JPS6327699Y2 - - Google Patents

Description

[Detailed explanation of the idea] This invention relates to an X-ray tomography apparatus.

2. Description of the Related Art In this type of apparatus, an apparatus is known that uses a certain tomographic plane of a subject as a reference and successively photographs tomographic planes at predetermined intervals from that tomographic plane. In this case, the center of rotation of the imaging device, including the X-ray tube, needs to be raised and lowered by a predetermined distance for each imaging session, but conventionally, a timer is used to set this fixed distance of elevation. Ordinarily, a limit switch was used.
When using a timer, it is sufficient to drive the timer every time one photograph is completed, and move the center of oscillation at a constant speed for a preset period of time. It has been difficult to always accurately move a fixed distance due to variations in the photographing device itself and fluctuations in the weight of the entire photographing device. If limit switches are used, a plurality of limit switches may be set at predetermined intervals along the travel path of the imaging device, and the limit switches may be operated one after another as the imaging device moves. However, according to this, the reference section is not always at the same height, so the set position of each limit switch must be adjusted each time, and the set position of each limit switch must be determined according to the fault plane interval. There are some inconveniences that you have to deal with.
Furthermore, in any of these cases, it is extremely difficult and troublesome to set the minimum fault interval.

The purpose of this invention is to enable the fault spacing to be set easily and accurately.

This idea includes a detection plate that rotates according to the movement of changing the tomographic plane, and generates a pulse every time it rotates by a unit angle, and each time the number of pulses reaches a predetermined number, the change of the tomographic plane starts. This is intended to enable accurate rotation detection by stopping the rotation and setting the detection plate at the correct relative position at the beginning of photographing.

An embodiment of this invention will be described with reference to the drawings. In FIG. It doesn't move, 6 is the center axis of the swing,
Reference numeral 7 denotes a pointer indicating the height of the tomographic plane to be photographed, which is installed on the axis of the swing center shaft 6, and moves up and down as a unit. Reference numeral 8 denotes an elevating device, in which a slider 11 is screwed into a screw shaft 10 rotatably supported by a fixed frame 9.
moves up and down in unison. The screw shaft 10 rotates as the rotation of the motor 12 is transmitted through a pulley 13, a belt 14, and a pulley 15 that is integral with the screw shaft 10. Slider 1 by unit angle rotation of screw shaft 10
The vertical distance of No. 1 can be known in advance. Therefore, by determining the rotation angle of the screw shaft 10, it becomes possible to set the vertical distance of the swing center shaft 6, and thus the height of the tomographic plane.

Detection device 1 for knowing the rotation angle of the screw shaft 10
6 is a detection plate 17 that rotates integrally with the pulley 15;
is prepared, and a detector 18 is fixedly supported by a fixed frame 19 across its periphery. In the example shown in the figure, the detection plate 17 has a plurality of notches 20 formed at equal intervals (one piece may be sufficient), and the detector 18
A photodetector is used as a. Specifically, it is constructed by installing a light emitting diode on one side of the periphery of the detection plate 17 and a phototransistor on the other side, so that one pulse is generated each time the notch 20 passes between the two. There is.

Reference numeral 21 denotes a position correction device for the detection plate, which is composed of a cam 22, a rotary solenoid 23, and a lever 24.

In the illustrated configuration, the detection plate 17 does not always rotate together with the pulley 15, but rather rotates in a direction perpendicular to the pulley 15.
Cam 2 is attracted by a permanent magnet M embedded in
A cam 22 is provided, to which a detection plate 17 is fixed, and the rotation of the pulley 15 is transmitted to the detection plate 17 via the cam 22 attracted by a permanent magnet M. Therefore, when a rotational force is applied separately to the cam 22 as described later, the cam 22 can rotate independently of the cam 22 against the attractive force of the permanent magnet M. In the illustrated example, the cam 22 is composed of a parallel surface 25 parallel to the straight line connecting the notches 20, and approximately triangular end surfaces 26 on both ends of the parallel surface 25. When the rotary solenoid 23 is excited, the lever 24 rotates clockwise.
When this rotation strikes the cam 22, the cam 22 rotates, sliding on the surface of the pulley 15, and when the lever 24 comes into contact with the parallel surface 25, the lever 24 can no longer rotate any further.
The cam 22 stops. At this stop position, the notch 20 is located directly below the detector 18 as shown in Figures 4 and 7. This allows the detector plate 17 to be set at a preset relative position with respect to the detector 18.

