PROJECTOR SYSTEMS WITH LIGHT BEAM ALIGNMENT
Embodiments of the present invention generally relate to circuits, systems and methods that can be used to detect light beam misalignment, so that compensation for such misalignment can be performed. In accordance with an embodiment, a circuit includes a photo-detector (PD) having a plurality of electrically isolated PD segments. Additionally, the circuit has circuitry, including switches, configured to control how currents indicative of light detected by the plurality of electrically isolated PD segments are arithmetically combined. When the switches are in a first configuration, a signal produced by the circuitry is indicative of vertical light beam alignment. When the switches are in a second configuration, the signal produced by the circuitry is indicative of horizontal light beam alignment. The signals indicative of vertical light beam alignment and horizontal light beam alignment can be used detect light beam misalignment, so that compensation for such misalignment can be performed.
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This application is a Divisional Application of U.S. patent application Ser. No. 12/868,343, filed Aug. 25, 2010, which claims priority under 35 U.S.C. 119(e) to U.S. Provisional Patent Application No. 61/296,987, filed Jan. 21, 2010, both of which are incorporated herein by reference.
BACKGROUNDReferring to
The controller 104 can perform scaling and/or pre-distortion of video signals before such signals are provided to the LDD 108. The voltage regulator 110 (e.g., a quad-output adjustable DC-DC buck-boost regulator) can convert a voltage provided by a voltage source (e.g., a battery or AC supply) into the various voltage levels (e.g., four voltage levels V1, V2, V3 and V4) for powering the various components of the projector display device 100.
The LDD 108 is shown as including three digital-to-analog converts DACs 1091, 1092 and 1093 (which can be collectively referred to as DACs 109). The LDD is also shown as including a serial interface 122 which may receive, via a serial bus 103, a serial enable (SEN) signal and a serial clock signal (SClk) from a serial interface of the controller 104. Additionally, a bi-directional serial data input/output (SDIO) line of the serial bus 103 allows the controller 104 to write data to and read data from registers within the LDD 108. Alternative serial buses and interfaces can be used, such as, but not limited to, an Inter-Integrated Circuit (I2C) or an Serial Peripheral Interface (SPI) bus and interface. The LDD 108 also includes registers, and the like, which are not shown.
The DACs 109 of the LDD 108 drive laser diodes 112, which can include, e.g., a red, a green and a blue laser diode, but are not limited thereto. Where the LDD 108 is used to drive a red (R), a green (G) and a blue (B) laser diode, the LDD can be referred to as a RGB triple laser diode driver.
The light produced by the laser diodes 112 can be provided to beam splitters 114, which can direct a small percentage of the light toward one or more calibration photo-detectors (PDs) 120, and direct the remainder of the light toward projector optics 116, which include lenses, mirrors, reflection plates and/or the like. The light output by the optics 116 can be provided to one or more micro mirror(s) 118. The mirror(s) 118 can be controlled by the controller 104, or another portion of the system, to raster-scan reflected light onto a surface, e.g., a screen, a wall, the back of a chair, etc. Because of the scanning of laser beams performed using the mirror(s) 118, the projector 100 can be referred to as a laser based scanning projector 100. In one configuration, a single mirror 118 that can be controlled in both the X and Y directions is used for scanning of the laser beams. In another configuration, a first mirror 118 is used for controlling horizontal scanning (i.e., scanning in the X direction), and a second mirror 118 is used for controlling vertical scanning (i.e., scanning in the Y direction). These are just two exemplary configurations, which are not meant to be limiting. It is also possible that more than two mirrors 118 be used.
In a laser based scanning projector, at each clock cycle, the R, G, and B lasers diodes output a pixel intensity at a location set by the linear speed of the scanning mirror(s) 118 and a clock time base, as can be appreciated from the exemplary timing diagram of
Over time, a laser beam pointing direction might shift for various reasons, which causes misalignment among pixel colors. This is illustrated in timing diagram of
The laser beams produced by the R, G and B laser diodes can be or become misaligned for various reasons. For example, there will be some inherent misalignment that results from imperfect mechanical manufacturing of a projector system. Further, misalignment can occur due to mechanical modifications that occur to a projector system, e.g., if the projector system is dropped. Additionally, misalignment can also result from the thermal changes to the laser diodes, as well as aging of the laser diodes.
