Apparatus and method for detecting defects in a multi-channel scan driver
First Claim
1. A test circuit for a discrete picture element detector, the detector including row and column electrodes coupled to drive circuitry for sampling signals generated at locations of the detector, the test circuit comprising:
- at least two row test circuit modules for enabling rows of the detector;
a first test enable input configured to apply a first test enable signal and coupled to a bias generator circuit, the bias generator circuit coupled to a positive bias and ground and configured to produce a second test enable signal;
a second test enable input configured to receive the second test enable signal and coupled to the test circuit modules for enabling test sequences for corresponding rows; and
a comparison module coupled to the test circuit modules and to the first test enable input to compare output signals generated by the test circuit modules during the test sequences to reference signals.
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Accused Products
Abstract
A technique is described for detecting defects such as short circuits in a device such as a discrete pixel detector used in a digital x-ray system. The technique employs test circuits associated with each row driver of the detector. The test circuits are enabled by a test enable input signal, and the row driver sequentially enables the rows of the detector, along with the individual test circuits. In a test sequence, output signals from the row test circuits are monitored to identify whether a defect, such as a short circuit, is likely to exist in the row or row driver. The test circuitry adds only minimal area and complexity to the row driver function, providing a high degree of test coverage at a low cost, with minimal likelihood of test circuitry-induced failures.
107 Citations
30 Claims
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1. A test circuit for a discrete picture element detector, the detector including row and column electrodes coupled to drive circuitry for sampling signals generated at locations of the detector, the test circuit comprising:
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at least two row test circuit modules for enabling rows of the detector;
a first test enable input configured to apply a first test enable signal and coupled to a bias generator circuit, the bias generator circuit coupled to a positive bias and ground and configured to produce a second test enable signal;
a second test enable input configured to receive the second test enable signal and coupled to the test circuit modules for enabling test sequences for corresponding rows; and
a comparison module coupled to the test circuit modules and to the first test enable input to compare output signals generated by the test circuit modules during the test sequences to reference signals. - View Dependent Claims (2, 3, 4, 5)
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6. A row control device for controlling operation of a plurality of rows of a discrete picture element detector, the device comprising:
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row driver circuitry having a plurality of row driver modules configured to be coupled to a plurality of row electrodes for respective rows of the detector, and to apply enable signals for sampling signals generated at locations on the detector; and
row test circuitry disposed on a common device with the row driver circuitry, the row test circuitry including a row test module for each row output of the row driver module, a first test enable input configured to apply a first test enable signal and coupled to a bias generator circuit, the bias generator circuit coupled to a positive bias and ground and configured to produce a second test enable signal, a second test enable input configured to receive the second test enable signal and coupled to the test circuit modules for enabling test sequences for corresponding rows, and at least one comparison module coupled to the test module and to the test enable to compare signals generated during the test sequences to reference signals. - View Dependent Claims (7, 8, 9, 10, 11)
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12. A discrete picture element detector system for a digital x-ray system, the detector system comprising:
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a detector panel including rows and columns of electrodes and detection circuitry at row and column crossings for generating signals in response to receipt of radiation during an x-ray examination;
column driver circuitry coupled to the column electrodes for sampling the signals;
row driver circuitry coupled to the row electrodes for enabling sampling of the signals; and
driver test circuitry coupled to the row driver circuitry, the test circuitry including a plurality of row test modules for enabling rows of the detector, a first test enable input configured to apply a first test enable signal and coupled to a bias generator circuit, the bias generator circuit coupled to a positive bias and ground and configured to produce a second test enable signal, a second test enable input configured to receive the second test enable signal and coupled to the test circuit modules for enabling test sequences for corresponding rows, and a comparison module coupled to the test modules and to the test enable to compare signals generated during the test sequences to reference signals. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A test circuit comprising:
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a first test enable input;
a first bias circuit coupled to the first test enable input, the first test enable input configured to apply a first test enable signal, and the first bias circuit configured to produce a second test enable signal;
a second bias circuit coupled to the first test enable input, the first test enable input configured to apply a first test enable signal, and the second bias circuit configured to produce a third test enable signal;
a first test module coupled to the second test enable signal and configured to test for shorts in a plurality of row electrodes of a detector, the shorts being one of a short from a first row to a second row, a short from a first row to ground and a short from a first row to a negative bias supply; and
a second test module coupled to the third test enable signal and configured to test for shorts in a plurality of row electrodes of a detector, the shorts being one of a short from a first row to a second row, a short from a first row to ground, and a short from a first row to a positive bias supply. - View Dependent Claims (20, 21, 22, 23, 24)
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25. A method for detecting defects in a discrete picture element detector system, the detector system including a test circuit as well as a detector panel including rows and columns of electrodes and detection circuitry at row and column crossings for generating signals, column driver circuitry coupled to the column electrodes for sampling the signals, and row driver circuitry coupled to the row electrodes for enabling sampling of the signals, the method comprising the steps of:
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pre-enabling a plurality of rows to a positive bias ON-state;
individually and sequentially driving each row to a negative bias OFF-state; and
comparing output signals from a test circuit with a reference signal to determine whether each test enabled row is defective. - View Dependent Claims (26, 27, 28, 29, 30)
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Specification