. In some configurations, the temperature sensitivity of the bristle material can be adjusted by modifying the composition or structure of the polymer, thus enabling precise control of the activation point of the softening response.

[0133] Such temperature-sensitive bristles can be used alone or in combination with other types of reaction-sensitive mechanisms, depending on the desired performance characteristics of the toothbrush head. Using temperature as a trigger for the reversible reduction of stiffness offers a passive and reliable way to adapt the bristle properties to the oral environment without the need for electronic sensors or active control systems.

[0134] In an alternative embodiment, the first condition that triggers the reversible reduction in bristle stiffness can be the application of a mechanical force to the bristles exceeding a first pressure threshold. In such a configuration, the stimulus-responsive material forming part or all of the bristles could be selected or designed to respond to a defined level of pressure or bending force. If the force applied to the bristles during brushing exceeds this predetermined threshold, the material can undergo a physical or structural change resulting in a temporary reduction in stiffness.

[0135] For example, the bristle material could contain polymers or composites that exhibit force-induced softening, such as those with reversible microstructural transitions or shear-thinning properties. Under excessive brushing pressure, these materials can become more flexible, allowing the bristles to bend more easily and reducing the risk of injury to oral tissues. Once the applied force falls below the threshold, the bristles can return to their original, stiffer state, thus restoring normal cleaning performance.

[0136] It is also conceivable that the bristles contain microcapsules, phase-change zones, or other technical features that allow for a reversible change in modulus when subjected to mechanical stress above a certain value. The pressure threshold at which the reduction in stiffness occurs can be adjusted during material selection or manufacturing to accommodate different user preferences or oral care requirements.

[0137] This force-dependent behavior can be implemented independently or in conjunction with other responsive mechanisms, such as temperature sensitivity, to achieve a multimodal protective response. By dynamically adapting the bristles to excessive brushing force, this design can contribute to improved safety and user comfort while ensuring effective plaque removal under normal brushing conditions.

[0138] In some embodiments, the reactive material incorporated into the bristles can be a shape-memory polymer. A shape-memory polymer is a polymeric material that can undergo a reversible change in its mechanical properties, such as stiffness or shape, in response to an external stimulus. This stimulus could be, for example, a change in temperature, the application of mechanical force, or exposure to moisture. When used in an electric toothbrush head, a shape-memory polymer can be selected to reduce bristle stiffness under certain conditions, such as when the bristles are exposed to the temperature in the mouth or when a specific brushing force is applied.The use of a shape-memory polymer as the reactive material can cause the bristles to temporarily soften or bend more easily in the presence of a specific stimulus, and then return to their original, stiffer shape once the stimulus is removed. For example, the shape-memory polymer can be designed to have a transition temperature within the range of temperatures typically found in the oral cavity (e.g., between 30°C and 40°C). When the bristles are exposed to this temperature range during brushing, the polymer can transition into a softer state, reducing the risk of excessive force being applied to the teeth and gums. After cooling to ambient temperature, the bristles can regain their original stiffness, ensuring a long lifespan and effective cleaning performance in subsequent uses.

[0139] Alternatively, the shape-memory polymer can be formulated to respond to mechanical stress, causing the bristles to become more flexible when forces exceed a predetermined threshold. This force-induced softening can provide additional protection against over-brushing, as the bristles yield more easily under excessive pressure and then return to their original shape once normal brushing conditions are restored.

[0140] It is also possible to combine the shape memory polymer with other materials or additives to tailor its responsiveness and mechanical properties. For example, the bristles can contain a blend of shape memory polymer and conventional nylon, or reinforcing fillers to adjust the modulus and wear resistance. The selection and formulation of the shape memory polymer can be customized to achieve the desired balance between flexibility, elasticity, and responsiveness to oral conditions.

[0141] The incorporation of a shape-memory polymer as a reactive material into the bristles can be achieved through various manufacturing techniques, such as co-extrusion, overmolding, or embedding shape-memory polymer filaments into a matrix of standard bristle material. This approach offers a passive, reliable, and reversible way to adapt the bristle properties to changing brushing conditions, thereby increasing user comfort and safety without the need for electronic sensors or active control systems.

[0142] In another possible embodiment, the reactive material incorporated into the bristles can comprise a piezoelectric composite. Such a piezoelectric composite can be selected to change its mechanical properties, for example, its stiffness, in response to mechanical or electrical stimuli that occur during brushing. The piezoelectric composite can contain a polymer matrix, such as polyvinylidene fluoride (PVDF), in which piezoelectric ceramic particles or fibers are dispersed. Alternatively, the bristles can be formed from a mixture of piezoelectric polymers and conventional bristle materials.The use of a piezoelectric composite as a stimulus-responsive material can cause the bristles to exhibit a reversible reduction in stiffness when subjected to an initial condition, such as excessive brushing pressure or force. When mechanical stress is applied to the bristles during brushing, the piezoelectric effect can generate an internal electric field within the composite, which in turn could induce a change in the orientation or structure of the polymer chains, leading to a temporary reduction in modulus. Once the stress is removed or reduced below a certain threshold, the bristles can regain their original stiffness and thus restore normal cleaning performance.

[0143] In some configurations, the piezoelectric composite material can be designed to respond to specific pressure levels or vibration frequencies, thereby adapting the bristle response to the operating characteristics of the electric toothbrush. It is also conceivable that the piezoelectric effect could be used passively or in conjunction with additional electronics to provide a feedback signal, further enhancing user safety or cleaning effectiveness. However, in the context of a passive, self-regulating system, the primary function of the piezoelectric composite material is to enable the bristles to dynamically adjust their stiffness to the brushing conditions without the need for external energy sources or active control mechanisms.

[0144] The incorporation of a piezoelectric composite material into bristles can be achieved through various manufacturing techniques such as coextrusion, melt mixing, or surface coating. The proportion and distribution of the piezoelectric phase within the bristle material can be adjusted to achieve the desired balance between flexibility, responsiveness, and durability. In some cases, the piezoelectric composite material can be combined with other stimulus-responsive materials, such as shape-memory polymers or thermoreactive polymers, to achieve a multimodal adaptive response.

[0145] By using a piezoelectric composite material as the reactive material, it is possible to produce bristles that reversibly lose stiffness under excessive brushing pressure, thus providing additional protection for the user's teeth and gums. This approach can be particularly advantageous when rapid, reversible, and passive adjustment of bristle properties is desired and integration into existing toothbrush head designs is required.

[0146] In another embodiment, the reactive material incorporated into the bristles can optionally be a magnetorheological elastomer. A magnetorheological elastomer is a composite material that can reversibly change its mechanical properties, such as stiffness, in response to an applied magnetic field. For example, the bristles can contain an elastomeric polymer matrix in which magnetizable particles, such as iron or ferrite particles, are dispersed. When a magnetic field is applied, the magnetic orientation or interaction of these particles within the elastomer can change, resulting in a rapid and reversible change in bristle stiffness.

[0147] It is also conceivable that the toothbrush head could additionally include a magnetic field generator, which could be configured to selectively modify the magnetic field exerted on the bristles. The magnetic field generator could take various forms, such as a miniature electromagnet, a coil embedded in the head, or a permanent magnet that is movable or rotatable relative to the bristle field. In some possible configurations, the magnetic field generator could be integrated into the drive unit or the coupling interface, allowing the field strength to be dynamically adjusted during operation. Alternatively, the magnetic field could be generated passively, for example, by positioning a permanent magnet near the bristles, with the field strength modulated by mechanical displacement or rotation.

[0148] By using a magnetorheological elastomer as the bristle material, it becomes possible to achieve a reversible reduction in stiffness by adjusting the magnetic field in response to specific brushing conditions, such as excessive pressure or force. For example, the system can be designed so that the magnetic field holds the bristles in a relatively stiff state under normal brushing conditions. If a threshold of excessive brushing force is detected—either passively through mechanical coupling or actively via a sensor—the magnetic field generator can be activated to reduce the field strength, making the bristles softer and more flexible. Once the excessive force subsides, the magnetic field can be restored, allowing the bristles to regain their original stiffness.

[0149] The use of a magnetorheological elastomer in combination with a magnetic field generator offers several advantages, including a fast response time, precise control of bristle stiffness, and the ability to tailor the adaptive behavior to individual user preferences or specific oral care requirements. This approach can be implemented alone or in conjunction with other stimulus-responsive materials such as shape-memory polymers or piezoelectric composites to achieve a multimodal protective response.

[0150] Manufacturing processes for such embodiments may include overmolding or co-extruding the magnetorheological elastomer into the bristle field, as well as integrating the magnetic field generator into the head or drive unit. The design can be adapted to ensure compatibility with commercially available electric toothbrush drives while providing the added benefit of adaptive bristle stiffness in response to magnetic field modulation. This arrangement can increase user comfort and safety by reducing the risk of excessive force transmission to teeth and gums, particularly during increased brushing pressure ( ).

[0151] In another possible embodiment, the reversible reduction in bristle stiffness can be achieved as a reduction in effective tip stiffness of at least 40 percent when measured between 22 °C and 37 °C. For example, the stimulus-reactive material incorporated into the bristles can be formulated such that when the temperature increases from ambient temperature (e.g., 22 °C) to typical oral temperatures (e.g., 37 °C), the modulus of the bristle tips decreases significantly, resulting in a marked softening. This reduction in effective tip stiffness can be determined using standard mechanical testing methods, such as dynamic mechanical analysis or force-displacement measurements, applied to the bristle field under controlled temperature conditions.

[0152] It is conceivable that the degree of stiffness reduction can be adjusted by modifying the composition or structure of the stimuli-responsive material. In some cases, the material can be selected or developed to reduce tip stiffness by at least 40 percent or even more within the specified temperature range. Such a pronounced change in mechanical properties can improve user comfort, as the bristles will yield more easily under pressure when warmed to oral temperature, thus reducing the risk of excessive force being applied to the teeth and gums.

[0153] Alternatively, the reversible reduction in stiffness can be achieved by using shape-memory polymers, thermoreactive elastomers, or other materials that exhibit a significant modulus transition within the relevant temperature range. The bristle design can be further optimized so that the softening effect occurs primarily at the bristle tips, where contact with the oral tissue takes place, while maintaining sufficient stiffness at the base to ensure effective cleaning and durability.

[0154] In some configurations, the reduction in effective tip stiffness can be measured as the percentage decrease in the force required to achieve a defined bristle tip deflection, comparing values ​​obtained at 22°C and 37°C. A minimum reduction of 40 percent is provided as an example of a suitable performance characteristic, and other degrees of stiffness change can be implemented depending on the specific requirements of the toothbrush head design.

[0155] By providing a bristle field with a reversible and significant reduction in tip stiffness in response to temperature changes, it is possible to achieve a toothbrush head that dynamically adapts to the oral environment, offering the user improved safety and comfort without compromising cleaning performance. This approach can be combined with other adaptive features, such as mechanical force protection mechanisms or additional irritation-sensitive materials, to further enhance the protective and functional properties of the toothbrush head. Mechanical force protection mechanism

[0156] In certain embodiments, the mechanical force protection mechanism can be configured to activate when the second condition corresponds to a force of more than 150 grams applied to the bristle tips. For example, the mechanism can be designed or calibrated to respond to a threshold force applied to the bristle ends, with the threshold optionally set to 150 grams or more. With this arrangement, the force protection mechanism remains inactive during normal brushing and is only activated when the user applies a force exceeding the preset limit.

[0157] It is also possible that the threshold force required to trigger the guard displacement—such as rotational slip, linear retraction, or angular tilt of the bristle field—is adjustable or selectable during manufacturing or assembly. In some configurations, the mechanism may employ a spring, friction clutch, or elastomeric coupling sized or tensioned to yield or slip when the peak force reaches approximately 150 grams. Alternatively, the mechanism could utilize a deformable component or magnetic detent that releases or changes position under similar force conditions.

[0158] Choosing a peak force threshold of approximately 150 grams may be based on clinical recommendations or user safety considerations to prevent excessive pressure on teeth and gums. However, other thresholds may be implemented depending on the intended user group or specific oral care requirements. The force protection mechanism can be further refined to provide a gradual or progressive response when the applied force exceeds the threshold, rather than triggering a sudden or binary activation.

