JP2001309911A - X-ray imaging device for round visit by doctor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray imaging device for round visits by doctors that can be smoothly operated at the start, additional, regular and reduced velocities and at a sudden stop to meet an emergency. SOLUTION: CPU 11 receives input signals F from a laver handle 14 and velocity signals V from right and left encoders 3, 4 provided at wheel shafts and judges whether or not it is in acceleration or deceleration and switches the circuit of a bridge-structured switching element of a motor driving circuit 9 through a switching circuit 37 at the off-duty time of a PWM control circuit 10. When in the acceleration, the switching element of grounded side is turned onto reflux the counter electromotive force at the time of switching off, while, when in the deceleration, all the switching elements are turned off to enable smooth operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power-driven X-ray apparatus that moves forward or backward in response to the force of an operating handle, and more particularly, to a power-driven X-ray apparatus that has a drive motor positioned at the center of a bridge.
A drive bridge circuit composed of switching elements, and the torque of the motor is turned on and off by the bridge circuit.
Round X having pulse width control circuit for duty control
The present invention relates to a radiographic apparatus.

[0002]

2. Description of the Related Art FIG. 5 shows a conventional X-ray imaging apparatus for rounds. (A) is a front view, (b) is a side view, and (c) is a top view. The apparatus includes an X-ray tube 18, an arm 19 for holding the X-ray tube 18, a column 20 that can be turned on a carriage 21, and a vertical moving unit that moves the arm 19 up and down along the column 20.
A lower wheel is provided by operating a lever handle 14 provided on a handle holding base 17 attached to a bogie 21 back and forth, including a front wheel 23 which can be turned freely and a rear wheel 22 (right wheel 2 and left wheel 1) which cannot be steered. And a carriage 21 mounted with an X-ray control unit that moves forward or backward with the drive motors (right motor 6 and left motor 5) provided in the vehicle.

[0003] An arm 19 having a support mechanism and a rotation mechanism for the X-ray tube 18 and extending and contracting in the horizontal direction is provided.
The mechanism is designed so that it can move vertically vertically and balance well, and the collimator (X-ray emission port) of the X-ray tube 18 is provided in all directions and spatial positions according to the imaging region of the subject. The weight of this round radiography device is 450
It is very difficult to move the trolley without the help of power, as it can be over kg. Generally, a pair of fixed non-steerable rear wheels 22 are provided at the rear of the cart 21,
The front part of the carriage 21 is supported by a pair of casters, that is, a front wheel 23 that can freely turn. The rear wheels 22 are generally driven by drive motors (right motor 6, left motor 5) mounted on a truck.

[0004] The truck 21 has a main circuit of 100 to 120 V and 60 Hz as an internal power source, including a vehicle battery and an inverter, and includes a high-voltage transformer and a capacitor.
The control circuit is implemented as a solid system, and one-touch type devices in which photographing operations are automatically programmed are often used.

[0005] The cart 21 uses rubber tires or the like.
It is designed to be freely accessible in and out of hospital rooms, operating rooms and elevators, and has a brake system, cassette box and accessories. It is important that this round radiography apparatus is small and lightweight and has good operability as a mobile device, and is used in hospitals such as bedrooms, labs, operating rooms,
It easily moves to a children's room, an X-ray room, an infant room, etc., and is easily used for X-ray photography on site.

FIG. 6 shows a control block diagram of the X-ray apparatus for a round examination. 6 are driven by a left motor 5 and a right motor 6, respectively, and the left motor 5 and the right motor 6 are individually controlled by a motor drive circuit 9. The switching of the motor drive circuit 9 is controlled by a PWM control circuit 10 by pulse width control (PWM). The duty control width of the switching control is controlled by a signal from the CPU 35. When the operator operates the lever handle 14 of the carriage 21 back and forth, the signals from the left pressure sensor 15 and the right pressure sensor 16 provided at both ends of the lever handle 14 are left and right independent as a left input 12 and a right input 13. The values are input to the CPU 35 as left Ft and right Ft.