SUMMARYEmbodiments of the present invention generally relate to circuits, systems and methods that can be used to detect light beam misalignment, so that compensation for such misalignment can be performed. Such light beams are produced by light emitting elements, such as, but not limited to, laser diodes or light emitting diodes (LEDs). Where the light beams are produced by laser diodes, the light beams can be referred to as laser beams.
In accordance with an embodiment, an opto-electronics circuit includes a plurality of electrically isolated PD segments. Additionally, the opto-electronics circuit has circuitry, including switches, configured to control how currents indicative of light detected by the plurality of electrically isolated PD segments are arithmetically combined. When the switches are in a first configuration, a signal produced by the opto-electronics circuit is indicative of vertical light beam alignment. When the switches are in a second configuration, a signal produced by the opto-electronics circuit is indicative of horizontal light beam alignment. When the switches are in a third configuration, a signal produced by the opto-electronics circuit is indicative of light beam power. The circuitry, configured to control how the currents are arithmetically combined, can also include trans-impedance amplifiers (TIAs) and summing circuitry. In a specific embodiment, only two TIAs are required, reducing the power and complexity of the opto-electronics circuit.
In accordance with an embodiment, the plurality of electrically isolated PD segments includes four electrically isolated PD segments. Each of the four electrically isolated PD segments produces a corresponding current indicative an amount of light detected by the PD segment.
In accordance with an embodiment, the equation Y_Offset=(A+B)−(C+D) is used to produce the signal indicative of vertical light beam alignment, where A is indicative of the current produced by a first one of the four electrically isolated PD segments, B is indicative of the current produced by a second one of the four electrically isolated PD segments, C is indicative of the current produced by a third one of the four electrically isolated PD segments, and D is indicative of the current produced by a fourth one of the four electrically isolated PD segments. In accordance with an embodiment, the equation X_Offset=(A+C)−(B+D) is used to produce the signal indicative of horizontal light beam alignment. Additionally, the equation Power=A+B+C+D can be used to determine a measure of power of a light beam, which can be used, e.g., for automatic power control (APC) and/or color calibration.
In dependence on the signals indicative of vertical light beam alignment and the signals indicative of horizontal light beam alignment, a controller can detect when one of the light beams produced by the light emitting elements is misaligned relative to the other light beams produced by the other light emitting elements. Additionally, the controller can compensate for the detected misalignment by controlling timing of color data that is used to produced the signals that drive the light emitting elements. In dependence on the signals indicative of light beam power, the controller can detect when an output power of one or more light beams produced by one or more of the light emitting elements changes. Additionally, the controller can compensate for the detected change in output power by changing an amplitude and/or pulse width of one or more signals that drive the light emitting elements.
Embodiments of the present invention are also directed to projector systems that include the opto-electronics circuit described above. Such a projector system can also include, e.g., a first laser diode that emits light of a first color, a second laser diode that emits light of a second color, and a third laser diode that emits light of a third color. Additionally, the projector system can also included a controller, a laser diode driver (LDD), and one or more micro-mirror(s). The controller can be configured to output first, second and third pixel data in dependence on a video signal received from a video source. The LDD can be configured to drive the first, second and third laser diodes in dependence on the first, second and third pixel data received from the controller. The one or more micro-mirror(s) can be controlled by the controller and can be configured to project an image in dependence on laser beams produced by the first, second and third laser diodes. Additionally, the controller can be configured to detect vertical and/or horizontal laser beam misalignment(s) in dependence on signals produced by the opto-electronics circuit, as well as to compensate for detected vertical and/or horizontal laser beam misalignment(s) so that laser beam misalignment(s) do not adversely affect the image projected by the one or more micro-mirror(s).