[0159] In some designs, the force-protection mechanism can be automatically reset once the applied force falls below the activation threshold, ensuring that the bristle field returns to its original position and the toothbrush head resumes normal operation. This reversible behavior can contribute to both user comfort and the longevity of the toothbrush head.

[0160] Overall, the configuration of the mechanical force protection mechanism, which activates when a force exceeding 150 grams is applied to the tip, represents an approach to improving the safety and adaptability of the electric toothbrush head. This function can be implemented alone or in combination with other protective or adaptable elements, such as stimulus-responsive bristles, to ensure a comprehensive response to excessive brushing force. Mechanical force protection mechanism: Rotational slippage

[0161] In another possible embodiment, the physical displacement of the bristle field relative to the drive unit can be implemented as rotational slip, and the mechanical force protection mechanism can include a clutch mechanism. For example, the clutch mechanism can be arranged between the bristle field and the clutch interface of the toothbrush head, so that in the event of excessive brushing force—for example, a peak force exceeding a predetermined threshold—the clutch allows the bristle field to rotate independently of the drive unit. This rotational slip can serve to dissipate excess force and thereby reduce the risk of transmitting harmful loads to the user's teeth and gums.

[0162] The clutch mechanism can take various forms, including but not limited to a friction clutch, a spring-loaded detent, or a ratchet device. In some configurations, the clutch may be designed to engage only when the applied torque or axial force exceeds a predetermined value, thus enabling normal transmission of rotary motion under typical brushing conditions. Once the threshold is exceeded, the clutch may temporarily disengage or slip, allowing the brush field to rotate relative to the drive shaft. After the excessive force is released, the clutch may automatically re-engage, restoring the original clutch and resuming normal operation.

[0163] Alternatively, the coupling mechanism could be implemented using elastomeric or viscoelastic materials that deform under load, thus providing controlled and reversible slip behavior. In other configurations, magnetic or fluid-based couplings could be used to achieve similar protective effects. The selection and design of the coupling mechanism can be tailored to the specific requirements of the toothbrush head, such as the desired actuation force, the permissible slip range, and the durability of the components.

[0164] It is also conceivable that the rotary slip function could be combined with other forms of displacement, such as linear retraction or angular tilting, to achieve a multimodal protective response. Depending on the overall design of the toothbrush head, the clutch mechanism can be integrated into the base of the bristle field, the mounting hub, or at the interface with the drive unit.

[0165] By integrating a clutch mechanism that allows for rotational slippage in response to excessive brushing force, the toothbrush head can offer enhanced protection against over-brushing while maintaining effective cleaning performance during normal use. This approach can be particularly advantageous when a passive, mechanical safety device is preferred and minimal impact on the user's brushing experience is desired.

[0166] In certain embodiments, the coupling mechanism can optionally be implemented as a magnetic torque micro-coupling calibrated to slip at a peak force between 160 and 200 grams. Such a magnetic torque micro-coupling can be configured to cause controlled and reversible rotational slip of the bristle field relative to the drive unit when the applied brushing force exceeds a predetermined threshold within this range. The use of magnetic coupling elements, such as miniature permanent magnets or magnetically responsive materials, can allow for precise adjustment of the slip torque, ensuring that the coupling is activated only when necessary to protect the oral tissue from excessive force.

[0167] It is conceivable that the magnetic micro-coupling could be integrated into the toothbrush head's mounting hub or positioned at the interface between the bristle field and the drive shaft. The coupling could utilize opposing magnetic poles arranged to generate a resistive torque under normal operating conditions. If the torque generated by excessive brushing force exceeds the calibrated threshold—corresponding to a peak force between approximately 160 and 200 grams—the magnetic coupling can disengage, allowing the bristle field to rotate independently of the drive unit. Once the applied force drops below the threshold, the magnetic attraction can re-engage the coupling, restoring normal operation without manual intervention.

[0168] Alternatively, the magnetic torque micro-coupling can be designed to allow gradual or progressive slippage instead of a sudden disengagement, resulting in a smoother and more comfortable response for the user. The slippage threshold can be calibrated by selecting appropriate magnet strengths, adjusting the spacing between the magnetic elements, or incorporating additional mechanical features such as springs or damping materials to fine-tune the response.

[0169] In some possible configurations, the magnetic coupling mechanism can be combined with other protective or adaptive features, such as stimulus-responsive bristles or additional mechanical force-protection elements, to provide a comprehensive safety system. The use of a magnetic torque micro-coupling offers advantages such as low wear, quiet operation, and the ability to maintain consistent performance over repeated use cycles.

[0170] By optionally integrating a magnetic torque micro-coupling, calibrated to prevent slippage at a peak force between 160 and 200 grams, the electric toothbrush head can offer enhanced protection against over-brushing while ensuring that cleaning performance and user comfort are maintained under normal brushing conditions. This approach provides a passive, reliable, and maintenance-free method for limiting excessive force transmission to teeth and gums. Mechanical force protection mechanism: Linear retraction

[0171] In some possible embodiments, the physical displacement of the bristle field relative to the drive unit can occur in the form of a linear retraction motion, and the mechanical force protection mechanism can include a spring-mounted subassembly. For example, the bristle field or its mounting hub within the toothbrush head can be supported by one or more springs, such as coil springs, leaf springs, or elastomeric spring elements. If an excessive brushing force is applied—for example, a peak force exceeding a predetermined threshold—the spring-mounted subassembly can allow the bristle field to retract axially from the drive unit, thereby absorbing or dissipating the excess force.

[0172] This linear retraction mechanism can be implemented in various ways. In one arrangement, the brush field can be mounted on a sliding carriage or piston, which is pre-tensioned into its normal operating position by a compression spring. Under normal brushing conditions, the spring holds the brush field firmly engaged with the drive unit, thus ensuring efficient motion transmission. If the applied force becomes too great, the spring can compress, allowing the brush field to move linearly away from the drive shaft. Once the force drops below the activation threshold, the spring can return the brush field to its original position and restore normal operation.

[0173] Alternatively, the spring-mounted assembly could use torsional springs or bending elements, allowing a combination of linear and slight angular movement depending on the specific design requirements. The stiffness and stroke of the spring elements can be selected or adjusted to achieve the desired balance between user comfort, protective function, and cleaning effect. In some configurations, the spring mechanism can be adjustable so that the activation force can be adapted to different user preferences or oral care needs.

[0174] It is also conceivable that the linear retraction function could be combined with other forms of displacement, such as rotation or angular tilt, to achieve a multimodal protective response. Depending on the overall architecture of the toothbrush head, the spring-mounted subassembly can be integrated into the base of the bristle field, the mounting hub, or at the interface with the drive unit.

[0175] By integrating a spring-loaded subassembly that allows the bristle field to retract linearly under excessive force, the toothbrush head can offer additional protection against over-brushing. This approach can help reduce the risk of damaging teeth and gums while maintaining effective cleaning performance during normal use. The use of a spring-based mechanism also enables a passive, reversible, and maintenance-free response, which can be particularly advantageous in applications where simplicity and reliability are paramount.

[0176] In another possible embodiment, the linear retraction of the bristle field relative to the drive unit can extend over a distance between 1.0 mm and 2.0 mm. For example, the spring-mounted subassembly supporting the bristle field can be configured such that, when excessive brushing force is applied, the bristle field can move axially from its normal position by an amount within this range. This retraction path can be selected to achieve an effective balance between user comfort and protective function, allowing sufficient movement to absorb or dissipate excessive forces while maintaining the cleaning effect of the toothbrush head.

[0177] It is conceivable that the retraction path is determined by the design and stiffness of the spring or elastomer elements used in the subassembly. In some embodiments, the mechanism can be designed so that the maximum linear displacement of the bristle field does not exceed 2.0 mm, while simultaneously ensuring that at least 1.0 mm of movement is available when the activation threshold is reached. Such a range of motion can be particularly advantageous for achieving a noticeable but controlled response to excessive brushing, thus preventing the transmission of excessive stress to the teeth and gums.

[0178] Alternatively, the linear retraction path can be adjustable, for example by incorporating interchangeable springs or spacers, allowing the toothbrush head to be adapted to different user preferences or oral care requirements. The specific range of 1.0 mm to 2.0 mm can be chosen based on clinical studies or user feedback indicating that this degree of movement is sufficient to mitigate the risks associated with excessive brushing force without compromising the stability or durability of the head.

[0179] In some possible designs, the spring-mounted assembly may include mechanical stops or limiters to ensure that the retraction path remains within the desired range, thus preventing overextension or mechanical failure. The retraction mechanism may also be designed to gently and reliably return the bristle field to its starting position once the excessive force is released, ensuring consistent performance throughout the toothbrush head's lifespan.

[0180] Overall, providing a linear retraction path between 1.0 mm and 2.0 mm represents a possible approach to optimizing the protective response of the toothbrush head and can be implemented alone or in combination with other adaptive or safety features, depending on the intended use.

[0181] In a further embodiment, the spring-mounted subassembly can additionally include a viscoelastic dashpot cartridge configured to provide velocity-dependent damping. The inclusion of a viscoelastic dashpot cartridge is intended to produce a damping effect that changes depending on the speed of the linear retraction movement of the bristle field. Such a dashpot cartridge can comprise a chamber filled with a viscoelastic material, such as silicone gel or a synthetic polymer, and a piston or plunger that moves within the chamber as the bristle field retracts or returns to its initial position.

[0182] The viscoelastic dashpot can be positioned parallel to the spring element, so that both elastic and damping forces act on the bristle field during movement. In this configuration, the dashpot can resist rapid movements more effectively than slow ones, resulting in greater damping when the bristle field is subjected to sudden or strong impacts. This speed-dependent behavior can help absorb shocks and prevent abrupt or excessive movement, thereby increasing user comfort and reducing the risk of mechanical wear or damage to the toothbrush head.

[0183] Alternatively, the dashpot cartridge could be integrated into the mounting hub or as part of the sliding carriage that supports the bristle field. The dashpot design can be customized by selecting the viscosity and composition of the viscoelastic material, as well as the geometry of the piston and chamber, to achieve the desired damping characteristics. In some configurations, the damping effect can be adjustable, for example, by using interchangeable cartridges with different viscosities or by incorporating a variable orifice into the dashpot assembly.

[0184] The use of a viscoelastic dashpot cartridge in conjunction with a spring-mounted subassembly can also contribute to a smoother and more controlled return of the bristle field to its starting position after the excess force has been removed. This can help prevent vibrations or rebound effects that might otherwise occur with a purely elastic system. In some possible designs, the dashpot can be combined with other protective or adaptive features, such as stimulus-responsive bristles or additional mechanical safety devices, to further enhance the overall performance and safety of the toothbrush head.

[0185] Overall, the optional integration of a viscoelastic dashpot cartridge into the spring-mounted assembly offers a way to achieve velocity-dependent damping during the linear retraction of the bristle field. This approach can be particularly advantageous when controlled, gradual movement and improved shock absorption are desired, contributing to a longer service life and a better user experience. Mechanical force protection mechanism: Angle inclination

[0186] In another possible embodiment, the physical displacement of the bristle field relative to the drive unit can optionally be realized as an angular tilt, with the mechanical force-protection mechanism located in a neck region of the toothbrush head. Angular tilt refers to a movement in which the bristle field pivots or tilts relative to its normal orientation, typically about an axis transverse to the longitudinal axis of the toothbrush head. This tilting movement can occur when excessive brushing force is applied, causing the bristle field to bend away from the direction of the applied force and thus reducing the transmission of excessive force to the user's teeth and gums.

[0187] The mechanical force protection mechanism can be located, for example, in the neck area of ​​the toothbrush head, i.e., in the section extending between the bristle field and the coupling interface with the drive unit. Positioning the mechanism in the neck area can offer a compact and effective way to allow angular movement while maintaining the structural integrity and aesthetics of the toothbrush head. The mechanism itself can take various forms, such as a flexible hinge, a torsion spring, an elastomeric joint, or a ball-and-socket joint, all of which allow controlled angular displacement of the bristle field when a threshold force is exceeded.

