JP2007074849A - Motor control circuit and endoscope operation section durability test device - Google Patents

Abstract

【Task】
A motor control circuit for controlling the driving and stopping of the motor, and an endoscope operation section durability test apparatus provided with the motor control circuit, the motor, and a jig, capable of preventing a malfunction of the motor that may occur when the power supply is started. I will provide a.
[Solution]
The motor control circuit includes a first Zener diode disposed upstream of the control terminal of the motor driver circuit. The zener voltage of the second zener diode provided downstream of the drive power supply is lower than the voltage value of the signal level H, the downstream side of the second zener diode and the base of the first NPN transistor are connected, and the first The collector of the NPN transistor and the base of the second NPN transistor are connected to the drive power supply in parallel with the second Zener diode, the emitters of both NPN transistors are grounded, and the collector of the second NPN transistor is connected to the input power supply and the resistor. The inverting Schmitt trigger circuit and the switch circuit may be provided in parallel.
[Selection] Figure 3

Description

  The present invention relates to a motor control circuit for controlling driving and stopping of a motor, and an endoscope operation unit endurance test apparatus including the motor control circuit, a motor, and a jig.

Conventionally, various devices using a motor have been used. For example, in the endoscope water supply device described in Patent Document 1, a pump that pumps out water stored in a tank and sends it to a water supply pipe of the endoscope is driven by a motor. The motor is driven or stopped by the user of the device operating the foot switch.
JP2001-275945

  In such an apparatus, a step motor or a constant speed motor is used. In the apparatus described in Patent Document 1, a constant speed step motor is used. In a DC stepping motor, the rotation speed and rotation angle of the motor are controlled by inputting drive pulses to a plurality of control terminals. This drive pulse is generated by a motor driver circuit and sent to the control terminal of the motor.

  The motor driver circuit includes a signal input terminal for receiving a pulse signal from an external control circuit, and a power input terminal for supplying DC power. The motor driver circuit generates drive pulses to be sent to the motor using an external pulse signal and a DC power supply. The pulse output from the external control circuit is a generally-known logic level voltage of about 3.3 to 5 V, and power consumption is suppressed. On the other hand, since the DC power supply serves as power for rotating the motor with high torque, the motor driver circuit has a high voltage of about 12 to 24V.

  Usually, a direct current supplied to an external control circuit and a motor driver circuit is supplied from an appropriate AC-DC converter (hereinafter referred to as a power source). In the case of the apparatus configured as described above, since the driving voltage of the external control circuit and the motor driver circuit are different, separate power supplies are often connected to the control circuit and the motor driver circuit.

  Logic elements such as a Schmitt trigger inverter are used in the control circuit, and pulses supplied to the motor driver circuit are generated by these logic elements. In these logic elements, the operable drive voltage range is the logic level voltage 3.3V to 5V as described above. If a voltage significantly lower than this range is supplied to the logic element, the logic level of the element is not stable, and the system may malfunction. When starting up the power supply that supplies current to the control circuit, a finite time is required for the voltage level to rise to a stable level. In such a period, a low voltage may be supplied to the logic element. As a result, an unintended pulse may be input to the motor driver circuit, causing the step motor to malfunction.

  In particular, in a device using a constant speed motor that controls rotation / stop depending on whether a signal input to a specific terminal of a motor driver circuit is at an H level or an L level, when a logic element malfunctions when the power supply is started. The motor could start rotating.

  In view of the above problems, the present invention provides a motor control circuit having means for preventing malfunction of a motor that may occur at the time of starting a power supply, and an endoscope operation unit durability test apparatus having the motor control circuit. With the goal.

  In order to achieve the above object, a motor control circuit of the present invention includes a first Zener diode disposed upstream of a control terminal of a motor driver circuit. The level of a signal that can be generated due to a malfunction of the logic element when the power supply is started is lower than a normal level H voltage value. For example, when the drive voltage of the logic element during normal use is 5V, the voltage value of the level H signal is approximately 5V. On the other hand, the voltage value of a signal that can be output due to a malfunction at power-on is about 2V. Therefore, by using an element having a Zener voltage of 3 V as the first Zener diode, a signal that can be generated due to a malfunction of the logic element can be cut.

  The Zener diode outputs a voltage of (input voltage−zener voltage) when the voltage value of the signal output from the element provided upstream thereof is equal to or higher than the Zener voltage. Therefore, it is preferable to amplify the signal voltage value input to the motor driver circuit to a desired voltage level by disposing a voltage amplifier circuit including a transistor or the like downstream of the first Zener diode.

