JP2006181257A - Silencing system of odontotherapy apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To silence a handpiece noise over a wide frequency band in both of air conduction and bone conduction. <P>SOLUTION: This silencing system of odontotherapy apparatus collects a handpiece rotating sound, which is a mental affliction for a patient under a treatment, in the oral cavity of the patient by a handpiece built-in microphone 12, and outputs a phase inversion sound from an air conduction speaker 42 to cancel it. This system allows a patient ear microphone 13 to collect the uncanceled sound (sound deviation), refers to the digital conversion value and the rotation frequency in operating the handpiece and/or racing it stored in a memory, extracts a difference value determined to pertain to the frequency band of the handpiece rotating sound, and corrects the sound deviation by a feedback control of adjusting the phase for canceling the difference value. When an operation determining means ALU determines the operation of the handpiece, the phase inversion sound, or the bone conduction sound, collected by a tooth press-fitted microphone 14 is output from the bone conduction speaker 3 to cancel it. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a system for eliminating noise generated from a dental treatment instrument such as a handpiece used as a tooth cutting machine.

  In general, a technique called ANC (Active Noise Control) is known as a system for eliminating the harmful effects of generated noise, and is used in various fields. The ANC creates the opposite phase (Secondary Noise) of the input sound wave (Primary Noise) using the LMS (Least Mean Square) algorithm and the DSP (Digital Signal Processor), releases it to the space, cancels each other, and cancels the sound. FIG. 1 shows an ANC equivalent circuit thereof. In the ANC technology, an analog sound is all converted to digital (A / D conversion), processed by a DSP using an LMS algorithm, and then converted to analog (D / A conversion) before being emitted. For this reason, it has been proved that ANC is effective when the sound wave has a low frequency but is less effective when the sound wave has a high frequency.

Patent Document 1 below proposes a dental treatment unit that eliminates the harmful effects of noise caused by dental treatment instruments such as handpieces by applying the ANC technique to the dental treatment field.
JP-A-5-285176

  This dental treatment unit detects sound generated by an instrument during dental treatment with a microphone, and generates sound from the speaker that is substantially the same amplitude and 180 ° in phase as the sound emitted by this treatment device. The sound to be canceled is cancelled.

  On the other hand, for high-frequency noise reduction, it is effective to absorb sound vibrations by physically blocking the sound using a sound insulating material such as glass wool and to attenuate or convert the sound into other energy. Has been proven. This method is called passive control mute technology.

  In dental treatment, tooth cutting is indispensable. However, noise generated when using a handpiece (hereinafter simply referred to as a handpiece) that is a cutting machine for the teeth (including rotation sound of cutting drill, cutting noise, and blowing water of cooling water used during cutting) ) Has made it difficult for the surgeon / assistant / patient to communicate with each other, and also has the negative effect of causing pain by causing the patient an image of pain.

  From the viewpoint of the frequency band, noise from the handpiece (rotating speed of the cutting drill is 300 to 400,000 rpm) includes a low frequency sound of 500 to 1000 Hz and a high frequency sound component of 3500 to 4000 Hz. Sometimes, the frequency component of this noise may be a wide band extending from 500 to 4000 Hz.

  In order to mute the noise over this wide band, as described above, since all analog signals of noise are converted into digital signals once and processed, the conventional ANC is effective for low frequencies but has little effect on high frequencies. It is impossible to achieve with technology alone. However, since handpieces are inevitably required to be miniaturized for use in the oral cavity of a patient, it is physically impossible to apply passive control silencing technology that requires a large amount of sound insulation such as glass wool. . Therefore, no handpiece has been silenced until now. Even in the dental treatment unit described in Patent Document 1, the sound generated from the dental treatment instrument is tried to be canceled by the output of the phase reversal sound depending on the conventional ANC technique, but cannot be completely erased. The high frequency component is heard by the patient, and the above-mentioned problem cannot be solved completely.