This summary is not intended to summarize all of the embodiments of the present invention. Further and alternative embodiments, and the features, aspects, and advantages of the embodiments of invention will become more apparent from the detailed description set forth below, the drawings and the claims.
Various reason for laser beam (and more generally, light beam) misalignment were described above. Embodiments of the present invention described herein can be used to detect and compensate for all of the above causes for misalignment.
An exemplary laser beam misalignment was described above with reference to the timing diagram of
Referring to
In accordance with an embodiment, the size of each segment of the quad PD 402 is slightly larger than the size of the laser beam that is being aligned using the quad PD 402. For example, each of the four segments of the quad PD can be approximately 350×350 micrometers (μm), and the diameter of the laser beam can be approximately 300 μm. The gap between the adjacent PD segments can be, e.g., 10 μm. Exemplary shapes of each PD segment are shown in
By placing the quad PD 402 at an appropriate location relative to the laser beams being scanned (e.g., such that the quad PD 402 detects beams projected near a center of the projector output), currents generated by the four PD segments (which can be referred to as currents A, B, C and D) can be combined in various manners to monitor the vertical and horizontal alignment of the R, G and B laser beams generated by the laser diodes 112. Such currents can also be used to monitor the power of each of the R, G and B laser beams, and thus, the quad PD 402 can also be used for automatic power control (APC). APC can be used to control the intensity output of the laser diodes to compensate for changes in characteristics of the laser diodes, e.g., due to environmental (e.g., thermal) variations and/or aging of the laser diodes 112.
Referring to
Y_Offset=(A+B)−(C+D) {Equation 1}.
Still referring to
X_Offset=(A+C)−(B+D) {Equation 2}.
Additionally, in accordance with an embodiment, to determine the power of a laser beam for use with automatic power control (APC) and color calibration, the following equation can be used:
Power=A+B+C+D {Equation 3}.
Such power measurements can be used to ensure that the power of the laser beams produced by each of the laser diodes (or more generally, the power of the light beams produced by each of the light emitting elements) can be consistently maintained at desired levels. This enables there to always be a known ratio between the red, blue and green color intensities, to provide for proper color calibration (the color calibration can include white balancing and gamma correction, but is not limited thereto). Additionally, this enables the power of each of the light beams to remain the same over time to provide for consistent operation as output power of a light emitting element changes due to changes in temperature and/or degrades over time due to long term drift (e.g., due to aging).
In these equations: A is a current indicative of the intensity of the light detected by PD segment A; B is a current indicative of the intensity of the light detected by PD segment B; C is a current indicative of the intensity of the light detected by PD segment C; and D is a current indicative of the intensity of the light detected by PD segment D. Such currents may be amplified prior to or after being combined, but their intensities relative to one another should remain the same.
Each of the four electrically isolated PD segments produces a corresponding current indicative an amount of light detected by the PD segment. In
The OEIC 330 also includes current a summing stage 410 (e.g., implemented using current mirrors and summing nodes), a gain stage 412 (which can be adjustable) and an output driver 414. The summing stage 410 (also referred to as summing circuitry) can perform subtraction, depending on how it is implemented, as can be appreciated from
to achieve (A+B)−(C+D): S1=1, S2=1, S3=1, S4=0, S5=0, S6=0;
to achieve (A+C)−(B+D): S1=0, S2=0, S3=1, S4=1, S5=1, S6=0; and
to achieve (A+B+C+D): S1=1, S2=1, S3=0, S4=0, S5=0, S6=1.
The voltage signal(s) output by the output driver 414 can be provided directly back to the controller 104 (in
to achieve (A+B)−(C+D): S1=0, S2=1, S3=1, S4=0, S5=0, S6=1;
to achieve (A+C)−(B+D): S1=1, S2=0, S3=0, S4=1, S5=0, S6=1; and
to achieve (A+B+C+D): S1=0, S2=1, S3=1, S4=0, S5=1, S6=0.
