US 11,536,950 B2Granted

Capacitive-based determination of micromirror status

AssigneeTexas Instruments Incorporated

InventorsRobert F. Payne, Molly Nelis Sing

Life of this patent

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Abstract

A digital micromirror device includes a plurality of micromirror cells on a semiconductor die. Each respective cell includes a memory circuit and an electrode selection circuit. At least some of the micromirror cells include a micromirror and each respective memory circuit controls a micromirror tilt angle. For a given memory circuit controlled to a first tilt angle, a measurement circuit measures a first value indicative of a capacitance between a first electrode and the micromirror and measures a second value indicative of a capacitance on the second electrode. For a second micromirror tilt angle, the measurement circuit measures a third value indicative of a capacitance between the first electrode and the micromirror and measures a fourth value indicative of a capacitance on the second electrode. The measurement circuit generates a signal indicative of whether the micromirror is stuck at a particular angle or missing.

Claims20

Dependent claims

A system comprising:

a micromirror cell comprising:
a micromirror;
a memory circuit capacitively coupled to the micromirror, the memory circuit comprising:
a first inverter having a first inverter input and a first inverter output;
a second inverter having a second inverter input and a second inverter output, the second inverter input coupled to the first inverter output and a the second inverter output coupled to the first inverter input;
and
a first transistor having a first current terminal, a second current terminal, and a first control terminal, the first current terminal coupled to the first inverter input;
and
a second transistor having a third current terminal, a fourth current terminal, and a second control terminal, the third current terminal coupled to the first inverter output and
a measurement circuit coupled to the second current terminal and the fourth current terminal, the measurement circuit comprising:
a current source coupled to the second current terminal and the fourth current terminal;
a comparator having a first comparator input, a second comparator input, and a comparator output, the first comparator input coupled to the second current terminal and the fourth current terminal;
and
a counter coupled to the comparator output.

11 more elements

A system comprising:

a micromirror cell comprising:
a micromirror;
a memory circuit capacitively coupled to the micromirror, the memory circuit comprising:
a first inverter having a first inverter input and a first inverter output;
a second inverter having a second inverter input and a second inverter output, the second inverter input coupled to the first inverter output and a the second inverter output coupled to the first inverter input;
and
a first transistor having a first current terminal, a second current terminal, and a first control terminal, the first current terminal coupled to the first inverter input;
and
a second transistor having a third current terminal, a fourth current terminal, and a second control terminal, the third current terminal coupled to the first inverter output;
and
a measurement circuit coupled to the second current terminal and to the fourth current terminal, the measurement circuit comprising:
a current source coupled to the second current terminal and to the fourth current terminal;
a comparator having a first comparator input, a second comparator input, and a comparator output, the first comparator input coupled to the second current terminal and to the fourth current terminal;
a counter having a first counter input, a second counter input, and a counter output, the first counter input coupled to the comparator output;
and
a logic circuit having a logic input and a logic output, the logic input coupled to the counter output;
and
a controller coupled to the first control terminal, to the second control terminal, to the second current terminal, and to the logic output.

15 more elements

Dependencies are inferred from the claim text.

Facts

Application: 16/226,420Filed 19 Dec 2018 · us provisional application
Priority: 29 Dec 2017
Published: US 2019/0204587 A14 Jul 2019
Granted: 27 Dec 2022
Term ends: Not estimatedThe source records don’t support an estimate.

Classification14 codes

G02B 26/0841
The reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD: the reflecting element being moved or deformed by electrostatic means
G01B 7/30
Measuring arrangements characterised by the use of electric or magnetic techniques: for measuring angles or tapers; for testing the alignment of axes
G09G 3/346
Using light modulating elements actuated by an electric field and being other than liquid crystal devices and electrochromic devices: based on…
G11C 11/41
Using transistors: forming static cells with positive feedback, i.e. cells not needing refreshing or charge regeneration, e.g. bistable…