The motor control circuit generates a stop button that is pressed when stopping the rotation of the motor and a signal level L when the stop button is pressed, and a signal level H when the motor control circuit is not pressed. A stop circuit configured to be generated, and a main circuit configured to read a signal generated by the stop circuit and apply a signal level L signal to a predetermined terminal of the motor driver circuit when the signal is at a signal level L And a control circuit,
It may be configured to further include a low-voltage control circuit that controls the stop circuit so that the stop circuit generates a signal level L when the drive voltage of the stop circuit is less than a predetermined value.

  According to such a configuration, when the logic element constituting the stop circuit malfunctions when the power supply is started and a level H signal can be output, the low level control circuit forcibly outputs the level L signal. Will be output. Therefore, according to this configuration, even if either the first Zener diode or the low-voltage control circuit is malfunctioning, it is possible to prevent malfunction of the motor.

  Also, the stop circuit is provided in parallel with the inverting Schmitt trigger circuit, the input power source of signal level H connected to the input terminal of the inverting Schmitt trigger circuit via a resistor, and the inverting Schmitt trigger circuit with respect to the input power source and the resistor. Switch circuit, one end of which is grounded and the stop button is provided in the middle of the switch circuit, the low voltage control circuit is connected to the input power source and the resistor. If the voltage of the input power supply of the stop circuit is lower than the predetermined value, current flows from the input power supply to the control circuit at the time of low voltage, and the input terminal of the reverse Schmitt trigger is provided. It is good also as a structure which reduces the voltage in.

  For example, the low voltage control circuit includes a drive power supply, a second Zener diode provided downstream of the drive power supply, and first and second NPN transistors, and the Zener voltage of the second Zener diode is The signal level H is lower, the downstream side of the second Zener diode is connected to the base terminal of the first NPN transistor, and the collector terminal of the first NPN transistor and the base terminal of the second NPN transistor are respectively Connected to the drive power supply in parallel with the second Zener diode, the emitter terminals of the first and second NPN transistors are grounded, and the collector terminal of the second NPN transistor is connected to the input power supply and the resistor. On the other hand, the reverse Schmitt trigger circuit and the switch circuit are provided in parallel.

  The motor control circuit described above includes, for example, an endoscope operation unit including a motor controlled by the motor control circuit, and a jig for repeatedly reciprocating the operation dial of the endoscope by power from the motor. Applies to durability testing equipment.

  As described above, according to the present invention, the present invention provides a motor control circuit having means for preventing malfunction of a motor that may occur at the time of starting a power supply, and an endoscope operation unit endurance test having the motor control circuit. A device is realized.

  Hereinafter, the drawings will be described to describe a motor control circuit of the present invention and an endoscope operation unit durability test apparatus having the motor control circuit. FIG. 1 is a schematic view showing the structure of the endoscope operation unit durability test apparatus according to the present embodiment. The endoscope operation unit durability test apparatus 1 (hereinafter abbreviated as “test apparatus 1”) of the present embodiment reciprocally rotates an operation dial for operating the bending operation of the distal end portion of the insertion tube of the endoscope a predetermined number of times. To test whether the dial breaks.

  The test apparatus 1 has a body 10 to which the endoscope S is fixed, and a fixing member 12 for fixing the handle S and the insertion tube base end of the endoscope S to the body 10 from above and below.

  In addition, an operation gear 14 including an engagement protrusion 14 a that engages with the operation dial D of the endoscope S when the endoscope S is fixed to the body 10 is provided on one side surface of the body 10. The operation dial D can be reciprocally rotated by reciprocatingly rotating the operation gear 14 in a state where the engagement protrusion 14 a is engaged with the operation dial D.

  A drive gear 16 for driving the operation gear 14 meshes with the operation gear 14. The rotation shaft of the drive gear 16 is connected to the drive shaft of the motor 20, and the operation dial D can be rotated via the drive gear 16 and the operation gear 14 by rotating the motor 20. .

  The rotating shaft of the motor 20 is driven to rotate both clockwise and counterclockwise, and by applying a predetermined signal to the motor driver circuit 130 for driving / controlling the motor 20, The rotation direction of the rotation shaft of the motor 20 (that is, the rotation direction of the operation dial D of the endoscope S) can be set.

