We claim:
1. A method of controlling the position of an optical pick-up unit over an optical media, comprising:
calculating a control signal in response to digitized optical signals received from the optical pick-up unit;
detecting periodic variations in the control signal;
forming a new control signal by adding the periodic variations into the control signal; and
controlling a position of the optical pick-up unit in response to the new control signal.
2. The method of claim 1, wherein the position is in a tracking direction, the tracking direction being in a plane parallel with the optical media.
3. The method of claim 1, wherein the position is in a focus direction, the focus direction being normal to a plane of the optical media.
4. The method of claim 1, wherein calculating the control signal includes
calculating an error signal in response to the digitized optical signals;
amplifying and offsetting the error signal to form an amplified error signal; and
filtering the amplified error signal to form the control signal.
5. The method of claim 1, wherein periodic variations in the control signal are removed from the control signal by forming the new control signal.
6. The method of claim 1, wherein the periodic variations have a frequency equal to harmonics of a rotation rate of the optical media.
7. The method of claim 1, wherein detecting periodic variations in the control signal includes
mixing the control signal with sin(t) to form a sin signal;
mixing the control signal with cos(cot) to form a cosine signal;
accumulating the sin signal over a number of cycles to form an accumulated sin signal;
accumulating the cosine signal over the number of cycles to form an accumulated cosine signal;
integrating the accumulated sin signal to form a sine coefficient; and
integrating the accumulated cosine signal to form a cosine coefficient.
8. The method of claim 7, wherein the number of cycles is an integer number of periods corresponding to the frequency co.
9. The method of claim 7, wherein the frequency c is a harmonic of the rotational frequency of the optical media.
10. The method of claim 7, wherein accumulating the sin signal includes
delaying for a delay period;
zeroing an integrator; and
integrating the sin signal over the number of cycles to form the accumulated sin signal.
11. The method of claim 10, wherein integrating the accumulated sin signal includes
delaying for a time equal to the delay period plus the number of cycles; and
adding the accumulated sin signal to previously acquired accumulated sin signals to form the sine coefficient.
12. The method of claim 7, wherein accumulating the cosine signal includes
delaying for a delay period;
zeroing an integrator; and
integrating the cosine signal over the number of cycles to form the accumulated cosine signal.
13. The method of claim 12, wherein integrating the accumulated cosine signal includes
delaying for a time equal to the delay period plus the number of cycles; and
adding the accumulated cosine signal to previously acquired accumulated cosine signals to form the cosine coefficients.
14. The method of claim 7, further including forming the periodic variations by multiplying the sine coefficients by sin(t) and multiplying the cosine coefficients by cos(t).
15. A servo system, comprising:
an optical pick-up unit;
an analog processor coupled to receive signals from detectors in the optical pickup unit and provide digital signals;
at least one processor coupled to receive the digital signals, the processor calculating a control signal; and
a driver coupled to control the position of the optical pick-up unit in response to the control signal,
wherein the at least one processor executes an algorithm that
calculates a control signal in response to the digital signals,
detects periodic variations in the control signal, forms a new control signal by adding the periodic variations into the control signal, and
substitutes the new control signal for the control signal so that the driver responds to the new control signal.
16. The system of claim 15, wherein the position is in a tracking direction, the tracking direction being in a plane parallel with an optical media over which the optical pick-up unit moves.
17. The system of claim 15, wherein the position is in a focus direction, the focus direction being normal to a plane of the optical media over which the optical pick-up unit moves.
18. The system of claim 15, wherein calculating the control signal includes
calculating an error signal in response to the digitized optical signals;
amplifying and offsetting the error signal to form an amplified error signal; and
filtering the amplified error signal to form the control signal.
19. The system of claim 15, wherein periodic variations in the control signal are removed from the control signal by forming the new control signal.
20. The system of claim 15, wherein the at least one processor detects the periodic variations by executing an algorithm that
mixes the control signal with sin(t) to form a sin signal;
mixes the control signal with cos(t) to form a cosine signal;
accumulates the sin signal over a number of cycles to form an accumulated sin signal;
accumulates the cosine signal over the number of cycles to form an accumulated cosine signal;
integrates the accumulated sin signal to form a sine coefficient;
integrates the accumulated cosine signal to form a cosine coefficient; and
forms the periodic by multiplying the sine coefficient by sint and adding the cosine coefficient multiplied by cost.
21. A servo system, comprising:
means for calculating a control signal;
means for detecting periodic variations in the control signal; and
means for forming a new control signal with the periodic variations.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A device for sensing a direction of rotation of an electric motor in a hand tool, said device comprising:
a rotatably supported brush plate engageable with said electric motor, wherein said brush plate is rotatable to different angular positions about its rotational axis depending on a direction of rotation of said electric motor;
at least one sensor for sensing said different angular positions of said brush plate to determine said direction of rotation of said electric motor of said hand tool, wherein said sensor is configured as a contactless sensor that is activated by exposure to a magnetic field of
at least one magnet, wherein said at least one magnet is mechanically linked to said rotatably supported brush plate; and
a lever whereon said at least one magnet is disposed, wherein said lever is actuated by said brush plate so that when said brush plate is rotated said lever is displaced and said magnet changes its position.
2. A device as defined in claim 1, wherein said sensor is configured as a Hall sensor.
3. A device as defined in claim 1, wherein said sensor is configured as a reed relay.
4. A device as defined in claim 1 further comprising an electronics module, said sensor being located in said electronics module.
5. A device as defined in claim 4, wherein said electronics module is located outside said electric motor and inside said hand tool.
6. A device as defined in claim 1, wherein said lever including said magnet is shifted into proximity with said sensor by a change in said angular positions of said brush plate upon rotation of said electric motor in only one direction.
7. A device as defined in claim 1 further comprising means for displaying said direction of rotation being sensed to a user, wherein said means for displaying is configured to receive at least one visual signal.
8. A device as defined in claim 1 further comprising means for displaying said direction of rotation being sensed to a user, wherein said means for displaying is configured to receive at least one acoustic signal.
9. A device as defined in claim 1 wherein said at least one magnet is a permanent magnet.
10. An electric hand tool comprising:
an electric motor including a rotatably supported brush plate, wherein said brush plate is rotatable about its axis to different positions based on a direction of rotation of said electric motor;
at least one magnet, wherein said at least one magnet is mechanically linked to said rotatably supported brush plate;
a lever whereon said at least one magnet is disposed, wherein said lever is actuated by said brush plate so that when said brush plate is rotated said lever is displaced and said magnet changes its position; and
at least one sensor for sensing said different positions of said rotatably supported brush plate to determine a direction of rotation of said electric motor, said at least one sensor being configured as a contactless sensor that is activated by exposure to a magnetic field of said magnet.
11. An electric hand tool as defined in claim 10, wherein said electric hand tool is a rotary hammer.
12. An electric hand tool as defined in claim 10, wherein said electric hand tool is an impact drill.