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US 2009/0021110 A1Published application
Method and apparatus for driving a piezoelectric actuator
OwnerJeffrey Basil Lendaroinventor
Life of this patent
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Abstract
Disclosed is an apparatus and a method for differentially driving a piezoelectric actuator (56) in a “smooth pixel” DLP projector (40). Actuator (56) is driven differentially in order to obtain a drive level (VM) that is larger than the available supply voltage (74). Drive is by anti-phase signals (S5,S6), one of which (S5) is DC offset to avoid a negative drive across actuator (56).
Claims18
Apparatus comprising:
- Means (74, 76, 82, 88, 90) for generating a first (S6), a second (S4) and a third (S5) signal, said first signal (S6) encompassing a first range, said second signal (S4) encompassing a second range and being of a different phase than said first signal (S6) and said third signal (55) being generated by level shifting (88, 90) said second signal (S4) to a DC bias at a different level from the DC bias of said first (S6) and said second signals (S4);
- and
- means (S5, S6) for differentially driving a load (56) from said first signal (S6) and said third signal (S5).
A method for providing a differential output signal comprising the steps of:
- generating a first signal;
- generating a second signal, said second signal being out of phase with said first signal;
- level shifting said second signal to generate a third signal, said third signal being biased differently from said second signal;
- and
- providing said first signal and said third signal as differential outputs.
2 more elements
Apparatus for generating differential drive signals comprising:
- a first switch (74) configured to alternately connect a first signal (S6) of a pair of differential signals (S6, S5) between a first level (V0) and a second level (V1);
- a second switch (82) configured to alternately connect to said second level (V1) and to said first level (V0) to generate an intermediate signal (S4);
- a DC restorer (88, 90) connected to said second switch (82) to level shift said intermediate signal (S4) to create a second signal (S5) of said pair of differential signals, said second signal (S5) being level shifted to operate between a third level and a fourth level.
A differential signal source comprising:
- a signal source (84);
- an inverting amplifier (86) whose input is connected to an output of said signal source (84) and whose output is connected to a first output (S3) of a pair of differential signals (S3, S2);
- a level shifter (88, 90) whose input is connected to said output of said signal source (84) and whose output is connected to a second output (S2) of said pair of differential signals.
Apparatus comprising:
- a source of supply voltage (89);
- a source of a first signal (S1) having a first DC level and a first phase and a second signal (S2) having a second phase different from said first phase and having a second DC level different from said first DC level;
- and
- first and second signal paths for providing said first and second signals, respectively, to a load (56) for producing a drive level at said load greater than the magnitude of said supply voltage (89) and for substantially preventing polarity reversal at said load.
1 more element
Dependencies are inferred from the claim text.