  A control unit 100 is provided below the body 10. A block diagram of the control unit 100 is shown in FIG. On the surface of the control unit 100, a start button SW1 that is pressed when starting the motor 20 and starting the test, a stop button SW2 that is pressed when stopping the rotation of the motor 20 and ending the test, A power connector 102 for supplying AC power to the control unit 100 is provided. In addition, the motor driver circuit 130, the control circuit 150 for controlling the operation of the motor 20 by sending a signal to the motor driver circuit, and the AC current supplied via the power connector 102 are converted into a DC voltage of 5V. The first power supply 104 supplied to the control circuit 150 and the second power supply 106 that converts the AC current supplied via the power supply connector 102 into a DC current of 12 V and supplies the DC current to the counter 108 are the control unit. 100.

  The AC current supplied via the power connector 102 is sent to the first power supply 104 and the second power supply 106 and is branched and sent to the motor driver circuit 130. The motor driver circuit 130 includes a power supply circuit that converts AC current into 24V DC current, and the motor driver circuit 130 itself and the motor 20 are driven by the 24V DC current.

  As shown in FIG. 1, the operating gear 14 has an arm 14 b extending in the radial direction. When the operating gear 14 rotates, the arm 14b swings between the rotation direction detection switches SW3 and SW4 provided on the body 10. The rotation direction detection switches SW3 and SW4 are respectively connected to the control circuit. When the arm 14b comes into contact with one of the switches SW3 and SW4 and the switch is short-circuited, the result is detected and input to the control circuit 150. . Based on the detection result, the control circuit 150 transmits a signal to the motor driver circuit 130 to change the rotation direction of the motor 20. With the above configuration, the operation dial D of the endoscope 20 reciprocally rotates.

  The control circuit 150 is connected to a counter 108 built in the control unit 100. The control circuit 150 transmits a count-up signal to the counter 108 when the switch SW4 and the arm 14b come into contact with each other. When the counter 108 receives the count-up signal, the counter display value of the counter 108 is incremented by one. The counter display value is displayed on the counter display indicator of the counter 108. With the above configuration, the counter 108 measures the number of times that the arm 14b contacts the switch SW4 after the start button is pressed (that is, the number of reciprocations of the operation dial D), and this number is displayed on the counter display indicator of the counter 108. Is done. The operator of the test apparatus 1 can measure the number of reciprocations of the operation dial D by visually recognizing the display value displayed on the counter display indicator of the counter 108.

  Further, when the value of the counter display value of the counter 108 exceeds a certain value (for example, 10,000), the counter 108 outputs a predetermined overflow signal. This overflow signal is input to the control circuit 150. When the control circuit 150 receives the overflow signal, the control circuit 150 outputs a signal for stopping the rotation of the motor 20 to the motor driver circuit 130. Accordingly, after the start button SW1 is pressed and the durability test is started, the motor 20 stops when the number of reciprocations of the operation dial D reaches a certain value. That is, in this configuration, when the endoscope S is set on the body 10 and the start button is pressed, the operation dial D is reciprocally rotated a certain number of times. When the operator visually recognizes the state of the operation dial D at this time, the durability of the operation dial D is determined.

  FIG. 3 shows a circuit diagram of the buttons SW1 and SW2, the switches SW3 and SW4, the control circuit 150, the motor driver circuit 130, and the counter 108. Note that the power supply voltage from the power supply input terminal described as “+5 V” in the drawing is supplied from the power supply 104.

  The normal operation of the control circuit 150 based on the above circuit diagram will be described below. Note that the circuits 210 and 220 for preventing malfunction at the time of a low voltage, which is a characteristic part of the present application, are not necessary during normal operation. Therefore, in the following description, it is assumed that the circuits 210 and 220 are not provided.

In the present embodiment, control of the motor driver circuit 130 is performed by the CPU 151. The first output terminal O ₁ and the second output terminal O ₂ of the CPU 151 are connected to the CCW / CW setting terminal M ₂ and the START / STOP terminal M ₁ of the motor driver circuit 130, respectively. The terminal _{M 3} of the motor driver 130 is a ground.

When the level H (usually a 4 V to 5 V) to the START / STOP terminal _{M 1} of the motor driver 130 is under voltage is controlled so that the motor 20 is rotated by the motor driver circuit 130. Further, when a voltage of level L (usually 0 to 0.5 V) is applied to the START / STOP terminal, the motor 20 is controlled to stop by the motor driver circuit 130.

If the CCW / CW setting terminal M ₂ of the motor driver 130 is under the voltage level H, the rotational direction of the motor 20 is set counterclockwise. Also, if the CCW / CW setting terminal M ₂ is under voltage level L, the rotational direction of the motor 20 is set in the clockwise direction.