The pulses emitted from the detector 18 are sent to the counter 3
Counted by 1. On the other hand, when the fault interval is set in advance by the setter 32, the number of pulses equal to the number of pulses from the detector 18 when raising and lowering the rotation center shaft 6 by that interval is automatically set in the setter 33. Ru. The count value of the counter 31 and the value set by the setting device 33 are determined by a matching circuit 34, and a signal output when the two values match is sent to the motor 12.
is applied to the stop circuit 35, thereby stopping the motor 12. A starting circuit 36 is separately prepared,
A signal is given each time one shooting is completed. As a result, the motor 12 starts rotating and continues to rotate until a signal is applied to the stop circuit 35.

In the above configuration, when tomography is to be performed continuously, the motor 12 is first driven to raise and lower the swing center shaft 6 to match the height of the tomographic plane with the pointer 7 as a reference. At this time, the detection plate 1
7 rotates at the same time, so when the reference tomographic plane and the swing center axis 6 are adjusted to match in height, the notch 20 of the detection plate 17 is not necessarily directly below the detector 18. For example, it may be located at a position offset from the detector 18 as shown in FIG. If continuous shooting is started in this state, the detection plate 17 will initially be at a predetermined angle (in the example shown in the figure).
Detector 18 to 1 when correct by 180 degrees)
Therefore, the number of pulses corresponding to the vertical distance of the swing center shaft 6 cannot be generated.

In order to avoid this, the notch 20 may be adjusted to be directly below the detector 18 prior to the start of imaging. Therefore, when the rotary solenoid 23 is energized, the lever 24 rotates counterclockwise, and the cam 22
Rotate. As a result, the detection plate 17 also rotates, and when the notch 20 reaches directly below the detector 18, the lever 24 abuts parallel to the parallel surface 25 of the cam 22 (see FIG. 7). This causes the detection plate 17 to move at a predetermined angle (180 degrees in the example shown).
Correctly one pulse is generated from the detector 18 each time it rotates, so that the central axis of oscillation 6
The detector 18 detects the number of pulses that correctly corresponds to the vertical distance.
It becomes possible to emanate from. In other words, it is possible to control the vertical distance with high precision.

As mentioned above, the reference fault plane and the central axis of oscillation 6
After energizing the rotary solenoid 23 and moving the notch 20 directly below the detector 18 (then, if the rotary solenoid 23 is returned, the lever 24 will return to its original position). ), then start shooting. Since a signal is given to the start circuit 36 every time one photographing is completed, the motor 12
starts rotating, and the swing center shaft 6 moves up and down in a predetermined direction. The detection plate 17 rotates as the motor 12 rotates, and a pulse is emitted every time the detection plate 17 rotates by a predetermined angle. This is counted by the counter 31, and if the counted value and the set value by the setting device 33 match, the motor 12 is stopped. The vertical distance of the swing center shaft 6 during one rotation of the motor 12 is nothing but a predetermined fault interval. Next photographing is started in conjunction with the stop of the motor 12 or manually. By repeating this process, tomographic planes can be photographed continuously.

Although the illustrated embodiment uses a permanent magnet M, a spring may be used instead. That is, the cam 22 may be pressed against the cam 22 by the elastic force of the spring, for example, from above, and the cam 22 may be rotated by the lever 24 against this elastic force.

As detailed above, according to this invention, the moving distance of the height of the tomographic plane to be imaged is converted into the number of pulses, and this is compared with a set value to control the moving distance, so it is different from the conventional method. By comparison, it is extremely easy to set and control the tomographic interval, and since the position of the detection plate for pulse generation is set at a predetermined position prior to imaging, the number of pulses and the vertical distance can always correspond correctly. Therefore, it is possible to perform highly accurate control.

[Brief explanation of the drawing]

Figure 1 is a front view showing an embodiment of this invention, Figure 2 is a front view showing an embodiment of this invention.
The figure is a block diagram of the control device, Figure 3 is a partially enlarged front view, Figure 4 is a plan view of the same, Figure 5 is a partial cross-sectional view, and Figures 6 and 7 are for explanation of operation. FIG. 4... X-ray tube, 6... Swinging center axis, 8... Elevating device, 12... Motor, 16... Detecting device, 17
...detection plate, 18 ...detector, 21 ...position correction device, 31 ...counter, 32, 33 ...setting device, 34 ...matching circuit, 35 ...stopping circuit.

Claims (1)

[Scope of utility model registration request] a detection plate that rotates in response to an operation of changing a tomographic plane to be imaged; a detector that generates a pulse every time the detection plate rotates by a unit angle; and a detection plate that generates a pulse when the number of pulses from the detector reaches a set value. X comprising a control device that sometimes stops the operation of changing the tomographic plane, and a position correction device that sets the detection plate at a predetermined relative position with respect to the detector prior to imaging.
Linear tomography device.