Self-propelled endoscope apparatus and control apparatus for the same

A self-propelled endoscope apparatus includes a rotation body, a motor, a drive circuit, and a regeneration protection circuit. The rotation body is provided on an outer peripheral surface of an elongated insertion section. The rotation body is configured to be rotatable. The motor rotates the rotation body. The drive circuit drives the motor. The regeneration protection circuit performs protecting operation for protecting the drive circuit from regeneration voltage generated by regeneration of the motor.

FIELD

The embodiment relates to a self-propelled endoscope apparatus and a control apparatus for the same.

BACKGROUND

Self-propelled endoscope apparatuses proposed in Jpn. Pat. Appln. KOKAI Publication No. 2009-055956, and the like are known as endoscope apparatuses to be inserted into a lumen. In the self-propelled endoscope apparatus, for example, an insertion section is moved forward and backward by a propulsive force generated by rotating a rotation body provided around the insertion section by a motor. Such an endoscope apparatus assists an insertion or removal operation of the insertion section by the user.

SUMMARY

According to an aspect, a self-propelled endoscope apparatus comprises a rotation body, a motor, a drive circuit, and a regeneration protection circuit. The rotation body is provided on an outer peripheral surface of an elongated insertion section. The rotation body is configured to be rotatable. The motor rotates the rotation body. The drive circuit drives the motor. The regeneration protection circuit performs protecting operation for protecting the drive circuit from regeneration voltage generated by regeneration of the motor.

Advantages of the embodiments will be set forth in the description which follows, and in part will be obvious from the description, or may be learned. The advantages may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.

DETAILED DESCRIPTION

An embodiment will be described below with reference to the drawings.FIG. 1is a diagram illustrating a configuration example of an endoscope apparatus according to an embodiment. An endoscope apparatus1comprises an endoscope100and a control apparatus200. The endoscope100is configured to be connected to the control apparatus200via a connector116provided on the endoscope100.

The endoscope100is a self-propelled endoscope apparatus including an insertion section101and an operation unit111.

The insertion section101is a distal end portion of the endoscope100. The insertion section101has an elongated shape and is configured to be flexible. Furthermore, an imager102is provided at the distal end of the insertion section101. The imager102images a subject existing on the distal end side of the insertion section101and acquires image data about the subject. Furthermore, the insertion section101is provided with a moving mechanism103. The moving mechanism103comprises a rotation body104and a spiral tube105. The rotation body104is provided on an outer peripheral surface of the insertion section101so as to be rotatable around a longitudinal axis. The spiral tube105is provided so as to have a spiral fin around the rotation body104. The spiral tube105may be configured to be removable from the rotation body104. The spiral tube105may also be configured to be disposable.

The operation unit111is a part that is gripped by the user, and comprises various operation members for operating the endoscope100. Furthermore, the operation unit111comprises a motor112. The motor112generates a driving force for the moving mechanism103. When the motor112rotates, the rotational motion is transmitted to the rotation body104via a transmission member113extending from the inside of the operation unit111to the insertion section101. As the rotation body104rotates, the spiral tube105rotates. Due to the rotation of the spiral tube105, a propulsive force is generated in the insertion section101. This propulsive force causes the insertion section101to self-propel. The self-propulsion of the insertion section101assists in the tasks of insertion and removal of the insertion section101by the user. Furthermore, for example, a rotary encoder114is provided near the motor112. The encoder114outputs an encoder signal corresponding to the rotating speed of the motor112. The encoder signal includes an encoder phase A signal and an encoder phase B signal. The encoder phase A signal and the encoder phase B signal are different from each other in phase by 90 degrees.

A universal cable115is connected to the operation unit111. The universal cable115is provided with various signal lines for transmitting and receiving signals between the endoscope100and the control apparatus200. The universal cable115is connected to the connector116. As described above, the endoscope100and the control apparatus200are connected via the connector116.

The control apparatus200comprises a foot switch201, a control circuit202, a drive circuit203, a regeneration protection circuit204, and a power source circuit205.