On the other hand, signals from the left encoder 3 and the right encoder 4 provided on the axles of the left wheel 1 and the right wheel 2 for detecting the rotation speed are supplied to the CPU from the left and right rotation speed Vt signals.
35 is input. Then, from the forward and backward input signals Ft from the left pressure sensor 15 and the right pressure sensor 16 and the speed signal Vt from the left encoder 3 and the right encoder 4, the CPU 35 generates a duty control width signal corresponding to the switching control. Input to the PWM control circuit 10 and P
The WM control circuit 10 controls the motor drive circuit 9, and the motor drive circuit 9 controls the rotation speed of the left motor 5 and the right motor 6.

FIG. 7 shows a driving circuit of the motor 34 by the PWM control circuit. (A) shows an operation state and (b) shows a stop state. Motor 34 has switching elements SW24, SW2
5, is disposed at the center of the bridge circuit composed of SW26 and SW27, and is subjected to switching control by the PWM control circuit 10. SW24, S to rotate the motor 34 in the forward direction
W27 is turned on, and SW25 and SW26 are turned off. DC power supply 28 to SW 24, point A, motor 34, B
The current flows through the point, the SW 27, and the ground 33, and the motor 34 rotates forward.

[0009] In order to reverse rotation, SW25,
SW26 is turned on, and SW24 and SW27 are turned off. DC power supply 28 to SW 25, point B, motor 34, A
A current flows through the point, the SW 26 and the ground 33, and the motor 34 rotates in the reverse direction. To increase or decrease the driving force of the motor 34, the ON-OFF duty control width of each switching element is set to P
This is performed under the control of the WM control circuit 10. When the motor 34 is stopped, all the switching elements SW24, SW25, SW26 and SW27 are turned off.

The lever handle 14 is connected to the carriage 21 via a relatively rigid but flexible spring member. The two spring members connected to both sides of the carriage 21 are constituted by rigid leaf springs. By providing the spring members, the two spring members respond to a force applied to the lever handle 14 such as pushing or pulling the lever handle 14. And lever handle 1
4 can be slightly displaced in the front-back direction.

At both ends of the lever handle 14, a pair of linear magnets that move together with the lever handle 14 are attached. On the other hand, a pair of Hall effect sensors (the left pressure sensor 15 and the right pressure sensor 16) are mounted on the bogie 21 and arranged adjacent to the corresponding magnets. The Hall effect sensors are each connected to a power supply (not shown). Hall effect sensor (left pressure sensor 15,
When the right pressure sensor 16 is at the center position with respect to the magnet, the output signals of the Hall effect sensors (the left pressure sensor 15 and the right pressure sensor 16) become zero level. The output signal of the pressure sensor 15 and the right pressure sensor 16) changes substantially linearly between a positive maximum value and a negative maximum value.

The sign or polarity of the sensor signal indicates the direction of displacement of the lever handle 14, and the magnitude of the sensor signal is proportional to the amount of displacement. By operating the lever handle 14 back and forth, the lever handle 14 can be relatively easily displaced by the spring action of the spring member,
When the lever handle 14 is released, it can be quickly returned to the neutral position or the center position.

[0013]

The conventional X-ray apparatus for medical examination is constructed as described above. However, the lever handle 14 has its both ends held by leaf springs of a spring member and the like. A mechanism that returns the lever handle 14 to the neutral position when the operating force is zero while supporting the load in the direction of gravity, and for detecting the operating force, the position of the magnet attached to the lever handle 14 is determined by the Hall effect. A method of detecting with a sensor (or a method of attaching a strain gauge to a leaf spring supporting the lever handle 14 is also used), however, the bridge circuit of the switching element is O
At the time of the FF duty, all the switching elements are turned off. At a duty of 50% or less, at the moment when the duty becomes the OFF duty, the energy stored in the inductance of the motor 34 does not return, and acts in the opposite direction to the ON duty, so that the motor 34 does not rotate. There's a problem.

