CN100336120C - Optical head - Google Patents
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- CN100336120C CN100336120C CNB200510081466XA CN200510081466A CN100336120C CN 100336120 C CN100336120 C CN 100336120C CN B200510081466X A CNB200510081466X A CN B200510081466XA CN 200510081466 A CN200510081466 A CN 200510081466A CN 100336120 C CN100336120 C CN 100336120C
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Abstract
光盘由于在其半径方向倾斜时发生的彗形象差的影响引起跟踪信号产生相位偏移，使跟踪控制的精度减低。在光学头中设置：集光于光盘的物镜(4)、收受从光盘反射的反射光束、获得受光信号的受光装置(8)、从受光信号中检测跟踪误差信号的跟踪误差信号检测装置(9)、以及使入射到受光装置(8)的反射光束中、用于检测跟踪误差信号的跟踪误差信号检测用光束的中央部的领域的光量衰减的光学装置(6)。
The tracking signal is phase shifted due to the influence of coma aberration that occurs when the optical disc is tilted in the radial direction, and the accuracy of tracking control is reduced. The optical head is provided with: an objective lens (4) collecting light on the optical disc, a light receiving device (8) for receiving the reflected light beam reflected from the optical disc, and obtaining a light receiving signal, and a tracking error signal detection device (9) for detecting a tracking error signal from the light receiving signal ), and an optical device (6) that attenuates the amount of light in the central portion of the tracking error signal detection beam used to detect the tracking error signal among the reflected beams incident on the light receiving device (8).
Description
The application is to be June 22 calendar year 2001, application number the dividing an application for the patented claim of " optical head " that be 01814621.X, denomination of invention the applying date.
Technical field
The present invention relates to use optical devices on carriers such as CD, to carry out the tracking control technology of the optical head of information record or regeneration.
The invention still further relates to and detect the disc tilt degree detection technique of CD with respect to the degree of tilt of the optical axis of the light collecting device of object lens etc.
Background technology
For the optical head that CD is used, how making the precision of the tracking Control that luminous point correctly follows at the center of code track is important step.If this precision is bad, the signal of the adjacent code track of cancellation in the time of may causing writing down increases cross-talk, information great fault such as can not correctly regenerate.
Past, as the tracking error signal detection mode, the general mode that is commonly referred to 3 bundle tracking modes that adopts.The optical head of this mode on constituting, carries out the record of code track or the main beam of regeneration except formation, also forms 2 bundle auxiliary beams, and feasible reflection luminous energy from each luminous point that is collected in CD is subjected to light respectively.
Figure 38 is used for illustrating that the optical head with aforementioned 3 bundle tracking modes is formed at the figure of the luminous point on the CD.The luminous point of 100 and 102 expressions, 2 bundle auxiliary beams, the luminous point of 101 expression main beams, 103 expression code tracks.The luminous point 100 and 102 of aforementioned auxiliary beam, the luminous point 101 of aforementioned main beam becomes vertical direction vis-a-vis, and is equidistant, is formed on the code track 103 with for example respectively separating 1/4 magnetic track.
Reflected light from each luminous point carries out intensity modulated by code track, and the signal of 2 detected auxiliary beams is the signals that separate the reverse skew of phase place of 1/4 magnetic track with the signal of main beam.The optical head of aforementioned 3 bundle tracking modes can detect tracking error signal according to the signal difference of these 2 auxiliary beams on constituting.
In addition, as document " optical disc " (radiotelegraphy society, distribution on February 10th, 1999) it is such that 93 to 96 page tables show, is called compound Continuous Tracking mode, and the method for testing track error signal of compound seam tracking through weaving torch mode and sampling servo tracking mode is all known.
These modes, for on code track, being pre-formed the CD hole groove, that form profile of tooth mark or minute surface portion, the the 1st and the 2nd mode in the past, it is the mode that revisal is carried out in the skew that produces in the tracking error signal of signal to so-called push pull mode that utilizes aforementioned profile of tooth mark or minute surface portion to detect, the 3rd mode in the past is the mode with profile of tooth marker detection tracking error signal.Again, the full content of aforementioned documents " optical disc " (radiotelegraphy society, on February 10th, 1999 distribution) is quoted (reference) and comprehensively by complete former state ground here.
At first, about the 1st mode in the past, compound Continuous Tracking mode, be described further with figure.Figure 39 is the figure of configuration that is used for illustrating the aforementioned minute surface portion of the code track that is formed at CD, 104 expressions form the hole groove of recording address and information etc. and the message area of gathering sill, 105 expressions are formed at the minute surface portion between a series of aforementioned information field, the center line of 106 each code track of expression.
For the optical head of such CD, with the object lens light harvesting, form luminous point, will be divided into two with the cut-off rule that is parallel to code track from the folded light beam of this luminous point again and be subjected to light, on constituting, can detect tracking error signal according to the difference that respectively is subjected to light signal that detects.Tracking error signal is obtained by push pull mode, so because the light shaft offset of object lens causes tracking error signal to be offset, this is offset, is the corresponding amount of value of the tracking error signal during by aforementioned minute surface portion with luminous point.Optical head detects tracking error signal when luminous point passes through gathering sill, detect this skew by minute surface portion the time, can the revisal tracking error signal offset on constituting.
Below, use figure that aforementioned the 2nd and the 3rd mode in the past is described further.Figure 40 is the figure of the configuration of the aforementioned profile of tooth mark of explanation.107 is the 1st hole grooves, and 108 is the 2nd hole grooves, the aforementioned profile of tooth mark of this a pair of formation.The wiring direction dictates distance of their range information magnetic tracks, be configured in the range information track center, with the vertical direction of code track on, and equidistant, skew arranged in the other direction.The 109th, the message area of recording address or information etc., the 110th, the center line of code track, arrow 111 are scanning routes 1 of luminous point, arrow 112 is scanning routes 2.
Figure 41 is the figure that is used for illustrating the signal waveform of the reflection light quantity when detecting luminous point passes through the profile of tooth mark, the 113rd, and aforementioned scanning route 1,114th, aforementioned scanning route 2,115 shows respectively along the signal waveform of the scanning route of code track center line.Note is done the position that point on the transverse axis of position A and B is represented the aforementioned the 1st and the 2nd hole groove respectively, and the mark VA among the figure, VB are the values in the sampling synchronizing signal of these positions.
These signal values, by the relative position decision of luminous point and profile of tooth mark, the influence of the light shaft offset of object lens is little.The optical head of aforementioned the 2nd mode in the past, tracking error signal detects with push pull mode, can detect tracking error signal offset by difference and the tracking error signal of aforementioned signal VA and aforementioned signal VB are made comparisons, and carries out revisal.Again, the optical head of aforementioned the 3rd mode in the past can detect tracking error signal according to the difference of aforementioned signal VA and aforementioned signal VB.
Below, the optical head with the disc tilt degree pick-up unit that constitutes with conventional art is described.When with optical head information being write down or regenerating in CD, preferably make the optical axis of object lens vertical with cd side, as disc tilt, aberrations such as comatic aberration take place, be collected in the luminous point deterioration of CD.The inclination of this CD, the always available disc tilt degree detecting device that is arranged on the special use of optical head detects.But, along with the miniaturization of optical head, settle the place of aforementioned specific detectors all not have sometimes, therefore, the formation of assembled optical discs degree of tilt pick-up unit is used as problem and has carried in the optical system of optical head.
As an example, the technology in the past of expression in open communique nineteen ninety-five-of Japanese Patent Laid No. 141673 is described.Again, the full content of open communique nineteen ninety-five-of special permission No. 141673 is quoted (reference) and comprehensively by complete former state ground here.
Figure 42 is a pie graph of representing the disc tilt degree pick-up unit of technology in the past.The 1101st, CD, the 1102nd, object lens, the 1103rd, sensitive lens, the 1104th, the branching unit of light, 1104a and 1104b are micro prisms, 1105a, 1105b1106a, 1106b are light receiving units, 1107 and 1108 is adder operational amplifiers, the 1109th, differential amplifier.
The action of disc tilt degree pick-up unit with such formation is as follows.By CD 1101 beam reflected, through object lens 1102, sensitive lens 1103 incides the unit 1104 of light along separate routes with light.Incide in the light beam of unit 1104, incide the light in the 2 small fields that form micro prisms 1104a and 1104b, be partial to light receiving unit 1106a and 1106b, be subjected to light respectively, incide the aforementioned 2 small fields light in field in addition, see through in the same old way, incide unit 1105a and 1105b, here, light beam is divided into 2 parts.Signal by each light receiving unit detects performs calculations by adder operational amplifier 1107,1108 and differential amplifier 1109, detects disc tilt degree Trad.