As described above, in the present embodiment, the rotation / stop and rotation direction of the motor 20 are controlled by signals output from the CPU 151 to the terminals O ₁ and O ₂ .

  Next, means for the CPU 151 to detect the states of the start button SW1, the stop button SW2, and the switches SW3 and SW4 will be described.

One end of the start button SW1 is connected to the input terminal of the inverting Schmitt trigger circuit S _1, the other end is grounded. The one end and the input terminal of the inverting Schmitt trigger circuits S ₁ of start button SW1, 5V power supply through the resistor R ₁ is connected. Therefore, in a state where both ends of the start button SW1 is not short-circuited, the input terminal of the inverting Schmitt trigger circuits S ₁ will be being pulled up at 5V (or level H). At this time, the inverting Schmitt trigger circuits S ₁ outputs a signal of level L.

Here, when both ends of the start button SW1 is short-circuited, the resistor R ₁ current flows, the voltage drop due to the resistance R _1, the voltage at the input terminal of the inverting Schmitt trigger circuits S ₁ level L, the inverting Schmitt trigger circuit S ₁ outputs a signal of level H. The output of the inverting Schmitt trigger circuit S ₁ is input to the input terminal I _{1 of the} CPU 151.

The basic configuration also stop button SW2 are similar, the inverting Schmitt trigger circuit _{S 2} and the resistor _{R 2,} when both ends of the stop button SW2 are not shorted, the voltage at the input terminal _{I 2} of the level H of the CPU151 now it takes, when the both ends are short-circuited, so that such a voltage input terminal I ₂ to the level L of the CPU 151.

The same applies to the switches SW3 and SW4. By the inverting Schmitt trigger circuit _S 3, _{S 4} and the resistor _R 3, _{R 4,} when the ends of the switches SW3, SW4 are not shorted, the input terminal _I 3 of CPU 151, so that the voltage of each level H to _{I 4} is applied When both ends are short-circuited, a voltage of level L is applied to the input terminals I ₃ and I ₄ of the CPU 151, respectively.

Accordingly, the CPU 151 can check the voltage level applied to the input terminals I ₁ and I ₂ to determine whether or not the start button SW1 and / or the stop button SW2 are pressed. Similarly, the CPU 151 can check the voltage level applied to the input terminals I ₃ and I ₄ to determine whether or not the switches SW3 and / or SW4 are in contact with the arm 14b (FIG. 1).

  The count-up mechanism of the counter 108 and the behavior at the time of overflow will be described below.

The signal output terminal O _{3 of the} CPU 151 is connected to the count-up pulse input terminal C ₁ of the counter 108. When a level H pulse is output from the signal output terminal O ₃ of the CPU 151, the counter 108 displays the counter display value. Count up by one. The terminal _{C 4} of the counter 108 is a ground.

The value of the counter display value exceeds a predetermined value, the terminal C ₂ and C ₃ of the counter 108 are short-circuited. Terminal C ₂ is connected to the input terminal of the inverting Schmitt trigger circuit S _5. The terminal C ₃ is grounded. Further, the input terminal of the inverting Schmitt trigger circuit S _5, via a resistor R ₅ 5V supply is connected. Therefore, when the terminals C ₂ and C ₃ are not short-circuited, a voltage of level H is applied to the input terminal of the inverting Schmitt trigger circuit S ₅ , and the voltage level of the output terminal is L. On the other hand, when the counter display value terminal C ₂ and C ₃ overflows are short-circuited, a current flows through the resistor R _5, the voltage level at the input terminal of the inverting Schmitt trigger circuit S ₅ by the voltage drop across the resistor R ₅ is L, The power level at the output end is H. The output of the inverting Schmitt trigger circuit _{S 5} is connected to the signal input terminal _{I 5} of CPU 151.

Therefore, the CPU 151 can increase the counter display value of the counter 108 by one by outputting a level H pulse to the signal output terminal O ₃ . Further, the CPU 151 can detect an overflow of the counter display value of the counter 108 by monitoring the signal input terminal I ₅ .

A mechanism for controlling rotation / stop of the motor 20 by the CPU 151 will be described below. The signal output terminal O ₂ of the CPU 151 is connected to the START / STOP terminal M ₁ of the motor driver circuit 130 via the inversion Schmitt trigger circuit S ₆ . Therefore, if the level of the signal output terminal O ₂ is L, the voltage level at the START / STOP terminal M ₁ becomes H, and the motor 20 rotates at this time. On the other hand, if the level of the signal output terminal O ₂ is H, the voltage level at the START / STOP terminal M ₁ becomes L, and the motor 20 does not rotate at this time.