  Further, in the dental treatment unit described in Patent Document 1, a place where it is easy to pick up noise from a dental treatment instrument such as a handpiece (inside the instrument, on the pedestal, the chest of the operator, a shadowless light part, A microphone is installed on the backrest side of the dental treatment chair, etc., but the handpiece rotation sound generated in the oral cavity changes its frequency when it goes out of the oral cavity. Even if the handpiece rotation sound is directly picked up by the microphone attached to the sound and the phase inversion sound is output, the sound corresponding to the sound deviation is heard by the patient and cannot be completely silenced. On the other hand, if a microphone is placed outside the oral cavity, there will be no problem with the misalignment of the handpiece rotation sound, but sounds other than the handpiece rotation sound, such as music flowing into the treatment room or metal when placing dental treatment instruments on the tray Since the microphone picks up sounds, voices spoken by the surgeon, and even the patient's own voice, when these phase-inverted sounds are output, all sounds including the handpiece rotation sound are muted and virtually silent As a result, there arises a new problem that it becomes difficult to hear important conversational speech between the surgeon and the patient. The patent document 1 describes that a plurality of microphones may be installed, but no specific configuration and specific processing in that case have been proposed.

  Furthermore, the noise from the handpiece is recorded externally at a level of 70 to 80 dB from the viewpoint of volume and propagation, but the volume felt by the patient himself is actually much higher than 80 dB, 100 dB to 120 dB. become. This is because it is transmitted as vibration sound due to bone conduction transmitted from the tooth to the skull. In other words, in addition to air conduction, there is bone conduction as a path through which noise is sensed by humans. Air Conduction is a path that propagates through the air and travels from the patient's outer ear to the inner ear, and Bone Conduction is a path that travels through the skull to the inner ear. The noise of both air conduction and bone conduction by the handpiece during dental treatment cutting is too loud, so that the external sound is shielded, for example, even if the patient speaks to the operator, the voice is drowned out and heard The phenomenon that it cannot be taken out occurs.

  Therefore, in order to mute the sound generated by the dental treatment instrument and heard by the patient as noise, it is necessary to take into account two types of propagation: air conduction and bone conduction. In this respect, the dental treatment unit described in the above-mentioned Patent Document 1 deals only with air conduction, and thus cannot sufficiently mute the sound.

  As described in detail above, the noise generated when using the handpiece is that the noise is over a wide frequency band and the narrow space of the human oral cavity is the source of the noise. It is difficult to achieve noise reduction by simply applying the conventional ANC technology. Furthermore, the noise is propagated in two systems, air conduction and bone conduction. In addition to the above problems, it is necessary to develop a complete silencing system in consideration of these propagations.

  In order to solve the above problems, the present invention substantially eliminates noise over a wide frequency band caused by rotation of a dental treatment instrument such as a handpiece while considering two systems of sound propagation, air conduction and bone conduction. It is an object of the present invention to provide a novel silencing system for dental treatment instruments that can be silenced.

  In order to achieve this object, the present invention according to claim 1 includes a first microphone for acquiring sound generated by rotation of a dental treatment instrument in the oral cavity of a patient being treated, and a tooth for which the dental treatment instrument is undergoing cutting treatment. A second microphone that obtains bone conduction sound generated by hitting, a memory that stores the frequency of the sound when the dental treatment instrument rotates in the oral cavity, and digitally converts the sound obtained by the first microphone A / D conversion means, operation determination means for determining whether or not the dental treatment instrument is in operation by comparing the output digital value from the A / D conversion means and the rotational sound frequency stored in the memory, An air conduction phase inversion means for generating a phase inversion sound of the sound acquired by the microphone, an air conduction speaker for outputting the phase inversion sound generated by the air conduction phase inversion means at the ear of the patient, and an operation determination means. Dental equipment Bone conduction phase reversing means for generating a phase reversal sound of the sound acquired by the second microphone when it is determined to be active for shaving treatment, and a phase reversal sound generated by the bone conduction phase reversing means are output. A bone silencing system comprising a speaker for bone conduction.