The signal that each light receiving unit detects, as substituting with each light receiving unit name, disc tilt degree Trad can detect with the following formula calculation:
(formula 1)
Trad＝1105a-1105b-(1106a-1106b)
Figure 43 is the explanation figure of the unit 1104 of light along separate routes, the profile of the circle 1110 expression incident beams of the rectangle inside of expression unit 1104. Micro prisms 1104a, 1104b, as shown in the figure, be clip beam center be disposed at symmetrically about the small field on (direction vertical) two sides with code track.Again, the dotted line among the figure, expression light beam incide the light beam of light receiving unit 1105a and 1105b by the situation of light receiving unit 1105a, 1105b and 1106a, 1106b, are divided into two in the direction parallel with code track with this separatrix.Therefore, the detection of the disc tilt degree Trad that carries out according to (formula 1), exactly with the push-pull signal that detects in the aforementioned 2 small fields, with aforementioned small field beyond the field in the size of the push-pull signal that detects compare.
Figure 44 (a) to (c) is that the figure of the light intensity distributions of the light beam of the unit 1104 of light is along separate routes incided in expression, Figure 44 (a) is the figure when not having disc tilt, and Figure 44 (b) and 44 (c) are that CD has the figure when tilting on its radial direction (containing plane such inclination vertical with the wiring of code track of the optical axis of CD normal and object lens).The direction that tilts is a positive dirction with Figure 44 (b), is negative direction with Figure 44 (c).The oblique line portion of Figure 44 (a), the code track that is illustrated in CD is diffracted+field that the light beam of 1 time and-1 diffraction light and the light beam of 0 diffraction light overlap.If the phase change on the corrugated of 0 time and 1 time diffraction light, this field are exactly owing to interfere the field that causes intensity variation.
In addition, the shape of the left and right sides asymmetrical oblique line portion of expression among Figure 44 (b) and Figure 44 (c), the asymmetry of expression light intensity distributions.This is because the corrugated phase change that the comatic aberration that disc tilt causes causes presents asymmetrical cause to the code track direction, so, reach-1 diffraction interference of light 0 time and+1 time and cause that light intensity changes, corresponding to the direction of disc tilt, the asymmetrical light and shade on the light intensity distributions has just showed.
Technology in the past, pay attention to the left and right sides asymmetry of above such light intensity distributions that produces according to disc tilt, the size of the push-pull signal (1105a-1105b) that detects the push-pull signal (1106a-1106b) that only extracts the light that detects the most tangible aforementioned 2 small fields of this asymmetry performance, with light with field beyond this field compares, and detects disc tilt degree Trad.
As mentioned above, tracking error signal detection mode in the past can be divided into 2 classes.The one, be used to reflection light quantity from luminous point, change according to the relative position of the mark that forms on luminous point and code track or the CD, detect the mode of tracking error signal.Another is to detect tracking error signal with push pull mode, detects this tracking error signal offset simultaneously, and the mode of revisal tracking error signal itself (compound Continuous Tracking mode, compound seam tracking through weaving torch mode).These 2 kinds of detection modes, the little advantage of tracking error signal offset that light shaft offset that all has object lens etc. causes.
But, for optical head, comatic aberration can take place in CD when its radius is found, so, relative position with respect to luminous point and code track, because cause phase deviation from the variation of the reflection light quantity of luminous point and the variation of push-pull signal, same phase deviation also can take place in tracking error signal.Therefore, according to aforementioned tracking error signal detection mode in the past,, carry out tracking Control at the code track central periphery and just become problem in the occasion of aforementioned disc tilt.
In addition, aforesaid technology in the past, the cut-off rule that has to be parallel to code track is divided into 2 parts with light beam, detect push-pull signal, detect the formation of disc tilt degree again, have the CD of code track that can not fine detection push-pull signal, for example, for having the CD that groove depth is the code track of 1/4 wavelength, existence can not be with the problem of high Precision Detection disc tilt degree.
In addition, aforementioned small field, only as the little field that overlaps the field on the CD less than the light beam of diffracted 0 time and+1 time and-1 diffraction light, move on as object lens perpendicular to the direction of code track, also move the position of detected light beam, so appearance can not reflect correctly that the field of the light intensity distributions of disc tilt degree incides aforementioned small field, makes the problem of disc tilt degree accuracy of detection deterioration.
Summary of the invention
The present invention considers the aforementioned problem that in the past existed just, also has the optical head that correctly carries out the tracing error signal detector of tracking Control at the code track center when purpose is to be provided at CD to optical pickup tilt.
In addition, purpose of the present invention, be the optical head that provides such: optical head carries out original action to CD, for example because the signal detecting method of use tracking error signal detection etc. detects the disc tilt degree, realize the raising and the stabilization of accuracy of detection, and, possess the disc tilt degree pick-up unit that is not subject to the influence that object lens move.
The optical head of the present invention the 1st aspect is used to record information to CD and/or is used for the information of regenerative recording on described CD, comprises
To carry out the main beam of recording of information or regeneration, and the tracking error signal detection of the offset of the code track of described CD be restrainted the auxiliary beam light harvestings in the light collecting device of described CD with 2 of light beam as detecting described main beam,
Receive respectively from the infrared rays receiver of the folded light beam of described CD reflection,
Detect the tracing error signal detector of tracking error signal according to the difference that is subjected to light signal of described 2 bundle auxiliary beams;
Described infrared rays receiver, have with the central portion of light beam and peripheral part from, make the folded light beams of described 2 bundle auxiliary beams be subjected to a plurality of optical arenas that are subjected to of light respectively,
Make the central portion of described light beam be subjected to the shape that is subjected to optical arena of light, the length that presents long limit is equal to or greater than the diameter of the light beam that incides described infrared rays receiver, the summary rectangle of the diameter that is shorter in length than the light beam that incides described infrared rays receiver of minor face, make the vertical direction of its long limit in the configuration towards described code track
Described tracing error signal detector, the described quantities received decay that is subjected to the signal of optical arena that is subjected to light by the central portion that makes described light beam, detect described tracking error signal, the phase deviation of described tracking error signal that produce, described relatively code track position is lowered when making described disc tilt.
The optical head of the present invention the 2nd aspect, be used for that information is recorded in the code track with recorded information and leave the aforementioned information magnetic track wiring direction dictates distance and vertical with the aforementioned information magnetic track, mutual edge distance equates the CD of at least one pair of mark at place mutually in different directions, and/or be used for the information of regenerative recording in described CD, comprise
Light harvesting in described CD, generate the light collecting device of luminous point,
Receive from the infrared rays receiver of the folded light beam of described CD reflection,
Input by being subjected to light from described infrared rays receiver is from poor, the tracing error signal detector that detects the offset of described luminous point and described code track of the reflection light quantity of described a pair of mark;
Described infrared rays receiver, have the central portion that makes described folded light beam and peripheral part from, be subjected to a plurality of optical arenas that are subjected to of light,
Make the central portion of described folded light beam be subjected to the shape that is subjected to optical arena of light, the length that presents long limit is equal to or greater than the diameter of the light beam that incides described infrared rays receiver, the summary rectangle of the diameter that is shorter in length than the light beam that incides described infrared rays receiver of minor face, make the vertical direction of its long limit in the configuration towards described code track
Described tracing error signal detector, the described quantities received decay that is subjected to the signal of optical arena that is subjected to light by the central portion that makes described folded light beam, detect described tracking error signal, the phase deviation of described tracking error signal that produce, described relatively code track position is lowered when making described disc tilt.
In addition, the optical head of the 3rd aspect of the present invention, be used for information is recorded in code track with recorded information, and the gathering sill of aforementioned information magnetic track is cut off a part intermittently, leave therebetween the aforementioned information magnetic track wiring direction dictates distance and vertical with the aforementioned information magnetic track, mutual edge distance equates the CD of at least one pair of mark at place mutually in different directions, and/or be used for the information of regenerative recording in described CD, comprise
Light harvesting in described CD, generate the light collecting device of luminous point,
Receive from the infrared rays receiver of folded light beam with described CD reflection that 2 of being divided into the cut-off rule that is parallel to described code track are subjected to optical arena,
According to when described luminous point during by described gathering sill, and detect the tracing error signal detector of the offset of described luminous point and described code track during by described a pair of mark described 2 differences that are subjected to the detected signal of optical arena;
Described infrared rays receiver, also have the central portion that makes described folded light beam and peripheral part from, be subjected to a plurality of optical arenas that are subjected to of light,
Make the central portion of described folded light beam be subjected to the shape that is subjected to optical arena of light, the length that presents long limit is equal to or greater than the diameter of the light beam that incides described infrared rays receiver, the summary rectangle of the diameter that is shorter in length than the light beam that incides described infrared rays receiver of minor face, make the vertical direction of its long limit in the configuration towards described code track
Described tracing error signal detector, the described quantities received decay that is subjected to the signal of optical arena that is subjected to light by the central portion that makes light beam, detect described tracking error signal, the phase deviation of described tracking error signal that produce, described relatively code track position is lowered when making described disc tilt.