  In the present embodiment, the CPU 151 operates according to the flow described below and controls the rotation operation of the motor 20.

  FIG. 4 is a flow executed by the CPU. This flow is executed when the test apparatus 1 is powered on. Further, this flow is a kind of infinite loop and continues to be executed unless the power supply to the test apparatus is cut off. When this flow starts, step S1 is performed.

In step S1, whether the signal level H to the signal input terminal I ₁ of the CPU151 is input, that is, whether the detection whether or not the start button SW1 is depressed is performed. To the signal input terminal _{I 1} signal level H is input, if the pressing of the start button SW1 is detected (S1: YES), the process proceeds to step S2. On the other hand, the input signal of the level L to the signal input terminal I ₁ If the start button SW1 is detected that not pressed (S1: NO), the step S1 is executed subsequently. That is, step S1 indicates that the process waits until the start button SW1 is pressed.

In step S2, whether the signal level H to the signal input terminal I ₂ of the CPU151 is input, that is, whether the detection stop button SW2 is pressed is performed. A signal input terminal I ₂ signal of the level L is input, when it is detected that the stop button SW2 is not pressed (S2: NO), the process proceeds to step S3. On the other hand, the signal input terminal _{I 2} signal of the level H is input, if the depression of the stop button SW2 is detected (S1: YES), the process returns to step S1.

In step S3, CPU 151 sets the voltage level of the signal output terminal _{O 2} to the L. As a result, the rotation of the motor 20 starts. Next, the process proceeds to step S4.

  As described above, in the routine of step S1-3, the motor 20 is started when the start button SW1 is pressed and the stop button SW2 is not pressed. Even if the start button SW1 is pressed, the motor 20 does not start when the stop button SW2 is pressed at the same time.

In step S4, whether the signal level H to the signal input terminal I ₃ of CPU151 is input, that is, whether the detection whether the contact switch SW3 and the arm 14b is performed. A signal input terminal _{I 3} signal level H is input, when the contact of the switch SW3 and the arm 14b is detected (S4: YES), the process proceeds to step S5.

In step S5, CPU 151 sets the voltage level of the signal output terminal _{O 1} to L. As a result, the direction of rotation of the motor 20 is set clockwise. Next, the process proceeds to step S6.

On the other hand, in step S4, and the signal of level L to the signal input terminal _{I 3} is input, if the switch SW3 and the arm 14b is not in contact is detected (S4: NO), the process proceeds to step S6.

In step S6, whether the signal level H to the signal input terminal I ₄ of CPU151 is input, that is, whether the detection whether the contact switch SW4 and the arm 14b is performed. A signal input terminal _{I 4} signal level H is input, when the contact of the switch SW4 and the arm 14b is detected (S4: YES), the process proceeds to step S7.

In step S7, CPU 151 sets the voltage level of the signal output terminal _{O 1} to H. As a result, the direction of rotation of the motor 20 is set counterclockwise. Next, the process proceeds to step S8. In step S8, CPU 151 outputs a pulse of the signal level H from the signal output terminal _{O 3.} As a result, the counter display value of the counter 108 is incremented by one. Next, the process proceeds to step S9.

On the other hand, in step S6, and the signal of level L to the signal input terminal _{I 4} is input, if the switch SW4 and the arm 14b is not in contact is detected (S6: NO), the process proceeds to step S9.

  As described above, according to the configuration of step S4-8 of this flow, when the arm 14b comes into contact with SW3 and SW4, the rotation direction of the motor 20 is switched. That is, the operation dial D of the endoscope S is reciprocally rotated so that the arm 14b reciprocates between the switches SW3 and SW4. Further, when the arm 14b makes a round trip between the switches SW3 and SW4 and contacts the SW4, the counter display value of the counter 108 is incremented by one.

In step S9, whether the signal level H to the signal input terminal I ₅ of CPU151 is input, that is, the detection counter display value of the counter 108 is whether exceeds a predetermined value is performed. A signal input terminal I ₅ signal of the level H is input, if the counter display value is detected that exceeds a predetermined value (S9: YES), the process proceeds to step S11. On the other hand, the signal input terminal I ₅ signal of the level L is input, if the counter display value is detected that does not exceed the predetermined value (S9: NO), the process proceeds to step S10.

