Medical power tools, medical screw tightening tools, and medical power drills

Abstract

We provide highly safe medical power tools equipped with advanced tools tailored to medical purposes. [Solution] The motor 4 that rotates the screw tightening bit 12 is started by a double-action type operating switch 14 having two switching function units 14a and 14b. One switching function unit switches the first threshold voltage of the motor's drive control unit 17, and the other switching function unit switches the second threshold voltage of the motor's drive control unit. When the two threshold voltages are switched, the drive control unit is activated to start the motor. With this configuration, even if there is a short-circuit abnormality due to an internal short circuit in either of the operating switch's switching function units, the motor will not start unless a medical professional presses the operating switch to turn on both switching function units. This provides a highly safe medical power tool that does not endanger patients undergoing medical procedures.

Description

Technical Field

[0001] The present invention relates to a medical power tool, a medical screw tightening tool, and a medical electric drill, each provided with a motor that drives a tip tool such as a screw tightening bit or a drill used for medical purposes.

Background Art

[0002] In conventional medical power tools equipped with a motor, the motor and a battery are mounted in a thin cylindrical tool main body, and a shape that is easy for medical personnel to hold with one hand is generally used. Further, in the medical power tool, the tip tool that rotates upon receiving the rotation of the motor according to the medical purpose is rotatably held by a bearing holder attached to the tip of the tool main body. Furthermore, in the medical power tool, an operation switch protruding on the outer peripheral surface of the tool main body is attached, and the operation switch turns on and off the supply of current from the battery to the motor to rotate the tip tool.

[0003] A momentary operation type is adopted as the operation switch, and it is configured such that the motor is driven while the medical personnel presses the operation switch to perform a predetermined medical procedure. Further, as for the operation switch, one having a single switching functional unit such as a contact for turning on and off the current supply to the motor is generally used.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the aforementioned medical power tools, the switching function of the operating switch may experience a short circuit due to aging, strong impacts applied during prolonged use, or some kind of abnormal current. Therefore, in cases where a medical power tool has a drill as a tip tool and an operating switch that only controls the on / off supply of current to the motor is connected to the battery, this short circuit can cause the motor to start and the tip tool to rotate before the medical professional presses the operating switch, endangering the patient just before they receive medical treatment.

[0006] In the case of the aforementioned medical power tool having a screw-tightening bit 12 as a tip tool and a torque control unit 20 that controls the drive of the motor 4 based on the screw-tightening torque applied to the screw-tightening bit 12 (see Figure 8), the battery 3 is connected to a control system power supply unit 16 and a motor drive power supply unit 15 composed of a Pch MOSFET transistor (hereinafter referred to as MOSFET). The control system power supply unit 16 is configured to have a predetermined voltage constantly applied from the battery 3, and to adjust this voltage to a drive voltage suitable for control before applying it to the drive control unit 17 of the motor 4. As a result, the drive voltage is applied to the torque control unit 20, specifically the microcomputer 24, which constitutes the drive control unit 17 together with the current supply unit 19 that supplies drive current to the motor 4. In addition, the motor drive power supply unit 15 is connected to an operation switch 14 having a switching function unit 14c that can be switched on or off, and when pressed, this operation switch 14 switches from off to on, grounding the gate terminal side of the MOSFET. As a result, a voltage drop occurs between the source and gate terminals of the MOSFET, causing the source and drain terminals of the MOSFET to conduct, switching the MOSFET to the ON state, and a predetermined drive voltage is applied from the battery 3 to the current supply unit 19. Consequently, a MOSFET switching signal is sent to the microcomputer 24, and torque control is initiated, that is, tightening torque control is performed based on the detected value detected by the current detection unit 23. Furthermore, the aforementioned operating switch 14 is configured such that its switching function unit 4c remains ON while it is pressed, and tightening torque control continues while the medical professional is pressing the operating switch 14.

[0007] In the case of this type of medical power tool, similar to the medical power drill having a drill 41 as the tip tool mentioned above, if a short circuit occurs in the switching function section 14c of the operating switch 14, the motor 4 starts and the drill rotates even before the medical professional presses the operating switch 14, which can endanger the patient just before they receive medical treatment.

[0008] Furthermore, a short circuit may occur in the switching function section 14c of the operating switch 14 while the medical professional is pressing the operating switch 14. In this case, even if the medical professional releases their fingers from the operating switch 14, the motor drive power supply unit 15 will remain ON. Regardless of this ON state, the motor 4 will rotate until the tightening torque applied to the screw tightening bit 12 reaches a predetermined value, as determined by the microcomputer 24, and the predetermined tightening operation can be completed. However, if the aforementioned ON state continues, as soon as the predetermined tightening operation is completed, the microcomputer 24 will determine whether the aforementioned drive voltage has been applied and prepare to start the next tightening operation. As a result, the motor 4 will start again, causing injury to the patient after the medical procedure has been completed. [Means for solving the problem]

[0009] The medical power tool of the present invention was invented to solve the above problems, and is characterized in that the motor that rotates the tip tool is started by an operating switch having two switching functions, one of which switches a first threshold voltage related to the operation of the motor drive control unit, and the other switching function switches a second threshold voltage related to the operation of the motor drive control unit, and when the two threshold voltages are switched, the drive control unit is activated and the motor is started.

[0010] With the above configuration, even if a short-circuit malfunction occurs in the switching function section of one of the operating switches due to an internal short circuit, the motor will not start unless a medical professional presses the operating switch to turn on both switching function sections. This provides a highly safe medical power tool that does not endanger patients undergoing medical procedures.

[0011] Another medical power tool of the present invention is characterized in that a battery and a motor are arranged in a cylindrical tool body, a tip tool that rotates with the motor is rotatably held by a bearing holder located at the tip of the tool body, and a motor drive power supply unit and a control system power supply unit are connected to the battery, and a predetermined voltage is applied from the battery to these motor drive power supply unit and control system power supply unit, respectively, the control system power supply unit is connected to the motor drive control unit to apply a drive voltage, and the motor drive power supply unit is connected to an operation switch that switches the application or interruption of voltage from the battery, the operation switch has multiple switching function units, one of the switching function units of the operation switches the application or interruption of voltage from the battery and switches a first threshold voltage related to the operation of the motor drive control unit, and the other switching function units switch the application or interruption of a second threshold voltage related to the operation of the drive control unit.

[0012] With the above configuration, the motor's drive control unit will not operate unless the medical professional turns on both switching functions. Even if a short circuit occurs in either of the switching functions of the operating switch, the drive control unit will not operate, and the medical power tool will not be activated. This prevents the motor from starting and the tip tool from rotating before the medical professional presses the operating switch, completely eliminating any risk to patients immediately before receiving medical treatment. Furthermore, with the above configuration, the motor's drive control unit will not operate unless the medical professional confirms that either switching function is off and releases their fingers from the operating switch after successfully completing a predetermined task. This prevents the next task from being performed even if a short circuit occurs in the switching function of the operating switch and one of the switching functions is turned on while the medical professional is using the medical power tool on a patient's treatment site. As a result, even after successfully completing a predetermined task, the motor will not start until the medical professional releases their fingers from the operating switch, completely eliminating any risk of harm to patients during medical treatment. Furthermore, even if a short circuit occurs in one of the aforementioned switching function units, the short circuit can be detected without pressing the operating switch by reattaching the battery to the tool body before starting work. This prevents the medical power tool from being operated at that point, thus providing a highly safe medical power tool.