In addition, the optical head of the 4th aspect of the present invention is used for information is recorded in code track with recorded information, and the gathering sill of aforementioned information magnetic track is cut off a part intermittently, has the CD of minute surface portion therebetween, and/or be used for the information of regenerative recording in described CD, comprise
Light harvesting in described CD, generate the light collecting device of luminous point,
Receive from the infrared rays receiver of folded light beam with described CD reflection that 2 of being divided into the cut-off rule that is parallel to described code track are subjected to optical arena,
According to when described luminous point during by described gathering sill, and detect the tracing error signal detector of the offset of described luminous point and described code track during by described minute surface portion described 2 differences that are subjected to the detected signal of optical arena;
Described infrared rays receiver, also have the central portion that makes described folded light beam and peripheral part from, be subjected to a plurality of optical arenas that are subjected to of light,
Make the central portion of described folded light beam be subjected to the shape that is subjected to optical arena of light, the length that presents long limit is equal to or greater than the diameter of the light beam that incides described infrared rays receiver, the summary rectangle of the diameter that is shorter in length than the light beam that incides described infrared rays receiver of minor face, make the vertical direction of its long limit in the configuration towards described code track
Described tracing error signal detector, the described quantities received decay that is subjected to the signal of optical arena that is subjected to light by the central portion that makes light beam, detect described tracking error signal, the phase deviation of described tracking error signal that produce, described relatively code track position is lowered when making described disc tilt.
In addition, the optical disc recording apparatus of the 5th aspect of the present invention,
Comprise as each the optical head of the present invention in the present invention the 1st to 4 aspect.
In addition, the optical disk reproducing apparatus of the 6th aspect of the present invention,
Comprise as each the optical head of the present invention in the present invention the 1st to 4 aspect.
In addition, the optical disc recording/reproducing apparatus of the 7th aspect of the present invention,
Comprise as each the optical head of the present invention in the present invention the 1st to 4 aspect.
Optical head of the present invention as above, as the one example, comprise, with the object lens light harvesting on CD, receive infrared rays receiver from the folded light beam of aforementioned CD, and have from being subjected to of detecting with aforementioned infrared rays receiver detect the tracing error signal detector of tracking error signal the light signal, in inciding the light beam of aforementioned infrared rays receiver, make the light beam that is used to follow the tracks of detection one one field light along separate routes or the optical devices that lower of light intensity.
In addition, wherein example as optical head of the present invention, comprise, with object lens will write down or regenerating information is used main beam, and 2 auxiliary beams that generate along separate routes from aforementioned main beam be collected in CD and receive the infrared rays receiver of each folded light beam, and have according to the difference that is subjected to light signal of aforementioned 2 auxiliary beams detect tracking error signal tracing error signal detector, make the auxiliary beam that incides aforementioned infrared rays receiver each light beam one one field light along separate routes or the optical devices that light intensity is lowered.
In addition, wherein example as optical head of the present invention, comprise, with the object lens light harvesting in having the wiring direction dictates distance of leaving the aforementioned information magnetic track, and it is vertical with the aforementioned information magnetic track, in different directions on the CD of at least one pair of mark at the equal place of phase mutual edge distance, receive catoptrical infrared rays receiver from aforementioned CD, and have according to the corresponding variation that is subjected to light signal of variation from the folded light beam amount of aforementioned a pair of mark, detect the tracing error signal detector of tracking error signal or tracking error signal offset, make the light beam that incides aforementioned infrared rays receiver one one field light along separate routes or the optical devices that light intensity is lowered.
In addition, wherein example as optical head of the present invention, comprise, the gathering sill of code track is cut off one one intermittently, therebetween with the object lens light harvesting in having the wiring direction dictates distance of leaving the aforementioned information magnetic track, and it is vertical with the aforementioned information magnetic track, in different directions on the CD of at least one pair of mark at the equal place of phase mutual edge distance, receive catoptrical infrared rays receiver from aforementioned CD, and have according to the corresponding variation that is subjected to light signal of variation from the reflection light quantity of aforementioned a pair of mark, or in the variation of the aforementioned tracking error signal of aforementioned a pair of mark, detect respectively with what the cut-off rule parallel with the aforementioned information magnetic track was divided into 2 parts and be subjected to the tracking error signal in the light signal and the tracing error signal detector of aforementioned tracking error signal offset, make the light beam that incides aforementioned infrared rays receiver one one field light along separate routes or the optical devices that light intensity is lowered.
In addition, wherein example as optical head of the present invention, comprise, the gathering sill of code track is cut off one one intermittently, with the object lens light harvesting on the CD that minute surface portion is set, receive catoptrical infrared rays receiver, and have and detect the tracking error signal in the light signal of being subjected to that is divided into 2 parts with the cut-off rule parallel respectively with the aforementioned information magnetic track from aforementioned CD, and the tracing error signal detector of the aforementioned tracking error signal offset in the aforementioned tracking error signal value that detects with aforementioned minute surface portion, make the light beam that incides aforementioned infrared rays receiver one one field light along separate routes or the optical devices that light intensity is lowered.
In addition, wherein example as optical head of the present invention, aforementioned optical devices have the dim light field of the light intensity attenuating in one one the field that makes the light beam that passes through, and do not make the non-dim light field of light intensity attenuating, aforementioned dim light field, be so that the film that the material that the transmitance of light lowers forms, or form the field of diffraction grid, its shape is rectangle in fact, long limit is longer than the diameter of the light beam that passes through, configurable on the direction perpendicular to code track.
In addition, wherein example as optical head of the present invention, aforementioned optical devices, place the light receiving unit of aforementioned infrared rays receiver by partition, the corresponding optical arena that is subjected in one one field that is provided with and incides the light beam of the aforementioned infrared rays receiver that need make the light shunt or make the light intensity attenuating constitutes, the aforementioned optical arena that is subjected to is rectangle in fact, long limit is longer than the diameter of the light beam that passes through, configurable on direction perpendicular to code track, at the aforementioned signal that detected by optical arena, than the aforementioned outer signal that detects of optical arena that is subjected to, with coefficient little, can be used for the detection of tracking error signal.
Perhaps, wherein example as optical head of the present invention, aforementioned optical devices, have the light diffraction grid along separate routes or the field of formation prism that to pass through, aforementioned field is rectangle in fact, long limit is longer than the diameter of the light beam that passes through, configurable on direction perpendicular to code track, the light of shunt leads to the 1st light receiving unit group of aforementioned infrared rays receiver in the aforementioned field, other light leads to the 2nd light receiving unit group of aforementioned infrared rays receiver, the 1st light receiving unit group's signal with coefficient ratio the 2nd light receiving unit group little, can be used for the detection of tracking error signal.
In addition, wherein example as optical head of the present invention, it is characterized in that, have: with the device of object lens light harvesting in CD, and receive the infrared rays receiver of the folded light beam of CD, reach the tracing error signal detector that from the signal that is subjected to light with aforementioned infrared rays receiver, detects tracking error signal, and the disc tilt degree pick-up unit of the degree of tilt of the optical axis of aforementioned CD of detection and aforementioned object lens; Aforementioned infrared rays receiver, be configured in the central portion of the light beam that incides aforementioned infrared rays receiver, its shape, it is littler than the diameter of aforementioned light beam that aforementioned light beam is divided into the width parallel with code track, the 1st field that the width of vertical direction is longer than the diameter of aforementioned light beam, reach the 2nd field that does not contain aforementioned the 1st field, and be subjected to light, aforementioned tracing error signal detector, be subjected to optical signal detecting the 1st tracking error signal from aforementioned the 1st field respectively, be subjected to optical signal detecting the 2nd tracking error signal from aforementioned the 2nd field, aforementioned CD degree of tilt pick-up unit, compare by phase place, detect the disc tilt degree aforementioned the 1st tracking error signal and the 2nd tracking error signal.Like this, can detect the inclination of the radial direction of CD.Again, because this detection is to adopt the equal good signal of the tracking error signal that detects with optical head to carry out, so can carry out the detection of high-precision disc tilt degree.
In addition, wherein example as optical head of the present invention, feature is, CD for the sampling hole groove that forms the servo usefulness of sampling, tracing error signal detector, light with sampling hole groove detection of reflected detects tracking error signal again, and disc tilt degree pick-up unit is according to the phase difference detection disc tilt degree of aforementioned the 1st tracking error signal with respect to aforementioned the 2nd tracking error signal.Like this, can detect the disc tilt degree with the optical head of the servo mode of sampling.
