An electric toothbrush based on detecting motor current to achieve pressure sensing

Abstract

The application discloses a motor current detection-based pressure-sensing electric toothbrush, which comprises a shell, one end of the shell is provided with a motor, the output shaft of the motor penetrates out of the shell and is connected with a brush head, an inner shell is further arranged in the shell, a battery is arranged in the inner shell, a circuit board is arranged on one side of the inner shell, the motor and the battery are electrically connected with the circuit board, a current sampling circuit is integrated on the circuit board, the current sampling circuit comprises a sampling resistor and a differential amplification circuit which are connected in series in a motor power supply loop, a main control chip is further integrated on the circuit board, and an ADC pin of the main control chip is connected with the output end of the differential amplification circuit.

Description

Technical Field

[0001] This utility model relates to the field of electric toothbrush technology, and in particular to an electric toothbrush that achieves pressure sensing based on detecting motor current. Background Technology

[0002] Compared to traditional toothbrushes, electric toothbrushes use the rapid rotation or vibration of a motor to create high-frequency vibrations in the brush head, instantly breaking down toothpaste into fine foam that deeply cleans between teeth. At the same time, the vibration of the bristles promotes blood circulation in the mouth and has a massaging effect on the gum tissue. After using an electric toothbrush, the user needs to charge it.

[0003] Electric toothbrushes typically include pressure sensors to monitor the pressure applied to the teeth / gum in real time. In traditional electric toothbrushes, the pressure sensor is glued to a fixed position on the motor's steel shaft and then connected to the control board via an FPC flexible board cable. This method requires a high level of craftsmanship in the gluing process. Due to the vibration of the motor during operation, the FPC flexible board may break after about 1 to 2 years of use, resulting in sensor malfunction, pressure detection failure, and the toothbrush becoming unusable.

[0004] Therefore, there is an urgent need to design an electric toothbrush that uses motor current detection to achieve pressure sensing in order to solve one or more technical problems that are lacking in the existing technology. Utility Model Content

[0005] The technical solution adopted by this utility model to solve the above-mentioned technical problems is: an electric toothbrush that realizes pressure sensing based on detecting motor current, characterized in that it includes: a housing, a motor is provided at one end of the housing, the output shaft of the motor extends out of the housing and is connected to a brush head, an inner shell is also provided inside the housing, a battery is installed in the inner shell, a circuit board is provided on one side of the inner shell, the motor and the battery are both electrically connected to the circuit board, a current sampling circuit is integrated on the circuit board, the current sampling circuit includes a sampling resistor and a differential amplifier circuit connected in series in the motor power supply circuit, a main control chip is also integrated on the circuit board, and the ADC pin of the main control chip is connected to the output terminal of the differential amplifier circuit.

[0006] In a preferred embodiment, the main control chip is also connected to an LED light group, which is located inside one end of the motor output shaft that extends out of the housing.

[0007] In a preferred embodiment, the sampling resistor is a surface-mount alloy resistor with a resistance of 5mΩ±1%, soldered between the positive terminal of the motor power input and the circuit board.

[0008] In a preferred embodiment, the differential amplifier circuit uses a quad operational amplifier integrated chip, the input terminal of the differential amplifier circuit is connected across the two ends of the acquisition resistor, and the output terminal is electrically connected to the main control chip.

[0009] The beneficial effects of this utility model are: this application realizes pressure detection by detecting motor current, which saves the cost of sensors, eliminates the need for FPC connection, eliminates the risk of FPC breakage and failure, improves reliability, improves assembly and usage space, allows for a wider range of motor types to be selected, and can also effectively improve service life. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the structure of this utility model;

[0011] Figure 2 This is an exploded view of the present invention;

[0012] Figure 3 This is a block diagram of the circuit structure of this utility model.

[0013] In the picture:

[0014] 10. Housing; 11. Motor; 12. Inner shell; 13. Battery; 14. Circuit board; 15. Current sampling circuit; 16. Differential amplifier circuit; 17. LED light group; 18. Sampling resistor; 19. Main control chip. Detailed Implementation

[0015] To make the above-mentioned objects, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a full understanding of this utility model. However, this utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.

[0016] In the description of the embodiments of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connection" and "installation" should be interpreted broadly. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. Furthermore, "connection" can be a direct connection or an indirect connection through an intermediate medium. "Fixed" means that the relative positional relationship remains unchanged after the connection. The directional terms mentioned in the embodiments of this utility model, such as "inner," "outer," "top," and "bottom," are only for reference to the directions in the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of this utility model, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this utility model.

[0017] In this embodiment of the invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0018] In this embodiment of the utility model, "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0019] References to "one embodiment" or "some embodiments" as used in this specification mean that one or more embodiments of the present invention include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0020] like Figures 1-3As shown, this utility model provides an electric toothbrush that realizes pressure sensing based on detecting motor current. It is characterized by comprising: a housing 10, a motor 11 at one end of the housing 10, the output shaft of the motor 11 extending out of the housing 10 and connected to a brush head; an inner shell 12 inside the housing 10, a battery 13 installed in the inner shell 12; a circuit board 14 on one side of the inner shell 12; the motor 11 and the battery 13 being electrically connected to the circuit board 14; a current sampling circuit 15 integrated on the circuit board 14, the current sampling circuit 15 including a sampling resistor 18 connected in series in the power supply circuit of the motor 11 and a differential amplifier circuit 16; and a main control chip 19 integrated on the circuit board 14, the ADC pin of the main control chip 19 being connected to the output terminal of the differential amplifier circuit 16.