[0188] It is conceivable that the degree of angular tilt is limited by mechanical stops or by the inherent elasticity of the force-protection mechanism, ensuring that the bristle field returns to its original position as soon as the excessive force is released. In some arrangements, the mechanism may be designed to produce a gradual or progressive tilt response rather than a sudden movement, thereby increasing user comfort and minimizing the risk of sudden changes in brush dynamics.

[0189] Alternatively, the angular tilt function can be combined with other forms of displacement, such as linear retraction or rotational slippage, to achieve a multimodal protective response. The force protection mechanism in the neck area can also be configured to operate in combination with responsive bristles, further enhancing the adaptability and safety of the toothbrush head.

[0190] The materials and construction of the neck section and its associated mechanism can be selected to balance flexibility, durability, and wear resistance. For example, the neck can be molded from an elastic polymer or contain embedded spring elements or elastomer inserts to facilitate the desired angular movement. In some designs, the mechanism can be seamlessly integrated into the neck, thus preserving the overall appearance and ergonomics of the toothbrush head.

[0191] The optional angled bristle field, achieved through a force-protection mechanism in the neck area, offers additional protection against excessive brushing. This approach can help reduce the risk of injury to oral tissues and improve the overall brushing experience, especially for users who tend to apply excessive pressure during oral care.

[0192] In certain embodiments, the angle of inclination of the bristle field relative to the longitudinal axis of the neck section can be in a range of approximately 10 to 15 degrees. For example, the mechanical force-protection mechanism in the neck region can be configured such that, when excessive brushing force is applied, the bristle field can oscillate or tilt by an angle within this interval. This degree of angular movement can be selected to achieve a noticeable but controlled deflection, allowing the bristle field to yield sufficiently to absorb or redirect excessive force while maintaining effective cleaning contact with the teeth.

[0193] It is also conceivable that the mechanism enabling the angular tilt is designed to allow a maximum tilt angle of no more than 15 degrees, while simultaneously ensuring that a movement of at least 10 degrees is possible once the activation threshold is reached. The specific angular tilt range can be determined by the geometry and material properties of the neck section, as well as by the design of the hinge, spring, or elastomeric joint integrated into the force-protection mechanism. In some designs, the angular displacement can be limited by integrated mechanical stops or by the elastic deformation of the neck material itself.

[0194] Alternatively, the angle of inclination can be adjustable, for example, through interchangeable neck modules or by incorporating a variable resistance mechanism, allowing the toothbrush head to be adapted to different user preferences or oral care needs. The range of 10 to 15 degrees can be chosen based on ergonomic studies or user feedback indicating that this degree of inclination is sufficient to mitigate the risks associated with excessive brushing force without compromising the stability or durability of the head.

[0195] In some possible designs, the tilting angle can occur around a single axis perpendicular to the longitudinal axis of the neck, or it can involve a compound movement that allows for multidirectional deflection, depending on the configuration of the force-protection mechanism. The tilting movement can be reversible, with the bristle field gently returning to its original orientation after the excessive force is released, thus ensuring consistent performance and high user comfort.

[0196] Overall, an angle of inclination between 10 and 15 degrees relative to the longitudinal axis of the neck section represents a possible approach to optimizing the protective response of the toothbrush head. This function can be implemented alone or in combination with other adjustment or safety mechanisms, depending on the intended application and desired performance characteristics.

[0197] In another possible embodiment, the mechanical force protection mechanism in the neck region can comprise an eccentric cam and a compliant joint. For example, the force protection mechanism could include an eccentric cam element located in the neck region of the toothbrush head. The eccentric cam can be arranged such that it rotates or shifts when excessive brushing force is applied to the bristle field, thereby inducing an angular tilt of the bristle field relative to the longitudinal axis of the neck. This arrangement can allow the bristle field to pivot by a controlled amount, for example, in a range of 10 to 15 degrees, depending on the geometry of the cam and the overall design of the neck section.

[0198] The compliant joint can optionally be incorporated in conjunction with the eccentric cam to allow for smooth and reversible angular movement. Such a compliant joint could be implemented as a flexible hinge, an elastomeric insert, or a hinge integrally formed with the neck structure. The compliant joint can deform elastically when the cam is actuated by excessive force, causing the bristle field to tilt and return to its original orientation once the force is released. In some embodiments, the compliant joint can also serve to limit the maximum angular displacement to ensure that the tilt remains within a safe and effective range.

[0199] Alternatively, the eccentric cam and the compliant joint can be configured so that the cam acts as a mechanical stop or guide, while the compliant joint provides the necessary flexibility for angular movement. The combination of these elements can be adjusted to achieve a desired balance between tilting resistance under normal plastering conditions and compliance under excessive force. In certain designs, the cam profile and the stiffness of the compliant joint can be selected to achieve a progressive or nonlinear response, offering greater resistance with increasing tilt angle.

[0200] It is also possible to seamlessly integrate the eccentric cam and flexible joint arrangement into the neck area, thus maintaining the overall aesthetics and ergonomics of the toothbrush head. The materials used for the cam and joint can be engineering plastics, elastomers, or composites, selected for their durability, elasticity, and suitability for oral care applications.

[0201] This approach, which uses an eccentric cam and a compliant joint as part of the mechanical force protection mechanism, can be implemented alone or in combination with other protective or adaptive features, such as stimulus-responsive bristles or additional displacement mechanisms. By providing a controlled and reversible angular tilt in response to excessive brushing force, this design can improve user safety and comfort while maintaining effective cleaning performance during normal use.

[0202] In certain embodiments, the eccentric cam mechanism may optionally include at least one detent configured to provide tactile feedback upon engagement. The inclusion of a detent in the cam mechanism can create a perceptible resistance or "click" as the cam rotates or changes position in response to excessive brushing force. This tactile feedback can be perceived by the user as a slight sensation or interruption of the toothbrush head's movement, signaling that the force-protection mechanism has been activated.

[0203] The detent can be configured, for example, as a recess, notch, or projection on the surface of the eccentric cam that engages with a corresponding feature on an adjacent component, such as a spring-loaded ball, a flexible tab, or a compliant arm. When the cam rotates into a specific position under load, the detent can engage, creating temporary resistance that dissipates after the cam passes through the detent. This arrangement can provide the user with a clear and repeatable indication that the tilting mechanism has responded to excessive force.

[0204] Alternatively, multiple detents could be integrated into the cam profile to allow for several discrete positions or feedback levels as the bristle field tilts across its range of motion. The strength and type of tactile feedback can be individually adjusted by modifying the geometry of the detent and the stiffness of the interacting components. In some designs, the detent mechanism can also serve to temporarily hold the cam in a tilted position until the applied force is released. The compliant joint can then return the bristle field to its original orientation.

[0205] The locking mechanism can also be combined with acoustic feedback, such as a quiet click or snap, which further alerts the user to the protective function. The materials used for the locking mechanism and its associated components can be engineering plastics, elastomers, or metals, selected for their durability and resistance to repeated cycles.

[0206] Providing a locking mechanism within the eccentric cam mechanism is not necessary in all embodiments, but it can be advantageous in applications where user feedback is desired to reinforce safe brushing habits or to confirm that the force-protection mechanism is functioning as intended. This feature can be implemented alone or in conjunction with other adaptive or protective elements, depending on the overall design goals of the toothbrush head. Feedback generator

[0207] In some embodiments, the electric toothbrush head may additionally include a feedback generator configured to emit a user-perceptible signal when the physical displacement of the bristle field relative to the drive unit is triggered. The feedback generator can be implemented in various forms and is intended to better alert the user to the activation of the force-protection mechanism.

[0208] For example, the feedback generator can be arranged to emit a tactile signal, such as a vibration or a short pulse, when the mechanical force protection mechanism is triggered and the bristle field undergoes a displacement—be it through rotational slippage, linear retraction, or angular tilt. This tactile feedback can be generated by a miniature vibration motor, a piezoelectric actuator, or a mechanical element such as a spring-loaded detent or cam that produces a perceptible "click" or resistance when actuated.

[0209] Alternatively, the feedback generator could be configured to emit an audible signal, such as a soft click, snap, or tone, to alert the user that excessive brushing force has been detected and the safety mechanism has been activated. In some possible configurations, the audible feedback may result from the interaction of mechanical components within the head, such as a detent engaging a cam or a yielding element that clicks into place. In other variations, an electronic buzzer or a buzzer may be integrated into the toothbrush head or handle, activated by a sensor that detects displacement.

[0210] It is also conceivable that the feedback generator outputs a visual signal, for example by illuminating an indicator light or an LED on the toothbrush head or handle, when the physical displacement occurs. Such a visual signal can be particularly useful in models where the toothbrush head communicates with the drive unit or handle via electrical contacts or wireless means.

[0211] The feedback generator can be designed to operate passively, relying solely on the mechanical action of the displacement mechanism, or it can be actively controlled by an electronic circuit that monitors the status of the force protection system. In some configurations, the feedback generator can be user-adjustable or selectable, allowing for customization of the type or intensity of the output signal.

[0212] Providing a user-perceptible signal when the physical sliding mechanism is activated can help reinforce safe brushing habits by warning the user of excessive force. This feature can be implemented alone or in combination with other adaptive or protective elements, depending on the desired functionality and user experience of the electric toothbrush head.

[0213] In certain embodiments, the user-perceived signal generated by the feedback generator can optionally be implemented as at least one of the following: a visual signal from an LED, a tactile signal such as a click or patterned vibration, or an acoustic signal. For example, the toothbrush head can incorporate a light-emitting diode (LED) that illuminates or flashes when the bristle field physically shifts, providing the user with a clear visual indication that the force-protection mechanism has been activated. The LED can be positioned on the toothbrush head itself or, in some configurations, on the handle, and emit light in a characteristic color or pattern to attract the user's attention.

[0214] Alternatively or additionally, the feedback generator can be designed to provide a tactile signal. This tactile feedback can take the form of a mechanical click device, generated by a detent or cam mechanism that engages during movement. In other possible configurations, a patterned vibration can be generated, for example, by a miniature vibration motor or a piezoelectric actuator integrated into the head or handle. Such tactile signals can be perceived directly through the user's grip or via the bristle field, providing an immediate and intuitive indication that excessive brushing force has been detected.

[0215] It is also conceivable that the feedback generator is configured to emit an acoustic signal. This acoustic feedback could be a quiet click or snap from the interlocking mechanical components, or an electronically generated tone or beep from a buzzer or buzzer device. The acoustic signal can be designed to be subtle so as not to disturb the user, yet clear enough to serve as an effective warning.

[0216] Depending on the specific design and intended user experience of the toothbrush head, one or a combination of these feedback modalities can be implemented. In some versions, the type or intensity of the signal perceived by the user can be selected or adjusted, allowing users to tailor the feedback to their personal preferences. Providing visual, tactile, or audible signals as possible feedback options can raise user awareness and promote safer brushing habits by clearly indicating when the toothbrush head's protective functions are active. Hydrogel cap tips

[0217] In some embodiments, the multiple bristles may additionally feature hydrogel cap tips configured to swell under pressure. The hydrogel cap tips can be formed by applying or molding a hydrogel material onto the distal ends of the bristles, either as a continuous coating or as discrete caps. Suitable hydrogels for this purpose may comprise cross-linked polymer networks capable of absorbing water or saliva from the oral environment and thereby increasing in volume under pressure during brushing.

[0218] It is conceivable that the hydrogel caps undergo a reversible swelling process when pressure is applied to the bristle ends, for example, when the user presses the toothbrush head against their teeth or gums. This swelling can lead to a temporary increase in the contact area between the bristle ends and the oral surfaces, thereby improving the cleaning effect and distributing the applied force more evenly. This can reduce the risk of localized pressure sores or abrasion, contributing to greater comfort and safety for the user.