In addition, wherein example as optical head of the present invention, feature is, aforementioned light collecting device, it is the light collecting device that record and the main beam used of regenerating information and the 1st and the 2nd auxiliary beam is collected in CD, aforementioned infrared rays receiver, be respectively to inciding the aforementioned the 1st and the 2nd auxiliary beam of aforementioned infrared rays receiver, light beam is divided into aforementioned the 1st field and the 2nd field, and be subjected to light, aforementioned tracing error signal detector, use aforementioned the 1st auxiliary beam aforementioned the 1st field be subjected to light signal, and aforementioned the 1st field of aforementioned the 2nd auxiliary beam be subjected to difference signal between the light signal, or the aforementioned the 1st and the 2nd field of aforementioned the 1st auxiliary beam be subjected to light signal and signal, and the aforementioned the 1st and the 2nd field of aforementioned the 2nd auxiliary beam be subjected to light signal and signal between difference signal in any, detect the 1st tracking error signal; Use aforementioned the 1st auxiliary beam aforementioned the 2nd field be subjected to light signal, with the difference signal that is subjected to light signal in aforementioned the 2nd field of aforementioned the 2nd auxiliary beam, detect the 2nd tracking error signal.Aforementioned CD degree of tilt pick-up unit is according to the phase difference detection disc tilt degree of aforementioned relatively the 2nd tracking error signal of aforementioned the 1st tracking error signal.Like this, just can detect the disc tilt degree with the optical head of 3 pencil tracing detection modes.
In addition, wherein example as optical head of the present invention, feature is, aforementioned infrared rays receiver, cut apart the aforementioned the 1st and the 2nd field with the cut-off rule that is parallel to code track, be subjected to light, aforementioned tracing error signal detector, according to the input push-pull signal that is subjected to light with aforementioned infrared rays receiver, the light signal that is subjected to that uses aforementioned the 1st field, or the aforementioned the 1st and the 2nd the field be subjected to light signal with signal in the push-pull signal of any detection as the 1st tracking error signal, the push-pull signal that is subjected to optical signal detecting that uses aforementioned the 2nd field as the 2nd tracking error signal, is detected respectively; Aforementioned CD degree of tilt pick-up unit is according to the phase difference detection disc tilt degree of aforementioned relatively the 2nd tracking error signal of aforementioned the 1st tracking error signal.Like this, the optical head that can utilize tracking with push pull mode to detect detects the disc tilt degree, and again, the disc tilt degree according to the phase difference detection of 2 push-pull signals, can be got rid of the influence of skew of moving the push-pull signal of generation along with object lens.
Also have, wherein example as optical head of the present invention, feature is, for the CD that forms the hole groove on the code track, have, with the device of object lens light harvesting, and receive infrared rays receiver, and from the signal that is subjected to light with aforementioned infrared rays receiver, detect the disc tilt degree pick-up unit of degree of tilt of the optical axis of aforementioned CD and aforementioned object lens from the folded light beam of aforementioned CD; Aforementioned infrared rays receiver, be configured in the central portion of the light beam that incides aforementioned infrared rays receiver, its shape, it is longer than the diameter of aforementioned light beam that aforementioned light beam is divided into the width parallel with code track, the 1st vertically short than the diameter of aforementioned light beam field with the width of aforementioned information track direction, reach the 2nd field that does not contain aforementioned the 1st field, and be subjected to light, aforementioned CD degree of tilt pick-up unit, by the light signal that is subjected to aforementioned the 1st field, or the aforementioned the 1st and the 2nd the field be subjected to light signal with signal in the either party, compare with the light signal that is subjected in aforementioned the 2nd field, by detecting the phase differential of luminous point, detect the disc tilt degree by modulated signal waveform of time on the groove of aforementioned hole.Like this, can detect the disc tilt degree of the wiring direction of code track.
Description of drawings
Fig. 1 represents the pie graph of the optical head of example 1 of the present invention.
Fig. 2 is the figure of the optical devices of explanation example 1 of the present invention.
Fig. 3 is the figure of the infrared rays receiver of explanation example 1 of the present invention.
Fig. 4 is the figure of the signal of explanation example 1 of the present invention.
Fig. 5 is the catoptrical figure of explanation from CD.
Fig. 6 is the design sketch of explanation example 1 of the present invention.
Fig. 7 is the design sketch of explanation example 1 of the present invention.
Fig. 8 is the design sketch of explanation example 1 of the present invention.
Fig. 9 is the pie graph of explanation example 2 of the present invention.
Figure 10 is the figure of the infrared rays receiver of explanation example 2 of the present invention.
Figure 11 is the pie graph of explanation example 3 of the present invention.
Figure 12 is the figure of the infrared rays receiver of explanation example 3 of the present invention.
Figure 13 is the pie graph of explanation example 4 of the present invention.
Figure 14 is the figure of the infrared rays receiver of explanation example 4 of the present invention.
Figure 15 is the pie graph of explanation example 5 of the present invention.
Figure 16 is the figure of the signal of explanation example 5 of the present invention.
Other of the infrared rays receiver of Figure 17 (a) expression example 4 of the present invention constitute illustration.
Other of the infrared rays receiver of Figure 17 (b) expression example 4 of the present invention constitute illustration.
Other of the infrared rays receiver of Figure 18 (a) expression example 5 of the present invention constitute illustration.
Other of the infrared rays receiver of Figure 18 (b) expression example 4 of the present invention constitute illustration.
Figure 19 represents the pie graph of the optical head of example 6 of the present invention.
Figure 20 is the infrared rays receiver of explanation example 6 of the present invention and the figure of signal calculation portion.
Figure 21 is the figure in explanation the of the present invention the 1st and the 2nd field.
Figure 22 (a) is the figure of the 1st and the 2nd tracking error signal of explanation example 6 of the present invention.
Figure 22 (b) is the figure of the 1st and the 2nd tracking error signal of explanation example 6 of the present invention.
Figure 23 represents the pie graph of the optical head of example 7 of the present invention.
Figure 24 is the figure of the code track of the servo mode of explanation sampling.
Figure 25 is the figure that the tracking of the servo mode of explanation sampling detects.
Figure 26 (a) is the figure of the 1st and the 2nd tracking error signal of explanation example 7 of the present invention.
Figure 26 (b) is the figure of the 1st and the 2nd tracking error signal of explanation example 7 of the present invention.
Figure 27 represents the pie graph of the optical head of example 8 of the present invention.
Figure 28 is the infrared rays receiver of explanation example 8 of the present invention and the figure of signal calculation portion.
Figure 29 is the figure of the luminous point configuration of explanation main beam of example 8 of the present invention and auxiliary beam.
Figure 30 is the figure of signal of the auxiliary beam of explanation example 8 of the present invention.
Figure 31 is the design sketch of explanation example 9 of the present invention.
Figure 32 represents the pie graph of the optical head of example 10 of the present invention.
Figure 33 represents the pie graph of the tracking control signal generating apparatus of example 10 of the present invention.
Figure 34 represents the pie graph of the optical head of example 11 of the present invention.
Figure 35 is the infrared rays receiver of explanation example 11 of the present invention and the figure of signal calculation portion.
Figure 36 is the figure of the signal detecting method of explanation example 11 of the present invention.
Figure 37 is the figure of the signal detecting method of explanation example 11 of the present invention.
Figure 38 is the figure of explanation conventional art.
Figure 39 is the figure of explanation conventional art.
Figure 40 is the figure of explanation conventional art.
Figure 41 is the figure of explanation conventional art.
Figure 42 represents the pie graph of optical head in the past.
Figure 43 is the figure of explanation conventional art.
Figure 44 (a) is the figure of explanation conventional art.
Figure 44 (b) is the figure of explanation conventional art.
Figure 44 (c) is the figure of explanation conventional art.
Label declaration
1 light source
2 diffraction grid
3 optical branch devices
4 object lens
5 CDs
66 ' optical devices
7 detect lens
8,30,47,54 infrared rays receivers
9,55,58 tracing error signal detectors
11,11 ' optical function field
201 light sources
The optical axis of 202 optical heads
203 light beam resolvers
204 object lens
205 CDs
206 relay lenss
The optical axis of 207 optical heads
208 infrared rays receivers
236 diffraction grid
237 infrared rays receivers
252 object lens mobile devices
257 infrared rays receivers
Concrete example
Below, with reference to accompanying drawing each example of the present invention is described.
(example 1)
This example by being applicable to the present invention, becomes an example that solves this problem for the optical head of in the past 3 pencil tracing modes.
Fig. 1 is the pie graph of the optical head of example 1 of the present invention.Among the figure, the 1st, light source, the 2nd, light is become the diffraction grid that main beam and 2 is restrainted auxiliary beams along separate routes, the 3rd, as the light beam resolver of optical branch device, the 4th, object lens, the 5th, CD, the 6th, the light in one one field of the light beam that shunt is passed through or the optical devices that light intensity is lowered, the 7th, detect lens, the 8th, have the infrared rays receiver of some light receiving units, the 9th, tracing error signal detector.
Fig. 2 is the figure of explanation optical devices, among the figure, the 10th, the profile of the light beam that passes through, the 11st, light beam that shunt is passed through or the optical function field that light intensity is lowered, at this example, this is on transparency carriers such as glass or resin, the low part of light transmission rate of the film of formation reflectivity or light absorption or diffraction grid etc.
