1. An X-ray imaging apparatus comprising:
X-ray generation means for emitting X rays;
an X-ray detector on which a grid selected from a plurality of different types of grids is removably mountable, wherein said X-ray detector receives the X-rays emitted from said X-ray generation means, and wherein said X-ray detector obtains X-ray image data;
said X-ray detector including an automatic exposure control (AEC) detector which includes plural exposure detection elements, said AEC detector for detecting the quantity of X-rays emitted from said X-ray generation means and for outputting a signal based on the detected quantity; and
driving means for driving said X-ray generation means based on the signal output from said AEC detector,
wherein a gain of the exposure detection elements is corrected by gain-correction data according to the selected grid in said AEC detector.
2. An X-ray imaging apparatus according to claim 1,
wherein the gain of the exposure detection elements is corrected by gain-correction data according to an unmounted grid state in the case that the grid is not mounted.
3. An X-ray imaging apparatus according to claim 1, further comprising:
storing means to store a plurality of different types of gain-correction data;
wherein said AEC detector selects the gain-correction data according to whether one of said plurality of different types of grids is mounted.
4. An X-ray imaging apparatus according to claim 3,
wherein said AEC detector further comprises gain-correction data calculation means and wherein said AEC detector calculates the gain-correction data based on the gain-correction data stored in the storing means, in the case where no gain-correction data corresponding to the selected grid.
5. An X-ray imaging apparatus according to claim 1, wherein said exposure detection elements are integrated into said X-ray detector.
6. An X-ray imaging apparatus according to claim 1,
wherein said AEC detector further comprises a plurality of pixels and wherein each pixel is formed as a detector element that can be read in non-destructive manner.
7. An X-ray imaging apparatus according to claim 1,
wherein said AEC detector further comprises a plurality of pixels and wherein each pixel is formed as a thin film transistor (TFT)-detector.
8. An X-ray imaging apparatus according to claim 1,
wherein said control means reads said signal output from said AEC detector in a cycle of 5 msec or less.
9. An X-ray imaging apparatus according to claim 1,
wherein the AEC detector further comprises a plurality of pixels formed as stripes of detector elements provided so as to be substantially parallel to the orientation of stripes of said grid.
10. A method for controlling an X-ray imaging apparatus comprising the steps of:
emitting X-rays;
changing the X-rays received through a selected grid into X-ray image data;
detecting a quantity of emitted X-rays using an AEC detector and outputting a signal based on the detected quantity; and
stopping said X-ray emission based on the signal,
wherein a gain of exposure detection elements forming a part of said AEC detector is corrected by gain-correction data according to the selected grid in said AEC detector.
11. Computer-executable process steps stored on a computer-readable medium, said computer-executable process steps for making a computer perform a method for controlling an X-ray imaging apparatus, said computer-executable process steps comprising process steps executable to perform a method according to claim 10.
12. A computer-readable medium which stores computer-executable process steps, the computer-executable process steps for making a computer perform a method for controlling an X-ray imaging apparatus, said computer-executable process steps comprising process steps executable to perform a method according to claim 10.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. A periodic process scheduling method of a computer system, said computer system including a plurality of processes, said periodic process scheduling method comprising the steps of:
receiving requests for periodical execution of processes each with a period of execution and execution time;
securing an allocation time for a process having shorter period than the other processes to be executed in each of respective periods of execution for said process;
securing another allocation time for a part of another process within first of said respective periods of execution of said process other than said allocation time in said first of said allocation time for said process if full execution time of said another process cannot be secured within said first of said respective periods of execution of said process; and
starting execution of said plurality of processes in respective secured allocation times provided for said plurality of processes.