[0013] The motor drive control unit according to the present invention is preferably configured to operate after waiting for the application of a first threshold voltage and the interruption of a second threshold voltage, which are switched by the two switching functions of the operating switch. As a result, the motor will not start unless a medical professional presses the operating switch, thus providing a highly safe medical power tool in which the tip tool, such as a drill or screw-driving bit, will not rotate against the intention of the medical professional.

[0014] Furthermore, the operating switch according to the present invention is preferably composed of a single double-action switch so that a medical professional can safely start the motor by simply pressing the operating switch once to turn on the two switching functions.

[0015] Furthermore, it is preferable that the operating switch according to the present invention is composed of two switches, each having a switching function. In this case, a medical professional can detect a short-circuit abnormality in the switching function by alternately pressing these two switches, based on whether or not the motor rotates.

[0016] Furthermore, it is desirable that the operating switches according to the present invention be arranged in parallel, with one serving as the forward rotation operating switch and the other as the reverse rotation operating switch, and that the forward rotation threshold voltage is applied to the motor's drive control unit when the forward rotation operating switch is pressed, and the reverse rotation threshold voltage is applied when the reverse rotation operating switch is pressed, thereby activating it. This makes it possible to respond to short-circuit abnormalities in the switching function unit in either the forward or reverse rotation of the motor.

[0017] The medical screw tightening tool of the present invention has a battery and a motor arranged in a cylindrical tool body, and a screw tightening bit rotated by the motor is rotatably held in a bearing holder located at the tip of the tool body, and a motor drive power supply unit and a control system power supply unit are connected to the battery, and a predetermined voltage is applied from the battery to these motor drive power supply unit and control system power supply unit respectively, the control system power supply unit is connected to the motor drive control unit to apply a drive voltage, and the motor drive power supply unit is connected to an operation switch that switches the application or interruption of voltage from the battery, the operation switch has multiple switching function units, and one of the switches of the operation switch The switching function unit switches the application and interruption of voltage from the motor drive power supply unit and switches the first threshold voltage related to the operation of the motor drive control unit, while another switching function unit switches the application and interruption of a second threshold voltage related to the operation of the drive control unit. The drive control unit consists of a current supply unit that supplies a predetermined current to the motor and a torque control unit that detects the motor load current and outputs a drive signal to the current supply unit until the motor load current reaches a current threshold corresponding to the set tightening torque. The torque control unit is characterized in that it operates after waiting for the application of the first threshold voltage and the interruption of the second threshold voltage, which are switched by the two switching function units of the operating switch.

[0018] With the above configuration, even if a short circuit occurs in one of the switching functions of the operating switch while a medical professional is pressing the operating switch, the motor will stop once the tightening torque applied to the screw tightening bit reaches a predetermined value, allowing the predetermined tightening work to be completed. Furthermore, once the medical professional releases their fingers from the operating switch after the medical procedure is finished, the switching functions that did not experience a short circuit will turn off. Therefore, even if a short circuit occurs in one of the switching functions, the motor will not restart unless the medical professional presses the operating switch again. This completely eliminates the risk of injuring the patient after the medical procedure is completed.

[0019] The electric drill of the present invention is configured such that a battery and a motor are arranged in a cylindrical tool body, the drill rotated by the motor is rotatably held by a bearing holder located at the tip of the tool body, and a motor drive power supply unit and a control system power supply unit are connected to the battery, and a predetermined voltage is applied from the battery to the motor drive power supply unit and the control system power supply unit, the control system power supply unit is connected to the motor drive control unit to apply a drive voltage, and the motor drive power supply unit is connected to an operation switch that switches the application or interruption of voltage from the battery, the operation switch has multiple switching function units, one of the switching function units of the operation switches the application or interruption of voltage from the battery and switches a first threshold voltage related to the operation of the motor drive control unit, and the other switching function units switch the application or interruption of a second threshold voltage related to the operation of the motor drive control unit, and the motor drive control unit operates after waiting for the application of the first threshold voltage or the interruption of the second threshold voltage switched by each of the two switching function units of the operation switch.

[0020] With the above configuration, since the two switching functions do not turn on when a medical professional does not press the operating switch, the motor will not start even if a short circuit occurs in one of the switching functions of the operating switch. As a result, the drill will not rotate, so there is absolutely no risk to the patient during medical procedures, and a highly safe electric drill can be provided. [Effects of the Invention]

[0021] As described above, the present invention provides multiple switching function units for the motor's operating switch. Therefore, even if a short-circuit malfunction occurs in one of them due to an internal short circuit, the motor will not start unless a medical professional presses the operating switch to turn on another switching function unit. This eliminates any risk to patients undergoing medical procedures, thus providing highly safe medical power tools, screw tightening tools, and electric drills. [Brief explanation of the drawing]

[0022] [Figure 1] A block diagram illustrating the overall configuration of a screw tightening tool, which is an example of the power tool according to Embodiment 1 of the present invention. [Figure 2] A partially cutaway cross-sectional view illustrating the tool main body of the medical screw tightening tool according to Embodiment 1 of the present invention. [Figure 3] A block diagram illustrating the main part configuration of the medical screw tightening tool according to Embodiment 1 of the present invention. [Figure 4] A flowchart illustrating tightening torque control of the medical screw tightening tool according to Embodiment 1 of the present invention. [Figure 5] A block diagram illustrating the overall configuration of the medical screw tightening tool according to Embodiment 2 of the present invention. [Figure 6] A flowchart illustrating the main part operation of the medical screw tightening tool according to Embodiment 2 of the present invention. [Figure 7] A block diagram illustrating the overall configuration of the medical power drill according to Embodiment 3 of the present invention. [Figure 8] A block diagram illustrating the overall configuration of a conventional medical power tool. [Mode for Carrying Out the Invention]

[0023] The medical power tool according to the embodiment of the present invention is configured such that starting of a motor for rotating a tip tool is performed by an operation switch having two switching function units, one switching function unit switches a first threshold voltage related to the operation of a drive control unit of the motor, the other switching function unit switches a second threshold voltage related to the operation of the drive control unit of the motor, and when the two threshold voltages are switched, the drive control unit is operated to start the motor.

[0024] With the above configuration, even if a short-circuit malfunction occurs in the switching function section of one of the operating switches due to an internal short circuit, the motor will not start unless a medical professional presses the operating switch to turn on both switching function sections. This provides a highly safe medical power tool that does not endanger patients undergoing medical procedures.