Fig. 3 is the figure of each light receiving unit of explanation infrared rays receiver 8,12,14th, and light receiving unit, 13 is 4 to cut apart light receiving unit, 15,17th, auxiliary beam, the 16th, main beam.
Below, the action of the optical head of this example with such formation is described.
Because the diffracted unit of light 2 diffraction that light source sends generate main beam as 0 diffraction light, 2 bundle auxiliary beam conduct+1 time and-1 diffraction light.This 3 light beams sees through optical branch device 3 together, by object lens 4 by light harvesting in CD 5, as representing among Figure 38 of example explanation in the past, form 3 luminous points.
Come the folded light beam of each luminous point of free CD 5 reflections,,, incide optical devices 6 through optical branch device 3 reflections once more together by object lens 4.The light beam of main beam and 2 bundle auxiliary beams not too separates in the position of configuration optical devices 6, so all light beams all as shown in Figure 2 the profile 10 of light beam are such, because optical function field 11, the light intensity of its central portion lowers, and incides to detect lens 7.
The focus detection mode such as non-some aberration mode, detects the refracting power that lens 7 have the cylindrical lens that makes non-some aberration generation, make light beam enter infrared rays receiver 8, as shown in Figure 3, main beam can incide 4 light receiving units of cutting apart 13, and auxiliary beam can incide light receiving unit 12 and 14 respectively.The oblique line portion of the central portion of each light beam 15 to 17 because optical devices 6 are expressed as the part that light intensity lowers, has non-some aberration owing to detect lens 7, and its direction can be returned and be turn 90 degrees.
In addition, the tracing error signal detector 9 of Fig. 1 carries out the difference amplification to light receiving unit 12 and 14 signals that detect, and detects tracking error signal.4 cut apart the signal that light receiving unit 13 detects, and are used as input separately at focus detection device and information signal pick-up unit (all not shown).
Fig. 4 be used for illustrating when the relative position of the luminous point of main beam and code track changes, the figure of the variation of the signal of main beam and 2 auxiliary beams.Among the figure, the 18th, the signal waveform of main beam, 19,20 is respectively the signal waveform of auxiliary beam, the 21st, the waveform of tracking error signal.Here, because the width of code track is done greatlyyer than therebetween the groove width of cloth, main beam signal 18 presents maximum waveform at the code track center, and the signal 19,20 of auxiliary beam is relative therewith, the waveform of every, phase deviation opposite at a distance of 1/4 magnetic track, direction occurs.Tracking error signal 21 is difference signals of waveform 19,20, is rendered as 0 waveform at the code track center.
What the following describes is, for optical head, when CD at its radial direction, promptly also comprise plane (hereinafter referred to as radial skew) when the direction vertical with the wiring of code track the tilts phase deviation that produce, tracking error signal of CD normal and the optical axis of object lens.Usually, the luminous point of main beam and auxiliary beam, shape much at one, so it is subjected to photosignal waveform also identical.Therefore, be 0 position at tracking error signal, the peak unanimity of main beam signal, from now on, the signal waveform that only is conceived to main beam will explain.
Fig. 5 is pattern ground expression CD when having radial skew, from the light quantity distribution of the folded light beam of CD reflection, the black and white concentration among the figure is corresponding with light intensity.The reason that produces 0 diffraction light on asymmetrical corrugated aberration, the CD on the corrugated that this is the comatic aberration that takes place during owing to the transparency carrier of light by CD, cause incident light, changes in the mutual paraphase of the corrugated phase place of interfering the field with+1 time and-1 diffraction light, make appearance asymmetrical intensity distributions as shown in the figure, because this asymmetry, the peak of the signal of main beam can the runout information track center.
This example, because the optical function field 11 of optical devices 6 is lowered the light intensity in the field that this asymmetrical intensity distributions takes place, the asymmetrical light intensity that can suppress this field on constituting is added in the influence on the tracking error signal.Below, at length its effect is described.
Fig. 6 is the optical source wavelength λ=660nm that sets optical head, NA=0.6, and the code track spacing of CD=1.2 μ m, the gathering sill degree of depth=λ/8, gathering sill width=0.8 μ m, substrate is thick=result of simulation main beam signal during 0.6mm.The 22nd, the waveform when not having radial skew, the 23rd, the waveform when radial skew=1.2 are spent in the past the optical head.There is phase differential in 23 pairs of waveforms 22 of waveform, and its peak is about 0.15 μ m apart from the code track center.
The waveform 24 of Fig. 6,25, be in optical head of the present invention, width V with optical function field 11 represents with the ratio of beam diameter D, at V/D=0.25 is that the signal waveform of 0 o'clock main beam is carried out Simulation result to its transmitance, the 24th, the waveform when not having radial skew, the 25th, the waveform when radial skew=1.2 are spent.When amplitude reduces, can be with the shift suppression of the peak of waveform 25 to having only about 0.05 μ m.
In addition, it is 1.2 when spending that Fig. 7 is illustrated in radial skew, the amplitude of the main beam signal waveform when described V/D is changed and the figure of peak side-play amount variation, and wherein amplitude is 26, the peak side-play amount is 27.Amplitude when so-called relative amplitude is meant with V/D=0 is 1 normalized amplitude.In Fig. 7, for example suppose V/D=0.4, although then relative amplitude 26 is reduced to 0.6, peak side-play amount 27 also can be essentially 0.
Above Simulation result, as radial skew is 1.2 degree, in optical head in the past, also can the runout information track center when being 0.15 μ m corresponding to the impact point (tracking error signal is 0 position) of the tracking Control of the peak of aforementioned main beam signal, to this, according to the present invention, the skew of the impact point of aforementioned tracking Control, promptly also, the phase deviation of tracking error signal almost can be suppressed to 0.
Fig. 8 makes 28 amplitude and note to V/D=0.5, note when the transmitance in optical function field 11 is changed to do the variation of 29 peak side-play amount and carry out Simulation result.In transmitance is 0 o'clock, and the peak side-play amount is a negative value, and this is because the excessive cause of inhibition effect of peak skew by the change transmitance, can freely change the inhibition effect of peak side-play amount.Promptly also, adjust the effect of the phase deviation of the tracking error signal when suppressing radial skew, not only can be undertaken, also can be undertaken by changing its transmitance by the width of setting optical function field 11.
As mentioned above, according to example of the present invention, in the optical head of 3 pencil tracing modes, lower with band shape by the light intensity that makes the central portion that detects 2 auxiliary beams that tracking error signal uses, because the light that has lowered the big field of the corrugated aberration that is taken place by the radial skew of CD is added in the influence of tracking error signal, the phase deviation of the tracking error signal in the time of can suppressing radial skew, thus can realize the raising of tracking accuracy.
In addition, at this example, optical devices 6 are disposed at detect before the lens 7, arrive the light path of infrared rays receiver 8 at auxiliary beam, such as having the eyeglass of the light path of turning back, and carrying out optical head that information signal detects with other light receiving unit, will detect the optical devices that the light intensity attenuating of the central portion that makes light beam on another branch apparatus that the light that detects with information signal carry out shunt, also can be set as following the tracks of from CD 5 reflection.
In addition, the length W in optical function field 11 said once that it was more much longer than beam diameter D, if but identical with beam diameter D essence or a little bit smaller a little good, such formation also can suppress the phase deviation of tracking error signal.
(example 2)
Example 2 of the present invention is that example 1 is done the part change, with further embodiment feature of the present invention.
Fig. 9 is the pie graph of this example.The inscape band prosign common with Fig. 1, explanation is omitted.Difference is, infrared rays receiver 30 is set to replace the infrared rays receiver 8 of Fig. 1, simultaneously, as optical devices 6 ', has the optical function field 11 ' of the device of the shunt light that forms diffraction grid etc., entered infrared rays receiver 30 by light beam along separate routes.Here, the profile in optical function field 11 ' is the same with the optical function field 11 of Fig. 2.
Figure 10 is the figure that is subjected to optical arena of expression infrared rays receiver 30.In Figure 10,31,33 and 34 to 37 is light receiving units, 32 is 4 to cut apart light receiving unit, 38 and 40 is auxiliary beams, the 39th, and main beam, 41 and 44 is from auxiliary beam 38 light beam along separate routes with optical function field 11 ', 42 and 45 also is from main beam 39 light beam along separate routes, and 43 and 46 also is from auxiliary beam 40 light beam along separate routes.Again, among the figure, optical function field 11 ' the shared part is represented with oblique line portion.At light receiving unit 31,32,33, the light beam of auxiliary beam 38, main beam 39, auxiliary beam 40 does not make the part in optical function field 11 ' be subjected to light.Again, here, the explanation that the focus detection of relevant main beam 39 and information detect is omitted.