The foot switch201comprises a forward pedal and a backward pedal. When the forward pedal is stepped on by the user, the forward pedal generates an operating state signal for causing the motor112to rotate forward. The backward pedal generates an operating state signal for reversing the rotation of the motor112when stepped on by the user. The foot switch201may be configured to generate an operating state signal having a strength corresponding to the amount of depression.

The control circuit202is a control circuit comprising pieces of hardware including an FPGA and a CPU, and the like and controls the operation of sections of the control apparatus200such as the drive circuit203and the regeneration protection circuit204. The control circuit202comprises a drive controller2021, a monitoring unit2022, and a regeneration controller2023. The control circuit202may comprise a single FPGA or comprise a plurality of FPGAs and the like. Some of the functions of the control circuit202may be implemented in a form of software.

The drive controller2021controls the drive circuit203to drive the motor112at a rotating speed corresponding to a body load. For example, the drive controller2021receives the encoder signal output from the encoder114. The drive controller2021then generates PWM data for controlling the magnitude of the voltage output from the drive circuit203so that the actual rotating speed of the motor112detected from the encoder signal matches the rotating speed corresponding to the amount of depression of the foot switch201. The rotating speed corresponding to the amount of depression of the foot switch201is a rotating speed corresponding to the operating state signal. The drive controller2021then turns on a servo control signal for starting the drive of the motor112by the drive circuit203and inputs the servo control signal into the drive circuit203together with the PWM data. The drive controller2021inputs the servo control signal and the encoder signal into the monitoring unit2022.

The monitoring unit2022monitors the operating state of the motor112and inputs the monitoring result into the regeneration controller2023. Here, the operating state of the motor112includes the state of the servo control signal and the actual rotating speed of the motor112. The state of the servo control signal includes the state of whether the motor is controlled by the drive controller2021. When the servo control signal is on, the monitoring unit2022detects that the motor112is controlled, and when the servo control signal is off, the monitoring unit2022detects that the motor112is not controlled. Furthermore, the monitoring unit2022detects the rotating speed of the motor112based on the encoder signal.

The regeneration controller2023controls the regeneration protection circuit204based on the monitoring result from the monitoring unit2022. When the control of the motor by the drive controller2021is stopped, the regeneration controller2023starts the protecting operation by the regeneration protection circuit204, which will be described below in detail. The regeneration controller2023then ends the protecting operation by the regeneration protection circuit204after a lapse of a predetermined set time since the motor112is actually stopped by stopping the control of the motor by the drive controller2021.

The drive circuit203generates a voltage to be supplied to the motor112according to the PWM data included in the servo control signal from the drive controller2021and applies the generated voltage to the motor112.

The regeneration protection circuit204is provided in a path between the motor112and the drive circuit203, and performs the protecting operation for protecting the sections of the control apparatus200from a regeneration voltage occurring by the regeneration in the motor112. This regeneration protection circuit204comprises a regeneration resistor2041and a regeneration resistor switching circuit2042. The regeneration resistor2041is a resistance that comprises one end being connected in parallel to a power source line connecting the motor112and the drive circuit203and comprises another end being grounded. The regeneration resistor switching circuit2042is a switch that is provided between the regeneration resistor2041and a ground (GND_F) and short-circuits or opens between the regeneration resistor2041and the ground (GND_F) according to a regeneration control signal from the regeneration controller2023of the control circuit202. The regeneration protection circuit204will be described below in detail.

The power source circuit205comprises, for example, an AC power supply and converts the electric power of this AC power supply into electric power needed by the sections of the control apparatus200. The power source circuit205then supplies the converted electric power to the sections of the control apparatus200. Furthermore, the power source circuit205also supplies electric power to the motor112, the encoder114, and the like of the endoscope100.