[0219] Alternatively, the hydrogel caps can be designed to exhibit a controlled swelling rate, so that expansion occurs primarily under sustained or excessive pressure. In this way, the hydrogel material can act as a passive, adaptive cushion that dynamically responds to the plastering conditions. The degree of swelling, as well as the mechanical properties of the hydrogel, can be adjusted by modifying the polymer composition, crosslinking density, or adding additives to achieve the desired balance between softness, elasticity, and durability.

[0220] In some possible configurations, the hydrogel caps can be selectively applied to only certain bristles within the bristle field, for example, those located at the edge or in areas most likely to be subjected to higher stress. Alternatively, all bristles can be fitted with hydrogel tips, or the hydrogel material can be combined with other tip treatments such as polishing or texturizing to further improve cleaning performance and user comfort.

[0221] The use of hydrogel caps that swell under pressure can be implemented alone or in conjunction with other adaptive or protective features of the toothbrush head, such as responsive bristle materials or mechanical force-protection mechanisms. This approach offers another way to create a gentle, responsive interface between the toothbrush and the oral tissues that adapts in real time to the forces encountered during brushing. The hydrogel caps can be designed to return to their original size and shape after the pressure is removed, thus ensuring consistent performance over repeated use. Telescopic spiral root anchors

[0222] In certain embodiments, the multiple bristles can be mounted on telescopic helical root anchors configured to expand reversibly under compressive stress. The use of telescopic helical root anchors represents a potential approach to enabling adaptive bristle movement in response to the forces encountered during brushing. Such anchors can be realized as spiral or helical bases, optionally formed from elastic polymeric or metallic materials, which can telescope or unwind to increase their effective length when a compressive force is applied to the bristle tips.

[0223] It is conceivable that during brushing, when the user presses the toothbrush head against the teeth or gums, the pressure causes the spiral root anchors to expand, allowing the bristles to protrude further from the base of the head. This reversible expansion may serve to absorb excess force, thereby reducing the risk of transferring harmful forces to the oral tissue and increasing user comfort. Once the pressure is released, the spiral anchors can return to their original, retracted position, restoring the original length and orientation of the bristles.

[0224] Alternatively, the telescopic spiral root anchors can be designed to allow progressive extension, with the degree of extension increasing proportionally to the applied force. This behavior can be achieved by selecting the spacing, diameter, and material properties of the spiral structure to produce a desired force-extension profile. In some possible arrangements, the spiral anchors can be integrated into the toothbrush head's mounting hub or designed as part of individual bristle holders, thus allowing independent movement of each bristle or bristle group.

[0225] It is also possible to combine the telescopic spiral root anchors with other adaptive features, such as stimulus-responsive bristle materials, hydrogel cap tips, or mechanical force protection mechanisms, to achieve a multi-layered response to varying cleaning conditions. Depending on the desired size and complexity of the structure, the spiral anchors can be manufactured using techniques such as micro-injection molding, co-extrusion, or additive manufacturing.

[0226] In some versions, the spiral root anchors can be configured to allow not only linear extension but also a slight rotational or pivoting movement of the bristles, further improving the adaptability of the bristle field to the contours of the teeth and gums. The materials used for the anchors can be selected based on their elasticity, fatigue resistance, and compatibility with oral care applications to ensure reliable performance over repeated use cycles.

[0227] Overall, the optional inclusion of telescopic, spiral root anchors for bristle attachment offers a way to achieve reversible extension of the bristle field under pressure. This feature can contribute to improved force distribution, enhanced cleaning performance, and greater user comfort, especially in situations where varying brushing forces occur. The design can be adapted to different toothbrush head geometries and user preferences and can be implemented alone or in combination with other protective or adaptive elements. Transparent window

[0228] In some embodiments, the electric toothbrush head may additionally feature a transparent window configured to allow a view of at least part of the mechanical force-protection mechanism. The transparent window may be made of a clear polymer material such as polycarbonate or acrylic and may be integrated into the toothbrush head housing at a location that allows a view of the internal components associated with the force-protection mechanism. For example, the window could be positioned on the side of the neck section, at the base of the bristle field, or at another suitable location where the movement or function of the mechanism can be observed.

[0229] It is also conceivable that the transparent window is designed as a separate insert, as a molded section of the head, or as a continuous band surrounding part of the housing. The size, shape, and arrangement of the window can be chosen according to design preferences, manufacturing considerations, or the specific configuration of the mechanical force protection mechanism. In some possible arrangements, the window can be dimensioned so that the user can monitor the activation or movement of elements such as a clutch, a spring-mounted assembly, an eccentric cam, or a compliant joint, thus providing a visual indication of the protective function in operation.

[0230] Alternatively, the transparent window can serve an informational or safety purpose by instilling confidence in the presence and functionality of the adaptive safety features. In certain versions, the window can be combined with visual indicators such as colored markers or moving elements to further enhance the clarity of feedback to the user. The transparent material can be selected for its durability, resistance to cleaning agents, and optical clarity to ensure that the window remains clear and functional throughout the toothbrush head's lifespan.

[0231] In some designs, the transparent window can be designed as a removable or replaceable component to allow for maintenance or inspection of the underlying mechanism when necessary. The window can also be integrated as a decorative element or trademark, thus contributing to the overall aesthetics of the toothbrush head while retaining its functional role.

[0232] The inclusion of a transparent window through which the mechanical force protection mechanism is visible is not required in all embodiments, but can be advantageous in applications where greater user engagement, product differentiation, or enhanced feedback is desired. This feature can be implemented alone or in conjunction with other adaptive or protective elements, depending on the intended user experience and the design goals of the electric toothbrush head. drive unit

[0233] In some embodiments, the electric toothbrush can be arranged such that the drive unit is configured to temporarily reduce its operating intensity in response to physical displacement of the toothbrush head. For example, the drive unit may include a control circuit or processor that can detect when the toothbrush head experiences displacement, such as rotational slippage, linear backward movement, or angular tilting, as might occur when a mechanical force protection mechanism is activated. Upon detecting such an event, the drive unit can temporarily reduce its power output, for example, by decreasing the speed, torque, or amplitude of movement applied to the toothbrush head.

[0234] Alternatively, the reduction in operating intensity can be achieved by modulating the power supplied to the drive motor, by adjusting the duty cycle of a pulse-width modulated signal, or by briefly activating a special energy-saving mode. The duration and extent of the intensity reduction can be adjusted according to user preferences, safety considerations, or the specific characteristics of the displacement mechanism. In some configurations, the drive unit can automatically resume its normal operating intensity once the displacement has subsided and the toothbrush head has returned to its starting position.

[0235] It is also conceivable that the drive unit is equipped with sensors, such as force, position, or acceleration sensors, that can detect the occurrence of a physical displacement in real time. In other configurations, the toothbrush head itself can contain a switch, a contact, or a wireless transmitter that communicates with the drive unit to signal when a displacement event has occurred. The control logic for reducing the intensity can be implemented in hardware, software, or a combination of both, depending on the design requirements and available components.

[0236] In some versions, the temporary reduction in operating intensity can be accompanied by a user-perceived signal, such as a brief pause, a vibration, or an audible tone, to further indicate that excessive force has been detected and the protective functions have been activated. The system may also allow users to adjust the response, enabling them to select the degree or duration of the intensity reduction according to their individual needs or preferences.

[0237] By optionally providing a drive unit capable of temporarily reducing its operating intensity in response to physical movement of the toothbrush head, user safety and comfort can be further enhanced. This feature can help prevent the continued application of excessive force during brushing, reduce the risk of oral tissue injury, and reinforce proper brushing technique. The arrangement can be implemented alone or in combination with other adaptive or protective elements, depending on the intended functionality and user experience of the electric toothbrush. Handle

[0238] In certain embodiments, the handle of the electric toothbrush can include a power source that is functionally coupled to a feedback generator located on the toothbrush head. The power source can be, for example, a rechargeable battery, a replaceable battery, or a supercapacitor, and can be housed in the handle area of ​​the toothbrush. The power source can be electrically connected to the feedback generator via conductive contacts, flexible wiring, or wireless power transmission methods such as inductive coupling. The feedback generator on the toothbrush head can be configured to respond to certain operational events, such as the activation of a mechanical force protection mechanism or the occurrence of excessive brushing force, with a signal perceptible to the user.

[0239] The feedback generator mounted on the toothbrush head can be configured to emit a user-perceived signal in response to specific operational events, such as the activation of a mechanical force protection mechanism or the occurrence of excessive brushing force. In some designs, the feedback generator may include an LED, a miniature vibration motor, a piezoelectric actuator, or an acoustic signal generator, all of which can be powered by the handle's power source. Depending on the toothbrush design, the connection between the power source and the feedback generator can be achieved through direct electrical contacts at the handle-head interface or, alternatively, through wireless power transmission.

[0240] It is also conceivable that the power source in the handle is positioned in such a way that, in addition to the feedback generator, it also supplies energy to other active components on the toothbrush head, such as sensors, microcontrollers, or communication modules. In some possible configurations, the feedback generator can be activated automatically in response to signals from the drive unit, a sensor, or a control circuit, or selected by the user via controls on the handle or head.

[0241] Alternatively, the feedback generator can be designed to operate only when the toothbrush is in use, with the power source supplying energy during brushing and switching to an energy-saving or standby mode at other times to extend battery life. The arrangement of the power source and feedback generator can be adapted to various toothbrush designs, including those with removable or fixed heads.

[0242] The optional provision of a handle with a power source that is functionally connected to a feedback generator on the toothbrush head can improve the functionality and user experience of the electric toothbrush.

[0243] This configuration can enable more effective delivery of visual, tactile, or auditory feedback to the user, thus supporting safer and more effective oral care routines. The specific implementation of the power source and feedback generator can be adapted according to performance requirements, manufacturing aspects, and user preferences. Operating procedures

[0244] A method for automatically regulating the brushing force exerted by an electric toothbrush is now described according to one embodiment.

[0245] In step 1, if the electric toothbrush is equipped with responsive bristles, the routine detects an initial condition indicating excessive brushing pressure on a bristle field. In step 2, in response to this initial condition, the routine automatically and reversibly reduces the stiffness of a large number of bristles within the bristle field, where the bristles are made of a responsive material.

[0246] In step 3, if the electric toothbrush is equipped with a force-protection mechanism, the routine detects a second condition indicating excessive brushing force on the bristle field. In step 4, in response to this second condition, the routine automatically induces a reversible physical displacement of the bristle field. This displacement can include at least a rotation, a linear retraction movement, or an angular tilt. Manufacturing process

[0247] A method for manufacturing an electric toothbrush head is now described according to one embodiment. In step 1, the routine forms a plurality of bristles from a stimulus-responsive material, the material being selected to cause a reversible reduction in stiffness in response to a first condition indicating excessive brushing pressure. In step 2, the routine assembles the plurality of bristles to form a bristle field on a head chassis. In step 3, the routine integrates the head chassis with a mechanical force-protection mechanism configured to induce a reversible physical displacement of the bristle field in response to a second condition indicating excessive brushing force, the displacement comprising at least one of the following movements: a rotational slip, a linear retraction movement, or an angular tilt.

[0248] In one possible embodiment of the manufacturing process, the step of forming the multiple bristles can include producing the bristles from a shape-memory polymer. The use of a shape-memory polymer as the bristle material can be selected as an option to impart reactive properties to the bristle array. Shape-memory polymers are a class of materials capable of reversibly changing their mechanical properties, such as stiffness or shape, in response to an external stimulus. This stimulus could be, for example, a change in temperature, the application of a mechanical force, or exposure to moisture.

[0249] It is conceivable that, through the use of a shape-memory polymer, the bristles would exhibit a reduction in stiffness when exposed to certain conditions, such as an increase in temperature to a level typical of the oral cavity or excessive brushing pressure. For example, the shape-memory polymer could be designed to have a transition temperature within the range of temperatures encountered during tooth brushing, such as between 30°C and 40°C. When exposed to this temperature range, the bristles could soften, thus providing a protective response against excessive force. After cooling or removal of the stimulus, the bristles could return to their original, stiffer configuration, ensuring durability and effective cleaning performance for subsequent uses.

