JP2001190540A - Error detector for position detection means - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an error detector for position detection means for controlling the travel of a pedestal of an X-ray CT apparatus. SOLUTION: In a configuration for controlling travel in which a position is detected by a rotary encoder 12 attached to the pedestal 20, a detection current I is conducted onto a meshing face of a detection gear 2 and a track gear 3 and is monitored in a current detection circuit 4. Moreover bevel gear 15 is used to prevent the adhesion of dust. Position detection accuracy of the rotary encoder 12 can be maintained by providing a charged brush 18 and an absorbing duct 19 to remove dust.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an error detecting device for a position detecting means, and more particularly to an error detecting device for a position detecting means used in combination with an X-ray CT apparatus.

[0002]

2. Description of the Related Art Conventionally, an X with a movable frame is used.
X-ray CT apparatuses are used in clinical settings. As shown in FIG. 6, in these X-ray CT apparatuses, a track groove 13 is provided on the floor 14 as means for moving the gantry 20, and the trajectory of the gantry 20 is guided by the track groove 13.
The movement of the gantry 20 is performed using a power source such as a motor (not shown), and a predetermined operation control of the motor is performed by a microprocessor or the like (not shown), for example, a predetermined movement is performed in the L direction in the figure. For this operation control, it is necessary to detect the movement state of the gantry 20 as position information,
For example, position detection means using an encoder such as a rotary encoder is used.

In position detection by this encoder, an encoder is provided on a gantry 20 and a gear is provided on a rotary shaft of the encoder. The gear provided on the rotary shaft of this encoder meshes with the gear provided on the track groove 13 provided on the floor surface 14, and the rotary shaft rotates as the gantry 20 moves.
A signal for position detection is output from the encoder by the rotation of the rotating shaft. Based on this position detection signal, position information such as the moving amount, moving speed, direction, and absolute position of the gantry 20 is input to a drive control unit for driving the gantry 20.

The drive control unit outputs a drive signal to a motor for driving the gantry 20 based on a position detection signal input from an encoder. In the built-in microprocessor, the gantry 20 moves based on an instruction input from an operator or an operation sequence input in advance, and a position detection signal from the encoder.

[0005]

However, the conventional encoder position detection described above has the following problems.

[0006] Since the track of the movable gantry is grounded on the floor, dust and the like tend to accumulate in the track. Therefore, there is a possibility that dust may adhere to a portion where the gear provided on the rotary shaft of the encoder meshes with the gear in the track.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has a detecting means for detecting the accumulation state of dust, and an accurate gear engagement by providing means for removing accumulated dust. And an object of the present invention is to provide a highly reliable error detecting device of the position detecting means.

[0008]

According to a first aspect of the present invention, there is provided a position detecting means for detecting a position of a gantry of a movable X-ray CT apparatus guided by an orbit. An error detection device, a position information output means provided on the gantry of the X-ray CT device, for obtaining position information while moving in contact with the track, and outputting the obtained position information; A contact state detecting means for detecting a contact state by energizing through a contact point between the information output means and the track, and outputting a position detection error signal based on an output of non-conduction detection from the contact state detecting means And a position detecting error signal output unit.

Further, in the present invention according to claim 2,
2. The apparatus according to claim 1, further comprising: dust removing means for removing dust near a contact surface between the track guide means of the gantry and the position detecting means. .

[0010]

FIG. 1 is a schematic diagram for explaining a configuration of an error detecting device of a position detecting means according to a first embodiment of the present invention.

The error detecting device of the position detecting means of the present invention shown in FIG. 1 receives an operation instruction means 7 for inputting an operation instruction of the X-ray CT apparatus, and an instruction output from the operation instruction means 7. FIG. 6 shows a control means 6, a motor control means 9, a clutch control means 10 and a brake control means 11 for performing individual control in response to a control signal from the control means 6.
, A driving means 8 having a motor / clutch / brake for moving a gantry 20, a detection gear 2 which meshes with and rotates a track gear 3 arranged on the floor, and the detection gear 2 and the track gear 3, a current detection circuit 4 for detecting a detection current I flowing between the current detection circuit 3, an error detector 5 for receiving an output from the current detection circuit 4, and detecting an error. And a rotary encoder 12 for outputting a signal.

In this configuration, the operator gives an operation instruction to the X-ray CT apparatus via the operation instruction means 7. The operation instructing means 7 can be input by, for example, a console or an operation panel provided in the X-ray CT apparatus. Control for driving the gantry 20 of FIG. 6 provided in the X-ray CT apparatus is performed by the control means 6 based on the operation instruction. The control means 6 includes a motor control means 9 and a clutch control means 1.
0 and the brake control means 11 are controlled.