In step S10, whether the signal level H to the signal input terminal I ₂ of the CPU151 is input, that is, whether the detection stop button SW2 is pressed is performed. A signal input terminal I ₂ signal of the level L is input, when it is detected that the stop button SW2 is not pressed (S10: NO), the flow returns to step S4. On the other hand, the signal input terminal _{I 2} signal of the level H is input, if the depression of the stop button SW2 is detected (S10: YES), the process proceeds to step S11.

In step S11, the voltage level of the signal output terminal _{O 2} of the CPU151 in H. As a result, the rotation of the motor 20 stops.

  That is, in step S9-11 of this flow, the counter 108 overflows, that is, the motor 20 stops when the dial D of the endoscope S reciprocates a predetermined number of times or when the stop button SW2 is pressed. It is shown.

  As described above, according to the above-described flow, when the start button SW1 is pressed, the rotation of the motor 20 starts and the endurance test of the dial D is started. Then, the rotation of the motor 20 stops. If the stop button SW2 is pressed during the test, the motor 20 stops and the test is forcibly interrupted.

  A mechanism for preventing malfunction at low voltage, which is a characteristic part of the present invention, will be described below. First, the characteristics of malfunction at low voltage will be described.

  In a state where an AC current is supplied to the power supply 104, the voltage on the output side of the power supply 104 is 5V. However, immediately after the commercial AC power source is connected to the power source 104 or immediately after the AC power source is disconnected from the power source 104, the voltage on the output side of the power source 104 is a low voltage of less than 5V.

Here, when the input terminal and the drive voltage supply terminal (Vcc) of the inverting Schmitt trigger circuits S _{1 to 6} and the power source 104 are connected, the drive voltage input to the Vcc and the voltage input to the input terminal. Is sufficiently high, a level L signal is output from the inverting Schmitt trigger circuit. However, when the drive voltage is lower than a certain threshold value, a level H signal may be output. This threshold value varies depending on individual differences of the inversion Schmitt trigger circuits _S1-6 . Therefore, when a low voltage immediately after after power reversal Schmitt from the trigger circuits S ₁ signal level H is outputted, there is a possibility that the output signal of the level L is from S _2. For this reason, if the low-voltage control circuits 210 and 220 described below are not provided, the motor 20 may start even when the start button SW1 is not pressed when the power is turned on.

The low voltage control circuits 210 and 220 described below are used to prevent the above phenomenon. The configuration of the circuit 210 will be described below. Circuit 210 is arranged to branch from between the stop button SW2 and the inverting Schmidt trigger circuit S _2. The circuit 210 includes a second Zener diode 211, a resistor 212, a first NPN transistor circuit 213, and a second NPN transistor 214. Here, the first and second NPN transistors are provided with a bias resistor on the base side.

The second Zener diode 211 and the resistor 212 are connected to the output terminal of the power supply 104 in parallel with each other. Downstream of the second Zener diode 211 is connected to the base of the first NPN transistor 213. The downstream of the resistor 212, the collector of the first NPN transistor 213, and the base of the second NPN transistor 214 are connected. The collector of the second NPN transistor 214 is connected to the stop button SW2 in the middle of the inverting Schmitt trigger circuit _{S 2.} The emitters of the first and second NPN transistors are both grounded. The Zener voltage of the second Zener diode 211 is set to 3.1V. This value is lower than the output voltage of the power supply 104 during normal, also, it is sufficiently higher than the minimum driving voltage of the Schmitt trigger circuit S _2.

Here, when the voltage of the direct current output from the power supply 104 is lower than the Zener voltage of the second Zener diode 211, the voltage applied to the base of the first NPN transistor 213 becomes 0, and the second NPN transistor 214 Voltage is applied to the base of the. As a result, a current flows from the collector of the second NPN transistor 214 toward the emitter. That is, a current flows through the resistor R ₂ , and as a result, the voltage at the input end of the inverting Schmitt trigger circuit S ₂ becomes L, and a level H signal is input to the signal input end I ₂ of the CPU 151. Therefore, even if a signal of level H is input to the signal input terminal I _{1 due} to a malfunction at a low voltage immediately after the power is turned on (S1: YES in FIG. 4), the signal input terminal I ₂ also has the level H at that time. signal is input (FIG. 4 S2: YES), the signal for starting the motor 20 from the signal output terminal O _2, not output.

On the other hand, when the voltage of the direct current output from the power supply 104 is higher than the Zener voltage of the second Zener diode 211, a predetermined voltage is applied to the base of the first NPN transistor 213, and the first NPN transistor 213 Current flows from the collector to the emitter. For this reason, the voltage applied to the base of the second NPN transistor 214 is zero due to the voltage drop in the resistor 212. In this state, no current flows from the collector to the emitter of the second NPN transistor 214. In other words, the circuit 210 is disconnected from other circuits. In this state, if the stop button SW2 is not pressed to the signal input terminal I ₂ signal of the level L is input, that signal level H if the is pressed is input, a normal operation state Become.