[0021] Specifically, an inner shell 12 is installed at one end of the outer shell 10. The inner shell 12 has a cavity for housing the battery 13. A circuit board 14 is provided on one side of the inner shell 12. The battery 13 is powered through a spring contact. A motor 11 is installed outside one end of the inner shell 12. The motor 11 is fixed inside the outer shell 10. The output steel shaft of the motor 11 passes through the outer shell 10 and is connected to the brush head. To detect the current of the motor 11, a current sampling circuit 15 is integrated on the circuit board 14. This current sampling circuit 15 includes a precision sampling resistor 18 connected in series in the power supply circuit of the motor 11. The sampling resistor 18 is a surface-mount alloy resistor with a resistance of 5mΩ ± 1%. The current sampling circuit 15, mounted on the power supply trace of the motor 11 on the circuit board 14, also includes a differential amplifier circuit 16. This differential amplifier circuit 16 uses a quad operational amplifier integrated chip. The input terminal of the differential amplifier circuit 16 is connected across the two ends of the sampling resistor 18, and the output terminal is connected to the PA1 pin of the main control chip 19 through a 0.1μF filter capacitor. To facilitate user reminders, the main control chip 19 is also connected to an LED light group 17. The LED light group 17 is located inside one end of the output shaft of the motor 11 that extends out of the housing 10. When a predetermined standard is reached, the LED light group 17 flashes to remind the user that too much force has been applied.

[0022] During use, when the user applies pressure to the brush head, the pressure is transmitted through the brush head to the output steel shaft of the motor 11. After the motor 11 is subjected to force, the rotor resistance increases. At this time, the current sampling circuit 15 captures the current increment, and the main control chip alarms according to the threshold and reduces speed, maintains the standard, or switches to gentle mode.

[0023] This embodiment also provides a pressure sensing method based on the above structure, including the following steps:

[0024] (1) The driving current of motor 11 is obtained in real time by sampling resistor 18 (201) connected in series in the power supply circuit of motor 11;

[0025] (2) A reference current value under no-pressure conditions is established using a dynamic reference calibration module (302). The calibration includes temperature compensation: I_adj=I_base×(1+α×(T-25)), where α is the temperature drift coefficient;

[0026] (3) Perform three-level filtering on the real-time current signal, including moving average filtering, IIR low-pass filtering and dynamic range limiting;

[0027] (4) Calculate the effective current change: ΔI = I_filtered - I_adj;

[0028] (5) ΔI is mapped to a pressure value by a piecewise linear interpolation model, which is based on a pre-calibrated current-pressure correspondence table;

[0029] (6) Trigger control decisions based on pressure values, including entering gentle mode, normal mode or overpressure alarm;

[0030] In step (3), the cutoff frequency of the three-stage filter is lower than 1 / 10 of the operating frequency of motor 11, and the dynamic range limiting threshold is set to ±20% of the reference current value; in step (5), the piecewise linear interpolation model includes an overpressure protection threshold, and when ΔI≥80mA, the maximum pressure value is forced to be output and the toothbrush speed is triggered to decrease.

[0031] In summary, this application achieves pressure detection by detecting the current of motor 11, eliminating the cost of sensors and eliminating the need for FPC connections, thus eliminating the risk of FPC breakage and failure, improving reliability, improving assembly and usage space, broadening the range of motor types to choose from, and effectively extending service life.

[0032] This invention is not limited to the description in the specification and embodiments. Therefore, other advantages and modifications can be readily realized by those skilled in the art. Thus, without departing from the spirit and scope of the general concept as defined by the claims and their equivalents, this invention is not limited to the specific details, representative devices and illustrated examples shown and described herein.

Claims

1. An electric toothbrush that senses pressure based on detecting motor current, characterized in that, The device includes: a housing, a motor at one end of which has an output shaft extending out of the housing and connected to a brush head; an inner housing inside the housing, in which a battery is installed; a circuit board on one side of the inner housing; the motor and the battery being electrically connected to the circuit board; a current sampling circuit integrated on the circuit board, which includes a sampling resistor and a differential amplifier circuit connected in series in the motor power supply circuit; and a main control chip integrated on the circuit board, with the ADC pin of the main control chip connected to the output of the differential amplifier circuit.

2. The electric toothbrush for pressure sensing based on detecting motor current according to claim 1, characterized in that, The main control chip is also connected to an LED light group, which is located inside one end of the motor output shaft that extends out of the housing.

3. The electric toothbrush for pressure sensing based on detecting motor current according to claim 1, characterized in that, The sampling resistor is a surface-mount alloy resistor with a resistance of 5mΩ±1%, soldered between the positive terminal of the motor power input and the circuit board.

4. The electric toothbrush for pressure sensing based on detecting motor current according to claim 1, characterized in that, The differential amplifier circuit uses a quad operational amplifier integrated chip. The input terminal of the differential amplifier circuit is connected across the two ends of the sampling resistor, and the output terminal is electrically connected to the main control chip.

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