The motor control means 9 receives a control signal from the control means 6 and supplies a drive signal to a motor serving as a driving force for moving the gantry 20. The moving speed and moving direction of the gantry 20 are determined by controlling the driving signal according to the control signal from the control means 6. In the clutch control means 10, the connection between the previous motor and the power transmission means for transmitting power to the floor is switched between connection and non-connection. Transmission of the driving force of the motor is controlled by switching between the connection and the non-connection. By separating the gantry 20 and the power shaft of the motor driving force,
For example, when the gantry 20 is moved manually, the gantry 20 can be moved with relatively light force. The brake control means 11 is for preventing the gantry 20 from moving other than intended in a state where the gantry 20 is stopped without moving.

A detection gear 2 meshes with a track gear 3 provided on the floor. The detection gear 2 is provided coaxially with the rotation shaft 1 of the rotary encoder 12. Detection gear 2
Is rotated in the direction of arrow R in the figure by the movement of the gantry 20. The movement amount, direction, speed, and current position associated with the movement of the gantry 20 are obtained as control information by signal output from the rotary encoder 12. The control means 6 controls the movement of the gantry 20 based on the control information from the rotary encoder 12.

In the part of the rotary encoder 12,
The detection gear 2 and the drive gear 3 form a circuit through which the detection current I flows in combination with the current detection circuit 4, and the detection current I flows regardless of the rotational movement of the detection gear 2. The detection current I is monitored by the current detection circuit 4. If the detection current is interrupted for some reason, for example, due to biting of dust or the like, a detection signal is sent to the error detector 5. The error detector 5 receives this detection signal and sends an error signal to the control means 6. The control means 6 stops the movement of the gantry 20 based on this error signal, and
A warning display for error detection is displayed. The operator can know that bite of a foreign substance such as dust has occurred in the track gear 3 by, for example, displaying an error detection on a console or an operation panel. Entrapment of foreign matter such as dust may impair the reliability of signal output by the rotary encoder 12,
By this error detection, it is possible to detect the attachment of foreign matter such as dust beforehand, and it is possible to obtain a highly reliable position detection signal.

The error detector 5 does not always need to monitor the detection signal from the current detection circuit 4, and it is effective to monitor only when the gantry 20 is in a movable or movable state. One way to do this is
A signal indicating whether the motor is operating or not operating is output from the motor control means 9 as a signal and input to the error detector 5. The error detector 5 controls whether or not the detection current I for error detection is supplied or not, based on the input signal indicating the operating / non-operating state of the motor. Since the gantry 20 does not move when the motor is not operating, control is performed so that the detection current I does not flow when the motor is not operating.

In addition to monitoring the energization and non-energization of the detection current I, for example, a small amount of foreign matter may adhere to the meshing portion and cause a noise-like contact failure in an extremely short cycle. In this case, the error detector 5 may be provided in advance with a filter for cutting these negligible noisy contact failures. This makes it possible to perform error detection with higher accuracy.

FIG. 2 schematically shows an error detecting device of the position detecting means according to the first embodiment of the present invention.

As shown in FIG. 2, the gantry 20 controlled by the structure shown in FIG. 1 is guided by the orbital gear 3 provided in the orbital groove 13 provided on the floor surface 14. Been moved. A detection gear 2 provided coaxially with the rotary shaft 1 of the rotary encoder 12 meshes with the race gear 3. The rotary encoder 12 is a gantry 20 shown in FIG.
, It moves in conjunction with the movement of the gantry 20. The detection gear 2 is rotatable about the rotation shaft 1.
, The detection gear 2 rotates with this movement, and a position detection signal is output from the rotary encoder 12.

When the dust D is caught between the meshing portions of the detection gear 2 and the orbital gear 3, the current detection circuit 4 shown in FIG. 1 detects that the detection current I is interrupted. In this state, accurate position detection by the rotary encoder 12 becomes difficult. Therefore, an error detection signal is sent from the error detector 5 to the control means 6, and for example, the movement of the gantry 20 is stopped immediately. At the same time, an alert for error detection is displayed on the console or operation panel of the operation instructing means 7 to alert the operator.

Further, the dust groove 21 is provided at the bottom of the raceway groove 13 so that dust and the like generated on the raceway gear 3 can be stored. As a result, even if some dust is generated, the dust falls into the dust groove 21, so that it is possible to effectively prevent the dust from adhering to the track gear 3 and the detection gear 2.

FIG. 3 shows a schematic configuration of an error detecting device of a position detecting means according to a second embodiment of the present invention.