That is, when the voltage is low (when the voltage of the direct current output from the power supply 104 is lower than the zener voltage of the second zener diode 211) by the circuit 210, the signal of the level H is forcibly input to the CPU 151. is input to the edge I _2, as a result, the motor 20 is controlled to stop.

The above circuit 210 is a normal inverting Schmitt trigger circuit S _6, it is effective when the inverting Schmitt trigger circuits S ₁ may cause a malfunction. However, there is a possibility that the inversion Schmitt trigger circuit S ₆ malfunctions at a low voltage and outputs an inappropriate signal level H to the motor driver circuit 130. Circuit 220 to be described below, under such circumstances, and inputs a signal of the forced level L during low voltage START / STOP terminal _{M 1} of the motor driver 130.

The circuit 220 includes a voltage amplification circuit 222 having an NPN transistor and a first Zener diode 221. The output terminal of the inverting Schmitt trigger circuit S ₆ is connected to the upstream side of the first Zener diode 221, the downstream side of the first Zener diode 221 is connected to the input terminal of the voltage amplifier circuit 222, and the voltage amplifier circuit 222 The output terminal is connected to the START / STOP terminal M ₁ of the motor driver circuit 130. The Zener voltage of the first Zener diode 221 is set to 2.9V. This value is lower than the output voltage of the power supply 104 during normal, also, it is sufficiently higher than the minimum driving voltage of the Schmitt trigger circuit S _6.

The voltage of the level H signal output from the inverting Schmitt trigger circuit is generally substantially the same voltage as the drive voltage of the inverting Schmitt trigger circuit. Therefore, when the inverting Schmitt trigger circuit S ₆ malfunctions at low voltage and outputs a level H signal, the voltage input to the first Zener diode 211 is substantially the same as the output voltage of the power supply 104. Since this voltage is at a lower value than the zener voltage of the first Zener diode, the output voltage of the first zener diode is zero, the level of the signal input to the START / STOP terminal M ₁ of the motor driver 130 Becomes L. Therefore, even when the inverting Schmitt trigger circuit S ₆ at a low voltage malfunctioning, the motor 20 is not rotated.

On the other hand, in the normal operation (when the output voltage of the power supply 104 is higher than the Zener voltage of the first Zener diode 221), if the signal level H from the inverting Schmitt trigger circuit S ₆ is output, the first zener The voltage on the downstream side of the diode 221 is approximately (the output voltage of the power supply 104 -the Zener voltage of the first Zener diode 221). Since this voltage may be judged to be level L by the motor driver circuit 130, the voltage is raised to the level H by the voltage amplification circuit 222.

  As described above, according to the present embodiment, the circuits 210 and 220 can prevent the motor 210 and 220 from starting unintentionally due to a malfunction of the inverting Schmitt trigger circuit that can occur when the output of the power supply 104 is at a low voltage. In the present embodiment, the Zener voltage of the first Zener diode 221 is set lower than the Zener voltage of the second Zener diode 211.

It is the schematic which shows the structure of the endoscope operation part durability test apparatus of this embodiment. It is a block diagram of the control unit in the endoscope operation part durability test apparatus of this embodiment. FIG. 3 is a circuit diagram of a control circuit, a motor driver circuit, a counter, and the like in the endoscope operation unit durability test apparatus of the present embodiment. It is an operation | movement flow of CPU of the endoscope operation part durability test apparatus of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Endoscope operation part durability test apparatus 14 Actuation gear 14b Arm 20 Motor 100 Control unit 104 1st power supply 108 Counter 130 Motor driver circuit 150 Control circuit 151 CPU
210 Low Voltage Control Circuit 211 Second Zener Diode 212 Resistor 213 First NPN Transistor 214 Second NPN Transistor 220 Low Voltage Control Circuit 221 First Zener Diode 222 Voltage Amplifier Circuit SW1 Start Button SW2 Stop Button

Claims (12)