[0025] Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. [Examples]

[0026] As an example of a medical power tool according to Embodiment 1 of the present invention, a medical screw tightening tool used in surgery and treatment in cosmetic surgery, plastic surgery, etc. will be described with reference to the drawings. As shown in Figures 1 and 2, this medical screw tightening tool 1 has a slender cylindrical tool body 2, and a battery 3 and a motor 4 are housed inside the cylinder of the tool body 2 via cylindrical battery cases 5 and motor cases 6, respectively. These battery cases 5 and motor cases 6 are pressed by end caps 8 via retaining members 7 and are configured not to move from their positions. Furthermore, the notches 2a side of the battery cases 5 and motor cases 6 described later are cut out so that a control board 10 described later can be attached and the battery 3 and motor 4 are exposed. In addition, the battery case 5 is provided with contact parts (not shown) that connect to both poles of the battery when the battery 3 is installed, and is configured to allow easy removal of the battery 3.

[0027] The central part of the tool body 2 is a gripping portion, and a notch 2a is provided in this gripping portion so that the aforementioned battery case 5 and motor case 6 are exposed. A partially cylindrical switch mounting cover 9 is attached to this notch 2a, forming a cylindrical shape for the tool body 2. This switch mounting cover 9 covers the battery 3 and motor 4 and is configured to fix the control board 10 to the tool body 2 by sandwiching the edge of the control board 10 between itself and the tool body 2. In addition, the switch mounting cover 9 has one switch hole 9a drilled through it at the location where the fingers of a medical professional are positioned when gripping the gripping portion, and the operation switch 14 described later is configured to fit into this switch hole 9a.

[0028] The motor 4 has a drive shaft 4a with a hexagonal prism-shaped tip, and the drive shaft 4a is fixed to the end face of the motor case 6 so as to protrude from the motor case 6. The drive shaft 4a is connected to a screw tightening bit 12, which is a medical tip tool, via a connecting shaft 11, which consists of a fitting portion 11a having a hexagonal hole into which the tip can be inserted, and a bit holding shaft 11b. The screw tightening bit 12 is configured to be rotatable via a bearing 13a by a bearing holder 13 attached to the tip of the tool body 2 together with the bit holding shaft 11b, and the screw tightening bit 12 is configured to be connectable to the connecting shaft 11 when the bearing holder 13 is attached to the tool body 2.

[0029] An operating switch 14 is mounted on the control board 10 at a position corresponding to the aforementioned switch hole 9a, and the operating switch 14 is configured to protrude from the circumferential surface of the tool body 2. As shown in Figure 3, the operating switch 14 is a momentarily operating push-type double-action switch and has a first switching function unit 14a and a second switching function unit 14b, which are contacts that switch between on and off. Note that the operating switch 14 may also be provided with two single-action switches (not shown), in which case a medical professional can detect a short-circuit abnormality in the switching function unit by alternately pressing these switches to determine whether or not the motor 4 rotates. The on / off switching of the switching function unit of the operating switch 14 does not have to be push-type, and may be of other types, such as a switching function unit used in a touch switch. Furthermore, the number of switching function units in the operating switch 14 is not limited to two, but may be three or more.

[0030] Furthermore, as shown in Figures 1 and 3, the control board 10 is equipped with a motor drive power supply unit 15 and a control system power supply unit 16 connected to the battery 3. The motor drive power supply unit 15 is composed of a MOSFET (the same as described in the summary of the invention section), and this MOSFET is configured such that when there is no voltage drop between its source terminal and gate terminal, that is, when the voltage at the gate terminal does not reach the threshold for switching the MOSFET on or off, the source terminal and drain terminal do not conduct and the MOSFET turns off, thereby interrupting the voltage applied from the battery 3 and preventing the battery 3 from being consumed. In addition, this MOSFET is configured such that when a voltage drop occurs between the source terminal and gate terminal and the voltage at the gate terminal becomes lower than the voltage at the source terminal and reaches the aforementioned threshold, the source terminal and drain terminal conduct and the MOSFET switches on. By switching the MOSFET on, a predetermined drive voltage is applied to the current supply unit 19 described later, and the current supply unit 19 is kept in a standby state.

[0031] As shown in Figure 3, the gate terminal of the MOSFET is connected to the first switching function unit 14a of the aforementioned operation switch 14 and the first threshold voltage supply unit 21, which has one end grounded. When the first switching function unit 14a is ON, the gate terminal is grounded. This creates the aforementioned voltage drop between the source terminal and the gate terminal, switching the MOSFET ON, and simultaneously applying the first threshold voltage from the first threshold voltage supply unit 21 to the microcomputer (hereinafter referred to as "microcontroller") 24. When the first switching function unit 14a is OFF, the gate terminal of the MOSFET is disconnected and not grounded. This turns off the MOSFET, interrupting the drive voltage applied from the motor drive power supply unit 15 to the current supply unit 19, and also interrupting the supply of the first threshold voltage to the microcontroller 24.

[0032] As shown in Figure 3, a second switching function unit 14b is connected between the first switching function unit 14a of the MOSFET and the microcontroller 24. The second switching function unit 14b is configured to interrupt the second threshold voltage applied to the microcontroller 24 from the second threshold voltage supply unit 22 (described later) when both the first switching function unit 14a and the second switching function unit 14b are ON. Conversely, when the first switching function unit 14a is ON and the second switching function unit 14b is OFF, the second threshold voltage is applied to the microcontroller 24.

[0033] The control system power supply unit 16 is configured to have a predetermined voltage constantly supplied from the battery 3, and to adjust this voltage to a drive voltage suitable for control before applying it to the drive control unit 17 of the motor 4.

[0034] The drive control unit 17 comprises a current supply unit 19 that supplies drive current to the motor 4, and a torque control unit 20 that outputs a drive signal to the current supply unit 19 until the load current of the motor 4 reaches a current threshold corresponding to the set tightening torque. The current supply unit 19 is configured to remain in a standby state when a drive voltage is applied from the motor drive power supply unit 15, wait for a drive signal to be input for the motor 4, and supply a current value to the motor corresponding to the drive signal. The current supply unit 19 is also configured to detect the load current flowing through the motor 4 and output it to the current detection unit 23 described below.

[0035] The torque control unit 20 comprises a microcontroller 24 that outputs a drive signal to the current supply unit 19 until the load current of the motor 4 reaches a current threshold corresponding to the set tightening torque, a current detection unit 23 that detects the load current of the motor 4 input from the current supply unit 19 and sends it to the microcontroller 24, a first threshold voltage supply unit 21 that applies a first threshold voltage to the microcontroller 24, and a second threshold voltage supply unit 22 that applies a second threshold voltage to the microcontroller 24. Furthermore, the first threshold voltage supply unit 21 is configured to interrupt the application of the first threshold voltage to the microcontroller 24 when the first switching function unit 14a of the aforementioned operation switch 14 is off and the MOSFET is off. The first threshold voltage supply unit 21 is configured to apply the first threshold voltage to the microcontroller 24 when the first switching function unit 14a is turned on and one end of it is grounded, causing the MOSFET to switch on. Furthermore, the second threshold voltage supply unit 22 is connected to the second switching function unit 14b of the operation switch 14 on its output side. The second threshold voltage is applied to the microcontroller 24 when the second switching function unit 14b is off, and when the second switching function unit 14b is on, the second switching function unit 14b is grounded, blocking the second threshold voltage applied to the microcontroller 24.