In the second embodiment of the present invention, a detection current I is applied between the race gear 16 and the bevel gear 15 similarly to the first embodiment of the present invention shown in FIG. However, the difference is that the gear shape is formed obliquely with respect to the floor surface 14. Since the engagement surface is inclined, dust and the like on the engagement surface fall and accumulate on the bottom of the raceway groove 13. For this reason, it is difficult for dust to accumulate on the meshing surface, and it is possible to prevent a malfunction of meshing due to dust being caught.

FIG. 4 shows a schematic configuration of an error detecting device of a position detecting means according to a third embodiment of the present invention.

In the third embodiment of the present invention, an error is detected by applying a detection current I to the meshing surface between the track gear 3 and the detection gear 2 as in the first and second embodiments. There is no change in composition. The present embodiment is different from the first embodiment in the configuration including the static electricity generator 17 and the charging brush 18 which is rotated by the rotating shaft of the static electricity generator 17.

The static electricity generated by the static electricity generator 17 charges the charging brush 18. Due to this charged state, dust and the like adhering to the track gear 3 and the detection gear 18 are sucked and adsorbed on the charging brush 18. The dust and the like adsorbed on the charging brush 18 can be easily removed. If the operation of the static electricity generator 17 is stopped, the charging of the charging brush 18 can be stopped, and the dust can be more easily removed.

FIG. 5 shows a schematic configuration of an error detecting device of a position detecting means according to a fourth embodiment of the present invention.

In the fourth embodiment of the present invention, an error is detected by applying a detection current I to the meshing surface between the track gear 3 and the detection gear 2. In the fourth embodiment, a suction duct 19 is provided, and sucks dust adhered to the track gear 3 and the detection gear 2 by negative pressure. The sucked dust and the like are collected in a dust chamber (not shown) and discarded. By providing the suction duct 19 on both sides of the detection gear 2 as shown in FIG. 5, it is possible to more effectively prevent dust from adhering. The suction of dust by the suction duct 19 is not limited to being performed at all times, and may be performed at predetermined intervals.

The embodiments described above are described to facilitate understanding of the present invention, but are not described to limit the present invention. Therefore, each element disclosed in the above embodiments includes all design changes and equivalents belonging to the technical scope of the present invention.

For example, only the configuration for error detection based on the detection current I may be applied.
It is also possible to combine and implement each configuration shown in the above embodiments, and to obtain the characteristic effects of the present invention also in these combinations.

[0031]

According to the present invention described above, the detection means capable of detecting the adhesion of foreign matter such as dust is provided, and the provision of the means for removing the accumulated dust enables accurate gear meshing to be achieved. It is possible to provide an error detecting device of a position detecting means having high reliability.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining a configuration of an error detection device of a position detection unit according to a first embodiment of the present invention.

FIG. 2 schematically shows an error detecting device of a position detecting means according to the first embodiment of the present invention.

FIG. 3 shows a schematic configuration of an error detection device of a position detection unit according to a second embodiment of the present invention.

FIG. 4 shows a schematic configuration of an error detecting device of a position detecting means according to a third embodiment of the present invention.

FIG. 5 shows a schematic configuration of an error detection device of a position detection unit according to a fourth embodiment of the present invention.

FIG. 6 is a schematic diagram illustrating an X-ray CT apparatus according to a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rotating shaft, 2 ... Detection gear, 3 ... Track gear, 4 ... Current detection circuit, 5 ... Error detector, 6 ... Control means, 7 ... Operation instruction means, 8 ... Drive means, 9 ... Motor control means, 10 ... clutch control means, 11 ... brake control means, 12 ... rotary encoder, 13 ... raceway groove, 14 ... floor surface, 15 ... bevel gear, 16 ... raceway gear, 17 ... static electricity generator, 18 ...
Charging brush, 19 ... Suction duct, 20 ... Stand

Claims (2)

[Claims] 1. An error detecting device of a position detecting means for detecting a position of a gantry of an X-ray CT apparatus movable along a track, wherein the error detecting apparatus is provided on the gantry of the X-ray CT apparatus and is in contact with the track. Position information output means for obtaining position information while moving and outputting the obtained position information; and detecting a contact state by energizing through a contact point between the position information output means and the track. An error detection device for a position detection unit, comprising: a contact state detection unit; and a position detection error signal output unit that outputs a position detection error signal based on an output of non-conduction detection from the contact state detection unit. 2. The error detecting device according to claim 1, further comprising dust removing means for removing dust near a contact surface between the track guide means of the gantry and the position detecting means. .