When performing laser beam alignment, both vertical alignment and horizontal alignment can be performed. For horizontal alignment, Equation 1 (i.e., Y_Offset=(A+B)−(C+D)) can be used. For vertical alignment, Equation 2 (i.e., X_Offset=(A+C)−(B+D)) can be used. In accordance with an embodiment, the laser beam alignment can be performed during initialization of the projector system, e.g., each time the projector system is turned from off to on, or more frequently if desired. For vertical alignment each laser beam is scanned vertically using the mirror(s) 118 (while the other laser beams are turned off) so that the beam vertically crosses the center of the quad PD 402. For horizontal alignment each laser beam is scanned horizontally using the mirror(s) 118 (while the other laser beams are turned off) so that the beam horizontally crosses the center of the quad PD 402. The controller 104 records the location and/or timing data indicative of when the laser beam crosses the center of the quad PD 402, which is when there is a zero crossing resulting from the equation (A+B)−(C+D) for vertical alignment, and when there is a zero crossing resulting from the equation (A+C)−(B+D) for horizontal alignment. Based on the signals received from the OEIC 330, the controller 104 can recognize when a laser beam is misaligned relative to the other laser beams, and the controller 104 can control when it outputs specific color pixel data signals to compensate for the laser misalignment. For example, referring to the exemplary signals in
Embodiments of the present invention can be used to detect laser beam misalignment (and compensate for such) as often as desired. For example, a system can be designed such that laser beam misalignment is only checked for relatively infrequently, e.g., upon power up of a projector system, as mentioned above. For another example, a system can be designed such that laser beam misalignment is checked for more frequently, e.g., once per scan line, once per frame, or once per period of time (e.g., once every 5 minutes), but is not limited thereto.
As mentioned above, Equation 3 (i.e., A+B+C+D) can be used for automatic power control (APC), to calibrate for changes in efficiency of laser diodes due to changing in temperature, aging, etc. Such use of the OEIC 330 in this manner can negate the need for the separate calibration PD 120 shown in
While the laser diodes described herein were described as being red, green and blue in color, it is within the scope of the present invention that the laser diodes emit light of colors other than red, green and blue, such as, but not limited to, cyan, magenta and yellow. It is also within the scope of the present invention that more three colors are produced per pixel by the laser diodes, e.g., red, green, blue and yellow (e.g., if four laser diodes are used, the LDD 108 could include four DACs).
While the OEIC 330 and its quad PD 402 were described as being used to detect and compensate for laser beam misalignment, the OEIC 330 and its quad PD 402 can alternatively be used to detect and compensate for misalignment of light beams produced by other types of light emitting element, including, but not limited to, light emitting diodes (LEDs). As the term light beam is used herein, it can be a beam produced by a laser diode (i.e., a laser beam), a beam produced by an LED, or a beam produced by some other light emitting element.
In the above discussion of
As indicated at step 502, a light beam produced by one of a plurality of light emitting elements is scanned vertically across a photo-detector (PD), including a plurality of electrically isolated PD segments, wherein each PD segment is used to detect light produced by the light emitting element, and wherein each PD segment produces a current indicative of light detected by the PD segment. The quad PD 402, shown in
As indicated at step 504, the currents produced by the plurality of PD segments are combined in a first manner, e.g., using Equation 1, to produce a signal indicative of vertical light beam alignment.
As indicated by step 506, steps 502 and 504 are repeated for each of a plurality of light beams, to thereby produce the signal indicative of vertical light beam alignment for each of the light emitting elements (e.g., each of a red, green and blue laser diode).
Referring now to step 512, a light beam produced by one of the plurality of light emitting elements is scanned horizontally across the same photo-detector (PD) including the plurality of electrically isolated PD segments, wherein each PD segment is used to detect light produced by the light emitting element, and wherein each PD segment produces a current indicative of light detected by the PD segment. As indicated at step 514, the currents produced by the plurality of PD segments are combined in a second manner, e.g., using Equation 2, to produce a signal indicative of horizontal light beam alignment.