  According to a second aspect of the present invention, there is provided a first microphone for obtaining a sound generated by rotation of a dental treatment instrument in the oral cavity of a patient being treated, and a bone conduction sound produced when the dental treatment instrument strikes a tooth under cutting treatment. A second microphone for acquiring a sound, a memory for storing a sound frequency generated when the dental treatment instrument is idle in the oral cavity, and a sound frequency generated when the dental treatment device is operating for tooth cutting treatment; The first A / D conversion means for digitally converting the sound acquired by one microphone, and the output digital value from the first A / D conversion means and whether or not the dental treatment instrument is in operation are stored in the memory. Operation determination means for determining by comparison with the idle and / or operating frequency, air conduction phase inversion means for generating a phase inversion sound of the sound acquired by the first microphone, and air conduction phase inversion means The phase inversion sound generated by the patient An original air-conducting speaker, a third microphone that obtains the sound that the patient still listens to by the phase-reversed sound output from the air-conducting speaker, and a digital signal that converts the sound obtained by the third microphone The sound acquired by the third microphone by referring to the second A / D conversion means, the output digital value from the second A / D conversion means and the idling and / or operating frequency stored in the memory. The sound that controls the air conduction phase reversing means is extracted so that the difference value determined to belong to the frequency band of the sound generated by the rotation of the dental treatment instrument is extracted and the phase adjustment for erasing the difference value is performed. Bone conduction phase inversion means for generating a phase inversion sound of the sound acquired by the second microphone when the shift correction means and the operation determination means determine that the dental treatment instrument is in operation for tooth cutting treatment; Generated by phase inversion means for bone conduction A bone conduction speaker that outputs a phase inversion sound, a silencing system of a dental treatment instrument, characterized in that it comprises a.

  According to a third aspect of the present invention, the first microphone used in the silencing system for the dental treatment instrument according to the first or second aspect is a position where the distance from the cutting drill of the dental treatment instrument is within a range of 10 to 30 mm. It is provided in.

  According to the silencing system for a dental treatment instrument of the present invention, a processing unit (digital line) and a sound wave circuit (analog line) are provided separately. That is, the sound (noise) acquired by each microphone is corrected by the input correction means via the analog line and appropriately input by the input control means, and then a phase inversion sound is generated for the input sound wave from the speaker. Output. The dental treatment instrument is turned on only in the patient's oral cavity, but the operation determining means for determining whether or not the dental treatment instrument is actually used for cutting treatment of the patient's teeth, and input switching based on the determination result A digital line is separately provided for operating input control means for selectively controlling sound waves input to the means. By adopting such a system configuration, it is possible to mute the broadband noise generated by the dental treatment instrument. At the same time, the BPF (Band-Pass Filter), which is indispensable in the conventional ANC by digital processing, is unnecessary, and it is possible to increase the speed. In addition, the built-in microphone in the handpiece, the tooth crimping microphone, and a series of system configurations deal with noise caused by bone conduction.

  As a result of the noise from the dental treatment device being substantially completely silenced through these, the patient can receive treatment without fear or stress, and can communicate with the surgeon.

  If the system of the present invention is used to mute the noise with a dental treatment instrument, there may be a concern that during the treatment, it may not be possible to judge whether or not the patient is currently being treated. Although it is not possible, because the surgeon is always paying attention to the patient's condition and reaction, for example, while a car without noise during driving is running, passers-by is difficult to notice the existence of the car Note that there is no danger of type.

  FIG. 2, which is a schematic configuration diagram of a silencing system for a dental treatment handpiece according to a preferred embodiment of the present invention, will be described in detail below with reference to FIG. 3, which is an image of treatment performed using the system.

  This system includes a microphone 12, a patient's ear microphone 13, and a tooth crimping microphone 14 built in the handpiece 11 as noise acquisition means 10. As shown in FIG. 4, the handpiece built-in microphone 12 is built in the main body 16 at a position slightly away from the cutting drill 15 of the handpiece 11, and acquires the rotation sound of the cutting drill 15 of the handpiece 11. The patient ear microphone 13 is installed on or near the headrest 17 of the dental treatment chair, and acquires air conduction noise. The tooth crimping microphone 14 is used for crimping a surgeon to a location that does not cause a physical obstacle in terms of treatment, for example, an upper tooth facing the treatment location, and acquires noise due to bone conduction. Since the lower jaw communicates with the skull through the joint space, it is only necessary to detect the vibration of the upper jaw tooth rather than the vibration of the lower jaw tooth. The noise acquisition means 10 acquires these sound waves as analog values.