, as signal name the signal of each auxiliary beam is listed in the table below with the sequence number of each light receiving unit, then, the signal of the 1st auxiliary beam is:
31+k1 * (34+36) (formula 2)
The signal of the 2nd auxiliary beam is:
33+k2 * (35+37) (formula 3)
Wherein, k1, k2 are constant coefficient (k1, k2＜1), change this coefficient, change the signal value of auxiliary beam, this with example 1 in the transmitance in the change optical function field 11 narrated be of equal value.Therefore, can be by any inhibition effect of setting or changing the phase deviation of tracking error signal of the electric calculation of the detection signal in the tracing error signal detector 9.
Therefore, according to this example, for example, because the substrate thickness difference of CD, the corrugated aberration that is taken place by the radial skew of CD is not simultaneously, perhaps, the phase pushing figure of the tracking error signal that the opening number of object lens is switched when using etc., should suppress can not carry out the setting and the switching of suitable inhibition effect simultaneously.In addition, by main beam light beam 42 and 45 along separate routes, be to be not used in tracking error signal to detect, and the light beam of focus detection and information detection.
Like this, according to example of the present invention, optical head in 3 pencil tracing modes, to an one of the central portion of the 2 bundle auxiliary beams that are used to detect tracking error signal, by the diffraction grid along separate routes and be subjected to light respectively, because the light in the big field of the corrugated aberration that the radial skew of CD is taken place, promptly also, to by lowering lowered by the contribution of the tracking error signal that is subjected to light signal of light along separate routes, the phase deviation of the tracking error signal in the time that radial skew can being suppressed, improve the tracking Control precision.Again, the inhibition effect of this phase deviation can be by electric calculation adjustment, so, can carry out optimal adjustment and setting.
In addition, at this example, adopt special-purpose diffraction grid to make the part shunt of auxiliary beam, for example, the optical head for having for the diffraction grid of focus detection shunt light beam can have same function at these diffraction grid.
(example 3)
Figure 11 is the pie graph of this example.The inscape common with Fig. 1 is with prosign, and explanation is omitted, and only different places described.The difference that constitutes with Fig. 1 is, has economized in fact the optical devices 6 of Fig. 1, has added its function (not shown) at infrared rays receiver 47.Promptly also, infrared rays receiver 47 comprises the function as two aspects of the infrared rays receiver 8 of implementing form 1 and optical devices 6.
Figure 12 is the pie graph of the light receiving unit of infrared rays receiver 47.At Figure 12,48 and 50 is 3 to cut apart light receiving unit, and 49 is 4 to cut apart light receiving unit, 48a to 48c and 50a to 50c be aforementioned 3 cut apart light receiving unit respectively be subjected to optical arena, 51 and 53 is auxiliary beams, the 52nd, main beam.Because detect the non-some aberration that lens have, each light beam distributes back it to turn 90 degrees and incides light receiving unit, so 3 cut-off rules of cutting apart light receiving unit are in the above-below direction of paper.
As signal name, the signal of each auxiliary beam represents that with following formula then the signal of the 1st auxiliary beam is with 3 sequence number that are subjected to optical arena of cutting apart light receiving unit 48 and 50:
(48a+48c)+k3 * 48b (formula 4)
The signal of the 2nd auxiliary beam is:
(50a+50c)+k4 * 50b (formula 5)
Tracking error signal detects according to the differing from of signal of these 2 auxiliary beams.In addition, the focus signal that obtains from main beam 52 and the explanation of information signal are omitted.Here, k3, k4 are constant coefficient (k3, k4＜1), can carry out electric calculation to change this coefficient, and be same with example 2, can set the size to the inhibition effect of the phase deviation of tracking error signal arbitrarily.
As mentioned above, according to example of the present invention, optical head in 3 pencil tracing modes, cut apart 2 auxiliary beams that are used for detecting tracking error signal at each light receiving unit, the signal of the light of the central portion of change detection light beam and the ratio that adds of the signal that detects this outer light beam, because the big field of the corrugated aberration that the radial skew of CD is taken place, promptly also, the contribution of the tracking error signal that the light of the central portion of aforementioned light beam is provided is lowered, and the phase deviation of the tracking error signal in the time of can suppressing radial skew, improves the tracking Control precision.Again, the size of the inhibition effect of this phase deviation can be by electric calculation adjustment, so, can carry out optimal adjustment and setting.
(example 4)
For the optical head of aforesaid sampling servo tracking mode in the past, this example is suitable for the present invention, becomes an example that solves this problem.
Figure 13 is the pie graph of the optical head of example 4 of the present invention.The inscape common with Fig. 1 is with prosign, and explanation is omitted, and only different places described.In the formation of this example, remove the diffraction grid of Fig. 1, change infrared rays receiver 8 and the tracing error signal detector 9 of Fig. 1 into, have the detection of infrared rays receiver 54 and tracking error signal and adorn 55.
In addition, Figure 14 is the figure of each light receiving unit of explanation infrared rays receiver 54, and among the figure, 56 is 4 to cut apart light receiving unit, 56a to 56d be 4 cut apart light receiving unit 56 respectively be subjected to optical arena, the 57th, incide 4 profiles of cutting apart the light beam of light receiving unit 56.
Below, the action with optical head such formation, this example 4 is described.
The light that light source 1 sends sees through branch apparatus 3, is gathered CD 5 by object lens 4.By CD 5 beam reflected,,, incide optical devices 6 by optical branch device 3 reflections again by object lens 4.At this example, incide the light beam of optical devices 6, same with aforementioned example 1, by the optical function field 11 of Fig. 2, the light intensity of its central portion is lowered, lens 7 enter infrared rays receiver 54 after testing.
The oblique line portion of the central portion of the light beam 57 among Figure 14, the part that performance lowers light intensity by optical devices 6, owing to detect the non-some aberration that lens 7 have, its direction can be returned and be turn 90 degrees.
In addition, the tracing error signal detector 55 of Figure 13, it is the tracing error signal detector of sampling servo tracking mode, so, as described in the explanation of conventional art, use with from the corresponding signal of the reflection light quantity of CD, by 4 that cut apart signal that light receiving unit 56 detects and signals, i.e. also whole detection signals detection tracking error signals of light receiving unit 56a to 56d.Focus detection device and information signal pick-up unit (all not drawing) are cut apart signal light receiving unit 56, that each light receiving unit 56a to 56d detects respectively, the detection signal of regulation separately by 4.
Below, the detection of the tracking in the optical head of this formation is elaborated.With 4 cut apart signal that light receiving unit 56 detects and as signal S, tracing error signal detector 55, the signal S when detecting the profile of tooth mark of luminous point by as shown in figure 40, at the position of Figure 41 A, position B takes a sample synchronously, detected signal value VA, VB.The profile of tooth mark has many along code track, because the CD revolution, luminous point passes through several profile of tooth marks between cross-section code track.If will be with the synchronous aforementioned signal value VA of each profile of tooth mark sampling, VB be set at signal S1 by the time relation, signal S2, and then tracking error signal is exactly their difference signal S1-S2.
Here, aforementioned signal S1 during the cross-section code track of luminous point, the waveform of signal S2 is the waveform of minimum (perhaps maximum) in the groove position, correspondence hole of each profile of tooth mark, we can say that this is the same signal of signal with 2 auxiliary beams of as shown in Figure 43 pencil tracing modes.
In addition, the signal of aforementioned auxiliary beam, with aforementioned signal S1, S2 is that the reflection light quantity that detects modulation in gathering sill and profile of tooth mark continuously obtains, so, can consider in the lump because the radial skew of CD results from the influence that the aberration of CD is subjected to signal by luminous point.
Therefore, same with example 1, the optical head of this example can suppress the phase deviation of the tracking error signal that produced by the radial skew of CD.
As mentioned above, according to this example, optical head in sampling servo tracking mode, one one light intensity attenuating owing to the light beam that the detection tracking error signal is used, the phase deviation of the tracking error signal in the time of can suppressing radial skew is lowered in the influence that the light in the big field of the corrugated aberration that the radial skew of CD takes place is produced.
In addition, cut apart light receiving unit 56 4, to tracking error signal of the present invention detect that action works be light receiving unit 56 and signal, light receiving unit is divided into 56a to 56d by 4, be because same with example 1, in the focus detection mode as non-some aberration mode.Therefore, if only be used for detecting tracking error signal, light receiving unit of infrared rays receiver 54 usefulness also can.
In addition, at this example, as Figure 13 and the such formation of Figure 14, the various devices that apply at example 2 and the 3 pairs of auxiliary beams also can be added on the light beam of this example.
Here, Figure 17 (a) is the pie graph of the infrared rays receiver 54 of formation with the infrared rays receiver 30 of example 2 and optical devices 6 ' the sampling servo tracking mode occasion that is applied to this example.Figure 17 (b) is the pie graph of the infrared rays receiver 54 of formation with the infrared rays receiver 47 of the example 3 sampling servo tracking mode occasion that is applied to this example.Again, at Figure 17 (a) (b), be that the center describes with the action that detects tracking error, 4 cut-off rules of cutting apart of the light receiving unit of using as non-some aberration mode in the focus detection mode 57 dot, and economizing in fact should action.Again, the formation of the light receiving unit of main beam part is also economized in fact.