2. A periodic process scheduling method of a computer system, said computer system including a plurality of processes, said periodic process scheduling method comprising the steps of:
receiving requests for periodical execution of processes each with a period of execution and execution time;
securing an allocation time for a process having shorter period than the other processes to be executed in each of respective periods of execution for said process;
securing another allocation time for a part of another process within first of said respective periods of execution of said process other than said allocation time in said first of said allocation time for said process if full execution time of said another process cannot be secured within said first of said respective periods of execution of said process; and
starting execution of said process in said secured allocation time and said another process in said secured another allocation time.
3. A periodic process scheduling method according to claim 2, further comprising the steps of:
checking whether an allocation time secured for said first of said respective periods of execution of said process expires in response to a timer interruption; and
suspending execution of said process when said allocation time secured for said first of said respective periods of execution of said process expires.
4. A periodic process scheduling method according to claim 2, further comprising the steps of:
creating a table for registering therein order of processes to which CPU time is allocated by taking a time slot as unit;
selecting processes so as to allocate time slots to processes in order from processes having a shorter execution period;
extracting adjacent free time slots in a range of execution period of the selected process group;
responding to existence of adjacent empty time slots having a size of at least a required CPU time, obtaining, from adjacent empty time slots corresponding to at least the required CPU time and having a minimum size, adjacent empty time slots corresponding to the required CPU time beginning from head thereof, and allocating the obtained adjacent empty time slots to the selected process group; and
responding to nonexistence of adjacent empty time slots having a size of at least a required CPU time, allocating all time slots belonging to adjacent empty time slots having a maximum size to the selected process group, and allocating a remaining time equivalent to the required CPU time minus the allocated time slots to the said process group by using the previous step and the present step.
5. A periodic process scheduling method of a computer system, said computer system including a plurality of processes, said periodic process scheduling method comprising the steps of:
receiving requests for periodical execution of processes each with a period of execution and execution time;
securing an allocation time for a process having shorter period than the other processes to be executed in each of respective periods of execution for said process;
securing another allocation time for a part of another process within first of said respective periods of execution of said process other than said allocation time in said first of said allocation time for said process if full execution time of said another process cannot be secured within said first of said respective periods of execution of said process;
starting execution of said process in said secured allocation time and said another process in said secured another allocation time;
checking whether an allocation time secured for said first of said respective periods of execution of said process expires in response to a timer interruption; and
suspending execution of said process when said allocation time secured for said first of said respective periods of execution of said process expires.
6. A periodic process scheduling method according to claim 5, further comprising the steps of:
creating a table for registering therein order of processes to which CPU time is allocated by taking a time slot as unit;
selecting processes so as to allocate time slots to processes in order from processes having a shorter execution period;
extracting adjacent free time slots in a range of execution period of the selected process group;
responding to existence of adjacent empty time slots having a size of at least a required CPU time, obtaining, from adjacent empty time slots corresponding to at least the required CPU time and having a minimum size, adjacent empty time slots corresponding to the required CPU time beginning from head thereof, and allocating the obtained adjacent empty time slots to the selected process group; and
responding to nonexistence of adjacent empty time slots having a size of at least a required CPU time, allocating all time slots belonging to adjacent empty time slots having a maximum size to the selected process group, and allocating a remaining time equivalent to the required CPU time minus the allocated time slots to the said process group by using the previous step and the present step.
7. A periodic process scheduling program having computer codes to be stored in a storage for running in a computer system, said program comprising the steps of:
receiving requests for periodical execution of processes each with a period of execution and execution time;
securing an allocation time for a process having shorter period than the other processes to be executed in each of respective periods of execution for said process;
securing another allocation time for a part of another process within first of said respective periods of execution of said process other than said allocation time in said first of said allocation time for said process if full execution time of said another process cannot be secured within said first of said respective periods of execution of said process; and
starting execution of said process in said secured allocation time and said another process in said secured another allocation time.
8. A periodic process scheduling program according to claim 7, further comprising the steps of:
checking whether an allocation time secured for said first of said respective periods of execution of said process expires in response to a timer interruption; and
suspending execution of said process when said allocation time secured for said first of said respective periods of execution of said process expires.