At step 522 the currents are optionally combined in a third manner, e.g., using Equation 3, to produce a signal indicative of power of the light beam produced by the light emitting element.
As indicated by step 526, steps 512 and 514 (and optionally 522) are repeated for each of the plurality of light beams, to thereby produce the signal indicative of horizontal light beam alignment for each of the light emitting elements (e.g., each of a red, green and blue laser diode), and optionally to also produce the signal indicative of power for each of the light emitting elements. As described above, the power measurements can be used for APC and/or color calibration, but is not limited thereto.
At step 532, vertical light beam misalignment and/or horizontal light beam misalignment can be detected, if such misalignment exists. More specifically, the signals indicative of vertical light beam alignment can be used to detect vertical light beam misalignment, and the signals indicative of horizontal light beam alignment can be used to detect horizontal light beam misalignment (e.g., as described above with reference to
At step 534, if vertical light beam misalignment and/or horizontal light beam misalignment is detected, compensation for such misalignment is performed by controlling the timing of color data. An example of this was described above.
The various steps of
The foregoing description is of the preferred embodiments of the present invention. These embodiments have been provided for the purposes of illustration and description, but are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations will be apparent to a practitioner skilled in the art.
Embodiments were chosen and described in order to best describe the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention. Slight modifications and variations are believed to be within the spirit and scope of the present invention. It is intended that the scope of the invention be defined by the following claims and their equivalents.
Claims
1. A projector system, comprising:
- a first light emitting element that emits light of a first color;
- a second light emitting element that emits light of a second color;
- a third light emitting element that emits light of a third color;
- a controller configured to produce first, second and third pixel data in dependence on a video signal received from a video source;
- a driver configured to drive the first, second and third light emitting elements in dependence on the first, second and third pixel data produced by the controller;
- one or more micro-mirror(s) that project an image in dependence on light beams produced in dependence on the light of the first, second and third colors emitted by the first, second and third light emitting elements; and
- an opto-electronics circuit including a plurality of electrically isolated photodetector (PD) segments; and circuitry configured to control how currents indicative of light detected by the plurality of electrically isolated PD segments are arithmetically combined;
- wherein the controller is also configured to detect vertical and/or horizontal light beam misalignment(s) in dependence on signals produced by the opto-electronics circuit, and compensate for detected vertical and/or horizontal light beam misalignment(s);
- wherein each of the plurality of electrically isolated PD segments produces a corresponding current indicative an amount of light detected by the PD segment;
- wherein the circuitry, configured to control how currents indicative of light detected by the plurality of electrically isolated PD segments are arithmetically combined, comprises switches, trans-impedance amplifiers (TIAs), and summing circuitry;
- wherein when the switches are in a first configuration, a signal produced by the opto-electronics circuit is used by the controller to detect vertical light beam misalignment; and
- wherein when the switches are in a second configuration, a signal produced by the opto-electronics circuit is used by the controller to detect horizontal light beam misalignment.
2. (canceled)
3. The projector system of claim 1, wherein when the switches are in a third configuration, a signal produced by the opto-electronics circuit is used by the controller to perform at least one of automatic power control (APC) or color calibration.
4. The projector system of claim 3, wherein the controller is configured to compensate for a detected change in output power by changing an amplitude and/or pulse width of one or more drive signals produced by the driver to drive the light emitting elements.
5. The projector system of claim 1, wherein:
- the first color is red;
- the second color is green;
- the third color is blue;
- the first pixel data is red pixel data;
- the second pixel data is green pixel data; and
- the third pixel data is blue pixel data.
6. The projector system of claim 5, wherein the controller is configured to compensate for detected vertical and/or horizontal light beam misalignment(s) by adjusting timing of at least one of the red pixel data, the green pixel data or the blue pixel data.
7. The projector system of claim 1, wherein the controller is configured to compensate for detected vertical and/or horizontal light beam misalignment(s) by adjusting timing of at least one of the first, second or third pixel data.
