Automatic exposure control realization method

Abstract

The invention discloses an automatic exposure control realization method. The method comprises: inputting an output voltage which controls the exposure quantity of an ionization chamber into a controller after the output voltage successively passes through a simulation switch circuit, a sampling holding circuit and an A / D circuit; and outputting an input voltage and a reference exposure voltage through a D / A circuit by the controller and carrying out comparison by a comparison circuit, and when the values of the two are equal, stopping exposure so as to realize control of an AEC feedback loop. The controller is realized by use of an FPGA chip. According to the invention, digital integration is realized by use of an FPGA, the digital quantity converted by a voltage Vi which controls exposure quantity and a reference value arranged inside the FPGA are outputted through a D / A chip and are compared, and when the values of the two are equal, an inversion high voltage is cut off, exposure is stopped, and the control of an AEC feedback loop is realized.

Description

technical field [0001] The invention relates to an exposure control technology, in particular to an implementation method for automatic exposure control of an X-ray sensor. Background technique [0002] Automatic exposure control (Automatic Exposure Control, AEC) is to use the X-ray sensor (ionization chamber) to detect the amount of radiation passing through the body to be irradiated and reach the film, so as to control the exposure time of the X-ray machine, which can make the images taken by different parts and different patients X-ray photos have the same light sensitivity, which completely solves the problem of inconsistent light sensitivity of different photos developed by automatic film processors. [0003] In AEC technology, the integral operation realized by the analog circuit needs to be cleared and maintained. If the processing is not good, it is easy to produce different integral voltages under the same AEC conditions, and abnormal phenomena such as the AEC volta...

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Problems solved by technology

[0003] In AEC technology, the integral operation realized by the analog circuit needs to be cleared and maintained. If the processing is not good, it is easy to produce different integral voltages under the same AEC conditions, and abnormal phenomena such as the AEC voltage generated by the exposure of the beamer and the analog integral There are problems such as zero drift, nonlinear error and capacitance leakage in the circuit

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