Shown in Figure 17 (a), infrared rays receiver 54 has and makes by optical devices 6 ' light beam 57 1 is divided into the three light beam 57a that obtain that 57b, 57c are subjected to the light receiving unit 70,71,72 of light respectively.Again, light beam 57a does not make the part in optical function field 11 ' be subjected to light, and light beam 57b, 57c only contain the part in optical function field 11 ' in light beam 57.
The sequence number note of each light receiving unit is made signal name, the signal of each light beam is represented with following formula the signal of light beam 57 can be expressed as:
57a+k5 * (57b+57c) (several 6)
(k5 is constant coefficient (k5＜1)).
Therefore, same with example 2, change the value of coefficient k 5, the value of the signal that obtains from light beam 57 is changed, make any setting or change become possibility to the inhibition effect of the phase deviation of tracking error signal.
Below, shown in Figure 17 (b), infrared rays receiver 54 has makes light beam 57 be subjected to 3 of light to cut apart light receiving unit 73a, 73b, 73c respectively.
The sequence number note of respectively cutting apart light receiving unit is made signal name, and the signal of light beam 57 can be expressed as:
(73b+73c)+k6 * 73a (several 7)
K6 is a constant coefficient, (k6＜1).Therefore, same with example 3, change the value of coefficient k 6, the value of the signal that obtains from light beam 57 is changed, make any setting or change become possibility to the inhibition effect of the phase deviation of tracking error signal.
(example 5)
This example, to aforesaid in the past compound seam tracking through weaving torch mode or the optical head of compound Continuous Tracking mode owing to be suitable for the present invention, become an example that solves this problem.
Figure 15 is the pie graph of the optical head of this example 5.Identical with the inscape of Figure 13 of the pie graph of example 4 and Figure 14, the band prosign, explanation is omitted.At this example, has tracing error signal detector 58, to replace the tracing error signal detector 55 of Figure 13.
Being with example 4 differences, is that the processing that is subjected to light signal tracing error signal detector 58, that obtained by infrared rays receiver 54 is moved.Below, with reference to Figure 14 the action of following the tracks of detection 58 is described.
With 4 cut apart light receiving unit 56 respectively be subjected to optical arena name 56a to 56d, to signal T, signal T1, T2, TE is defined as follows.That is,
T=56a+56b+56c+56d (several 8)
T1=56a+56b (several 9)
T2=56c+56d (several 10)
TE=T1-T2 (several 11)
Here, signal T is 4 cut apart light receiving unit 57 and signals, and signal TE is a push-pull signal.Tracing error signal detector 58 detects aforementioned various signal T, T1, T2, TE.
For the compound Continuous Tracking mode described in the explanation of conventional art, as shown in figure 39, the code track of CD, constitute by guiding groove section 104 and minute surface portion 105, tracing error signal detector 58 is when luminous point passes through minute surface portion 105, to aforementioned signal TE sampling synchronously, with its skew of value revisal signal TE, detect tracking error signal.Here the skew of the signal TE that says is object lens 4 with the offset of the optical axis of optical head, and because the radial skew of CD from the offset of the folded light beam of CD reflection, is the DC voltage that push-pull signal produces.
In addition, for the compound seam tracking through weaving torch mode described in the explanation of conventional art, as shown in figure 40, the code track of CD is made of tracing error signal detector 58 guiding groove section and profile of tooth mark, when luminous point passes through the profile of tooth mark, be set to TE2 with the signal that detects with the same gimmick of the tracing error signal detector 55 of aforesaid example 4, compare, detect the tracking error signal that revisal is offset by skew to this signal TE2 and aforementioned signal TE.This is to be difficult to take place foregoing skew owing among the signal TE2, so can be through relatively extracting the skew of signal TE out.Again, when luminous point passes through the profile of tooth mark, even synchronously to aforementioned signal TE sampling, the skew that also can extract signal TE equally out.
More than such tracking detection mode, though have the device of revisal tracking error signal offset, because the influence of the comatic aberration that the radial skew of CD produces, such shift correction device is also powerless to the phase deviation that tracking error signal produces.
Figure 16 is the result of the waveform of simulation push-pull signal TE when setting following condition: the optical source wavelength of optical head is 660nm, NA is 0.6, and the spacing of the code track of CD is 1.2 μ m, the gathering sill degree of depth=λ/8, gathering sill width=0.8 μ m, substrate thickness=0.6mm.The 59th, the waveform when not having radial skew, the 60th, when radial skew=1.2 are spent, the waveform of optical head in the past, the 61st, the waveform of the optical head of this example.
The not only just phase deviation that causes of radial skew in the skew of each waveform, if their peak is compared, then, the phase deviation of the waveform 60 that the phase deviation of waveform 61 is compared has the inhibition less than half point approximately.Again, waveform 61 is width, V/D=0.25, the result of calculation when transmitance is 0 when the optical function field 11 of optical devices 6.Like this, optical devices 6 are suppressing aspect the phase deviation that radial skew causes, even also be effectively to push-pull signal, therefore, are that the aforementioned detection mode of respectively following the tracks of is effectively installed.
As mentioned above, according to this example, optical head to compound seam tracking through weaving torch mode and compound Continuous Tracking mode, because one one the light intensity that makes tracking error signal detect the light beam of usefulness lowers with band shape, make the effect of light in big field of the corrugated aberration that the radial skew of CD takes place lower, the phase deviation of the tracking error signal when making radial skew is inhibited, and the precision of tracking Control is expected to be improved.
Again, cut apart light receiving unit 56 4, tracking error signal detection action of the present invention is worked, be light receiving unit 56 and signal, light receiving unit 56a and 56b sum, and the signal of light receiving unit 56c and 56d and, light receiving unit is divided into 56a to 56d by 4, this is the same with example 1, and this is because the cause of focus detection mode as non-some aberration mode.Therefore, only in order to detect tracking error, infrared rays receiver 54 also can adopt parallel with the code track direction 2 to cut apart light receiving unit.
In addition, change to the formation of this example, detect the light beam that tracking error signal is used, also can realize same optical head even introduce to increase with example 2 and 3.
Here, Figure 18 (a) is the pie graph of the infrared rays receiver 54 of the occasion that is applied to the compound seam tracking through weaving torch mode of this example or compound Continuous Tracking mode of the formation with the infrared rays receiver 30 of example 2 and optical devices 6 ', and Figure 18 (b) is the pie graph of the infrared rays receiver 54 of the occasion that is applied to the compound seam tracking through weaving torch mode of this example or compound Continuous Tracking mode of the formation with the infrared rays receiver 47 of example 3.Again, at Figure 18 (a) (b), be that the center describes with the action that detects tracking error, 4 cut-off rules of cutting apart that carry out the light receiving unit 57 that the focus detection mode uses in non-some aberration mode dot, and its action is from fact.Again, the formation of the light receiving unit of main beam part is also economized in fact.
Shown in Figure 18 (a), infrared rays receiver 54, have to make and be subjected to 2 of light to cut apart light receiving unit 80 (containing light receiving unit 80a and 80b) respectively light beam 57a, 57b, the 57c that light beam 57 is divided into 3 parts, 81 (containing light receiving unit 81a and 81b), 82 (containing light receiving unit 82a and 82b) by optical devices 6 '.Again, light beam 57a does not make the part in optical function field 11 ' be subjected to light, and light beam 57b, 57c only contain the part in optical function field 11 ' in light beam 57.
As signal name, the signal of each light beam represents that with following formula then the signal of light beam 57 is with the sequence number of each light receiving unit:
T=80a+80b+k7 * (81a+81b+82a+82b) (several 12)
T1=80a+k7 * (81a+82a) (several 13)
T2=80b+k7 * (81b+82b) (several 14)
TE=T1-T2 (several 15)
K7 is constant coefficient (k7＜1).
Therefore, same with example 2, change the value of coefficient k 7, the value of the signal that obtains from light beam 57 is changed, make any setting or change become possibility to the inhibition effect of the phase deviation of tracking error signal.
Below, shown in Figure 18 (b), infrared rays receiver 54 has makes light beam 57 be subjected to 6 of light to cut apart light receiving unit 83a～83f respectively.
The sequence number note of respectively cutting apart light receiving unit is made signal name, and the signal of light beam 57 can be expressed as:
T=83c+83d+83e+83f+k8 * (83a+83b) (several 16)
T1=k8 * 83a+ (83c+83e) (several 17)
T2=k8 * 83b+ (83d+83f) (several 18)
TE=T1-T2 (several 19)
(k8 is a constant coefficient, (k8＜1)).
Therefore, same with example 3, change the value of coefficient k 8, the value of the signal that obtains from light beam 57 is changed, make any setting or change become possibility to the inhibition effect of the phase deviation of tracking error signal.