[0250] Alternatively, the shape-memory polymer can be formulated to respond to mechanical stress, causing the bristles to become more flexible when forces exceed a predetermined threshold. This force-induced softening can provide an additional protective layer, as the bristles yield more easily under excessive pressure and then return to their original state once normal brushing conditions are restored.

[0251] The selection and formulation of the shape memory polymer can be tailored to achieve the desired balance between flexibility, elasticity, and responsiveness to oral conditions. For example, the bristles can comprise a blend of shape memory polymer and conventional bristle materials or contain reinforcing fillers to adjust the modulus and wear resistance. Manufacturing techniques such as co-extrusion, overmolding, or embedding shape memory polymer filaments in a standard bristle matrix can be used to realize this embodiment.

[0252] The use of shape-memory polymers as bristle material is one of several approaches to achieve a reversible reduction in stiffness in response to an initial state indicating excessive brushing pressure. This option can be implemented alone or in combination with other responsive materials or adaptive features, depending on the intended performance characteristics and the application of the electric toothbrush head.

[0253] In some embodiments, the step of forming the multiple bristles can optionally include embedding ferromagnetic particles in an elastomeric polymer. For example, it is possible to produce the bristles from an elastomeric base material, such as a silicone or a thermoplastic elastomer, into which finely dispersed ferromagnetic particles, such as iron, nickel, cobalt, or their alloys, are dispersed during compounding or molding. The concentration, particle size, and distribution of the ferromagnetic material within the polymer matrix can be selected to achieve a desired balance between the mechanical flexibility, magnetic reactivity, and durability of the bristles.

[0254] By incorporating ferromagnetic particles, the bristles can react to external magnetic fields, thereby influencing or modulating their mechanical properties—such as stiffness or orientation—on-site. In certain possible configurations, the ferromagnetic content of the bristles can be restricted to specific areas, such as the tip or root, or distributed evenly throughout the entire bristle structure. The choice of elastomeric polymer, as well as the type and quantity of ferromagnetic particles, can be tailored to the desired performance characteristics, manufacturing considerations, and compatibility with oral care applications.

[0255] Additionally, in some variants it can be advantageous to integrate a magnetic field generator into the head housing near the bristle field. The magnetic field generator can take various forms, such as a miniature electromagnet, a coil, or a movable permanent magnet, and can be positioned within or adjacent to the area of ​​the head that carries the bristles. In certain configurations, the magnetic field generator can be arranged to selectively apply a magnetic field to the bristle field, thereby inducing a reversible change in the mechanical properties of the bristles, such as a reduction in stiffness or a change in orientation, in response to specific operating conditions.

[0256] The activation of the magnetic field generator can be passive, for example, through mechanical coupling to the force-protection mechanism, or actively controlled via an electronic circuit that responds to the detected brushing force, pressure, or user input. In some designs, the strength and direction of the magnetic field can be adjusted, allowing the bristle response to be tailored to different user preferences or oral care needs. Integrating a magnetic field generator near the bristle field can also enable additional functions, such as aligning the bristles for optimal cleaning or providing user feedback through magnetic activation.

[0257] It is also conceivable that the combination of ferromagnetic particles in the bristles and a magnetic field generator, along with other adaptive or protective elements such as stimulation-sensitive polymers, mechanical force protection mechanisms, or feedback generators, could be implemented to achieve a multimodal response to varying cleaning conditions. The manufacturing process for such embodiments could include steps such as compounding the elastomeric polymer with ferromagnetic particles, forming or extruding the bristles, mounting the bristle array onto the head chassis, and attaching the magnetic field generator at the desired location.

[0258] Overall, the optional inclusion of ferromagnetic particles in the bristle material, along with the potential integration of a magnetic field generator into the head housing near the bristle field, offers a further means of achieving adaptive, reversible control of the bristle properties in response to operational stimuli. This approach can improve the safety, comfort, and effectiveness of the electric toothbrush head and can be tailored to a wide variety of product designs and user needs.

[0259] In some embodiments, the step of installing the mechanical force protection mechanism may include assembling a magnetic torque micro-coupling configured to allow rotational slippage of the bristle field relative to the drive unit. The magnetic torque micro-coupling may be implemented as a compact assembly within the head housing or at the interface between the bristle field and the coupling section of the toothbrush head. This arrangement may optionally provide a means by which the bristle field can rotate independently of the drive shaft when a torque or force threshold is exceeded, thus acting as a safeguard against excessive brushing force.

[0260] The magnetic torque micro-coupling can, for example, comprise one or more pairs of miniature permanent magnets or magnetically responsive elements arranged to generate a resistive coupling under normal operating conditions. If the torque generated by excessive brushing force exceeds a predetermined limit, the magnetic coupling can disengage, allowing the brush field to rotate and slip relative to the drive unit. This slippage can be reversible, so that the coupling automatically re-engages once the excessive force subsides, restoring normal operation without user intervention.

[0261] Alternatively, the micro-clutch can be designed to provide a gradual or progressive slip response instead of a sudden disengagement, resulting in a smoother and more comfortable experience for the user. The clutch's slip threshold can be adjusted by modifying the strength, spacing, or configuration of the magnetic elements, or by incorporating additional features such as springs or damping materials to fine-tune the response. In some possible variations, depending on the overall design and intended functionality, the clutch mechanism can be integrated into the bristle field's mounting hub or the neck area of ​​the head.

[0262] It is also conceivable that the magnetic torque micro-coupling could be combined with other forms of mechanical force protection, such as spring-mounted assemblies or compliant joints, to achieve a multimodal adaptive response to excessive brushing force. The use of a magnetic clutch mechanism can offer advantages such as low wear, quiet operation, and consistent performance over repeated use cycles. In certain designs, the clutch can be configured to allow a specific rotational slippage range before re-engagement, or it can be adjustable to accommodate different user preferences or oral care requirements.

[0263] The magnetic torque micro-coupling can be assembled using conventional manufacturing techniques such as press fitting, gluing or snap connections and is compatible with a wide variety of toothbrush head geometries and materials.

[0264] The integration of such a coupling mechanism is not required in all embodiments, but can be particularly advantageous when passive, maintenance-free protection against excessive torque is desired. This approach can be implemented alone or in conjunction with other adaptive or protective features, depending on the intended performance characteristics and the user experience with the electric toothbrush head.

[0265] In certain embodiments, the method may further include the step of calibrating the magnetic torque micro-clutch so that it is configured to slip at an equivalent peak force within a range of 160 grams to 200 grams. This calibration process can be performed during assembly or as a readjustment after assembly and may involve selecting or tuning the magnetic elements, such as permanent magnets or magnetically responsive components, to achieve the desired slip threshold. For example, the strength, orientation, or spacing of the magnetic elements may be adjusted so that the clutch disengages or allows rotational slip when the force applied to the bristle tips corresponds to a value within the specified range.

[0266] Alternatively, calibration can be achieved by incorporating additional mechanical features such as springs, detents, or damping materials, which can be selected or modified to fine-tune the torque required for clutch slippage. In some possible configurations, the clutch mechanism can be designed to allow incremental or stepless adjustment, enabling the slippage threshold to be set according to user preference, clinical recommendations, or specific oral care requirements.

[0267] It is also conceivable that the calibration step is performed using a test device or measuring instrument that applies a controlled force to the bristle field while simultaneously monitoring the onset of rotational slippage. This approach can facilitate quality control and ensure consistency between production batches. In certain variations, calibration can be performed manually by an operator or automatically by an assembly robot or an integrated testing system.

[0268] The ability to calibrate the magnetic torque micro-coupling to slip at a peak force between 160 and 200 grams can be advantageous for striking a balance between effective cleaning performance and user safety. Selecting a slip threshold within this range reduces the risk of excessive force being transmitted to teeth and gums while still ensuring adequate cleaning under normal conditions. The specific threshold value can be tailored to different user groups, product models, or legal standards.

[0269] In some embodiments, the calibrated clutch can also be designed to provide a gradual or progressive slip response instead of a sudden disengagement, thereby increasing user comfort and minimizing abrupt changes in brushing dynamics. The calibration process can be repeated or adjusted throughout the toothbrush head's lifespan to compensate for wear or changes in component properties.

[0270] Overall, incorporating a calibration step for the magnetic torque micro-coupling, which allows slippage at a peak force in the range of 160 to 200 grams, represents a potential approach to optimizing the protective function of the electric toothbrush head. This function can be implemented alone or in combination with other adaptive or safety mechanisms, depending on the intended application and performance targets.

[0271] In some embodiments, the integration of the mechanical force protection mechanism may optionally include the mounting of a spring-mounted subassembly configured to allow linear retraction of the bristle field relative to the head chassis. This spring-mounted subassembly can be implemented in various forms, such as a compression spring, leaf spring, or elastomeric spring element, which may be positioned between the bristle field or its mounting hub and the main body of the toothbrush head. The spring element can be arranged such that, when excessive brushing force is applied—for example, a peak force exceeding a predetermined threshold—the bristle field can move axially from its normal position, thereby absorbing or dissipating the excess force.

[0272] It is conceivable that the spring-mounted subassembly comprises a sliding carriage, a plunger, or a telescopic structure that supports the bristle field and is pre-tensioned to its starting position by the spring. Under typical cleaning conditions, the spring can hold the bristle field firmly engaged with the drive unit, thus ensuring efficient motion transmission. If the applied force becomes too great, the spring can compress or deform, allowing the bristle field to retract linearly by a controlled distance. Once the force drops below the activation threshold, the spring can return the bristle field to its original position and restore normal operation.

[0273] Alternatively, the spring-mounted assembly could use torsional springs, bending elements, or elastomeric couplings, allowing a combination of linear and slight angular movement depending on the specific design requirements. The stiffness and stroke of the spring elements can be selected or adjusted to achieve the desired balance between user comfort, protective response, and cleaning effect. In some configurations, the spring mechanism can be adjustable, allowing the activation force or retraction distance to be adapted to different user preferences or oral care needs.

[0274] The spring-mounted assembly can also be combined with additional features such as damping elements or mechanical stops to achieve speed-dependent resistance or limit the maximum retraction distance. For example, a viscoelastic dashpot or friction damper can be installed parallel to the spring to absorb shocks and prevent abrupt or excessive movement. Integrating such features can further improve the protective function and durability of the toothbrush head.

[0275] Depending on the overall architecture of the toothbrush head, the spring-mounted subassembly can be integrated into the base of the bristle field, the mounting hub, or at the interface with the drive unit. The materials used for the spring and associated components can include metals, engineering plastics, or elastomers, selected for their elasticity, fatigue resistance, and suitability for oral care applications.

[0276] The optional inclusion of a spring-loaded subassembly configured for linear retraction provides additional protection against excessive brushing force. This approach can help reduce the risk of transferring harmful loads to teeth and gums while maintaining effective cleaning performance during normal use. The use of a spring-based mechanism also allows for a passive, reversible, and maintenance-free response, which can be particularly beneficial in applications where simplicity and reliability are paramount. This feature can be implemented alone or in combination with other adaptive or protective elements, depending on the intended functionality and design goals of the electric toothbrush head.

[0277] In another possible embodiment of the method for manufacturing an electric toothbrush head, the step of integrating the mechanical force protection mechanism can include assembling an eccentric cam and a compliant joint within a neck section of the toothbrush head, the assembly being configured to allow an angular tilt of the bristle field relative to the drive unit. The inclusion of an eccentric cam and a compliant joint in the neck region is intended to provide a mechanism by which the bristle field can pivot or tilt in the event of excessive brushing force, thereby offering an additional adaptive level of protection.

[0278] The eccentric cam can, for example, be positioned within the neck section of the head chassis and arranged so that, when a force exceeding a predetermined threshold is applied, the cam rotates or shifts, resulting in a controlled angular displacement of the bristle field. The cam's geometry can be chosen to define the range and trajectory of the inclination, allowing for a gradual or progressive response with increasing force. In some configurations, the cam can be a molded or machined component, optionally made from a durable polymer or metal, and integrated into the bristle field's mounting hub or support structure.