8. The projector system of claim 1, wherein:
- the plurality of electrically isolated PD segments comprises four electrically isolated PD segments;
- each of the four electrically isolated PD segments produces a corresponding current indicative an amount of light detected by the PD segment;
- the equation Y_Offset=(A+B)−(C+D) is used to produce the signal indicative of vertical light beam alignment for each of the light emitting elements; and
- the equation X_Offset=(A+C)−(B+D) is used to produce the signal indicative of horizontal light beam alignment for each of the light emitting elements, where A is indicative of the current produced by a first one of the four electrically isolated PD segments, B is indicative of the current produced by a second one of the four electrically isolated PD segments, C is indicative of the current produced by a third one of the four electrically isolated PD segments, and D is indicative of the current produced by a fourth one of the four electrically isolated PD segments.
9. The projector system of claim 8, wherein the equation Power=A+B+C+D is used to produce a signal indicative of light beam power for each of the light emitting elements.
10. A projector system, comprising:
- a first light emitting element that emits light of a first color;
- a second light emitting element that emits light of a second color;
- a third light emitting element that emits light of a third color;
- a controller configured to produce first, second and third pixel data in dependence on a video signal received from a video source;
- a driver configured to drive the first, second and third light emitting elements in dependence on the first, second and third pixel data produced by the controller;
- one or more micro-mirror(s) that project an image in dependence on light beams produced in dependence on the light of the first, second and third colors emitted by the first, second and third light emitting elements; and
- an opto-electronics circuit including a plurality of electrically isolated photodetector (PD) segments; and circuitry configured to control how currents indicative of light detected by the plurality of electrically isolated PD segments are arithmetically combined;
- wherein the controller is configured to detect vertical and/or horizontal light beam misalignment(s) in dependence on signals produced by the opto-electronics circuit; the controller is configured to compensate for detected vertical and/or horizontal light beam misalignment(s); each of the plurality of electrically isolated PD segments produces a corresponding current indicative an amount of light detected by the PD segment; the circuitry, configured to control how currents indicative of light detected by the plurality of electrically isolated PD segments are arithmetically combined, comprises switches, trans-impedance amplifiers (TIAs) and a current mirror; when the switches are in a first configuration, the TIAs and the current mirror are used to produce a signal that is indicative of vertical light beam alignment; when the switches are in a second configuration, the TIAs and the current mirror are used to produce a signal that is indicative of horizontal light beam alignment; and when the switches are in a third configuration, the TIAs are used to produce a signal indicative of light beam power.
11. A method for use with a projector system, comprising:
- receiving a video signal;
- producing first, second and third pixel data in dependence on the received video signal;
- driving first, second and third light emitting elements, in dependence on the first, second and third pixel data, to thereby emit light of first, second and third colors;
- producing light beams of the first, second and third colors in dependence on the emitted light of the first, second and third colors;
- controlling one or more micro-mirror(s) to thereby project an image in dependence on the light beams of the first color, the second color and the third color;
- using a plurality of electrically isolated photodetector (PD) segments to detect portions of the light beams of the first color, the second color and the third color, wherein each of the PD segments produces a current indicative of light detected by the PD segment;
- for each of the light beams of the first color, the second color and the third color, arithmetically combining the currents indicative of light detected by the plurality of electrically isolated PD segments in at least two different manners;
- detecting vertical and/or horizontal light beam misalignment(s) in dependence on results of the arithmetically combining the currents; and
- compensating for detected vertical and/or horizontal light beam misalignment(s);
- wherein the arithmetically combining is performed using switches, trans-impedance amplifiers (TIAs) and a current mirror, and includes for each of the light beams of the first color, the second color and the third color, configuring the switches in a first configuration that causes the TIAs and the current mirror to produce a signal that is indicative of vertical light beam alignment; and for each of the light beams of the first color, the second color and the third color, configuring the switches in a second configuration that causes the TIAs and the current mirror to produce a signal that is indicative of horizontal light beam alignment.
12. (canceled)
13. The method of claim 11, further comprising:
- for each of the light beams of the first color, the second color and the third color, configuring the switches in a third configuration that causes the TIAs to produce a signal indicative of light beam power.