The regeneration protection circuit204will be described below more in detail.FIG. 2is a diagram for explaining a configuration of a regeneration protection circuit. As described above, the regeneration protection circuit204is provided in the path between the motor112and the drive circuit203. In the example illustrated inFIG. 2, the motor112and the drive circuit203are connected via motor power source lines1121. The motor power source lines1121comprise a power source line (M+) connected to the positive (+) terminal of the motor112and a power source line (M−) connected to the negative (−) terminal of the motor112. When the drive circuit203causes current to flow from the power source line M+ to the power source line M−, the motor112rotates forward. Conversely, when the drive circuit203flows current from the power source line M− to the power source line M+, the motor112rotates backward. Furthermore, the power source line M− is provided with a motor relay1122. The motor relay1122brings the power source line M− into a connected state when the servo control signal is on, and the motor relay1122brings the power source line M− into a disconnected state when the servo control signal is off. When the power source line M− is in the disconnected state, the motor112is in a free state where the motor112is not supplied with the electric power from the drive circuit203. When the motor112is in the free state, the motor112freely rotates by receiving, for example, an external force from the body.

In the example illustrated inFIG. 2, the regeneration resistor2041of the regeneration protection circuit204comprises a first regeneration resistor2041athat is connected in parallel to the power source line M+ being a first power source line and a second regeneration resistor2041bthat is connected in parallel to the power source line M− being a second power source line. The first regeneration resistor2041ais connected to the ground (GND_F) via a first regeneration resistor switching circuit2042athat constitutes the regeneration resistor switching circuit2042. The second regeneration resistor2041bis connected to the ground (GND_F) via a second regeneration resistor switching circuit2042bthat constitutes the regeneration resistor switching circuit2042. Note that the first regeneration resistor2041aand the second regeneration resistor2041bare desirably resistors having the same resistance value and the same structure.

The first regeneration resistor switching circuit2042aand the second regeneration resistor switching circuit2042bare each turned on or off according to the regeneration control signal from the control circuit202. When the first regeneration resistor switching circuit2042ais turned on, the first regeneration resistor2041ais short-circuited to the ground. In contrast, when the first regeneration resistor switching circuit2042ais turned off, the first regeneration resistor2041ais opened. Similarly, when the second regeneration resistor switching circuit2042bis turned on, the second regeneration resistor2041bis short-circuited to the ground. In contrast, when the second regeneration resistor switching circuit2042bis turned off, the second regeneration resistor2041bis opened. Note that, in the example illustrated inFIG. 2, the first regeneration resistor2041aand the second regeneration resistor2041bare earthed or opened simultaneously. Of course, the first regeneration resistor2041aand the second regeneration resistor2041bmay be configured to be separately earthed or opened.

Here, for decreasing the diameter of the universal cable115or for other purposes, an encoder power source line1141is disposed near the motor power source lines1121, as illustrated inFIG. 2. The encoder power source line1141is a power source line connecting the encoder114and the power circuit205and transmits electric power for the encoder114generated in the power circuit205to the encoder114.

The operation of the endoscope apparatus1in the embodiment will be described below.FIG. 3is a timing chart relating to regeneration processing for the endoscope apparatus1. Here, “OPERATING STATE SIGNAL” illustrated inFIG. 3indicates the on-state or the off-state of the foot switch201. “SERVO CONTROL SIGNAL” indicates the on-state or the off-state of the servo control signal. “PWM DATA” indicates the state of the PWM data transmitted to the drive circuit203. “REGENERATION CONTROL SIGNAL” indicates the on-state or the off-state of the regeneration control signal. “ENCODER PHASE A” indicates the state of the encoder phase A signal. “ENCODER PHASE B” indicates the state of the encoder phase B signal. “MOTOR OUTPUT VOLTAGE (+)” indicates the voltage of the power source line M+. “MOTOR OUTPUT VOLTAGE (−)” indicates the voltage of the power source line M−.

As illustrated inFIG. 3, the sequence of regeneration processing in the embodiment is divided into three sequences: (1) a sequence in a foot-switch not-stepped-on state; (2) a sequence in a foot-switch stepped-on state; and (3) a sequence in a regeneration control state. The foot-switch not-stepped-on state is a state where the motor112is stopped and the foot switch201is not stepped on. The foot-switch stepped-on state is a state where the foot switch201is stepped on. The regeneration control state is a state immediately after the state where the foot switch201is stepped on is switched to the state where the foot switch201is not stepped on.

