Automatic test system for an analog micromirror device
AssigneeTexas Instruments Incorporated
InventorNarayana Sateesh Pillai
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Abstract
An automatic tester for an analog micromirror device includes a computer having an ADC and DAC connected to its peripheral bus. A micromirror device under test is mounted on a black box containing a light source such as a laser and a position sensitive device. The light beam is reflected by the micromirror device onto the position sensitive device so that the deflection of the mirror in two axes can be measured. The output of the position sensitive device is amplified and coupled to the ADC via a tester board. The computer can test the micromirror device to detect mechanical failure and to measure the resonant frequency and Q of the driving coils, and SNR of the internal package feedback which measures the position of the mirror.
Claims20
A tester for a micromirror device comprising:
- a housing having a mounting for receiving a micromirror device;
- a light source mounted to direct a light beam onto a micromirror device when installed in the mounting, to produce a reflected beam;
- a position sensitive device for generating a position signal indicative of the position of the reflected beam;
- and
- a computer having an output coupled to the micromirror device and to the light source and an input coupled to the position sensitive device.
A method of testing a micromirror device comprising:
- activating a light source to generate a light beam which impinges on a mirror surface of the micromirror device to produce a reflected beam which impinges on a position sensitive device;
- applying a voltage signal to a current driver for generating a current signal through coils for moving the mirror which is directly proportional to the amplitude of the voltage signal and unrelated to resistance or inductance of the coil;
- detecting a position signal generated by the position sensitive device which is representative of a position of the reflected beam on the position sensitive device;
- and
- calculating an angular position of the mirror surface from the detected position signal;
- and
- determining if the angular position calculated meets predetermined criteria.
A method of mechanically testing a micromirror device comprising:
- determining the resonant frequency and Q for the micromirror device;
- exciting the micromirror device at the resonant frequency for a predetermined time period;
- determining the resonant frequency and Q of the micromirror device after excitation at the resonant frequency;
- and
- comparing the resonant frequency and Q before and after excitation of the micromirror device at the resonant frequency.
Dependencies are inferred from the claim text.