CN107633190B - Code reading method for rotary part code of CT (computed tomography) machine frame - Google Patents
Code reading method for rotary part code of CT (computed tomography) machine frame Download PDFInfo
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Abstract
The invention relates to a code reading method for a rotary part code of a CT (computed tomography) rack, which is characterized in that a phase difference between two signals is subjected to OR value by reading two-phase signal channels of a first sensor and a second sensor, so that even if dust blocks an opening corresponding to one sensor, the opening corresponding to the other sensor can still be read and processed, and the rotating position and speed of the rack can be further judged. The invention can improve the tolerance of CT to the environment, automatically remove the influence on the machine when the coding hole is blocked, does not increase the material cost, increases the robustness of the system by a method for processing coding signals, and can generate correct signals even if the open hole of the coder is blocked, so that the use of CT is not influenced.
Description
Technical Field
The invention belongs to data identification; a data representation; a record carrier; the technical field of processing of record carriers, in particular to a code reading method for a rotary part code of a CT (computed tomography) machine frame.
Background
The medical image is a medical auxiliary mode for researching interaction with human body by means of some medium (such as X-ray, electromagnetic field and ultrasonic wave), and expressing internal tissue organ structure and density of human body in the form of image, and making diagnosis doctor judge according to the information provided by image so as to make evaluation of health condition of human body, including two aspects of medical imaging system and medical image processing. The medical images mainly include X-ray imaging instruments, CT instruments, Positron Emission Tomography (PET) instruments, magnetic resonance imaging instruments, and the like.
In the medical imaging process, the position and the speed of the rotation of the CT rack are usually realized by using a photoelectric coding ring, and the environment of the hospital using the CT is clean compared with other industrial fields, but the CT fault caused by the blockage of the encoder holes by human hair, clothing fibers and the like is inevitable.
In an actual use environment, the situation that dust enters a CT rack cannot be prevented in advance by means of manual cleaning and the like, once the dust enters the rack and blocks any one opening of a photoelectric encoding ring, pulses of code reading of the encoding ring are lost, and a corresponding angle error is caused, so that a CT locating piece image deflects, an artifact occurs in tomographic image reconstruction, and the judgment of a doctor on the CT image and the treatment of a patient are influenced.
In the prior art, for the condition that the coding hole is blocked, filter materials such as an air filter screen are generally installed, dust is prevented from entering the rack, however, even if the air filter screen is installed on the rack, the dust cannot be prevented from entering from a gap of the outer cover, or the dust is generated on an internal abrasion device, and in the process of installing the filter materials such as the air filter screen, the material cost is increased, and the installation process is also complicated.
Disclosure of Invention
The technical problem solved by the invention is that in the prior art, for the condition that a coding hole is blocked, filtering materials such as an air filter screen are generally installed, so that dust is prevented from entering a rack, and even if the air filter screen is installed on the rack, the dust cannot be prevented from entering from a gap of an outer cover or being generated on an internal abrasion device, and in the process of installing the filtering materials such as the air filter screen, the material cost is increased, and the installation process is complicated, thereby providing an optimized code reading method for the rotating part of the CT rack.
The technical scheme adopted by the invention is that the code reading method for the CT frame rotating part is characterized in that a photoelectric encoder is arranged on the CT frame rotating part and is connected with a 0-bit sensor, a first sensor and a second sensor; the code reading method comprises the following steps:
step 1: respectively reading a signal A generated by a signal channel of a first sensor and a signal B generated by a signal channel of a second sensor by taking a 0-bit sensor as a reference;
step 2: judging the phase difference between the signal A and the signal B; when the phase difference is greater than 0 degree, performing the step 3, and when the phase difference is equal to 0 degree, performing the step 4;
and step 3: reading the time for obtaining the signal A and the time for obtaining the signal B, calculating the time difference t, generating a code reading signal triggerC ═ A + t | | | B, outputting, and ending code reading;
and 4, step 4: and generating a code reading signal triggerC ═ a | | | B, outputting, and ending code reading.
Preferably, in step 3, the time difference t is L/w, where L is a phase overlapping distance of the openings corresponding to the first sensor and the second sensor, and w is a rotation speed of the CT gantry.
Preferably, in the step 3, when the phase difference is 90 degrees,
wherein l is half of the length of the first sensor and the second sensor, and w is the rotating speed of the CT frame.
Preferably, in step 4, the first sensor and the second sensor are calibrated to obtain the phase compensation value T between the signal a and the signal BoffsetTo obtain a time compensation value toffset＝ToffsetGenerating a code reading signal triggerC ═ A + toffset) And | B, outputting and ending code reading.
The invention provides an optimized code reading method for a rotary part code of a CT (computed tomography) rack, which is characterized in that a phase difference between two signals is subjected to OR value by reading two-phase signal channels of a first sensor and a second sensor, so that even if dust blocks an opening corresponding to one sensor, the opening corresponding to the other sensor can still be read and processed, and the rotating position and speed of the rack are further judged. The invention can improve the tolerance of CT to the environment, automatically remove the influence on the machine when the coding hole is blocked, does not increase the material cost, increases the robustness of the system by a method for processing coding signals, and can generate correct signals even if the open hole of the coder is blocked, so that the use of CT is not influenced.
