1. An ink jet print head, comprising:
a cavity plate that includes a plurality of nozzles and a plurality of pressure chambers communicating with the respective nozzles;
a plate-like piezoelectric actuator formed into a single laminated structure by laminating a plurality of piezoelectric sheets including a plurality of electrodes which are formed at positions so as to be aligned with the respective pressure chambers, the laminated piezoelectric actuator sintered and bonded to the cavity plate so as to close the pressure chambers provided in the cavity plate;
surface electrodes provided at an end portion of a surface of the piezoelectric actuator, which is opposed to a surface to be bonded to the cavity plate, and electrically connected with the plurality of electrodes; and
protrusions that each has a thickness of the surface electrodes and is provided on the surface of the piezoelectric actuator at a location corresponding to the surface where the surface electrodes are not provided.
2. The ink jet print head according to claim 1, wherein the plurality of pressure chambers are aligned in a number of rows, the surface electrodes connected with the electrodes are aligned in a number of rows at both end portions along the rows of the pressure chambers, and the protrusions are disposed between the rows of the surface electrodes.
3. The ink jet print head according to claim 2, wherein the cavity plate has lands to separate the adjacent pressure chambers, and the protrusions are provided on the surface of the piezoelectric actuator with respect to the lands.
4. The ink jet print head according to claim 3, wherein the surface electrodes and the protrusions are printed on the surface of the piezoelectric actuator using the same material.
5. The ink jet print head according to claim 4, wherein each of the piezoelectric sheets has a thickness of between 15-30 \u03bcm.
6. The ink jet print head according to claim 5, wherein the electrodes are driving electrodes, which are formed at positions with respect to the pressure chambers, and common electrodes, which are formed at a position to cover the pressure chambers, wherein each of the driving electrodes has a width of between 50-500 \u03bcm and a thickness of between 0.7-5 \u03bcm.
7. The ink jet print head according to claim 6, wherein each of the driving electrodes has a width of between 80-200 \u03bcm and a thickness of between 1-3 \u03bcm.
8. The ink jet print head according to claim 7, the piezoelectric actuator has the flatness of 30 \u03bcm or less in an area of 5 mm2.
9. The ink jet print head according to claim 4, wherein each of the piezoelectric sheets has a thickness of between 22.5-30 \u03bcm.
10. The ink jet print head according to claim 1, wherein the piezoelectric actuator has a flatness of 30 \u03bcm or less, which is a difference of height between projections and depressions formed on the piezoelectric actuator at its surface to which the cavity plate is bonded.
11. The ink jet print head according to claim 10, wherein the flatness is 30 \u03bcm or less in an area of 5 mm2.
12. A method of fabricating an ink jet print head, comprising the steps
forming a cavity plate by laminating a plate, in which a plurality of nozzles are provided, and a plurality of plates, in which a plurality of pressure chambers communicating with the respective nozzles are provided;
forming a plate-like piezoelectric actuator by laminating a plurality of piezoelectric sheets, on each of which a plurality of driving electrodes are formed at positions with respect to the pressure chambers, and a plurality of piezoelectric sheets, on each of which a common electrode is formed at a position to cover the pressure chambers;
providing surface electrodes, which electrically connect one of the driving electrodes and the common electrodes, at both end portions of a surface of the piezoelectric actuator, which is opposed to a surface to be bonded to the cavity plate;
providing protrusions having a thickness of the surface electrodes, between the surface electrodes on the surface of the piezoelectric actuator;
forming the piezoelectric actuator into a single piece by sintering the piezoelectric actuator; and
bonding the piezoelectric actuator to the cavity plate so as to close the pressure chambers in the cavity plate while pressing both the surface electrodes and the protrusions using a jig having a flat surface.
13. The method of fabricating the ink jet head according to claim 12, wherein the surface electrodes and the protrusions are printed on the surface of the piezoelectric actuator at the same time using the same material.
14. The method of fabricating the ink jet print head according to claim 13, wherein each of the piezoelectric sheets has a thickness of between 15-30 \u03bcm.
15. The method of fabricating the ink jet print head according to claim 14, wherein each of the driving electrodes has a width of between 50-500 \u03bcm and a thickness of between 0.7-5 \u03bcm.
16. The method of fabricating the ink jet print head according to claim 14, wherein each of the driving electrodes has a width of between 80-200 \u03bcm and a thickness of between 1-3 \u03bcm.
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 method for detecting a mechanical shock affecting an optical disc drive during reading or recording information onto an optical disc, the optical disc drive comprising a lens system used in reading or recording information from the optical disc, servo means for controlling the positioning of the lens system relative to the optical disc, the servo means generating servo signals, the method comprising steps of
generating a first shock detection signal based on using at least one servo signal;
deciding that a mechanical shock is present if a value of the first shock detection signal exceeds a first threshold value;
the method characterized by
using a focus error signal (FE) andor a tracking error (TE) signal from available servo signals for generating the first shock detection signal;
the first shock detection signal being proportional to a weighted time integration of the focus error signal (FE) andor the tracking error (TE) signal.