In order to solve this problem, there is a drive circuit for the motor 34 by PWM control as shown in FIG.
Motor 34 has switching elements SW24, SW25, S
It is arranged at the center of the bridge circuit composed of W26 and SW27, and is subjected to switching control by the PWM control circuit 10. SW24 and SW25 are n-channel power MOS
FETs are used, and p-channel power MOSFETs are used for SW26 and SW27. In order to rotate the motor 34 in the normal direction, the switch at the top of FIG.
Turn ON.

On the other hand, the gates of SW24 and SW26 are grounded 33, and SW24 is ON and SW26 is OFF. Therefore, SW24 and SW27 are turned ON, SW25,
The switch 26 is turned off. DC power supply 28 to SW 24, point A, motor 34, point B, SW 27, ground 3
3 and the current flows, and the motor 34 rotates forward. In order to perform reverse rotation, the upper switch in FIG. 8 is switched to the opposite side and controlled. To increase or decrease the driving force of the motor 34, the PWM control circuit 10 controls the ON / OFF duty control width of each switching element.

However, when the PWM pulse of the PWM control circuit 10 changes from H (HIGH) to L (LOW), SW
27 changes from the ON state to the OFF state, and SW 25 changes from the OFF state to the ON state. On the other hand, SW24 is ON state,
SW 26 is held in the OFF state. At this time, the drive voltage applied to the DC motor 34 changes from a predetermined value to zero. Therefore, a back electromotive force is generated between the two terminals of the motor 34, and the point A has a higher potential than the point B. At this time, A
A closed circuit of a path consisting of a point, a motor 34, a point B, SW25, SW24, and a point A is formed.

Therefore, an annular current, that is, a circulating current, flows through the closed circuit due to the back electromotive force. In this case, a diode D3 is connected between the source and the drain of SW25.
0 is provided in a forward direction with respect to the reflux. However, the forward resistance of D30 is sufficiently larger than the resistance between the source and the drain in the ON state of SW25. Therefore, most of the circulating current flows through between the source and the drain of SW25, and the current flowing through D30 is small.

However, using the above technique, the motor 3
As the rotation speed of the motor increases, a short brake more than necessary occurs during the OFF duty. In particular, round X
The radiographic apparatus has a structure in which the operator presses the handle of the traveling apparatus, so that the force applied during acceleration is easily released. Therefore, there is a problem that an excessive brake is generated at the moment when the force is released, and the jerky behavior is exhibited.

The present invention has been made in view of such circumstances, and enables a smooth start at startup, no jerky behavior during acceleration and constant speed, and a smooth deceleration at deceleration. An object of the present invention is to provide an X-ray imaging apparatus for a round-trip which can be suddenly stopped during an emergency stop.

[0020]

In order to achieve the above-mentioned object, the X-ray imaging apparatus for medical examination according to the present invention is independent of left, right, front and rear in accordance with the operation force applied to both ends of the operation handle in the traveling direction. A pressure sensor that is provided and detects an operating force that is squeezed, a pair of independently driven drive wheels, a motor provided on the shaft of the wheel, and a switching element that positions the motor at the center of the bridge The configured driving bridge circuit and the motor torque are turned on by the bridge circuit.
A pulse width control circuit for performing OFF duty control, and an encoder for detecting a rotation speed of a driven wheel,
Controlling the torque of the left and right motors in response to the signal from the pressure sensor and the signal from the encoder, and in a X-ray imaging apparatus for medical examination that moves by rotating a drive wheel, the signal from the pressure sensor and the signal from the encoder Means for judging whether the vehicle is accelerating or decelerating from the signal, and when the pulse width control circuit is in an OFF duty, when the vehicle is accelerating or traveling at a constant speed, the switching element connected to the ground side is turned off.
N, and a switching circuit that controls so that all the switching elements are turned off during deceleration traveling.