14. The method of claim 13, further comprising:
- performing automatic power control (APC) in dependence on the signal indicative of light beam power that is produced for each of the light beams of the first color, the second color and the third color.
15. The method of claim 14, wherein performing APC includes compensating for a detected change in output power by changing an amplitude and/or pulse width of one or more signals used for driving the first, second and third light emitting elements.
16. The method of claim 14, further comprising:
- performing color calibration in dependence on the signal indicative of light beam power that is produced for each of the light beams of the first color, the second color and the third color.
17. A method for use with a projector system, comprising:
- receiving a video signal;
- producing first, second and third pixel data in dependence on the received video signal;
- driving first, second and third light emitting elements, in dependence on the first, second and third pixel data, to thereby emit light of first, second and third colors;
- producing light beams of the first, second and third colors in dependence on the emitted light of the first, second and third colors;
- controlling one or more micro-mirror(s) to thereby project an image in dependence on the light beams of the first color, the second color and the third color;
- using a plurality of electrically isolated photodetector (PD) segments to detect portions of the light beams of the first color, the second color and the third color, wherein each of the PD segments produces a current indicative of light detected by the PD segment;
- for each of the light beams of the first color, the second color and the third color, arithmetically combining the currents indicative of light detected by the plurality of electrically isolated PD segments in at least two different manners;
- detecting vertical and/or horizontal light beam misalignment(s) in dependence on results of the arithmetically combining the currents; and
- compensating for detected vertical and/or horizontal light beam misalignment(s);
- wherein the arithmetically combining is performed using switches, trans-impedance amplifiers (TIAs) and a current mirror, and includes for each of the light beams of the first color, the second color and the third color, while the light beam is being scanned vertically, configuring the switches in a first configuration that causes the TIAs and the current mirror to produce a signal that is indicative of vertical light beam alignment; and for each of the light beams of the first color, the second color and the third color, while the light beam is being scanned horizontally, configuring the switches in a second configuration that causes the TIAs and the current mirror to produce a signal that is indicative of horizontal light beam alignment.
18. A projector system, comprising:
- a first light emitting element that emits light of a first color;
- a second light emitting element that emits light of a second color;
- a third light emitting element that emits light of a third color;
- a controller configured to produce first, second and third pixel data in dependence on a video signal;
- a driver configured to drive the first, second and third light emitting elements in dependence on the first, second and third pixel data produced by the controller;
- one or more micro-mirror(s) that project an image in dependence on light beams produced in dependence on the light of the first, second and third colors emitted by the first, second and third light emitting elements;
- a plurality of electrically isolated photodetector (PD) segments, each of which produces a corresponding current indicative an amount of light detected by the PD segment;
- switches, trans-impedance amplifiers (TIAs) and a current mirror that are collectively configured to control how currents indicative of light detected by the plurality of electrically isolated PD segments are arithmetically combined;
- wherein when the switches are in a first configuration, a signal indicative of vertical light beam misalignment is produced;
- wherein when the switches are in a second configuration, a signal indicative of horizontal light beam misalignment is produced; and
- wherein the controller is also configured to detect and compensate for vertical and/or horizontal light beam misalignment(s) in dependence on the produced signals indicative of vertical light beam misalignment and horizontal light beam misalignment.
19. The projector system of claim 18, wherein:
- when the switches are in a third configuration, a signal indicative of light beam power is produced; and
- the controller is also configured to performing automatic power control (APC) in dependence on the produced signal indicative of light beam power.
20. The projector system of claim 19, wherein:
- the controller is also configured to performing color calibration in dependence on the produced signal indicative of light beam power.
Type: Application
Filed: Dec 17, 2012
Publication Date: May 2, 2013
Applicant: INTERSIL AMERICAS INC. (Milpitas, CA)
Inventor: INTERSIL AMERICAS INC. (Milpitas, CA)
Application Number: 13/717,413
International Classification: H04N 5/74 (20060101);