Drawings
FIG. 1 is a diagram illustrating encoded signals when the phase difference is greater than 0 degrees according to the present invention;
FIG. 2 is a diagram illustrating encoded signals when the phase difference is equal to 0 degrees according to the present invention;
where a and B are signal a and signal B, respectively, and t in fig. 1 is a time difference.
Detailed Description
The present invention is described in further detail with reference to the following examples, but the scope of the present invention is not limited thereto.
As shown in the figure, the invention relates to a code reading method for a CT (computed tomography) rack rotating part, wherein a photoelectric encoder is arranged on the CT rack rotating part and is connected with a 0-bit sensor, a first sensor and a second sensor; the code reading method comprises the following steps.
Step 1: and respectively reading a signal A generated by a signal channel of the first sensor and a signal B generated by a signal channel of the second sensor by taking the 0-bit sensor as a reference.
The invention adopts the premise that a universal encoder code reading plate is provided with a first sensor and a second sensor besides a 0-bit sensor, wherein the first sensor and the second sensor respectively generate signal channels which are usually used for generating 4-time frequency division and judging the motion direction of an encoding strip.
In the invention, in the application process related to CT, 4 times of frequency division is not needed, the rotation direction of the CT frame is single, and the judgment of turning is not needed, therefore, in the practical application process, the two-phase signals generated by the first sensor and the second sensor are only used in any one phase, and the other phase signal is ignored.
Step 2: judging the phase difference between the signal A and the signal B; when the phase difference is greater than 0 degrees, step 3 is performed, and when the phase difference is equal to 0, step 4 is performed.
In the present invention, the first sensor generates a signal a, the second sensor generates a signal B, and there may be a phase difference between the signals a and B, or there may be an overlap between the signals a and B.
And step 3: and reading the time for obtaining the signal A and the time for obtaining the signal B, calculating the time difference t, generating a code reading signal triggerC ═ A + t | | | B, outputting, and ending code reading.
In the step 3, the time difference t is equal to L/w, where L is a phase overlapping distance of the openings corresponding to the first sensor and the second sensor, and w is a rotation speed of the CT gantry.
In the step 3, when the phase difference is 90 degrees,
wherein l is half of the length of the first sensor and the second sensor, and w is the rotating speed of the CT frame.
In the invention, when the phase difference is more than 0 degree, the time for obtaining the signal A and the time for obtaining the signal B are read, and the time difference t is calculated, wherein the time difference t is the difference between the time for obtaining the signal A from the signal channel of the first sensor and the time for obtaining the signal B from the signal channel of the second sensor, so that the code reading signal triggerC ═ A + t | | | | B, namely after the code reading signal is the A signal and is delayed by t, the code reading signal and the B signal are subjected to OR operation, namely, when any one of the (A + t) signal or the B signal is effective, the code reading signal can be generated, even if dust blocks any corresponding opening hole of the first sensor or the second sensor, the opening hole corresponding to the other sensor can still be read, and a correct code reading signal can still be generated.
In the invention, the time difference t is equal to the phase overlapping distance of the openings corresponding to the first sensor and the second sensor divided by the rotation speed of the CT gantry, i.e. t is equal to L/w, the rotation speed of the CT gantry here can be obtained by automatic measurement by a digital logic device, the automatic measurement method is a general method, and a person skilled in the art can measure the time difference by himself.
In the invention, in the practical use process, the phase difference of the corresponding openings of the first sensor and the second sensor in the photoelectric sensor is generally set to be 90 degrees, at the moment, the time difference t is equal to half of the length of the opening and then divided by the rotating speed of the CT frame, namely the time difference t is equal to
In the invention, when the phase difference is greater than 0 degree, the step 3 can use a coding plate which is commonly used by technicians in the field to realize code reading, and further judge the rotating position and speed of the rack.
And 4, step 4: and generating a code reading signal triggerC ═ a | | | B, outputting, and ending code reading.
In the step 4, the first sensor and the second sensor are calibrated to obtain the phase compensation value T between the signal a and the signal BoffsetTo obtain a time compensation value toffset＝ToffsetGenerating a code reading signal triggerC ═ A + toffset) And | B, outputting and ending code reading.
In the invention, the method in the step 3 has an error point, and because the CT frame may have a rotation speed error, the error may cause an error of the time difference t, and further cause an error of a code reading signal, which may cause the position accuracy of the CT frame to be reduced.
In the invention, the condition that the phase difference is equal to 0 degree is further provided, namely the positions of the first sensor and the second sensor relative to the CT frame are moved to enable the phase difference of the corresponding openings of the first sensor and the second sensor to be 0 degree, and the pulse phases generated by the first sensor and the second sensor are completely the same, so that the interference caused by the error of the rotation speed of the CT frame is avoided.
In the invention, when the phase difference is equal to 0 degree, the code reading signal triggerC is generated as a | | B, that is, the signals a and B generated by the first sensor and the second sensor can be simultaneously utilized to carry out or operation, any one signal is effective and can generate the code reading signal, even if dust blocks any one corresponding opening of the first sensor or the second sensor, the opening corresponding to the other sensor can still be read, and a correct code reading signal can still be generated.