The X-ray radiographic apparatus for roundtrip of the present invention is configured as described above. When the pulse width control circuit is in the OFF duty, the CPU of the apparatus receives a signal from the pressure sensor and a signal from the encoder. It is determined whether the vehicle is accelerating or decelerating, and a switching circuit is provided. When the device is accelerating or traveling at a constant speed, the switching element of the bridge circuit connected to the ground side is controlled to be turned on. Therefore, the energy accumulated in the inductance of the motor is circulated, and the energy during the ON duty is not cancelled. When the motor rotates, a torque acts in a direction opposite to the rotation, so that a short brake torque proportional to the speed is generated.

As a result, the jerky behavior during acceleration and constant speed is eliminated, and an emergency stop can be performed during an emergency stop. In addition, during deceleration traveling, a switching circuit is provided and controlled so that all the switching elements are turned off, so that the energy at the ON duty is canceled by the reverse voltage generated in the inductance at the time of stopping. Since no short brake occurs during rotation of the motor, the motor can be decelerated smoothly during deceleration. Then, a smooth start can be made at the time of startup.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the X-ray imaging apparatus for a round examination according to the present invention will be described with reference to FIG. FIG. 1 is a diagram showing a control circuit of the X-ray imaging apparatus for a round examination of the present invention. The present device is provided independently on the left, right, front and rear in accordance with a pair of independently driven drive wheels (left wheel 1 and right wheel 2) and operation forces applied to both ends of the lever handle 14 in the traveling direction. A pressure sensor (left pressure sensor 1) that detects operating force when pressed
5, right pressure sensor 16), left and right independent motors (left motor 5, right motor 6), and encoders (left encoder 3, right encoder 4) for detecting the rotational speed of the driven wheels. , Input signals F from pressure sensors (left pressure sensor 15 and right pressure sensor 16) and wheel rotation speed V from encoders (left encoder 3 and right encoder 4)
CPU 11 having a judgment circuit for judging whether the vehicle is accelerating or decelerating in response to the above signal, and a PWM control circuit 1 for controlling the pulse width of the motor drive circuit 9 in response to the signal from the CPU 11
0, and a switching circuit 37 which receives a signal determined by the CPU 11 via the PWM control circuit 10 and controls ON / OFF of each switching element of the motor driving circuit 9, thereby enabling the left and right motors (left motor 5, right motor 6) and a motor drive circuit 9 for controlling

The motor drive circuit 9 is, as shown in FIG.
The motor 34 has switching elements SW24, SW25,
It is arranged at the center of the bridge circuit composed of SW26 and SW27, and is subjected to switching control by the PWM control circuit 10. To increase or decrease the driving force of the motor 34, the PWM control circuit 10 controls the ON-OFF duty control width of each switching element. The apparatus further includes switching switches 35a and 35b and switching switches 36a and 36b that determine whether the CPU 11 is accelerating or decelerating at the time of the OFF duty and switch the circuit of each switching element controlled by the above-described duty cycle. It operates at the OFF duty.

At the time of OFF duty, the CPU 11
The signal determined in step (1) is input via the PWM control circuit 10 to the switching switches 35a, 35b, 36a, and 36b that control ON-OFF of each switching element of the motor drive circuit 9. Thereby, all the switching elements SW24, S
W25, SW26 and SW27 are controlled to perform the operation at the OFF duty.

The CPU 11 receives the input signal F from the pressure sensors (the left pressure sensor 15 and the right pressure sensor 16) and the signal of the wheel rotation speed V from the encoders (the left encoder 3 and the right encoder 4). A determination circuit is provided for determining whether the vehicle is accelerating or decelerating. Table 1 shows the PWM control circuit 1
Each switching element SW of the bridge configuration of the motor drive circuit 9 at the time of OFF duty by the control signal of 0
24 shows ON-OFF states of SW24, SW25, SW26, and SW27.

[0027]

[Table 1] The criterion for determining whether the vehicle is accelerating or decelerating is performed as follows. The input signal F from the pressure sensors (the left pressure sensor 15 and the right pressure sensor 16) is 0 when there is no lever input, + in the forward pushing state, and-in the backward moving state. The rotation speed V from the encoders (left encoder 3 and right encoder 4) is 0 when the wheels (left wheel 1 and right wheel 2) are stopped, + when the wheels are rotating forward (forward), When the motor is rotating backward (retreating), the value is set to-. When F = 0, V = 0, stop, F = +, when V = 0, start forward, F =-, V =
When 0, it starts and retreats, when F = 0, V = +, it decelerates, F =
Forward acceleration when +, V = +, deceleration when F =-, V = +, deceleration when F = 0, V =-, deceleration when F = +, V =-, F =- , V =-, it is determined that the vehicle is moving backward.