In the foot-switch not-stepped-on state, the operating state signal is off. At this time, the drive controller2021does not control the motor112. That is, the drive controller2021turns off the servo control signal to be input into the drive circuit203. At this time, the motor relay1122also operates to bring the power source line M− to the disconnected state. Therefore, the motor112is in the free state. When the motor112is in the free state, the drive controller2021need not input the PWM data into the drive circuit203. In the foot-switch not-stepped-on state, since the motor112does not rotate, the encoder signal (phase A and phase B) indicates a value shown at the time when the rotation of the motor112is stopped.

The monitoring unit2022of the control circuit202acquires the servo control signal and the encoder signal from the drive controller2021and inputs the servo control signal and the encoder signal into the regeneration controller2023. The regeneration controller2023recognizes that the motor112is currently not controlled, based on the servo control signal being off, and recognizes that the motor112is currently stopped, based on the rotating speed indicated by the encoder signal. At this time, the regeneration controller2023turns off the regeneration control signal. The first regeneration resistor switching circuit2042ais thereby turned off, and the first regeneration resistor2041ais opened. Similarly, the second regeneration resistor switching circuit2042bis also turned off, and the second regeneration resistor2041bis opened.

In the foot-switch stepped-on state, the operating state signal is on. At this time, the drive controller2021controls the motor112. That is, the drive controller2021receives the encoder signal output from the encoder114. The drive controller2021then generates PWM data for controlling the magnitude of the voltage output from the drive circuit203so that the actual rotating speed of the motor112detected from the encoder signal matches the rotating speed corresponding to the amount of depression of the foot switch201. The rotating speed corresponding to the amount of depression of the foot switch201is a rotating speed corresponding to the operating state signal. The drive controller2021then turns on a servo control signal for starting the drive of the motor112by the drive circuit203and inputs the servo control signal into the drive circuit203together with the PWM data.

The drive circuit203generates the voltage to be supplied to the motor112according to the PWM data from the drive controller2021and applies the generated voltage to the motor112. This causes the motor112to rotate. By the rotation of the motor112, the encoder signal (phase A and phase B) indicates a value corresponding to the rotating speed of the motor112.

The regeneration controller2023recognizes that the motor112is currently controlled, based on the servo control signal being on. At this time, the regeneration controller2023keeps the regeneration control signal off.

In the foot-switch stepped-on state, the operating state signal is turned off when the depression of the foot switch201is released. That is, the drive controller2021turns off the servo control signal to be input into the drive circuit203. At this time, the motor relay1122also operates to bring the power source line M− to the disconnected state. Therefore, the motor112is brought into the free state.

Here, while the motor112is rotating, the insertion section101self-propels against the body load. If the motor112becomes free in this state, there is a possibility that the influence of the body load causes the motor112to rotate in a reverse direction to the previous rotating direction. By such a reverse rotation (regeneration) of the motor112, the motor112itself serves as an electric power generator to generate a regeneration voltage.FIG. 3illustrates an example in which the regeneration causes the motor112to rotate backward, and a regeneration voltage occurs in the power source line M−. There is a possibility that such a regeneration voltage has an adverse effect on the drive circuit203and the like.

Hence, in the present embodiment, the protecting operation for protecting the sections of control apparatus200from the regeneration voltage is performed in the regeneration control state being a state immediately after the state where the foot switch201is stepped on is switched to the state where the foot switch201is not stepped on. Specifically, the regeneration controller2023recognizes that the control of the motor112is currently stopped since the servo control signal is switched from on to off. At this time, the regeneration controller2023turns on the regeneration control signal. The first regeneration resistor switching circuit2042ais thereby turned on, and the first regeneration resistor2041ais earthed. Similarly, the second regeneration resistor switching circuit2042bis also turned on, and the second regeneration resistor2041bis earthed. This causes, as illustrated inFIG. 2, a regeneration current RC corresponding to the regeneration voltage to flow to the ground via the regeneration resistor2041. The regeneration voltage is thereby prevented from being applied to the drive circuit203and the like. Note thatFIG. 2illustrates an example in which the motor112rotates forward due to the regeneration. In this case, the regeneration current RC flows to the ground via the second regeneration resistor2041b.In contrast, when the motor112rotates backward by the regeneration, the regeneration current RC flows to the ground via the first regeneration resistor2041a.