  An arithmetic / control means (hereinafter referred to as ALU) 20 having a memory 21 performs arithmetic operations such as determination and control of other components based on the sound wave acquired by the noise acquisition means 10. Since the sound wave acquired by the noise acquisition means 10 is an analog value, the ALU 20 handles the digital values (frequency, amplitude, etc.) converted by the A / D conversion means 22, 23, 24 as data. The sound wave of the microphone 12 with a built-in handpiece is digitally converted by the A / D conversion means 24 after being controlled to an optimum input level by the amplification means (AMP) 25.

  One of the important roles of the ALU 20 is to determine the operating status of the handpiece 11, that is, whether the handpiece 11 is cutting or idling the affected tooth. This determination is performed based on whether or not the frequency of the input sound wave from the microphone 12 with a built-in handpiece matches the frequency when the handpiece 11 is idling (300 to 400,000 rpm). Since the rotation speed when the handpiece 11 is cutting the teeth is greatly reduced to about 200,000 rpm compared with the idling (300 to 400,000 rpm), the frequency of the generated sound is also greatly different. Therefore, when the frequency of the input sound wave does not coincide with the frequency during idling (when it is below the threshold value), it can be determined that cutting is in progress. In order to make this determination, the frequency of the rotational sound during idling and cutting of the handpiece 11 is stored in advance in the memory 21 for each individual handpiece in consideration of individual differences of the handpiece.

  Whether or not the bone conduction input control means (Comparator) 30 uses the sound wave (vibration sound) from the tooth crimping microphone 14 as the system input sound wave based on the determination result of the handpiece operating status (cutting / idling) by the ALU 20. Control. The system input sound wave is an input sound wave by the noise acquisition means that should be a processing target for generating the phase inversion sound by the phase inversion means 31 and 41.

  Phase inversion means (Phase Inverters) 31 and 40 invert the phase of the system input sound wave. In addition to simple phase inversion (angle 180 degrees as a phase difference), fine adjustment within a phase difference of ± 4 degrees is performed as necessary.

  The bone conduction amplification unit (Bone Conduction AMP) 32 and the air conduction amplification unit (Air Conduction AMP) 41 each control the phase inversion sound of the system input sound wave to the optimum output level.

  The bone conduction speaker 33 and the air conduction speaker 42 are each a speaker that generates a phase inversion sound of a system input sound wave adjusted to an optimum output level. The bone conduction speaker 33 is installed at the headrest 17 portion of the dental treatment chair so that vibration (phase-inverted vibration) is directly transmitted to the skull of the patient being treated. It is preferable to install near both ears so that the patient can hear the phase-reversed sound directly and clearly.

  Among the above components, the input switching timing in the bone conduction input control means 30, the phase inversion status of the phase inversion means 31, 40, the function of the bone conduction amplification means 32 and the air conduction amplification means 41 are turned on / off. The ALU 20 controls the optimum output level.

  In addition, if it explains supplementarily about handling of the handpiece 11, in order to dissipate the frictional heat generated when the cutting part cuts teeth when the handpiece is in operation, water is discharged from the tip portion. Therefore, the surgeon always operates the handpiece in the patient's mouth (switch ON / OFF).

  Here, the silencing process of air conduction noise will be described in detail.

  In the dental treatment unit described in Patent Document 1 described as the prior art, as described above, the air guiding microphone corresponding to the patient's ear microphone 13 is attached to the head base, the operator's chest, the surgical light part, and the dental treatment chair. When installed on the side of the backrest etc., the method of acquiring all the air conduction noise and outputting the phase inversion sound at the same time has been adopted, so the conversation sound of the surgeon and patient is also muted In addition, when the microphone is installed on the handpiece, there is a drawback that the sound shift cannot be eliminated. In either case, it is difficult to reliably mute only the noise generated by the handpiece. . In order to solve this problem, in this system, as a method of purely acquiring only the noise of the handpiece, a microphone 12 with a built-in handpiece is installed, and a patient ear microphone 13 is installed as an error sensor to eliminate sound deviation. Propose.