[0036] The microcontroller 24 is configured to drive the motor 4 and control the tightening torque according to the operation program shown in Figure 4 when a drive voltage is applied from the control system power supply unit 16. This operation program executes the following steps P1 to P14. Note that the microcontroller 24 is kept in standby mode when neither the first switching function unit 14a nor the second switching function unit 14b of the aforementioned operation switch 14 is short-circuited. P1) Determine whether or not a first threshold voltage is applied from the first threshold voltage supply unit 21, and if so, jump to P15. In this case, a short-circuit abnormality due to an internal short circuit in the first switching function unit 14a of the operation switch 14 may be displayed. P2) Determine whether or not a second threshold voltage is applied from the second threshold voltage supply unit 22. If not, jump to P15. In this case, a short-circuit abnormality of the second switching function unit 14b of the operation switch 14 may be displayed. P3) Determine whether the first threshold voltage from the first threshold voltage supply unit 21 is not 0 and the second threshold voltage from the second threshold voltage supply unit 22 is 0, and wait until the conditions that the first threshold voltage is not 0 and the second threshold voltage is 0 are met. P4) Set a timer to measure the cycle time set to exceed the normal tightening time. P5) Read the detected value input from the current detection unit 23. P6) Determine whether the detected value exceeds the current threshold corresponding to the set tightening torque. If it exceeds the current threshold, jump to P12. P7) The drive signal is calculated from the difference between the detected value and the current threshold corresponding to the set tightening torque. P8) A drive signal corresponding to the difference is output to the current supply unit 19. P9) When either the condition that the first threshold voltage from the first threshold voltage supply unit 21 is 0 or the condition that the second threshold voltage from the second threshold voltage supply unit 22 is not 0 is met, the program jumps to P12. P10) Determine whether the cycle time has elapsed, and if not, return to P5. P11) Performs error processing such as displaying a tightening error, resetting the cycle time measurement timer, and stopping the drive signal to the current supply unit 19, then jumps to P15. P12) Reset the timer that measures the cycle time. P13) Output a drive stop signal to the current supply unit 19. P14) The system waits for either the condition that the first threshold voltage from the first threshold voltage supply unit 21 is 0, or the condition that the second threshold voltage from the second threshold voltage supply unit 22 is not 0 to be met. When this condition is met, the system returns to P3. P15) End.

[0037] In the above-described medical screw tightening tool, when the battery 3 is attached to the tool body 2, a drive voltage is applied from the control system power supply unit 16 connected to the battery 3 to the microcontroller 24 of the torque control unit 20. The microcontroller 24 then determines whether a first threshold voltage and a second threshold voltage are applied from the first threshold voltage supply unit 21 and the second threshold voltage supply unit, respectively. If the first threshold voltage is applied, it is determined that the first threshold voltage is being applied while the operation switch 14 is not pressed, resulting in a short-circuit abnormality due to an internal short circuit in the first switching function unit 14a, and the microcontroller 24 terminates its operation. If the first threshold voltage is not applied, it is determined whether the second threshold voltage is not being applied, i.e., whether it is being shut off. If the second threshold voltage is shut off, it is determined that the second threshold voltage is being shut off while the operation switch 14 is not pressed, resulting in a short-circuit abnormality due to an internal short circuit in the second switching function unit 14b, and the microcontroller 24 terminates its operation.

[0038] When, based on the aforementioned determination, no short-circuit abnormality is found in either the switching function unit 14a or 14b of the operation switch 14, the first switching function unit 14a of the operation switch 14 is turned on and grounded, applying the first threshold voltage to the microcontroller 24. At the same time, the second switching function unit 14b of the operation switch 14 is turned on, with one end grounded, and a standby state is maintained where the microcontroller 24 awaits to be shut off, i.e., to have the second threshold voltage applied to it become 0.

[0039] When a medical screw (not shown; hereinafter referred to as "screw") is fastened to a patient's medical site using the aforementioned standby medical screw fastening tool, the medical professional grasps the gripping part of the tool body 2 and fits the tip of the screw fastening bit 12 onto the medical screw that has been slightly screwed into the medical site. Then, when the medical professional presses the double-action type operating switch 14 protruding from the switch mounting cover 9 with their fingers, the first switching function unit 14a is turned on in the first stage of action, and one end of the first switching function unit 14a is grounded. As a result, a voltage drop occurs between the source terminal and gate terminal of the MOSFET constituting the motor drive power supply unit 15, and when it reaches the threshold for switching the MOSFET on or off, the source terminal and drain terminal conduct, the MOSFET turns on, and a predetermined drive voltage is supplied from the motor drive power supply unit 15 to the current supply unit 19. At the same time that the MOSFET turns on, the first threshold voltage is applied to the microcontroller 24 from the first threshold voltage supply unit 21.

[0040] When the operation switch 14 is pressed, the first switching function unit 14a is turned on in the first stage of the action, and the second switching function unit 14b is turned on in the second stage of the action, and the output side of the second threshold voltage supply unit 22 connected to the second switching function unit 14b is grounded, the second threshold voltage applied to the microcontroller 24 becomes 0, i.e., is shut off. This confirms that the operation switch 14 has been pressed, and a timer is set to measure a cycle time that is set to be sufficiently longer than the tightening time.

[0041] Subsequently, the current detection unit 23 sends a value obtained by attenuating the load current of the motor 4 detected by the current supply unit 19 to the microcontroller 24 as a detected value. This detected value is read and compared with a current threshold corresponding to the set tightening torque. If the detected value does not exceed the current threshold in the comparison, a drive signal is calculated from the difference between the detected value and the current threshold, and this drive signal is output to the current supply unit 19. The current supply unit 19 sends a current corresponding to this drive signal to the motor 4, causing the motor 4 to rotate. This rotation of the motor 4 rotates the screw tightening bit 12, allowing the screw located at its tip to be tightened into the treatment area.

[0042] When the screw is tightened by the screw tightening bit 12 and seated in contact with the medical object to be fastened, the load current of the motor 4 increases, which is detected by the current supply unit 19. As described above, this load current is attenuated by the current detection unit 23 and sent to the microcontroller 24 as a detected value.