[0279] The compliant joint, which may be provided in conjunction with the eccentric cam, can be implemented as a flexible hinge, an elastomeric insert, or a hinge integrally formed with the neck structure. This joint can be designed to deform elastically when the cam is actuated, allowing the bristle field to tilt by a defined angle and then return to its original orientation once the excessive force is released. In certain arrangements, the compliant joint can also serve to limit the maximum angular displacement, ensuring that the tilt remains within a safe and effective range for oral care.

[0280] Alternatively, the arrangement of the eccentric cam and the compliant joint can be configured such that the cam acts as a mechanical stop or guide, while the compliant joint provides the necessary flexibility for angular movement. The combination of these elements can be adjusted to achieve a desired balance between tilting resistance under normal brushing conditions and compliance under excessive force. In some variations, the cam profile and the stiffness of the compliant joint can be selected to achieve a nonlinear or progressive response, offering greater resistance with increasing tilt angle.

[0281] It is also conceivable that the eccentric cam and flexible joint arrangement could be seamlessly integrated into the neck area, thus preserving the overall aesthetics and ergonomics of the toothbrush head. The materials used for the cam and joint could include engineering plastics, elastomers, or composites, selected for their elasticity, durability, and suitability for oral care applications.

[0282] The installation of an eccentric cam and a compliant joint in the neck area can be performed alone or in combination with other mechanical force-protection mechanisms, such as spring-mounted assemblies or magnetic couplings, to achieve a multimodal adaptive response to excessive brushing force. This approach can be particularly advantageous when a passive, reversible, and maintenance-free method for limiting angular displacement is desired, and user comfort and safety are paramount. The specific configuration and integration of these components can be tailored to the intended performance characteristics, manufacturing considerations, and design objectives of the electric toothbrush head.

[0283] In some embodiments, the method for manufacturing an electric toothbrush head may additionally include the step of incorporating a feedback generator into the toothbrush head, wherein the feedback generator is configured to be activated by the mechanical force protection mechanism. The feedback generator can be implemented in various forms and is intended to provide a signal perceptible to the user when the force protection mechanism reacts to excessive brushing force.

[0284] For example, the feedback generator can be implemented as a tactile device, such as a miniature vibration motor or a mechanical detent, that produces a brief vibration or a perceptible click when the mechanical force protection mechanism is triggered. In other possible configurations, the feedback generator can include an acoustic element, such as a piezoelectric buzzer or a mechanical component that emits a soft click or tone when activated. Alternatively, a visual feedback generator can be provided, for example, in the form of a light-emitting diode (LED) or other indicator light that can illuminate or flash to indicate to the user that the protection mechanism has been activated.

[0285] Depending on the overall design and intended feedback method, the feedback generator could be positioned within the head housing, in the neck area, or near the bristle field. Activation of the feedback generator can be passive, for example, through direct mechanical coupling with the moving parts of the force-protection mechanism, or active via an electrical switch or sensor that detects the movement or engagement of the mechanism.

[0286] In some variations, the feedback generator can be configured to provide a single type of signal, such as a tactile pulse, or arranged to provide multiple forms of feedback, such as a combination of light and vibration. The characteristics of the feedback signal—such as intensity, duration, and pattern—can be customized during manufacturing to suit different user preferences or product requirements. It is also possible for the feedback generator to be user-adjustable or selectable, allowing each user to tailor the type or strength of the signal to their needs.

[0287] Alternatively, the feedback generator can be designed to function only when the toothbrush is in use, or it can be linked to other operating functions such as a timer or a brushing mode selector switch. In some embodiments, the feedback generator could be powered by the toothbrush's main power source or by a dedicated energy storage element in the toothbrush head.

[0288] The integration of a feedback generator, activated by the mechanical force protection mechanism, is not required in all designs, but can be advantageous in applications with a "safety" function where increased user awareness and the reinforcement of safe brushing habits are desired. This function can be implemented alone or in conjunction with other adaptive or protective elements, depending on the intended functionality and user experience of the electric toothbrush head.

[0289] In another possible embodiment, the feedback generator can include an LED and either a microswitch or a Hall-effect sensor, which can be positioned to detect the physical displacement of the bristle field or associated components. For example, the feedback generator could include a light-emitting diode located inside the toothbrush head, optionally at a position visible to the user during brushing. The LED could be configured to emit a visual signal, such as a pulse or flash of light, when activated in response to the triggering of the mechanical force protection mechanism.

[0290] The LED can be activated in several ways. In some designs, a microswitch might be located near the moving parts of the force protection mechanism, such as a clutch, a spring-loaded assembly, or a rocker joint. The microswitch can be mechanically actuated when the brush field undergoes a displacement—for example, rotational slippage, linear retraction, or angular tilting—thus closing an electrical circuit and illuminating the LED. This approach can provide a simple and reliable way to give the user immediate visual feedback when excessive brushing force is detected.

[0291] Alternatively, a Hall effect sensor can be used as part of the feedback generator. In such configurations, the Hall effect sensor could be positioned to monitor the relative movement of a magnetic element attached to the bristle field or force protection mechanism. When physical displacement occurs, the change in the magnetic field detected by the sensor can be used to trigger the LED, providing a contactless and potentially more durable activation method. Using a Hall effect sensor can be particularly advantageous when minimizing mechanical wear or ensuring long-term reliability is a primary design consideration.

[0292] The feedback generator can also incorporate both a microswitch and a Hall-effect sensor, allowing for redundancy or the selection of different activation methods depending on the specific design or user preference. The characteristics of the LED signal—such as brightness, color, or flashing pattern—can be customized to improve visibility and usability, and may be adjustable during manufacturing or by the end user.

[0293] In some versions, the feedback generator can be combined with other user-perceived signals, such as tactile or audible feedback, to issue a multimodal warning when the force protection mechanism is activated. The power supply for the LED and associated sensors can come from the toothbrush's main power source or from a dedicated battery or capacitor in the head.

[0294] Overall, combining an LED with a microswitch or a Hall-effect sensor, optionally positioned to detect the physical displacement of the bristle field, represents a possible approach to providing the user with clear and immediate feedback. This arrangement can be implemented alone or in conjunction with other adaptive or protective features, depending on the intended functionality and design goals of the electric toothbrush head.

[0295] In certain embodiments, the method for manufacturing an electric toothbrush head may further include the step of forming a transparent window in the head housing to allow a view of at least part of the mechanical force protection mechanism. The transparent window can be implemented as an optional feature, for example, by incorporating a section of clear polymer material, such as polycarbonate or acrylic, into the toothbrush head housing. This window can be positioned to allow a view of the internal components associated with the force protection mechanism, such as a coupling, a spring-mounted subassembly, an eccentric cam, or a compliant joint.

[0296] The transparent window can also be integrated into the head housing as a separate insert, a molded area, or a continuous strip. The window's size, shape, and arrangement can be selected according to design preferences, manufacturing requirements, or the specific configuration of the mechanical force-protection mechanism. In some designs, the window can be sized to allow the user or a technician to monitor the activation or movement of the mechanism during operation or maintenance.

[0297] Alternatively, the transparent window can serve an informative or reassuring function by allowing the user to observe the presence and operation of the adaptive safety features. In certain versions, the window can be combined with visual indicators such as colored markers, moving elements, or feedback lights to further enhance the clarity of feedback to the user. The transparent material can be selected for its durability, resistance to cleaning agents, and optical clarity to ensure that the window remains clear and functional throughout the toothbrush head's lifespan.

[0298] In some possible designs, the transparent window can be designed as a removable or replaceable component to allow for inspection, cleaning, or replacement when necessary. It is also conceivable that the window could be integrated as part of a decorative or branding element, contributing to the overall aesthetics of the toothbrush head while maintaining its functional role.

[0299] The inclusion of a transparent window through which at least part of the mechanical force-protection mechanism is visible is not required in all embodiments, but can be advantageous in applications where greater user involvement, product differentiation, or improved feedback is desired. This feature can be implemented alone or in conjunction with other adaptive or protective elements, depending on the intended user experience and the design goals of the electric toothbrush head. Example 1: Characterization of shape memory polymer bristles for a pressure-adaptive response

[0300] A series of bristle filaments is fabricated using a shape-memory polymer (SMP) based on polyurethane with a glass transition temperature (Tg) of 32 °C. The polymer is extruded into filaments with a diameter of 0.20 mm and cut to a length of 11 mm. For comparison, control bristles of identical dimensions are fabricated from conventional nylon 612. The bristles are arranged in bundles of 40 filaments each and attached to a test fixture that mimics the head geometry of an electric toothbrush. Using a dynamic mechanical analyzer (DMA), the effective stiffness of the bristles is measured at temperatures from 22 °C to 40 °C in 3 °C increments. At each temperature point, the deflection of the bristle tips is measured under loads of 10 g to 200 g.In measurements taken at 22°C and 37°C, the SMP bristles exhibited a modulus reduction of 45%, while the control bristles showed only a 7% reduction. Under cyclic loading at mouth temperature, the SMP bristles displayed reversible softening behavior, returning to their original stiffness after release. The tests confirmed that the SMP bristles maintain sufficient stiffness for effective plaque removal under gentle pressure (50-150 g) and automatically soften under excessive force, demonstrating a self-regulating protective mechanism to safeguard the gums during aggressive brushing. Example 2: Performance analysis of the magnetic torque micro-coupling system

[0301] A prototype of the magnetic torque micro-coupling consists of two rare-earth magnets (NdFeB, grade N42) with biocompatible nickel coatings. The magnets are arranged as concentric rings with a mean radius of 10 mm, separated by a precision-machined PTFE spacer with a 0.3 mm gap. The coupling assembly is integrated into a functional toothbrush head prototype connected to a commercially available vibratory drive operating at 8,800 oscillations per minute. The assembly is mounted on a calibrated torque measuring device that applies progressive radial loads to the bristle tips. The load is increased in 10 g increments from 50 g to 250 g. The coupling is observed to maintain a rigid connection up to an equivalent peak force of 175 g.From this point, it begins to slip, generating characteristic tactile feedback in the form of a soft clicking sound and a fluttering. The slip behavior exhibits remarkable consistency, with a coefficient of variation of less than 5% over 1,000 test cycles. A Hall-effect sensor mounted next to the clutch successfully detects each slip event and triggers a 450 ms LED pulse. The clutch maintains its functionality over 100,000 slip cycles without any measurable deviation in the slip threshold, confirming the mechanism's durability for long-term operation while ensuring consistent protection against excessive brushing force. Example 3: Functional evaluation of the self-tilting neck mechanism of Cam-Flex

[0302] A prototype neck mechanism was fabricated, comprising an eccentric cam made of medical-grade acetal copolymer and a compliant joint made of thermoplastic polyurethane (TPU, Shore A 85). The cam profile is designed with an increasing inclination, culminating in two distinct detent positions at 6° and 12° of inclination relative to the longitudinal axis. The assembly is installed in a complete toothbrush prototype and mounted on an instrumented test rig that applies a controlled torque to the head while optically monitoring its angular displacement. The torque is applied in 0.5 Ncm increments from 0 to 5.0 Ncm. The neck remains stable in its neutral position until the torque reaches 1.8 Ncm. At this point, it transitions into the first detent position at 6° (±0.5°), indicated by distinct tactile feedback.When the torque increases to 3.2 Ncm, the mechanism moves to the second detent position at 12° (±0.5°). High-speed video analysis (1000 fps) shows that the reset time after torque reduction is 85 ms, well within the specified limit of 100 ms. An elastomeric lip, located at the edge of the bristle field, automatically extends when the head reaches the 12° position, protruding 0.8 mm downwards to protect the gum line from contact with the bristles. The mechanism completes 250,000 actuation cycles without mechanical failure or significant deviations in performance parameters, demonstrating excellent durability for the expected product lifespan. Example 4: Quantitative evaluation of the shock-absorbing brush head system

[0303] The shock-absorbing brush head system consists of a compression spring (stainless steel, wire diameter 0.3 mm, free length 4.0 mm, spring constant 1.5 N / mm) positioned between the drive connector and the bristle holder plate. A silicone dashpot cartridge (1.0 mm inner diameter, filled with 5,000 cSt silicone fluid) is installed parallel to the spring to provide speed-dependent damping. The assembly is mounted on a force-displacement test station that applies loads at speeds from 1 mm / s to 200 mm / s. At low load speeds (1–10 mm / s), the head is gently compressed and achieves a full retraction length of 1.5 mm with an applied force of 180 g.At high loading speeds (100-200 mm / s, simulating impact movements), the damping effect becomes significant, limiting the initial displacement to 0.8 mm under the same force, thus ensuring improved protection against sudden impacts. A color-coded mechanical indicator slides along a scale with a window at the neck, providing visual feedback on the pressure level (green for 0-100 g, yellow for 100-180 g, red above 180 g). A micro Hall effect sensor detects retraction and signals the controller to reduce the motor amplitude by 30% if the retraction exceeds 1.0 mm. The system reliably returns to its extended position within 280 ms of release, providing effective protection against aggressive brushing while maintaining proper bristle contact during normal use.