  FIG. 5 shows which noise acquisition means acquires the system input sound wave (noise) according to the type. Regarding air conduction noise, the microphone 12 with a built-in handpiece acquires purely noise from the handpiece, that is, only rotation sound of the cutting drill 15 (strictly speaking, water noise that is emitted at the same time is included). To do. In this system, the noise is silenced by emitting the phase inversion sound of the noise acquired by the handpiece built-in microphone 12 from the air guiding speaker 42.

  It should be noted that the process from the handpiece built-in microphone 12 until the sound of the air conduction speaker 42 is emitted is an electrical process, and the air conduction speaker 42 is slightly less than the noise from the handpiece 11. However, when the noise of the handpiece diffuses from the oral cavity to the oral cavity, it is released into the oral cavity. As a result of the occurrence of a slight error (sound shift) due to reverberation or cheeks, the phase inversion sound is output using only the handpiece built-in microphone 12 as the noise acquisition means. However, complete silencing cannot be realized, and the noise part of this sound shift is heard by the patient. Therefore, in this system, the sound that cannot be completely erased by outputting the phase inversion sound of the noise acquired by the microphone 12 with the built-in handpiece from the air conduction speaker 42 (when the noise goes out of the oral cavity from the oral cavity). When the frequency or phase changes due to environmental changes such as temperature, the sound that is heard by the patient as a sound shift due to the frequency or phase is acquired by the patient ear microphone 13, and based on the acquired sound (differential sound wave) To correct the misalignment. That is, the patient's ear microphone 13 functions as a sound shift correction error sensor by acquiring the result of muffling performed by the phase inversion process using the handpiece built-in microphone 12. In terms of the function as this error sensor, it is only necessary to acquire a sound shift corresponding to noise caused by handpiece rotation. However, since the patient's ear microphone 13 is installed in an open space, only the sound shift of handpiece rotation noise is obtained. Since the surrounding sounds such as conversation voices are also acquired together, the following processing is performed.

  The ALU 20 stores the noise acquired by the patient's ear microphone 13, that is, the digital data obtained by A / D converting the noise including the sound deviation and the conversation voice, in the memory 21 in advance. The noise within the noise range (frequency range of the noise) of the received handpiece 11 is extracted to obtain data corresponding to the sound deviation. Next, under the control of the ALU 20 based on the sound deviation equivalent data, the phase inversion means 40 finely adjusts the phase of noise (analog value) from the handpiece built-in microphone 12 (including amplitude adjustment). By repeating this adjustment many times (feedback), an ideal phase reversal sound that finally realizes complete silencing is output and the state is maintained. This noise deviation correction process is realized using all system components except for the tooth crimping microphone 14, the A / D converter 23, and the processing means 30 to 33 relating to bone conduction.

  6 and 7 are conceptually simplified illustrations of the noise shift correction process for noise. FIGS. 6A to 6C illustrate the case where the noise is viewed in a temporal flow, and FIGS. 7D to 7G illustrate the frequency components at a moment when the noise is present. It is.

  First, when the noise is viewed in a temporal flow, (A) shows the noise acquired by the handpiece built-in microphone 12 and the patient's ear microphone 13 when the sound is not muted at all. Here, when only the phase inversion sound of the microphone 12 with built-in handpiece is output, the result is (B). As a noise that can be heard by the patient. That is, according to this process, noise equivalent to the sound shift of the handpiece is heard by the patient, and complete silence of the handpiece noise cannot be realized.

  Next, when the noise is viewed as a frequency component at a certain moment, the frequency component display of the noise corresponding to a certain moment in (A) corresponds to (D). When the phase inversion sound of the handpiece built-in microphone 12 in (B) is output, it corresponds to (E), and the result is the frequency component display of the noise of the patient ear microphone 13 (F). Here, as described above, the ALU 20 extracts the noise within the noise range of the handpiece 11 stored in advance in the memory 21 and acquires data corresponding to the sound deviation.

