Circuits, systems and methods for vertical and horizontal light beam alignment

1. An opto-electronics circuit, comprising:

a plurality of electrically isolated photodetector (PD) segments; and

circuitry, including switches, trans-impedance amplifiers (TIAs) and a current mirror, 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, the TIAs and the current mirror are used to produce a signal that is indicative of vertical light beam alignment;

wherein 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

wherein when the switches are in a third configuration, the TIAs are used to produce a signal indicative of light beam power.

2. The opto-electronics circuit of claim 1 , wherein:

the plurality of electrically isolated PD segments comprises four electrically isolated PD segments; and

each of the four electrically isolated PD segments produces a corresponding current indicative an amount of light detected by the PD segment.

3. The opto-electronics circuit of claim 2 , wherein when the switches are in the first configuration the currents produced by the four electrically isolated PD segments are arithmetically combined in accordance with the following equation to produce the signal indicative of vertical light beam alignment:

Y _Offset=( +B )−( C+D )

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.

4. The opto-electronics circuit of claim 3 , wherein when the switches are in the second configuration the currents produced by the four electrically isolated PD segments are arithmetically combined in accordance with the following equation to produce the signal indicative of horizontal light beam alignment:

X _Offset=( A+C )−( B+D ).

5. The opto-electronics circuit of claim 4 , wherein when the switches are in the third configuration the currents produced by the four electrically isolated PD segments are arithmetically combined in accordance with the following equation to produce a signal indicative of light beam power:

Power= A+B+C+D.

6. The opto-electronics circuit of claim 2 , wherein when the switches are in the second configuration the currents produced by the four electrically isolated PD segments are arithmetically combined in accordance with the following equation to produce the signal indicative of horizontal light beam alignment:

X _Offset=( A+C )−( B+D ).

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.

7. The opto-electronics circuit of claim 1 , wherein the TIAs, of the circuitry configured to control how currents indicative of light detected by the plurality of electrically isolated PD segments are arithmetically combined, comprise only two TIAs.

8. A method comprising:

(a) using a plurality of electrically isolated PD segments to detect a light beam, wherein each PD segment produces a current indicative of light detected by the PD segment;

(b) combining the currents produced by the plurality of PD segments in a first manner to produce a signal indicative of vertical light beam alignment; and

(c) combining the currents produced by the plurality of PD segments in a second manner to produce a signal indicative of horizontal light beam alignment;

(d) detecting horizontal and/or vertical light beam misalignment based on the produced signal indicative of vertical light beam alignment and the produced signal indicative of horizontal light beam alignment and

(e) compensating for the detected horizontal and/or vertical light beam misalignment by controlling timing of color data that is used to produce a signal that drives a light emitting element used to produce the light beam detected by the plurality of electrically isolated PD segments.

9. The method of claim 8 , further comprising:

combining the currents produced by the plurality of PD segments in a third manner to produce a signal indicative of light beam power.

10. The method of claim 8 , 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 at step (b) to produce the signal indicative of vertical light beam alignment; and

the equation X_Offset=(A+C)−(B+D) is used at step (c) to produce the signal indicative of horizontal 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.

11. The method of claim 10 , further comprising:

combining the currents produced by the plurality of PD segments in a third manner to produce a signal indicative of light beam power;

wherein the equation Power =A+B+C+D is used at step (d) to produce the signal indicative of light beam power.

12. The method of claim 8 , wherein the method is for use with switches, trans-impedance amplifiers (TIAs) and a current mirror, and wherein:

step (b) is performed by configuring the plurality of switches in a first configuration that causes the TIAs and the current mirror to produce the signal indicative of vertical light beam alignment; and

step (c) is performed by configuring the plurality of switches in a second configuration that causes the TIAs and the current mirror to produce the signal indicative of horizontal light beam.

13. The method of claim 8 , wherein:

step (b) is performed when the light beam detected at step (a) is being scanned vertically; and

step (c) is performed when the light beam detected at step (a) is being scanned horizontally.

14. A method comprising:

(a) using a plurality of electrically isolated PD segments to detect a light beam, wherein each PD segment produces a current indicative of light detected by the PD segment;

(b) combining the currents produced by the plurality of PD segments in a first manner to produce a signal indicative of vertical light beam alignment;

(c) combining the currents produced by the plurality of PD segments in a second manner to produce a signal indicative of horizontal light beam alignment; and

(d) combining the currents produced by the plurality of PD segments in a third manner to produce a signal indicative of light beam power;

wherein steps (a), (b), (c) and (d) are performed for each of a plurality of light emitting elements; and further comprising

(e) detecting when an output power of one or more light beams produced by one or more of the light emitting elements changes, the detecting performed in dependence on the signals indicative of light beam power produced at step (d); and

(e) compensating 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.

15. A method comprising:

(a) using a plurality of electrically isolated PD segments to detect a light beam, wherein each PD segment produces a current indicative of light detected by the PD segment;

(b) combining the currents produced by the plurality of PD segments in a first manner to produce a signal indicative of vertical light beam alignment; and

(c) combining the currents produced by the plurality of PD segments in a second manner to produce a signal indicative of horizontal light beam alignment;

wherein steps (a), (b) and (c) are performed for each of a plurality of light emitting elements; and further comprising

(d) detecting 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, the detecting performed in dependence on the signals indicative of vertical light beam alignment produced at step (b) and/or the signals indicative of horizontal light beam alignment produced at step (c); and

(e) compensating for the detected misalignment by controlling timing of color data that is used to produce signals that drive the light emitting elements.

16. Circuitry for use with a plurality of electrically isolated photo-detector (PD) segments and a plurality of light emitting elements each of which emits light of a different color, the circuitry comprising:

a controller; and

switches and transimpedance amplifiers configured to selectively combine signals indicative of light detected by the plurality of electrically isolated PD segments;

wherein when the switches are in a first configuration, the signals are combined in a first manner to produce a signal indicative of vertical light beam alignment;

wherein when the switches are in a second configuration, the signals are combined in a second manner to produce a signal indicative of horizontal light beam alignment;

wherein when the switches are in a third configuration, the signals are combined in a third manner to produce a signal indicative of light beam power; and

wherein the controller is configured to compensate for detected horizontal and/or vertical light beam misalignment by controlling timing of color data that is used to produce signals that drive the light emitting elements.

17. A method comprising:

(a) using a plurality of electrically isolated PD segments to detect a light beam, wherein each PD segment produces a current indicative of light detected by the PD segment;

(b) combining the currents produced by the plurality of PD segments in a first manner to produce a signal indicative of vertical light beam alignment; and

(c) combining the currents produced by the plurality of PD segments in a second manner to produce a signal indicative of horizontal light beam alignment;

wherein steps (a), (b) and (c) are performed for each of a plurality of light beams, which each one of the light beams has a different color than the other light beams; and further comprising

(d) detecting when one of the light beams is misaligned relative to the other light beams, the detecting performed in dependence on the signals indicative of vertical light beam alignment produced at step (b) and/or the signals indicative of horizontal light beam alignment produced at step (c); and

(e) compensating for the detected misalignment by controlling timing of color data that is used to produce the light beams.