In the invention, when the phase difference is equal to 0 degree, the problem of the rotation error of the CT frame is solved, the step is based on that the mechanical size of the holes of the whole coding strip is uniform, and the manufacturing error is within an allowable range.
In the present invention, when there is a mechanical error in the position of the opening, the generated pulse signal will have jitter, so calibration is required.
In the present invention, for one coding band, the mechanical errors of all the opening positions are fixed, so that the phase compensation value T between the signal A and the signal B is obtainedoffsetWhen generating the code signal, the phase compensation value T is usedoffsetDividing by the frame speed to obtain a time compensation value toffset＝ToffsetAnd w, completing calibration, and returning to the condition that the signal A and the signal B have phase difference, generating a code reading signal triggerC ═ A + toffset) And | B, outputting.
In the present invention, the phase compensation value ToffsetDigital logic devices may be used to automatically measure, record and read as will be readily understood by those skilled in the art.
In the present invention, all the calculation and data processing processes can be implemented by any digital processing device, such as MCU, FPGA, DSP or CPU, CPLD, etc., and can be operated by the skilled in the art according to the understanding of the technology.
The invention solves the problems that in the prior art, when a coding hole is blocked, filter materials such as an air filter screen are generally installed to prevent dust from entering a rack, and the problem that the installation process is complicated because the dust cannot be prevented from entering from a gap of an outer cover or generated on an internal abrasion device even if the air filter screen is installed on the rack, and the material cost is increased in the process of installing the filter materials such as the air filter screen is solved. The invention can improve the tolerance of CT to the environment, automatically remove the influence on the machine when the coding hole is blocked, does not increase the material cost, increases the robustness of the system by a method for processing coding signals, and can generate correct signals even if the open hole of the coder is blocked, so that the use of CT is not influenced.
Claims (3)
1. A code reading method for a rotary part of a CT (computed tomography) rack is characterized in that a photoelectric encoder is arranged on the rotary part of the CT rack and is connected with a 0-bit sensor, a first sensor and a second sensor; the method is characterized in that: the code reading method comprises the following steps:
step 1: respectively reading a signal A generated by a signal channel of a first sensor and a signal B generated by a signal channel of a second sensor by taking a 0-bit sensor as a reference;
step 2: judging the phase difference between the signal A and the signal B; when the phase difference is greater than 0 degree, performing the step 3, and when the phase difference is equal to 0 degree, performing the step 4;
and step 3: reading the time for obtaining the signal A and the time for obtaining the signal B, calculating a time difference t, generating a code reading signal triggerC ═ A + t | | | B, outputting, and ending code reading, namely, after the code reading signal is delayed by the time t of the signal A, carrying out OR operation with the signal B, namely, the (A + t) signal or the signal B, wherein any one of the signals is effective and can generate the code reading signal, and the time difference t is L/w, wherein L is the phase overlapping distance of the corresponding openings of the first sensor and the second sensor, and w is the rotating speed of the CT rack;
and 4, step 4: and generating a code reading signal triggerC ═ a | | | B, outputting, and ending code reading.
2. The method of claim 1, wherein the method comprises: in the step 3, when the phase difference is 90 °, t is equal to
Wherein l is half of the length of the first sensor and the second sensor, and w is the rotation speed of the CT frame.
3. The method of claim 1, wherein the method comprises: in the step 4, the first sensor and the second sensor are calibrated, a phase compensation value Toffset between the signal a and the signal B is obtained, a time compensation value Toffset/w is obtained, a code reading signal triggerC is generated as (a + Toffset) | | B, the output is performed, and code reading is finished.
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| CN112617869B (en) * | 2020-11-24 | 2023-04-18 | 明峰医疗系统股份有限公司 | Method and system for positioning communication breakpoint of CT slip ring |
| CN113686369B (en) * | 2021-08-27 | 2022-12-20 | 明峰医疗系统股份有限公司 | Identification and positioning system for coding ring hole site blockage of CT frame encoder |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1290999A (en) * | 1999-09-30 | 2001-04-11 | 株式会社东芝 | Non-linear compensator |
| CN101382443A (en) * | 2007-09-06 | 2009-03-11 | 夏普株式会社 | Photoelectric encoder and electronic equipment using the same |
| JP2017125866A (en) * | 2017-04-27 | 2017-07-20 | パナソニックＩｐマネジメント株式会社 | Optical encoder |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1290999A (en) * | 1999-09-30 | 2001-04-11 | 株式会社东芝 | Non-linear compensator |
| CN1183661C (en) * | 1999-09-30 | 2005-01-05 | 株式会社东芝 | Non-linear compensator |
| CN101382443A (en) * | 2007-09-06 | 2009-03-11 | 夏普株式会社 | Photoelectric encoder and electronic equipment using the same |
| JP2017125866A (en) * | 2017-04-27 | 2017-07-20 | パナソニックＩｐマネジメント株式会社 | Optical encoder |
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