  Finally, under the control of the ALU 20 based on the sound deviation equivalent data, the phase inversion means 40 performs a process of finely adjusting the phase of the noise from the handpiece built-in microphone 12 and outputting an ideal phase inversion sound. (C) corresponds to this processing, and as a result, the frequency component display is as shown in (G). Note that the fine adjustment method of the noise phase is a software process and is not directly related to the essence of the system, and thus the description thereof is omitted. Further, when noise other than the noise shift of the noise of the handpiece 11, for example, noise that occurs when a metal dish is dropped around the handpiece 11 enters the noise range of the handpiece 11, the noise is muted together. However, there is usually no inconvenience.

  In this system, the ANC technology is used in the process of the above-described noise deviation correction process. Since the existing ANC technology is used by using digital data obtained by A / D converting the input sound from the handpiece built-in microphone 12 as a sound source, as described above, it covers a wide frequency band. It was very difficult to perform the processing (processing corresponding to the processing of the phase inverting means 40) instantaneously (this is because time is required for the frequency spectrum (analysis) processing of the voice particularly in the high frequency portion). Therefore, in this system, the ALU 20 uses the digital data of the A / D conversion 22 from the patient ear microphone 13 as data for controlling the adjustment of the phase and amplitude of the phase inverting means 40, and the handpiece built-in microphone 12 as the sound source. Since the ANC technology is used by the method of handling the analog values of the above, the above-described problem when the digital data is used as a sound source has been successfully avoided.

  Although the description has been given of the process for correcting the deviation of the air conduction noise, in the simplified system (FIG. 8), only the microphone 12 with a built-in handpiece is used as the air conduction noise acquisition means, and the acquired sound from the patient ear microphone 13 is used. The phase-reversed sound of the handpiece noise acquired by the handpiece built-in microphone 12 is output without performing the correction processing. In the case of this system, as described with reference to FIG. 6B, a sound equivalent to the sound shift of the handpiece noise will be heard by the patient. Therefore, it is possible to mute most of the noise of the handpiece.

  Note that the bone conduction noise acquired from the tooth crimping microphone 14 also slightly deviates from the sound that is actually perceived by the patient, but the vibration deviation is almost negligible. A correction process corresponding to the correction process for the lead sound deviation is unnecessary.

  In this system, since the air conducting speaker 42 is provided at a position close to the patient's ear microphone 13, howling may occur, but this system also has this howling prevention function. This function is because the ALU 20 can also control the A / D conversion 22 from the patient ear microphone 13 in addition to the air conduction amplifying means 41, so that the A / D conversion 22 or the air conduction amplifying means before entering the howling state. 41 is realized by instantaneously turning on / off or controlling the input / output level. Such a method for preventing howling is known per se and will not be described in detail.

  Each step will be described below with reference to FIG. 9 which is a flowchart showing a processing flow by the handpiece silencing system described above.

  S1: Noise (analog value) is acquired from the microphone 12 with a built-in handpiece.

  S2: The noise of the microphone 12 with a built-in handpiece acquired in S1 is amplified by the AMP 25 to the optimum input level.

  S3: The noise of the handpiece built-in microphone 12 at the level amplified in S2 is converted from an analog value to a digital value by the A / D conversion means 24.

  S4: Since the ALU 20 is digitally converted in S3 in order to determine the operating status of the handpiece (whether it is being used for tooth cutting when the power is turned on or simply idling in the oral cavity), the microphone 12 with a built-in handpiece 12 The frequency band of noise (digital value) is compared with the frequency band of the handpiece idling previously stored in the memory 21. The determination method is as described above. As a result, when it is determined that cutting is in progress (see also FIG. 10), the process proceeds to S10 and S20 at the same time, and it is determined that idling is occurring (also FIG. (See also 11). That is, the processing is always performed in S20 to S22 regardless of the operating state of the handpiece.