At the time of the OFF duty, the CPU 11 sets the switching switches 35a and 35b and the switching SWs 36a and 36b as shown in Table 1.
And the switching elements SW24, SW25, SW26, and SW2 of the bridge configuration of the motor drive circuit 9.
7 is controlled as shown in Table 1. LOW SIDE in Table 1
SW refers to a switching element on the side where the drain electrode of the switching element is grounded. UP SIDE
SW refers to a switching element on the side where the drain electrode of the switching element is not grounded. FIG.
The state of each switching element during deceleration at the time of duty is shown. (A) shows a state when the motor 34 is rotating forward, and (b) shows a switching state at the time of deceleration at OFF duty. That is, control is performed so that all the switching elements are turned off during deceleration traveling.

FIG. 4 shows the state of each switching element during acceleration and constant speed during OFF duty. (A) shows a state when the motor 34 is rotating forward, and (b) shows an OF state.
This shows the switching state during acceleration and constant speed during F-duty. That is, when the vehicle is accelerating or traveling at a constant speed, control is performed so that the switching element, which is connected to the ground side and flows a current in the positive direction, is turned on.

Next, the operation of the present apparatus will be described with reference to FIG. S of bridge-structured switching element
W24, SW25, SW26, and SW27 use n-type power MOSFETs. When the apparatus is stopped, the switching switches 35a and 35b are set to the H (HIGH) side,
36a and 36b are switched to the L (LOW) side,
SW24 and SW25 are OFF, SW26 and SW27 are O
N state.

When F = + is activated (during acceleration), O
When the duty is N, the switching switches 35a and 36b are in the L state, and the switching SWs 35b and 36a are in the H state. Therefore, SW24 and SW27 are turned on,
DC power supply 28 to SW 24, point A, motor 34, point B,
A current flows through the SW 27, and the motor 34 rotates.
At the time of OFF duty, the switching switches 35a, 35
b and 36a are in the H state, and the switch SW 36b is in the L state. Therefore, SW24, SW25 and SW26 are O
FF state, SW27 (LOW SIDE SW)
Is turned on.

In this state, the energy stored in the inductance of the motor 34 is equal to the motor 34, the point B, the SW2
7, in the circuit of D31, point A, and the motor 34, the current flows and circulates. Then, the energy during the ON duty is not canceled out, and a torque acts in a direction opposite to the rotation when the motor 34 rotates, so that a short brake torque proportional to the speed is generated. Therefore, the jerky behavior at the time of acceleration and at a constant speed is eliminated, and an emergency stop can be performed at the time of an emergency stop.

Next, during traveling, when the input signal F = 0 from the pressure sensors (the left pressure sensor 15 and the right pressure sensor 16) (when the lever handle 14 is in a free state), that is, when the vehicle is decelerated, the OFF duty state is obtained. And switch SW
35a, 35b, 36a, 36b all become H state, and the switching elements SW24, SW25, SW26,
All the switches 27 are turned off. Therefore, the ON voltage is generated by the reverse voltage generated in the inductance at the time of stop.
Since the energy at the time of duty is canceled and no short brake occurs at the time of rotation of the motor 34, it is possible to smoothly decelerate at the time of deceleration.

In addition, as shown in Table 1, there are nine operating states as a whole, and as described above, when the vehicle is accelerating or running at a constant speed during the OFF duty, it is connected to the ground side. The switching elements are controlled to be turned on, and all the switching elements are set to O
By controlling the switching circuit 37 so as to be the FF, it is possible to perform a smooth start, a non-jerky acceleration running, and an emergency stop.