[0043] When the aforementioned drive signal is sent to the current supply unit 19, it is then determined whether the first threshold voltage is 0 or the second threshold voltage is not 0, that is, whether the medical professional's fingers have left the operation switch 14. Based on this determination, if the medical professional's fingers have left the operation switch 14, the timer is reset and a drive stop signal is output to the current supply unit 19, stopping the supply of current to the motor 4 and interrupting the tightening work. After confirming again that the medical professional's fingers have left the operation switch 14, the unit waits for the next press of the operation switch 14. If the medical professional's fingers have not left the operation switch 14 at the time of the aforementioned determination, it is determined whether the cycle time has elapsed. If the cycle time has not elapsed, the control to send the aforementioned drive signal to the current detection unit 23 is repeated until the detected value exceeds the current threshold. Furthermore, if the cycle time has elapsed, the system determines that there is a tightening failure or a short-circuit abnormality in either the first switching function unit 14a or the second switching function unit 14b of the operation switch 14, and some kind of abnormal processing is performed, such as outputting a drive stop signal to the current supply unit 19 or resetting the timer. As a result, the current supply unit 19 stops supplying current to the motor 4, and the tightening operation can be terminated abnormally.

[0044] When the current threshold exceedance judgment described above determines that the detected value exceeds the current threshold, it is determined that the tightening torque has reached the set tightening torque, and a drive stop signal is output to the current supply unit 19. As a result, the current supply unit 19 stops supplying current to the motor 4 and the timer is reset, allowing the tightening operation to be completed normally and the system to wait for the next press of the operation switch 14.

[0045] During the aforementioned tightening process, even if a short circuit occurs in any of the switching function units of the operation switch 14 before the tightening work begins, the drive voltage is reapplied to the microcontroller 24 by replacing the battery 3. As a result, the short circuit abnormality in each switching function unit is detected each time, and the tightening work can be terminated immediately.

[0046] Furthermore, even if a short circuit occurs in either the switching function section 14a or 14b of the operating switch 14 while a medical professional is using the medical screw tightening tool 1 on a patient's treatment site during the aforementioned tightening process, the predetermined tightening torque can still be controlled. Moreover, the motor 4 will not start even if the medical professional continues to press the operating switch 14 after normal tightening is complete, let alone during abnormal tightening, thus providing a highly safe medical tightening tool. [Examples]

[0047] Another example of a medical screw tightening tool according to Embodiment 1 of the present invention will be described with reference to the drawings. This medical screw tightening tool has the same configuration as the one described in Embodiment 1 above, except for a few parts, so only the differing configurations will be described below. The same part numbers will be used for parts that are the same as those of screw tightening tool 1 described in Embodiment 1.

[0048] The switch mounting cover 9 attached to the tool body 2 of the medical screw tightening tool 1 has two switch holes (not shown) drilled in it, and these switch holes are positioned so that two fingers of the medical professional can be positioned when gripping the tool body 2. In addition, a forward rotation operation switch 30 and a reverse rotation operation switch 31 are attached to the control board 10 (see Figure 5), and these operation switches 30 and 31 are configured to fit into the switch holes with a portion of each exposed. Furthermore, a forward / reverse motor is used for the motor 4, and the forward / reverse current supply unit 32 (described later) is configured to supply a current in the opposite direction to the current supplied to the motor 4 during forward rotation during reverse rotation, thereby reversing the motor 4.

[0049] As shown in Figure 5, the forward rotation operation switch 30 and the reverse rotation operation switch 31 are connected in parallel to the gate terminals of the MOSFETs constituting the motor drive power supply unit 15. These operation switches 30 and 31 have the same structure as the operation switch 14 of Embodiment 1 and each has a first switching function unit 30a, 31a and a second switching function unit 30b, 31b. One end of the first switching function unit 30a, 31a of the forward rotation operation switch 30 and the reverse rotation operation switch 31 is connected to the gate terminal of the MOSFET constituting the motor drive power supply unit 15, similar to the first switching function unit 14a of the operation switch in Embodiment 1, and the other end is grounded. When these are turned on, the gate terminals of the MOSFETs are grounded. Furthermore, the first switching function units 30a and 31a of the forward rotation operation switch 30 and the reverse rotation operation switch 31 are connected to the forward rotation input port and the reverse rotation input port of the microcontroller 24, i.e., the second threshold voltage supply unit 33 for forward rotation and the second threshold voltage supply unit 34 for reverse rotation, via second switching function units 30a and 31b, each with one end grounded. Considering that the two operation switches 30 and 31 may be pressed simultaneously, the signal from the other operation switch 31 or 30 may be blocked when one of the operation switches 30 or 31 is pressed.

[0050] The forward / reverse current supply unit 32 has the same structure as the current supply unit 19 in Embodiment 1, and is configured to process the load current of the motor 4 as an absolute value and output it to the current detection unit 23. Furthermore, when the forward / reverse current supply unit 32 receives a drive signal at the input port for forward rotation current, it is configured to supply a current corresponding to the drive signal from one terminal of the motor 4 and to detect the load current of the motor 4 from the other terminal. In addition, when the forward / reverse current supply unit 32 receives a drive signal at the input port for reverse rotation current, it is configured to supply a current from the terminal opposite to that used for a drive signal during forward rotation and to detect the load current of the motor 4 from the terminal opposite to that used for a drive signal during forward rotation.

[0051] The torque control unit 20 consists of a current detection unit 23 configured to output a detected value to the microcontroller 24 in the same way as in Embodiment 1 when the load current of the motor 4 is supplied from the forward / reverse current supply unit 32, a microcontroller 24, a first threshold voltage supply unit 21 having the same structure as the first threshold voltage supply unit 21 of Embodiment 1, a second forward threshold voltage supply unit 33 having the same structure as the second threshold voltage supply unit 22 of Embodiment 1 and applying the second threshold voltage to the forward input port, and a second reverse threshold voltage supply unit 34 having the same structure as the second threshold voltage supply unit 22 of Embodiment 1 and supplying the second reverse threshold voltage to the reverse input port.

[0052] The microcontroller 24 is configured to drive the motor 4 according to the operation program shown in Figure 6 and control the tightening torque when a drive voltage is applied from the control system power supply unit 16. In this operation program, the only difference is that the second threshold voltage supply unit 22 of Embodiment 1 is divided into a second threshold voltage supply unit 33 for forward rotation and a second threshold voltage supply unit 34 for reverse rotation, and the number of steps related to short-circuit abnormality detection of the second threshold voltage increases. Therefore, the explanation of short-circuit abnormality detection for the switching functions of the forward rotation operation switch 30 and the reverse rotation operation switch 31 is omitted. As a result, this operation program explains the steps from waiting for either the forward rotation operation switch 30 or the reverse rotation operation switch 31 to be pressed, up to the tightening completion step which includes the abnormality processing step.