  S10: Based on the result determined that the handpiece 11 is cutting in S4, the bone conduction input control means 30 uses the vibration sound (analog value) of the tooth crimping microphone 14 as a system input sound wave.

  S11: The phase inversion means 31 outputs a phase inversion sound for canceling the vibration sound based on the vibration sound (analog value) of the tooth crimping microphone 14.

  S12: The bone conduction amplifying means 32 amplifies the phase inversion sound of the tooth crimping microphone 14 that is the output of S11 to the optimum output level.

  S13: The bone conduction speaker 33 transmits the phase inversion sound of the tooth crimping microphone 14 output from S12 to the patient's back of the head as vibration sound. By outputting the phase inversion sound from the bone conduction speaker 33, the vibration sound generated during cutting is canceled.

  S20: Based on the result of determining that the handpiece 11 is cutting or idling in S4, the phase inverting means 40 is for canceling the noise based on the noise (analog value) of the microphone 12 with a built-in handpiece. Outputs phase inversion sound. As described above, this step includes a silencing process for noise shift of the noise of the handpiece 11.

  S21: The air conduction amplifying means 41 amplifies the phase inversion sound of the microphone 12 with a built-in handpiece, which is the output of S20, to an optimum output level.

  S22: The air guiding speaker 42 outputs the phase reversal sound of the microphone 12 with a built-in handpiece, which is the output of S21, at the patient's ear. This output cancels out noise generated from the main body of the handpiece 11 during cutting.

  As described above, in the steps from S10 to S12 during the range (A), the ALU 20 performs the phase inversion of the phase inversion means 31 and 40 based on the digital data of the vibration sound acquired by the tooth crimping microphone 14. The situation, the bone conduction amplification means 32 and the air conduction amplification means 41 are responsible for controlling the optimum output level. Similarly, in the steps from S20 to S21 during the range (B), the ALU 20 performs the bone conduction input control means 30 based on the noise digital data acquired by the handpiece built-in microphone 12 and the patient's ear microphone 13. The input switching timing, the phase inversion state of the phase inversion means 40, and the optimum output level in the air conduction amplifying means 41 are controlled. The ALU 20 also plays a role of appropriately switching on / off the functions of the bone conduction amplifying means 32 and the air conduction amplifying means 41 according to the result after determining the operating state of the handpiece in S4.

  Regarding the microphone 12 with a built-in handpiece, it is necessary to faithfully acquire noise generated by the high-speed rotation of the cutting drill 15 of the handpiece 11. As a result of repeated experiments by the inventor on the necessary conditions for this, the cutting of the handpiece 11 is performed. It has been found that it is desirable to incorporate the microphone 12 at a position 10 mm to 30 mm away from the drill 15.

  When the microphone 12 is installed at a position close to 10 mm from the cutting drill 15, the cooling water discharged at the same time for cooling the cutting drill 15 rather than the noise generated by the rotation of the cutting drill 15 of the handpiece 11. I picked up the water discharge sound. On the other hand, when the microphone 12 is installed at a position more than 30 mm away from the cutting drill 15, it becomes close to the part where the operator grips the hand piece, and the delicate rotation sound is absorbed by the operator's hand, There is a possibility that it cannot be picked up effectively. Therefore, the distance d from the installation position of the handpiece built-in microphone 12 to the cutting drill 15 preferably satisfies 10 mm ≦ d ≦ 30 mm.

It is the schematic of an ANC equivalent circuit. It is a schematic block diagram of the silencing system of the handpiece for dental treatment by one Example of this invention. It is an image figure of treatment performed using this system. It is a CG diagram showing a handpiece with a built-in microphone used in the present system. It is a figure which shows the noise acquisition means destination according to the kind of system input sound wave (noise) in this system. It is a figure explaining notionally the case where the sound shift correction process of the noise of the handpiece used for this system is seen in the time flow. It is a figure which illustrates notionally the noise shift correction process of the noise of the handpiece used for this system by the frequency component display in a certain moment. FIG. 3 is a diagram showing a silencing system for a dental treatment handpiece according to another embodiment of the present invention, in which only a handpiece microphone is used to acquire air conduction noise (no noise shift correction processing for handpiece noise). FIG. It is a schematic block diagram in the case. It is a flowchart which shows the processing flow by this system. It is a transition diagram which shows the flow of a sound wave and a signal when it determines with a handpiece being cutting in this system. It is a transition diagram which shows the flow of a sound wave and a signal when it determines with the handpiece idling in this system.