[0035]

According to the present invention, the X-ray imaging apparatus for a round examination is constructed as described above, and the CPU controls the operation signal from the pressure sensor provided on the lever handle and the speed from the encoder provided on the axle. Upon receiving the signal, it is determined whether the vehicle is accelerating, traveling at a constant speed, or decelerating, and the pulse width control circuit is turned off.
At the time of duty, the switching element connected to the ground side of the bridge configuration of the motor drive circuit is turned on during acceleration or running at a constant speed by the switching circuit. Therefore, the back electromotive force energy due to the inductance of the motor at the time of switch OFF can be circulated in the circuit, and the energy at the time of ON duty is not canceled out, and the torque acts in the opposite direction to the rotation at the time of motor rotation. A short brake torque proportional to the speed is generated. Therefore, the jerky behavior at the time of acceleration and at a constant speed is eliminated, and an emergency stop can be performed at the time of an emergency stop.

Also, since all the switching elements are turned off by the changeover switch during deceleration, the back electromotive force due to the inductance of the motor causes the O
The energy at the time of N duty is canceled. Since short braking does not occur during rotation of the motor, deceleration can be performed smoothly during deceleration. Further, at the time of startup, a smooth start can be achieved by switching the Hall effect sensor provided on the lever handle 14 and the switching element.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a round-trip X-ray imaging apparatus according to the present invention.

FIG. 2 is a diagram showing a switch switching circuit of the X-ray imaging apparatus for a round examination according to the present invention.

FIG. 3 is a diagram illustrating an operation state of a switch switching circuit during deceleration of the X-ray imaging apparatus for round-trip examination of the present invention.

FIG. 4 is a diagram showing an operation state of the switch switching circuit during acceleration and constant speed of the X-ray imaging apparatus for roundabout according to the present invention.

FIG. 5 is a diagram showing an external appearance of a round examination X-ray imaging apparatus.

FIG. 6 is a drive circuit diagram of a conventional X-ray imaging apparatus for a round examination.

FIG. 7 is a diagram showing a motor drive circuit by PWM control of a conventional X-ray imaging apparatus for round-trips.

FIG. 8 is a diagram showing another motor drive circuit by PWM control of a conventional round radiography apparatus.

[Explanation of symbols]

Reference Signs List 1 left wheel 2 right wheel 3 left encoder 4 right encoder 5 left motor 6 right motor 7 left output 8 right output 9 motor drive circuit 10 PWM control circuit 11 CPU 12 left input 13 ... Right input 14 ... Lever handle 15 ... Left pressure sensor 16 ... Right pressure sensor 17 ... Handle holder 18 ... X-ray tube 19 ... Arm 20 ... Strut 21 ... Dolly 22 ... Rear wheel 23 ... Front wheel 24 ... SW 25 ... SW 26 ... SW 27 ... SW 28 ... DC power supply 29 ... D 30 ... D 31 ... D 32 ... D 33 ... ground 34 ... Motor 35a ... Switch SW 35a ... Switch SW 36a ... Switch SW 36b ... Switch SW 37 ... Switch circuit

Claims (1)

[Claims] 1. A pressure sensor which is provided independently at the left, right, front and rear in accordance with an operation force applied to both ends of an operation handle in a traveling direction and detects a pressed operation force, and a pair of independently driven drives A wheel, a motor provided on a shaft of the wheel, a driving bridge circuit including the motor at the center of the bridge and including a switching element, and ON-OFF duty control of the motor torque by the bridge circuit. A pulse width control circuit, and an encoder that detects the rotational speed of the driven wheel, receives the signal from the pressure sensor and the signal from the encoder, controls the motor torque, and rotates the drive wheel. The moving X-ray apparatus for medical examination has means for determining whether acceleration or deceleration is being performed based on a signal from the pressure sensor and a signal from an encoder. When OFF duty of the scan width control circuit, when during acceleration or constant speed running is controlled to be ON the switching element connected to the ground, all the switching elements in the case during deceleration traveling O
An X-ray imaging apparatus for a round examination, comprising: a switching circuit for controlling an FF.