[0053] The aforementioned operating program executes the following steps S1 to S22. S1) It is determined whether the conditions are met, namely whether the first threshold voltage from the first voltage gate supply unit 21 is not 0 and the second forward rotation threshold voltage from the forward rotation second threshold voltage supply unit 33 is 0, that is, whether the forward rotation operation switch 30 is pressed, and if the forward rotation operation switch 30 is pressed, the program jumps to S12. S2) It is determined whether the conditions are met such that the first threshold voltage from the first threshold voltage supply unit 21 is not 0 and the second reverse threshold voltage from the second reverse threshold voltage supply unit 33 is 0, that is, whether the reverse operation switch 31 is pressed or not, and if the reverse operation switch 31 is not pressed, the process returns to S1. S3) Set a timer to measure the reverse cycle time, which is set to exceed the reverse tightening time. S4) Read the detected value input from the current detection unit 23. S5) Determine whether the detected value exceeds the reverse current threshold corresponding to the reverse direction tightening torque. If it exceeds the reverse current threshold, jump to S11. S6) The drive signal is calculated from the difference between the detected value and the reverse current threshold corresponding to the tightening torque in the reverse direction. S7) A drive signal corresponding to the difference is output to the reverse current input port of the forward / reverse current supply unit 32. S8) When either the condition that the first threshold voltage from the first threshold voltage supply unit 21 is 0 or the condition that the second threshold voltage for reverse operation from the second threshold voltage supply unit 34 for reverse operation is not 0 is met, that is, it is determined whether or not either the forward operation switch 30 or the reverse operation switch 31 is pressed, and when it is determined that neither of these switches 30 or 31 is pressed, the process jumps to S11. S9) Determine whether the reverse cycle time has elapsed, and if it has not, return to S4. S10) Perform some kind of abnormality processing, such as indicating a tightening failure, resetting the timer that measures the reverse cycle time or forward cycle time, or outputting a drive stop signal to the forward / reverse current supply unit 32, and then jump to S22. S11) Reset the timer that measures the reverse cycle time and jump to S20. S12) Set a timer to measure the forward rotation cycle time, which is set to exceed the forward rotation tightening work time. S13) Read the detected value input from the current detection unit 23. S14) Determine whether the detected value exceeds the forward rotation current threshold corresponding to the forward rotation tightening torque setting. If it exceeds the forward rotation current threshold, jump to S19. S15) The drive signal is calculated from the difference between the detected value and the forward rotation current threshold corresponding to the forward rotation tightening torque. S16) A drive signal corresponding to the difference is output to the forward rotation current input port of the forward / reverse current supply unit 32. S17) When either the condition that the first threshold voltage from the first threshold voltage supply unit 21 is 0 or the condition that the second forward threshold voltage from the second forward threshold voltage supply unit 33 is not 0 is met, the program jumps to S19. S18) Determine whether the forward rotation cycle time has elapsed. If it has not elapsed, return to S13; if the forward rotation cycle time has elapsed, return to S10. S19) Reset the forward rotation cycle time measurement timer. S20) Output a drive stop signal to the forward / reverse current supply unit 32. S21) The system waits for any of the following conditions to be met: the first threshold voltage from the first threshold voltage supply unit 21 is 0, the second threshold voltage from the second threshold voltage supply unit 33 for forward rotation is not 0, or the second threshold voltage from the second threshold voltage supply unit 34 for reverse rotation is not 0. In other words, it is determined whether or not either the forward rotation operation switch 30 or the reverse rotation operation switch 31 is pressed. When this condition is met, the system returns to S1. S22) End.

[0054] In the above-described medical screw tightening tool, when a medical professional presses the forward rotation operation switch 30, the motor 4 is operated in the same manner as in Embodiment 1, and the screw can be tightened by the screw tightening bit 12. When the medical professional presses the reverse rotation operation switch 31, in the same manner as in Embodiment 1, the first switching function unit 31a is turned on in the first stage of action and one end is grounded, causing a voltage drop between the source terminal and gate terminal of the MOSFET constituting the motor drive power supply unit 15, and the MOSFET turns on. As a result, a predetermined drive voltage is supplied from the motor drive power supply unit 15 to the current supply unit 19, and the first threshold voltage is applied from the first threshold voltage supply unit 21 to the microcontroller 24 of the torque control unit 20. When the medical professional further presses the reverse rotation operation switch 31, the second switching function unit 31b is turned on in the second stage of action and one end is grounded. As a result, the output side of the reverse rotation second threshold voltage supply unit 34 is grounded, and the reverse rotation second threshold voltage applied to the microcontroller 24 is cut off. By interrupting the second threshold voltage for reverse rotation, the detected value of the current detection unit 23 is read, and torque control for reverse tightening is started in the same way as for forward tightening, allowing tightening work to be performed in the reverse direction.

[0055] Even if a short-circuit malfunction occurs in any of the switching function units 30a, 30b, 31a, or 31b of the forward operation switch 30 or the reverse operation switch 31 during the aforementioned forward and reverse tightening, the drive voltage is reapplied to the microcontroller 24 by replacing the battery 3 before starting work. As a result, the short-circuit malfunction in each switching function unit is detected each time, and the tightening work can be immediately terminated.

[0056] Furthermore, when tightening in both forward and reverse directions as described above, even if a short circuit occurs in either the forward operation switch 30 or the reverse operation switch 31, or in either of their switching functions, while a medical professional is using the screw tightening tool 1 on a patient's treatment site, the predetermined tightening torque control can continue. Moreover, even if the medical professional continues to press the operation switch 14 after normal tightening is completed, the motor 4 will not start, providing a highly safe medical tightening tool.

[0057] Although the reversal of the motor 4 described above is explained in the context of its use in tightening left-hand screws for medical applications, the torque control unit 20 may be removed and a known rotational speed control unit (description omitted) added to allow it to be used for loosening screws. [Examples]

[0058] As another example of a medical power tool according to an embodiment of the present invention, a medical power drill will be described with reference to the drawings. This medical power drill has the same configuration as the one described in Embodiment 1 above, except for the motor drive control unit, so only the differing configurations will be described below. The same part numbers will be used for parts that are the same as those for the screw tightening tool described in Embodiment 1.

[0059] As shown in Figure 7, the medical electric drill 40 has a structure in which the screw tightening bit 12 of the medical screw tightening tool 1 of Embodiment 1 is replaced with a drill 41. Although not shown in the figure, the microcontroller 24 constituting the drive control unit 17 of the motor 4 is configured to output a drive signal to the current supply unit 19 that maintains the speed of the motor 4 at a constant level, provided that the first threshold voltage applied from the first threshold voltage supply unit 21 and the second threshold voltage from the second threshold voltage supply unit 22 are cut off. Note that the microcontroller 24 does not perform torque control as in Embodiment 1, so the current detection unit 23 of Embodiment 1 has been removed.