2. A method according to claim 1, characterized by subtracting from the used servo signal a memory loop signal, the memory loop signal being proportional to a time delayed copy of the used servo signal.
3. A method according to claim 2, characterized by the subtraction being performed after the weighted time integration.
4. A method according to claim 2, characterized by memory loop signal corresponding to passing the used servo signal through a comb filter.
5. A method according to claim 1, characterized by using the focus error (FE) signal in generating the first hock detection signal.
6. A method according to claim 5, characterized by
generating a second shock detection signal, corresponding to integrating over time the tracking error (TE) signal;
deciding that a mechanical shock is present, if either a value of the second shock detection signal exceeds a second threshold value or a value of the first shock detection signal exceeds the first threshold value.
7. A method according to claim 1, characterized by low pass filtering the used servo signal in the generation step, the low pas filter having a cut-off frequency below a mechanical resonance frequency of the optical disc drive.
8. A method according to claim 1, characterized by
generating a scratch detection signal based on the at least one servo signal used for generating the first shock detection signal;
deciding that a mechanical shock is present if simultaneously a value of the first shock detection signal is above the first threshold value and a value of the scratch detection signal is below a scratch detection threshold value.
9. A method according to claim 8, characterized by using a characteristic rise time of the shock detection signal as the scratch detection signal.
10. A method according to claim 8, characterized by generating a scratch detection signal comprises
measuring a rise time corresponding to the time needed for the first shock detection signal to rise from a low defect threshold value to a high defect threshold value;
comparing the measured rise time against a scratch detection threshold value.
11. An apparatus for recording data onto an optical disc, comprising
a lens system for controlling an electromagnetic beam, used in reading or recording information from the optical disc;
servo means for controlling the positioning of the lens system relative to the optical disc, the servo means generating servo signals, the servo signals comprising at least a focus error (FE) signal and a tracking error (TE) signal;
signal generation means for generating a first shock detection signal based on using at least one servo signal;
comparison means for comparing the value of the first shock detection signal with a first threshold value;
decision means arranged such that a decision is made that a mechanical shock is present, if a value of the first shock detection signal is above the first threshold value;
characterized in that, the signal generation means are arranged such that the first shock detection signal is proportional to a time integral of the focus error (FE) signal andor of the tracking error (TE) signal.
12. An apparatus according to claim 11, characterized in that further comprises
a memory loop filter; and
subtraction means for subtracting from the used servo signal a memory loop signal, the memory loop signal being generated by passing the used servo signal through the memory loop filter.
13. An apparatus according to claim 12, characterized in that the subtraction being performed after the weighted time integration.
14. An apparatus according to claim 11, characterized in that memory loop filter is a comb filter.
15. An apparatus according to claim 11, characterized in that the first shock detection signal is proportional to a time integral of the focus error (FE) signal.
16. An apparatus according to claim 12, characterized in that the apparatus further comprises
second signal generation means for generating a second shock detection signal proportional to time integral of the tracking error (TE) signal;
second decision means arranged such that a decision is made that a mechanical shock is present, if either a value of the second shock detection signal exceeds a second threshold value or a value of the first shock detection signal exceeds the first threshold value.
17. An apparatus according to claim 15, characterized in that, the signal generation means are arranged such that the shock detection signal is proportional to a low pass filtered focus error (FE) signal andor of tracking error (TE) signal, wherein a cut-off frequency of the low pass filter is below a mechanical resonance frequency of the optical disc drive.
18. An apparatus according to claim 15, characterized in that it further comprises
means for generating a scratch detection signal based on the at least one servo signal used in generating the shock detection signal;
second decision means arranged such that a decision is made that a mechanical shock is present, if simultaneously a value of the first shock detection signal is above the first threshold value and a value of the scratch detection signal is below a scratch detection threshold value.
19. An apparatus according to claim 18, characterized in that, the scratch detection signal corresponds to a characteristic rise time of the first shock detection signal.
20. An apparatus according to claim 18, characterized in that, it further comprises means for:
measuring a rise time corresponding to the time needed for the first shock detection signal to rise from a low defect threshold value to a high defect threshold value.
comparing the measured rise time against a scratch detection threshold value.
21. An apparatus according to claim 15, characterized in that, the signal generation means comprise a digital signal processor arranged to integrate the used servo signal.
22. An apparatus according to claim 15, characterized in that, the shock detection signal is generated by a digital signal processor.
23. An apparatus according to claim 22, characterized in that, the digital signal processor is further arranged to comparing the first shock detection signal to the first threshold value.
24. An apparatus according to claim 22, characterized in that, the digital signal processor is further arranged to decide if a mechanical shock is present.
25. An apparatus according to claim 20, characterized in that the scratch detection signal is generated by a digital signal processor.
26. A recording method for recording data onto an optical disc in an optical disc drive, the method comprising
recording data onto the optical disc;
detecting if a mechanical shock affects the optical disc drive;
interrupting the recording if a mechanical shock is detected;
resuming the recording according to a suitable linking method when no shock is detected;
the recording method characterized by detecting if a mechanical shock affects the optical disc drive according to a method as claimed in claim 1.