[0304] Example 5: Integrated System Performance Under Simulated Brushing Conditions. A fully assembled prototype with all four safeguards (pressure-adaptive bristles, magnetic torque clutch, flexible neck, and shock-absorbing head) is evaluated in a simulated brushing test using a robotic arm programmed to reproduce typical human brushing patterns with varying force profiles. A tooth model with simulated plaque (fluorescent indicator) serves as the brushing surface. The test matrix includes scenarios with gentle brushing (50–100 g), moderate brushing (100–150 g), and aggressive brushing (150–250 g). With gentle and moderate brushing, the toothbrush functions normally with full cleaning power, removing 92% and 95% of the simulated plaque, respectively. When aggressive force is applied, the safeguards engage sequentially: First, the SMP bristles soften by approximately 40% at an oral temperature of 37 °C.The shock-absorbing head then begins to retract at forces exceeding 150 g. Thirdly, the flexible neck tilts to align the bristles more parallel to the tooth surface. Finally, the magnetic clutch slips at forces exceeding 180 g, providing tactile and visual feedback. Despite these protective measures, 88% of plaque is still removed during aggressive brushing, demonstrating that the cleaning effect is maintained even when the brush is actively protecting against potential gum damage. Thermal imaging confirms that the bristle tips maintain contact with the surface throughout the protective response, while pressure measurements show a significant reduction in local pressure points when the protective mechanisms are activated.These results confirm that the integrated system effectively maintains cleaning performance while automatically counteracting excessive force exerted during a variety of brushing behaviors.

[0305] Example 6: Reactive Bristle Configurations for Various Materials. A range of advanced bristle configurations are being produced using combinations of reactive materials to create multi-stage protective mechanisms. The first configuration comprises a core-shell structure with a piezoelectric composite core (barium titanate nanoparticles in a flexible polymer matrix) surrounded by a magnetorheological elastomer shell containing carbonyl iron microparticles. A miniature electromagnet coil is embedded in the brush head below the bristle field. During normal brushing (50–120 g), the bristles maintain their optimal stiffness. When the pressure increases to 130–150 g, the piezoelectric core generates a small voltage proportional to the applied force.This is detected by a microcontroller, which reduces the field strength in the electromagnetic coil, softening the magnetorheological sheath by up to 60%. In a second configuration, temperature-sensitive hydrogel particles are distributed within a shape-memory polymer matrix, creating bristles that respond to both oral temperature and mechanical pressure. At body temperature, the hydrogel particles expand slightly, placing the bristles in a pre-soft state. Under excessive pressure, the shape-memory polymer component undergoes a second transition, reducing bristle stiffness by a further 35%. A third configuration features bristles with telescopic, spiral roots that expand under pressure, increasing the bristle length by 0.3 to 0.5 mm when the force exceeds 160 g, thus distributing the pressure over a larger area.These multi-material bristles with multiple mechanisms demonstrate how combinations of reactive materials can achieve sophisticated pressure adjustment that maintains cleaning performance while providing improved gum protection.

[0306] Example 7: Adaptive Clutch Systems with Variable Engagement Thresholds. An advanced magnetic torque clutch system with programmable engagement thresholds has been developed that adapts to different users and brushing areas. The system incorporates a primary magnetic clutch similar to that in Example 2, but additionally features a secondary electromagnetic component that can modulate the magnetic clutch strength. When the toothbrush is used on the front teeth (detected by an orientation sensor), the electromagnetic component strengthens the magnetic clutch and increases the slippage threshold to 190 g to enable effective cleaning of these more accessible surfaces.When the brush is moved to the rear, the electromagnetic component reduces the clutch force and lowers the slip threshold to 160 g to provide better protection in these hard-to-reach areas where users typically apply more force. In another embodiment, the clutch system features a continuous slip mode instead of a binary on / off state. When the force exceeds 150 g, the clutch begins to partially slip, creating a soft stop that increases proportionally to the applied force. This progressive slip behavior provides the user with more nuanced feedback than a simple on / off slip mechanism.Another variant involves a magnetorheological fluid coupling, in which the viscosity of the fluid changes depending on the applied magnetic fields, resulting in a continuously variable torque transmission that can be precisely tailored to the user's preferences or the dentist's recommendations. These adaptive coupling systems demonstrate how the force limiting mechanism can be individually adjusted to ensure personalized protection while maintaining optimal cleaning performance.

[0307] Example 8: Integrated Fluid Delivery Systems for Force-Activated Enhancement. A toothbrush head was developed that integrates a microfluidic system with force-protection mechanisms. The bristle holder plate contains a small reservoir with a special oral care fluid (e.g., a hydrogen peroxide solution or a remineralizing agent). When the shock-absorbing mechanism is compressed beyond 1.0 mm (indicating excessive pressure), a mechanical valve opens briefly, releasing a micro-jet of fluid through small channels adjacent to the bristle tufts. This compensatory fluid release ensures that the cleaning effect is maintained even with limited mechanical force.In a further developed version, the cam-flex tilting mechanism is coupled with a variable-opening microvalve that meters the fluid delivery proportionally to the tilt angle—a greater tilt results in a greater fluid delivery to compensate for the reduced mechanical effect. Another variant utilizes the magnetic coupling slippage to trigger precisely timed pulses of an antimicrobial solution, replacing excessive mechanical forces with a chemical cleaning action. The fluid delivery system can also be designed to deliver different formulations depending on the activated protective mechanism: a mild analgesic at high pressures, a lubricant during prolonged slippage events, or an enamel-strengthening compound during rapid pressure fluctuations.These integrated fluid supply systems demonstrate how force protection mechanisms can be coupled with additional cleaning technologies to maintain effectiveness while increasing safety.

[0308] Example 9: Advanced Feedback and User Training Systems. A comprehensive feedback system was developed that goes beyond simple LED indicators and enables sophisticated user training. The system includes a small accelerometer and an angle position sensor in the brush head, which work in conjunction with the force protection mechanisms. If the magnetic clutch slips, the system not only triggers an LED signal but also records the orientation and position of the brush at the moment of excessive force. After brushing, this data is transmitted to a smartphone app, which creates a 3D map of the user's mouth and highlights areas where excessive pressure was applied. Over time, the system creates a personalized pressure profile that helps users adjust their brushing technique.In another implementation, the feedback system includes haptic training signals that vary depending on the activated protection mechanism: a single vibration pulse for the initial softening of the bristles, a double pulse for shock absorber compression, and a triple pulse for clutch slippage events. The system also includes a mechanical "pressure odometer," visible through a window in the handle, which continues to run with each protection event, providing a cumulative record of brushing behavior between charges. A professional version allows dentists to program specific force thresholds and feedback patterns for patients with special needs, such as post-operative patients or patients with receding gums.These advanced feedback systems demonstrate how force protection mechanisms can be used not only for immediate protection but also for long-term behavioral change.