[0060] In the medical electric drill 40, similar to Embodiment 1, the application and interruption of two threshold voltages generated by switching the first switching function unit 14a and the second switching function unit 14b of the operating switch 14 on and off confirms the pressing of the operating switch 14, activates the drive control unit 17 of the motor 4, and rotates the motor 4 at a predetermined speed by receiving the rotational speed from the motor 4. As a result, the motor 4 will not start when the medical professional does not press the operating switch 14, and therefore the drill 41 will not rotate, thus completely eliminating any risk to patients during medical procedures and providing a highly safe medical electric drill 40. Furthermore, in the medical drill 40, similar to the screw tightening tool 1 of Embodiment 1, a short-circuit abnormality in the switching function units 14a and 14b can be detected before work begins, so there is absolutely no risk of harming the patient. Furthermore, even if a short circuit occurs in the switching function sections 14a and 14b of the operating switch 14 while a medical professional is using the electric drill 40 on a patient's treatment site, the rotation of the drill 41 will stop once the cycle time has elapsed, thus preventing any harm to the patient. The drive control unit 17 of the motor 4 is configured to activate the current supply unit 19 by confirming the application of a first threshold voltage and the interruption of a second threshold voltage using the microcontroller 24, but the current supply unit 19 may also be activated by a switching circuit (not shown) using a general-purpose transistor instead of the microcontroller 24.

[0061] As described above, the medical power tool of the present invention is configured such that the motor 4 that rotates the tip tool is started by an operating switch 14 having two switching functions. One switching function 14a switches the first threshold voltage related to the operation of the drive control unit 17 of the motor 4, and the other switching function 14b switches the second threshold voltage related to the operation of the drive control unit 17 of the motor 4. When the two threshold voltages are switched, the drive control unit 17 is activated and the motor 4 is started.

[0062] With the above configuration, even if a short-circuit abnormality occurs due to an internal short circuit in either of the switching function units 14a or 14b of the operation switch 14, the motor 4 will not start unless a medical professional presses the operation switch 14 to turn on both switching function units 14a and 14b. This provides a highly safe medical power tool that does not endanger patients undergoing medical procedures.

[0063] Another medical power tool of the present invention has a battery 3 and a motor 4 arranged in a cylindrical tool body 2, and a tip tool that rotates by the rotation of the motor 4 is rotatably held by a bearing holder 13 located at the tip of the tool body 2, and a motor drive power supply unit 15 and a control system power supply unit 16 are connected to the battery 3, and a predetermined voltage is applied from the battery 3 to the motor drive power supply unit 15 and the control system power supply unit 16 respectively, and the control system power supply unit 16 is connected to apply a drive voltage to the drive control unit 17 of the motor 4, and the motor drive power The power source 15 is a medical power tool connected to an operating switch 14 that switches the application or interruption of voltage from the battery 3. The operating switch 14 has multiple switching function units 14a and 14b, and one of the switching function units 14a switches the application and interruption of voltage from the battery 3 and switches the first threshold voltage related to the operation of the drive control unit 17 of the motor 4, while the other switching function units 14b switches the application and interruption of the second threshold voltage related to the operation of the drive control unit 17.

[0064] With the above configuration, the drive control unit 17 of the motor 4 can be prevented from operating unless the medical professional turns on both switching functions 14a and 14b. Even if a short-circuit error occurs in either of the switching functions 14a or 14b of the operating switch 14, the drive control unit 17 will not operate, and the medical power tool will not be operated. This prevents the motor 4 from starting and the tip tool from rotating before the medical professional presses the operating switch 14, thus completely eliminating any risk to the patient immediately before receiving medical treatment. Furthermore, with the above configuration, the motor drive control unit will not operate unless the medical professional confirms that either switching function is off and releases their fingers from the operating switch when a predetermined task is completed normally. This prevents the next task from being performed even if a short-circuit error occurs in either of the switching functions 14a or 14b of the operating switch 14 and one of the switching functions is turned on while the medical professional is using the medical power tool on the patient's treatment site. As a result, even if a predetermined task is completed correctly, the motor 4 will not start unless the medical professional removes their fingers from the operating switch 14, eliminating any risk of harm to the patient during medical treatment. Furthermore, even if a short circuit occurs in one of the aforementioned switching function units 14a or 14b, the short circuit can be detected without pressing the operating switch 14 by reattaching the battery 3 to the tool body 2 before starting work. This prevents the medical power tool from being operated at that point, providing a highly safe medical power tool.

[0065] The drive control unit 17 of the motor 4 in the medical power tool of the present invention may be configured to be driven after waiting for the application of a first threshold voltage and the interruption of a second threshold voltage, which are switched by the two switching function units 14a and 14b of the operation switch 14, respectively. With this configuration, the motor 4 will not start unless a medical professional presses the operation switch 14, so a highly safe medical power tool can be provided in which the tip tool such as a drill or screw-driving bit will not rotate against the intention of the medical professional.

[0066] The operating switch 14 for the medical power tool of the present invention may be composed of a single double-action switch. In this case, a medical professional can safely start the motor 4 by simply pressing the operating switch 14 once to turn on the two switching function units 14a and 14b.

[0067] The operating switch 14 for the medical power tool of the present invention may be composed of two switch components, each having a switching function. In this case, a medical professional can detect an internal short circuit in the switching function by alternately pressing the switch components, based on whether or not the motor 4 rotates.

[0068] The operating switches 14 for the medical power tool of the present invention may be configured to be arranged in parallel, with one being a forward rotation operating switch 30 and the other a reverse rotation operating switch 31, and the forward rotation threshold voltage applied to the drive control unit 17 of the motor 4 when the forward rotation operating switch 30 is pressed, and the reverse rotation threshold voltage applied when the reverse rotation operating switch 31 is pressed, thereby activating the motor 4. In this case, in either forward rotation or reverse rotation of the motor 4, it is possible to respond to short-circuit abnormalities in the switching function units 30a, 30b, 31a, and 31b.

[0069] The medical screw tightening tool 1 of the present invention has a battery 3 and a motor 4 arranged in a cylindrical tool body 2, and a screw tightening bit 12 rotated by the motor 4 is rotatably held by a bearing holder 13 located at the tip of the tool body 2, and a motor drive power supply unit 15 and a control system power supply unit 16 are connected to the battery 3, and a predetermined voltage is applied from the battery 3 to the motor drive power supply unit 15 and the control system power supply unit 16 respectively, the control system power supply unit 16 is connected to the drive control unit 17 of the motor 4 to apply a drive voltage, and the motor drive power supply unit 15 is connected to an operation switch 14 that switches the application or interruption of voltage from the battery 3, the operation switch 14 has a plurality of switching function units 14a, 14b, and one of the operation switch 14 One switching function unit 14a switches the application and interruption of voltage from the motor drive power supply unit 15 and switches the first threshold voltage related to the operation of the motor drive control unit 17, and the other switching function unit 14b switches the application and interruption of a second threshold voltage related to the operation of the drive control unit 17. The drive control unit 17 consists of a current supply unit 19 that supplies a predetermined current to the motor 4 and a torque control unit 20 that detects the load current of the motor 4 and outputs a drive signal to the current supply unit 19 until the load current of the motor reaches a current threshold corresponding to the set tightening torque. The torque control unit 20 is characterized in that it operates after waiting for the application of the first threshold voltage and the interruption of the second threshold voltage, which are switched by the two switching function units 14a and 14b of the operation switch 14, respectively.