  A motor control circuit for driving a motor by applying a signal level H signal to a predetermined terminal of a motor driver circuit and stopping the rotation of the motor by applying a signal level L signal. A motor control circuit comprising: a first Zener diode provided on the upstream side of a terminal, the Zener voltage of which is lower than a signal level H voltage value.   The motor control circuit according to claim 1, wherein a voltage amplifier circuit is provided on the downstream side of the first Zener diode. A stop button that is pressed to stop the rotation of the motor;
A stop circuit configured to generate a signal level L signal when the stop button is pressed, and to generate a signal level H signal when the stop button is not pressed;
A main control circuit configured to read a signal generated by the stop circuit and apply a signal level L signal to a predetermined terminal of the motor driver circuit when the signal is at a signal level L;
A low voltage control circuit that controls the stop circuit so that the stop circuit generates a signal of a signal level L when the drive voltage of the stop circuit is less than a predetermined value;
The motor control circuit according to claim 1, further comprising: The stop circuit is
An inversion Schmitt trigger circuit;
An input power source having a voltage value of signal level H connected to the input end of the inverting Schmitt trigger circuit via a resistor;
A switch circuit provided in parallel with the inverting Schmitt trigger circuit with respect to the input power source and the resistor, one end of which is grounded and the stop button provided in the middle;
The motor control circuit according to claim 3, further comprising: The low voltage control circuit is provided in parallel with the inverting Schmitt trigger circuit and the switch circuit with respect to the input power supply and the resistor,
When the voltage of the input power source of the stop circuit is lower than a predetermined value, a current flows from the input power source to the low voltage control circuit, and the voltage at the input terminal of the inverting Schmitt trigger is reduced. The motor control circuit according to claim 4. The low voltage control circuit includes a drive power supply, a second Zener diode provided downstream of the drive power supply, and first and second transistors,
The Zener voltage of the second Zener diode is lower than the voltage value of the signal level H;
A downstream side of the second Zener diode and a base terminal of the first transistor are connected;
The collector terminal of the first transistor and the base terminal of the second transistor are each connected to the drive power supply so as to be in parallel with the second Zener diode,
The emitter terminals of the first and second transistors are grounded;
6. The motor control circuit according to claim 5, wherein a collector terminal of the second transistor is provided in parallel with the inverting Schmitt trigger circuit and the switch circuit with respect to the input power supply and a resistor. .   The motor control circuit according to claim 6, wherein a Zener voltage of the second Zener diode is set higher than a Zener voltage of the first Zener diode. A motor control circuit for driving the motor by applying a signal level H signal to a predetermined terminal of the motor driver circuit and stopping the rotation of the motor by applying a signal level L signal;
A stop button that is pressed to stop the rotation of the motor;
A stop circuit configured to generate a signal level L signal when the stop button is pressed, and to generate a signal level H signal when the stop button is not pressed;
A main control circuit configured to read a signal generated by the stop circuit and apply a signal level L signal to a predetermined terminal of the motor driver circuit when the signal is at a signal level L;
A low voltage control circuit that controls the stop circuit so that the stop circuit generates a signal of a signal level L when the drive voltage of the stop circuit is less than a predetermined value;
A motor control circuit. The stop circuit is
An inversion Schmitt trigger circuit;
An input power source having a voltage value of signal level H connected to the input end of the inverting Schmitt trigger circuit via a resistor;
A switch circuit provided in parallel with the inverting Schmitt trigger circuit with respect to the input power source and the resistor, one end of which is grounded and the stop button provided in the middle;
The motor control circuit according to claim 8, further comprising: The low voltage control circuit is provided in parallel with the inverting Schmitt trigger circuit and the switch circuit with respect to the input power supply and the resistor,
When the voltage of the input power source of the stop circuit is lower than a predetermined value, a current flows from the input power source to the low voltage control circuit, and the voltage at the input terminal of the inverting Schmitt trigger is reduced. The motor control circuit according to claim 9. The low-voltage control circuit includes a drive power supply, a Zener diode provided downstream of the drive power supply, and first and second NPN transistors,
The Zener voltage of the Zener diode is lower than the signal level H voltage value,
A downstream side of the Zener diode and a base terminal of the first NPN transistor are connected;
The collector terminal of the first transistor and the base terminal of the second NPN transistor are connected to the drive power supply so as to be in parallel with the Zener diode, respectively.
The emitter terminals of the first and second NPN transistors are grounded;
11. The motor control circuit according to claim 10, wherein a collector terminal of the second transistor is provided in parallel with the inverting Schmitt trigger circuit and the switch circuit with respect to the input power supply and a resistor. . A motor control circuit according to any one of claims 1 to 11,
A motor controlled by the motor control circuit;
A jig for repeatedly reciprocating the operation dial of the endoscope by power from the motor;
Endoscope operation unit durability test device with

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