Here, since the motor power source lines1121are near the encoder power source line1141as described above, there is a possibility that a short circuit fault occurs between a motor power source line1121and the encoder power source line1141, as illustrated by S inFIG. 2. If a motor power source line1121is short-circuited to the encoder power source line1141, current flows from the encoder power source line1141to the motor112. If the regeneration resistor2041is earthed at this time, the encoder power source line1141, the motor112, the regeneration resistor2041, and the ground form a closed circuit, and the motor112is thereby caused to rotate although the foot switch201is not stepped on.

The regeneration of the motor112occurs under the influence of the body load. Therefore, if the body load to the motor112disappears, the rotation of the motor112ends. After the rotation of the motor112has ended, there is no possibility that such the regeneration voltage has the adverse effect on the drive circuit203and the like even when the regeneration resistor2041is opened.

Hence, in the embodiment, the regeneration controller2023determines whether the motor112has been stopped, based on the encoder signal after short-circuiting the regeneration resistor2041(turning on the regeneration resistor switching circuit2042). When determining that the motor112has been stopped, the regeneration controller2023then determines whether the predetermined set time has elapsed, and when determining the set time has elapsed, the regeneration controller2023turns off the regeneration resistor switching circuit2042to open the regeneration resistor2041. This enables restraint on an unintended rotation of the motor112even when a short circuit thereafter occurs between a motor power source line1121and the encoder power source line1141. Note that the set time may be a fixed time or may be set as appropriate according to, for example, a possible magnitude of the load. The magnitude of the load can be detected based on, for example, the magnitude of current supplied to the motor112.

According to the embodiment, as described above, providing the regeneration protection circuit between the motor and the drive circuit enables the sections of the control apparatus such as the drive circuit to be protected from the regeneration voltage generated by the regeneration of the motor due to, for example, the influence of the body load.

In addition, in the embodiment, the protecting operation by the regeneration protection circuit is not performed at timings when the regeneration does not occur, such as in the foot-switch not-stepped-on state and in the foot-switch stepped-on state. By not performing the protecting operation by the regeneration protection circuit all the time, the load on the motor can be kept low as compared with a case where the regeneration resistor is always interposed.

In addition, in the present embodiment, the protecting operation by the regeneration protection circuit is configured not to be performed at a timing when the regeneration of the motor is considered to disappear in the regeneration control state. This enables restraint on an unintended rotation of the motor even when a short circuit occurs between a motor power source line and the encoder power source line. That is, in the foot-switch not-stepped-on state, the motor is in the free state, and thus the protecting operation by the regeneration protection circuit is not performed even when the short circuit occurs between a motor power source line and the encoder power source line. That is, since the regeneration resistor is not earthed, the motor does not rotate. In contrast, in the foot-switch stepped-on state, when the short circuit occurs between a motor power source line and the encoder power source line, the motor rotates also on the current from the encoder power source line. In this case, however, since the motor is under the control by the drive controller, the rotating speed of the motor is a rotating speed corresponding to the amount of depression of the foot switch even when the short circuit occurs between a motor power source line and the encoder power source line.

In addition, the regeneration protection circuit in the embodiment has a simple configuration comprising resistors and switches. This contributes to a reduction in size of the control apparatus. Furthermore, by making the regeneration protection circuit on the M+ side and the regeneration protection circuit on the M− side have the same configuration, the configuration of the control apparatus can be further simplified.

The invention has been explained based on the embodiment; however, the present invention is not limited to the embodiment. The present invention may be, of course, modified in various ways without departing from the gist and scope of the invention. For example, in the above-described embodiment, a rotating body for moving the insertion section101of the endoscope100forward and backward is the spiral tube105. In contrast to this, the technique according to the present embodiment is applicable to various insertion devices that move the insertion section101forward and backward using a rotating body.