[0070] With the above configuration, even if a short circuit occurs in one of the switching function units 14a or 14b of the operating switch 14 while a medical professional is pressing the operating switch 14, the motor 4 will stop once the tightening torque applied to the screw tightening bit 12 reaches a predetermined value, allowing the predetermined tightening work to be completed. Furthermore, once the medical professional releases their fingers from the operating switch 14 after completing the medical procedure, the switching function units 14a and 14b that did not experience a short circuit will turn off. Therefore, even if a short circuit occurs in one of the switching function units 14a or 14b, the motor 4 will not restart unless the medical professional presses the operating switch 14 again. This completely eliminates the risk of injuring the patient after the medical procedure is completed.

[0071] The medical electric drill 40 of the present invention has a battery 3 and a motor 4 arranged in a cylindrical tool body 2, and a drill 41 that rotates with the motor 4 is rotatably held by a bearing holder 13 located at the tip of the tool body 2. A motor drive power supply unit 15 and a control system power supply unit 16 are connected to the battery 3, and a predetermined voltage is applied from the battery 3 to the motor drive power supply unit 15 and the control system power supply unit 16. The motor drive power supply unit 15 is connected to an operation switch 14 that switches between applying or cutting off the voltage from the battery 3, and the control system power supply unit 16 is connected to apply a drive voltage to the motor drive control unit. The motor 40 is configured such that the operating switch 14 has multiple switching function units 14a and 14b, and one of the switching function units 14a of the operating switch 14 switches the application and interruption of voltage from the battery 3 and switches the first threshold voltage related to the operation of the drive control unit 17 of the motor 4, and the other switching function units switches the application and interruption of a second threshold voltage related to the operation of the drive control unit 17 of the motor 4, and the drive control unit 17 of the motor 4 operates after waiting for the application of the first threshold voltage and the interruption of the second threshold voltage switched by the two switching function units 14a and 14b of the operating switch 14, respectively.

[0072] With the above configuration, when a medical professional does not press the operating switch 14, the two switching function units 14a and 14b do not turn on, so the motor 4 does not start, and therefore the drill 41 does not rotate. As a result, there is absolutely no risk to the patient during medical procedures, and a highly safe medical electric drill 40 can be provided.

[0073] Furthermore, the specific configuration of each part is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the present invention. [Explanation of Symbols]

[0074] 1…Medical screw tightening tool 2…Tool body 3…Battery 4…motor 4a... Drive shaft 12... Screw tightening bit 13…Bearing holder 14…Operation switch 14a...First switching function unit 14b...Second switching function unit 15…Motor drive power supply unit 16…Control system power supply unit 17…Drive Control Unit 19...Current supply section 20... Torque control unit 23...Current detection unit 24... Microcomputer

Claims

1. A medical power tool characterized in that the motor that rotates the tip tool is started by an operating switch having two switching functions, one of which switches a first threshold voltage related to the operation of the motor's drive control unit, and the other switching function switches a second threshold voltage related to the operation of the drive control unit, and when the two threshold voltages are switched, the drive control unit is activated and the motor is started.

2. A medical power tool comprising a battery and a motor arranged in a cylindrical tool body, a tip tool rotated by the motor held rotatably by a bearing holder located at the tip of the tool body, a motor drive power supply unit and a control system power supply unit connected to the battery, a predetermined voltage applied from the battery to the motor drive power supply unit and the control system power supply unit, the control system power supply unit connected to apply a drive voltage to the motor drive control unit, and the motor drive power supply unit connected to an operating switch that switches the application or interruption of voltage from the battery, wherein the operating switch has multiple switching function units, one of which switches the application or interruption of voltage from the battery and switches a first threshold voltage related to the operation of the motor drive control unit, and the other switching function units switch the application or interruption of a second threshold voltage related to the operation of the drive control unit.

3. The medical power tool according to claim 2, characterized in that the drive control unit of the motor operates after waiting for the application of a first threshold voltage and the interruption of a second threshold voltage, which are switched by each of the two switching function units of the operating switch.

4. The medical power tool according to claim 2 or 3, characterized in that the operating switch is composed of a single double-action switch.

5. The medical power tool according to claim 2 or 3, characterized in that the operating switch is composed of two switch components, each having a switching function.

6. The medical power tool according to claim 2 or 3, characterized in that the operation switches are arranged in parallel, with one being a forward rotation operation switch and the other a reverse rotation operation switch, and a forward rotation threshold voltage is applied to the drive control unit 17 of the motor 4 when the forward rotation operation switch is pressed, and a reverse rotation threshold voltage is applied when the reverse rotation operation switch is pressed.

7. A medical screw tightening tool is provided in which a battery and motor are arranged in a cylindrical tool body, a screw tightening bit rotated by the motor is rotatably held in a bearing holder located at the tip of the tool body, a motor drive power supply unit and a control system power supply unit are connected to the battery, a predetermined voltage is applied from the battery to the motor drive power supply unit and the control system power supply unit, the control system power supply unit is connected to the motor drive control unit to apply the drive voltage, and the motor drive power supply unit is connected to an operating switch that switches the application or interruption of voltage from the battery, the operating switch has multiple switching function units, and one of the switching function units of the operating switch controls the motor A medical screw tightening tool characterized in that it switches the application and interruption of voltage from the drive power supply unit and switches a first threshold voltage related to the operation of the motor drive control unit, and switches the application and interruption of a second threshold voltage related to the operation of the drive control unit by another switching function unit, the drive control unit consists of a current supply unit that supplies a predetermined current to the motor and a torque control unit that detects the load current of the motor and outputs a drive signal to the current supply unit until the load current of the motor reaches a current threshold corresponding to the set tightening torque, and the torque control unit is configured to operate after waiting for the application of the first threshold voltage and the interruption of the second threshold voltage, which are switched by the two switching function units of the operation switch.

8. A medical electric drill is characterized in that a battery and motor are arranged in a cylindrical tool body, a drill rotated by the motor is rotatably held by a bearing holder located at the tip of the tool body, a motor drive power supply unit and a control system power supply unit are connected to the battery, a predetermined voltage is applied from the battery to the motor drive power supply unit and the control system power supply unit, the control system power supply unit is connected to the motor drive control unit to apply a drive voltage, and the motor drive power supply unit is connected to an operation switch that switches the application or interruption of voltage from the battery, the operation switch has multiple switching functions, one of the switching functions of the operation switch switches the application or interruption of voltage from the battery and switches a first threshold voltage related to the operation of the motor drive control unit, the other switching functions switch the application or interruption of a second threshold voltage related to the operation of the motor drive control unit, and the motor drive control unit operates after waiting for the application of the first threshold voltage or the interruption of the second threshold voltage switched by each of the two switching functions of the operation switch.

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