Explanation of symbols

10 Noise acquisition means 11 Handpiece (dental treatment instrument)
12 Microphone with built-in handpiece (first microphone)
13 Patient ear microphone (third microphone)
14 Tooth crimping microphone (second microphone)
15 Handpiece cutting drill 16 Handpiece body 17 Headrest 20 of dental treatment chair Arithmetic / control means (ALU) (operation determination means, sound deviation correction means)
21 Memory 22, 23, 24 A / D conversion means 25 Amplification means (AMP)
30 Bone conduction input control means (Comparator)
31 Phase Inverter (Bone conduction phase inversion means)
32 Bone Conduction AMP
33 Bone Conduction Speaker
40 Phase Inverter (Air Induction Phase Inverter)
41 Air Conduction AMP
42 Air Conduction Speaker

Claims (3)

A first microphone for obtaining sound generated by rotation of the dental treatment instrument in the oral cavity of the patient being treated; a second microphone for obtaining bone conduction sound produced by the dental treatment instrument hitting the tooth being cut; and A memory for storing the frequency of sound when the dental treatment instrument is rotating in the oral cavity, A / D conversion means for digitally converting the sound acquired by the first microphone, and whether the dental treatment instrument is in operation Operation determination means for determining whether or not the output digital value from the A / D conversion means is compared with the rotational sound frequency stored in the memory, and air conduction for generating a phase inversion sound of the sound acquired by the first microphone The phase reversing means, the air conduction speaker that outputs the phase reversal sound generated by the air conduction phase reversing means at the patient's ear, and the operation determining means determine that the dental treatment instrument is in operation for tooth cutting treatment. When the second microphone A bone conduction phase inversion means for generating a phase inversion sound of an acquired sound, and a bone conduction speaker for outputting a phase inversion sound generated by the bone conduction phase inversion means. Silencer system. A first microphone for obtaining sound generated by rotation of the dental treatment instrument in the oral cavity of the patient being treated; a second microphone for obtaining bone conduction sound produced by the dental treatment instrument hitting the tooth being cut; and A memory for storing the frequency of the sound generated when the dental treatment device is idle in the oral cavity and the frequency of the sound generated when operating the tooth cutting treatment, and the sound acquired by the first microphone is digitally recorded. The first A / D conversion means for conversion and the digital value output from the first A / D conversion means and whether or not the dental treatment instrument is in operation and the idle and / or in operation stored in the memory The operation judging means for judging by comparison with the frequency, the air phase inversion means for generating the phase inversion sound of the sound acquired by the first microphone, and the phase inversion sound generated by the air conduction phase inversion means Air conduction sound output at the ear And a third microphone for acquiring the sound that the patient still listens to by the phase inversion sound output from the air conduction speaker, and a second A / D conversion means for digitally converting the sound acquired by the third microphone , Referring to the output digital value from the second A / D conversion means and the idling and / or operating frequency stored in the memory, the rotation of the dental treatment instrument among the sounds acquired by the third microphone A sound deviation correction unit that extracts a difference value determined to belong to the frequency band of the generated sound and controls the air conduction phase inversion unit so as to perform phase adjustment for erasing the difference value, and an operation determination unit Generates bone conduction phase reversal means and bone conduction phase reversal means for generating a phase reversal sound of the sound acquired by the second microphone when it is determined that the dental treatment instrument is in operation for tooth cutting treatment. Bones that output a phase-inverted sound Silencing system of a dental treatment instrument, characterized in that it comprises a use speakers,. The silencing system for a dental treatment instrument according to claim 1 or 2, wherein the first microphone is provided at a position where the distance from the cutting drill of the dental treatment instrument is within a range of 10 to 30 mm.

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