[0309] Example 10: Special Applications for Clinical and Sensitive Users. Based on core technologies for excessive pressure protection, a range of specialized toothbrushes has been developed to meet the specific needs of users. For patients recovering from periodontal surgery, a recovery brush has been developed featuring highly responsive shape-memory polymer bristles that soften at a pressure of only 80 g, combined with a low-threshold magnetic clutch (slipping at 120 g) and a shock-absorbing, extended-stroke system that allows for 2.5 mm of retraction. For users with dental implants, a modified brush features zone-specific bristle adaptation, with bristles around the implant sites designed with lower initial stiffness and increased temperature sensitivity.A children's version features a quick-release magnetic clutch that temporarily disconnects the brush head if a child applies excessive pressure (over 140 g) and then automatically reconnects when the pressure returns to normal, providing immediate tactile feedback. For older users with reduced hand sensitivity, the Cam-Flex tilting mechanism has been improved to provide more pronounced tactile feedback when activated, making the pressure warning more noticeable. A professional oral hygiene model features an adjustable magnetic clutch that can be calibrated to different thresholds using a simple dial, allowing hygienists to tailor the level of protection to each patient's specific oral health condition.These specific applications demonstrate how core technologies for protection against excessive pressure can be adapted and optimized for different user groups with varying protection requirements. Other embodiments Embodiment 1. Electric toothbrush head, comprising: • a bristle field with a plurality of bristles, wherein the bristles comprise a stimulus-responsive material configured to cause a reversible reduction in stiffness in response to an initial condition indicating excessive brushing pressure; and • a mechanical force protection mechanism configured to induce a reversible physical displacement of the bristle field in response to a second condition indicating excessive brushing force, wherein the displacement has at least one of the following properties: rotational slip, linear retraction, or angular tilt. Embodiment 2. The electric toothbrush head of embodiment 1, wherein the first state is an increase in the temperature of the bristles to mouth temperature. Embodiment 3. The electric toothbrush head of embodiment 1, wherein the first state is a mechanical force exerted on the bristles which exceeds a first pressure threshold. Embodiment 4. The electric toothbrush head from one of embodiments 1 to 3, wherein the stimuli-responsive material is a shape memory polymer. Embodiment 5. The electric toothbrush head from one of embodiments 1 to 3, wherein the stimuli-responsive material is a piezoelectric composite material. Embodiment 6. Electric toothbrush head according to one of embodiments 1 to 3, wherein the stimuli-responsive material is a magnetorheological elastomer and wherein the head further comprises a magnetic field generator configured to modify a magnetic field applied to the bristles in order to effect the reversible reduction of stiffness. Embodiment 7. Electric toothbrush head according to one of embodiments 1 to 6, wherein the reversible reduction in stiffness is a reduction in the effective tip stiffness by at least 40 percent, measured between 22 °C and 37 °C. Embodiment 8. Electric toothbrush head according to one of the preceding embodiments, wherein the mechanical force protection mechanism is configured to be activated when the second condition corresponds to an applied peak force of more than 150 grams. Embodiment 9. Electric toothbrush head according to one of the preceding embodiments, wherein the physical displacement is the rotary slip and the mechanical force protection mechanism comprises a clutch mechanism. Embodiment 10. The electric toothbrush head of embodiment 9, wherein the coupling mechanism is a magnetic torque micro-coupling calibrated to slip at a peak force between 160 grams and 200 grams. Embodiment 11. The electric toothbrush head from one of embodiments 1 to 8, wherein the physical displacement is the linear retraction movement and the mechanical force protection mechanism comprises a spring-mounted subassembly. Embodiment 12. The electric toothbrush head of embodiment 11, wherein the linear retraction takes place over a distance between 1.0 mm and 2.0 mm. Embodiment 13. Electric toothbrush head according to embodiment 11 or 12, wherein the spring-mounted subassembly further comprises a viscoelastic dashpot cartridge configured to provide speed-dependent damping. Embodiment 14. The electric toothbrush head from one of embodiments 1 to 8, wherein the physical displacement is the angular inclination and the mechanical force protection mechanism is arranged in a neck section of the toothbrush head. Embodiment 15. The electric toothbrush head of embodiment 14, wherein the angle of inclination is between 10 degrees and 15 degrees relative to a longitudinal axis of the neck section. Embodiment 16. Electric toothbrush head according to embodiment 14 or 15, wherein the mechanical force protection mechanism comprises an eccentric and a compliant joint. Embodiment 17. Electric toothbrush head according to embodiment 16, wherein the eccentric cam mechanism comprises at least one detent device configured to provide tactile feedback upon engagement. Embodiment 18. Electric toothbrush head according to one of the preceding embodiments, further comprising a feedback generator configured to provide a user-perceivable signal when the physical displacement is triggered. Embodiment 19. Electric toothbrush head of embodiment 18, wherein the signal perceptible to the user is at least one of a visual signal from an LED, a tactile signal comprising a click or a patterned vibration, or an acoustic signal. Embodiment 20. Electric toothbrush head according to one of the preceding embodiments, wherein the multiple bristles further comprise hydrogel cap tips configured to swell under pressure. Embodiment 21. Electric toothbrush head according to one of the preceding embodiments, wherein the multiple bristles are attached to telescopic spiral root anchors configured to expand reversibly under pressure. Embodiment 22. Electric toothbrush head according to one of the preceding embodiments, further comprising a transparent window configured such that at least part of the mechanical force protection mechanism is visible. Design 23. Electric toothbrush, comprising: • a handle that includes a drive unit; and • the electric toothbrush head of one of the embodiments 1 to 22, which is functionally coupled to the drive unit. Embodiment 24. The electric toothbrush of embodiment 23, wherein the drive unit is configured to temporarily reduce its operating intensity in response to the physical displacement of the toothbrush head. Embodiment 25. The electric toothbrush of embodiment 23 or 24, wherein the handle comprises a power source which is functionally coupled to a feedback generator located on the toothbrush head. Embodiment 26. Method for automatically regulating the brushing force exerted by an electric toothbrush, the method comprising the following steps: • Detecting an initial condition indicating excessive brushing pressure on a bristle field; • in response to the first state, automatically inducing a reversible reduction in the stiffness of a plurality of bristles within the bristle field, wherein the bristles comprise a stimulus-responsive material; • Detecting a second condition indicating excessive brushing force on the bristle field; and • in response to the second state, automatic initiation of a reversible physical displacement of the bristle field, wherein the displacement includes at least one of the following movements: a rotational slip, a linear retraction movement, or an angular tilt. Embodiment 27. Method according to embodiment 26, wherein the first condition comprises raising the temperature of the bristles to mouth temperature. Embodiment 28. Method according to embodiment 26, wherein the first state comprises applying a mechanical force to the bristles which exceeds a first pressure threshold. Embodiment 29. Method according to one of embodiments 26 to 28, wherein the second condition comprises the application of a peak force exceeding 150 grams. Embodiment 30. Method according to one of embodiments 26 to 29, wherein the step of bringing about the reversible physical displacement includes causing a magnetic clutch slippage. Embodiment 31. Method according to one of embodiments 26 to 29, wherein the step of bringing about the reversible physical displacement comprises the linear retraction of the bristle field by a distance between 1.0 mm and 2.0 mm. Embodiment 32. Method according to one of embodiments 26 to 29, wherein the step of bringing about the reversible physical displacement comprises tilting the bristle field by an angle between 10 degrees and 15 degrees. Embodiment 33. Method according to one of embodiments 26 to 32, which further includes the step of generating a feedback signal perceptible to the user in response to the second condition. Embodiment 34. Method according to embodiment 33, wherein generating the feedback signal perceptible to the user comprises emitting a light pulse from an LED. Embodiment 35. Method according to one of embodiments 26 to 34, which further comprises that a fluid or air jet is released from the electric toothbrush head in response to the second condition. Embodiment 36. Method for manufacturing an electric toothbrush head, the method comprising: • Forming a multitude of bristles from a stimuli-responsive material, wherein the material is selected to cause a reversible reduction in stiffness in response to an initial condition indicating excessive brushing pressure; • Attaching the multiple bristles to form a bristle field on a head chassis; and • Integrating the head chassis with a mechanical force protection mechanism configured to induce a reversible physical displacement of the bristle field in response to a second condition indicating excessive brushing force, the displacement comprising at least one of the following: rotational slip, linear retraction, or angular tilt. Embodiment 37. Method according to embodiment 36, wherein the step of forming the multiple bristles comprises forming the bristles from a shape memory polymer. Embodiment 38. Method according to embodiment 36, wherein the step of forming the multiple bristles comprises embedding ferromagnetic particles in an elastomeric polymer and further comprises integrating a magnetic field generator into the head housing near the bristle field. Embodiment 39. Method according to one of embodiments 36 to 38, wherein the step of integrating the mechanical force protection mechanism comprises assembling a magnetic torque micro-coupling configured for rotary slip. Embodiment 40. Method according to embodiment 39, wherein the magnetic torque micro-coupling is calibrated so that it slips at an equivalent peak force between 160 grams and 200 grams. Embodiment 41. Method according to one of embodiments 36 to 38, wherein the step of integrating the mechanical force protection mechanism comprises assembling a spring-mounted subassembly configured for linear retraction. Embodiment 42. Method according to one of embodiments 36 to 38, wherein the step of integrating the mechanical force protection mechanism comprises assembling an eccentric cam and a compliant joint in a neck section of the toothbrush head configured for an angular inclination. Embodiment 43. Method according to one of embodiments 36 to 42, further comprising integrating a feedback generator into the toothbrush head, wherein the feedback generator is configured to be activated by the mechanical force protection mechanism. Embodiment 44. Method according to embodiment 43, wherein the feedback generator comprises an LED and a microswitch or a Hall effect sensor positioned to detect the physical displacement. Embodiment 45. Method according to one of embodiments 36 to 44, wherein a transparent window is further formed in the head housing to allow a view of at least a part of the mechanical force protection mechanism. Embodiment 46: An electric toothbrush head comprising: • a bristle field with a plurality of bristles, wherein the bristles comprise a stimulus-responsive material configured to cause a reversible reduction in stiffness in response to a condition indicating excessive brushing pressure. Embodiment 47: The electric toothbrush head of embodiment 46, wherein the state is one or more of the following: • an increase in the temperature of the bristles to mouth temperature; • a mechanical force exerted on the bristles that exceeds a first pressure threshold. Embodiment 48: The electric toothbrush head of embodiment 46 or 47, wherein the stimuli-responsive material comprises one or more of the following elements: • a shape memory polymer; • a piezoelectric composite material; • a magnetorheological elastomer. Embodiment 49: Electric toothbrush head, comprising: • a mechanical force protection mechanism configured to induce a reversible physical displacement of the bristle field in response to a condition indicating excessive brushing force, wherein the displacement has at least one of the following characteristics: rotational slip, linear retraction or angular tilt.

[0310] Although various aspects and embodiments have been presented and described in detail in the foregoing description and the drawings, these presentations and descriptions are for illustrative or exemplary purposes only and are not limiting. Deviations from the disclosed embodiments can be understood and implemented by those skilled in the art when implementing the claimed subject matter with reference to the drawings, the disclosure, and the accompanying claims.

[0311] Although some aspects relating to a product, device, apparatus, or system have been described, these aspects also constitute a description of the corresponding process, method, or use, where a block or component corresponds to a process step or a feature of a process step. Similarly, aspects described in connection with a process step also constitute a description of a corresponding block, component, or feature of a corresponding product, device, apparatus, or system.

[0312] The order in which the operations are performed in the described embodiments is not essential unless otherwise specified. That is, the operations can be performed in any order unless otherwise specified, and embodiments may include additional or fewer operations than those mentioned.

[0313] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude multiple elements. A single unit can perform the functions of several units listed in the claims. The mere fact that certain measures are listed in different dependent claims does not mean that a combination of these measures cannot be used advantageously. All reference numerals in the claims are not to be interpreted as limiting the scope. REFERENCE MARK 100 electric toothbrushes 102 Borstenfeld 104 bristles 106 Neck area 108 toothbrush heads 110 drive unit 112 Force protection mechanism 114 Handle

Claims

Electric toothbrush head (108) comprising: a bristle field (102) with a plurality of bristles (104), wherein the bristles (104) comprise a stimulus-responsive material configured to cause a reversible reduction in stiffness in response to a first condition indicating excessive brushing pressure; and a mechanical force protection mechanism (112) configured to induce a reversible physical displacement of the bristle field (102) in response to a second condition indicating excessive brushing force, wherein the displacement has at least one of the following properties: rotational slippage, linear retraction, or angular tilt. Electric toothbrush head according to claim 1, wherein the first state is an increase in the temperature of the bristles to oral temperature. Electric toothbrush head according to claim 1, wherein the first state is a mechanical force exerted on the bristles which exceeds a first pressure threshold. Electric toothbrush head according to claim 1, wherein the stimuli-responsive material is a shape memory polymer. Electric toothbrush head according to claim 1, wherein the stimuli-responsive material is a piezoelectric composite material. Electric toothbrush head according to claim 1, wherein the stimuli-responsive material is a magnetorheological elastomer and wherein the head further comprises a magnetic field generator configured to modify a magnetic field applied to the bristles in order to effect the reversible reduction of stiffness. Electric toothbrush head according to claim 1, wherein the reversible reduction in stiffness is a reduction in the effective tip stiffness by at least 40 percent, measured between 22 °C and 37 °C. Electric toothbrush head according to one of the preceding claims 1, wherein the mechanical force protection mechanism is configured to be activated when the second condition corresponds to a force of more than 150 grams exerted on the tip. Electric toothbrush head according to one of the preceding claims 1, wherein the physical displacement is the rotational slip and the mechanical force protection mechanism comprises a clutch mechanism; wherein the clutch mechanism is a magnetic torque micro-coupling calibrated to slip at an equivalent peak force between 160 grams and 200 grams. Electric toothbrush head according to claim 1, wherein the physical displacement is the linear retraction movement and the mechanical force protection mechanism comprises a spring-mounted subassembly; wherein the linear retraction occurs over a distance between 1.0 mm and 2.0 mm; wherein the spring-mounted subassembly further comprises a viscoelastic dashpot cartridge configured to provide velocity-dependent damping. Electric toothbrush head according to claim 1, wherein the physical displacement is the angular inclination; wherein the mechanical force protection mechanism is arranged in a neck region of the toothbrush head; wherein the angular inclination is between 10 degrees and 15 degrees relative to a longitudinal axis of the neck section; wherein the mechanical force protection mechanism comprises an eccentric cam and a compliant joint. Electric toothbrush head according to claim 11, wherein the eccentric cam mechanism comprises at least one detent device configured to provide tactile feedback upon engagement. An electric toothbrush head according to any one of the preceding claims 1 to 12, further comprising a feedback generator configured to provide a user-perceivable signal upon triggering the physical displacement; wherein the user-perceivable signal is at least one of the following: a visual signal from an LED, a tactile signal comprising a click or patterned vibration, or an acoustic signal. Electric toothbrush head according to any one of the preceding claims 1 to 13, wherein the multiple bristles further comprise hydrogel cap tips configured to swell under pressure. Electric toothbrush head according to any one of the preceding claims 1 to 14, wherein the multiple bristles are attached to telescopic spiral root anchors configured to expand reversibly under pressure. Electric toothbrush head according to any one of the preceding claims 1 to 15, further comprising a transparent window configured such that at least part of the mechanical force protection mechanism is visible. Electric toothbrush head (108) comprising: a bristle field (102) with a plurality of bristles (104), wherein the bristles (104) comprise a stimuli-responsive material configured to cause a reversible reduction in stiffness in response to a condition indicating excessive brushing pressure. Electric toothbrush head according to claim 17, wherein the state is one or more of the following: an increase in the temperature of the bristles to mouth temperature; an application of a mechanical force to the bristles that exceeds a first pressure threshold. Electric toothbrush head according to claim 17, wherein the stimuli-responsive material comprises one or more of the following elements: a shape memory polymer; a piezoelectric composite material; a magnetorheological elastomer. Electric toothbrush head (108) comprising: a bristle field (102) with a plurality of bristles (104); and a mechanical force protection mechanism (112) configured to induce a reversible physical displacement of the bristle field (102) in response to a condition indicating excessive brushing force, the displacement comprising at least one of the following elements: a rotational slip, a linear retraction movement, or an angular tilt.

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