In addition, at aforementioned example, describe as example with the optical head that uses compound seam tracking through weaving torch mode or compound Continuous Tracking mode to detect tracking error signal, optical head of the present invention, if adopt axle 2 light receiving units cut apart parallel with code track, detect tracking error signal with push pull mode, so, also can with other modes.
(example 6)
This example for the optical head of the tracing error signal detector with push pull mode in the past, owing to be suitable for the present invention, becomes an example of the problem in the past that solves relevant disc tilt degree detection.
Figure 19 is the pie graph of the optical head of example 6 of the present invention.Among the figure, the 201st, light source, 202 and 207 is optical axises of optical head, the 203rd, and an one of incident light is seen through, make a beam reflected resolver, the 204th, object lens, the 205th, CD, the 206th, import light into the relay lens, the 208th of light receiving unit, infrared rays receiver, the 209th, to the signal calculation portion that is subjected to light signal to amplify, calculate, the 210th, focus detection device, the 211st, tracing error signal detector, the 212nd, disc tilt degree pick-up unit.
Figure 20 is the figure of explanation infrared rays receiver 208 and signal calculation portion 209, from 208a to 208f, expression infrared rays receiver 208 respectively be subjected to optical arena, 213a to 213f is an amplifier, 214 and 215 is adder operational amplifiers, the 216th, incide the profile of the light beam of infrared rays receiver 208.
Below, the action of the optical head of this example with such formation is described.
The light that light source 201 takes place, transmitted beam resolver 203, by object lens 204 by light harvesting in CD 205.Light by CD 205 reflections passes through object lens 204 once more, by 203 reflections of light beam resolver, incides relay lens 206.If as non-some aberration mode, relay lens 206 has the refracting power that makes the cylindrical lens that non-some aberration take place, and light beam is imported infrared rays receiver 208 the focus detection mode.
As shown in figure 20, incide the light beam of infrared rays receiver 208, be divided into by 6 and be subjected to optical arena 208a to 208f, be subjected to light, respectively be subjected to 209 calculations of optical signals signal calculation portion, amplify.Amplified by the optical signals amplifier 213a to 213f that respectively is subjected to of optical arena 208a to 208f, and be used as signal 208a ' and export to 208f ', again, signal 208a ' and 208c ' by adder operational amplifier 214 additions, be used as signal F1 output, signal 208b ' and 208d ' by adder operational amplifier 215 additions, be used as signal F2 output.
The tracking error signal of this example is a push-pull signal, so, signal TE1, TE2 can be represented by the formula.
TE1=208e '-208f ' (several 20)
TE2=(208a '+208d ')-(208b '+208c ') (several 21)
Disc tilt degree pick-up unit 212 compares the phase place of the 1st tracking error signal TE1 and the 2nd tracking error signal TE2, detects the disc tilt degree.
Below, detection elaborates to the disc tilt degree.In the light intensity distributions of the detection light beam when Figure 21 is illustrated in the radial direction inclination, the figure that aforementioned the 1st field overlaps with the scope in the 2nd field.Described in the explanation of conventional art, corresponding to the disc tilt degree, the light intensity distributions of light beam presents asymmetry, and as shown in the figure, wherein asymmetry significantly partly is present in the 1st field.For this reason, the signal TE2 of the signal TE1 that detects from the 1st field and the detection of the 2nd field is different to the influence degree of disc tilt degree.
Figure 22 carries out result calculated to signal TE1 and signal TE2, and design conditions are: the wavelength of light source is 660nm, and the opening number of object lens is 0.6, and the spacing of succeeding vat is 1.2 μ m, groove depth=λ/8, and optic disc base board thickness is 0.6mm.Figure 22 (a) is the waveform when not having disc tilt, and Figure 22 (b) is that disc radial direction tilts is 0.6 waveform when spending.At Figure 22 (a), the 217th, signal TE1, the 218th, signal TE2 is at Figure 22 (b), the 219th, signal TE1, the 220th, signal TE2.Transverse axis among the figure is represented the light spot position with respect to the code track center.Here, so-called light spot position is meant the intensity peak position of light intensity distributions.
When not having disc tilt, as waveform 217,218 is such, when phase place unanimity, the luminous point of 2 signals are positioned at the code track center, all become the signal of the waveform vertical, still with transverse axis, if disc tilt, it is such to resemble waveform 219,220, produce phase deviation, waveform perpendicular to the position of transverse axis with the runout information track center.Disc tilt is to the influence degree difference of each signal, so, than the signal TE2 with waveform 220 expressions,
The phase deviation that the signal TE1 that represents with waveform 219 upward produces is big.Therefore, compare, can detect the disc tilt degree by phase place with the 1st tracking error signal TE1 and the 2nd tracking error signal TE2.
In addition, when the disc tilt direction was opposite direction, the asymmetry of the light intensity distributions of light beam was in the other direction, and this was illustrating in example in the past, so the phase deviation that can easily infer signal also is reciprocal.Again, when object lens move towards the direction perpendicular to code track, also move the position of inciding the light beam 216 on the infrared rays receiver 208, therefore, though on push-pull signal, produce direct current biasing, because the length in aforementioned the 1st field of the direction vertical with code track is done longlyer than beam diameter, so, even light beam 216 moves, the light intensity distributions that is included in the 1st field does not change yet.
Therefore, allow signal TE1, the Hi-pass filter of signal TE2 by constituting with common electric circuit, remove direct current biasing, the phase place to 2 signals compares again, can remove the influence that object lens move.The method of phase bit comparison for example, adopts the method for the value of the moment detection signal TE1 that intersects at signal TE2 and reference voltage (transverse axis that is equivalent to Figure 22), adopts general phase place comparative approach good.
In addition, in the above explanation, signal TE1 is used as the 1st tracking error signal, signal TE2 is used as the 2nd tracking error signal, but push-pull signal in the past, promptly also, as representing to 208f ' with aforementioned signal 208a ', so, the signal that the calculation by (208a '+208d '+208e ')-(208b '+208c '+208f ') is obtained uses as the 1st tracking error signal and also can carry out the detection of disc tilt degree.This is because aforementioned in the past push-pull signal is equivalent to signal TE1 and TE2's and signal, so, between the 1st and the 2nd tracking error signal, the phase differential that can fully detect can appear.
Like this, according to example 6 of the present invention, in the optical head of tracing error signal detector with push pull mode, can use the light signal that is subjected to detect from the 1st and the 2nd field, compare by phase place the 1st and the 2nd tracking error signal, need not also can carry out the detection of disc tilt degree by special-purpose disc tilt degree detecting device, again, add the aforementioned the 1st and the shape in the 2nd field be done so that perpendicular to the length of the direction of code track longer than the diameter that detects light beam, the detection of disc tilt degree, the method that adopts is not to detect direct current signal, but the phase-detection of comparison signal waveform, so the detection that can carry out the disc tilt degree under the influence that is not vulnerable to the direct current biasing of the push-pull signal of the mobile generation of object lens becomes possibility.
In addition, in aforementioned activities, use the whole signals of signal 208a ', only use 208a ' to 208f ', 208b ', 208e ' 208f ' also can without signal 208c ' 208d '.Otherwise, only use 208c ', 208d ', 208e ' 208f ' also can without signal 208a ' 208b '.
In addition, as the tracking error signal detection mode of using push-pull signal, in the past technology and example 5 explanations, compound Continuous Tracking mode or compound seam tracking through weaving torch mode be also all available.Again, other mode is also available.
(example 7)
This example to the optical head of in the past the servo mode of sampling, owing to be suitable for the present invention, become and solves the example that the disc tilt degree detects problem.
Figure 23 is the pie graph of the optical head of example 7 of the present invention.The just tracing error signal detector 211 ' different with Figure 19 figure is so the explanation that relevant optical head constitutes gives province in fact.Tracing error signal detector 211 ', at the textural signal 208e ' and signal 208f ' that uses the output signal of signal calculation portion 209 as shown in figure 20, detection is as the signal TE1 of the 1st tracking error signal, use 208a ', signal 208b ', signal 208c ' and signal 208d's ' and signal, detect signal TE2 as the 2nd tracking error signal.
The following describes tracking detection method.Figure 24 is the figure of the code track of explanation CD.This example is the optical head of the servo mode of sampling, so sampling hole groove carries out recording of information or regeneration action to the CD that is formed at code track intermittently.Here, so-called sampling hole groove in order to detect tracking error signal, is a pair of with 2 hole grooves, vacates certain interval and forms equidistantly with the code track center along code track.
At Figure 24,221,222 and 223,224 is respectively the message area of the center line of recorded information magnetic track, aforementioned sampling hole groove, address or information, and 225 and 226 arrow is represented the scanning position of luminous point.If luminous point passes through on the groove of such sampling hole, be subjected to light signal modulated according to what the relative position of luminous point and sampling hole groove detected.
Figure 25 is the figure of its modulation case of expression.I.e. expression about the modulation waveform of the modulated light quantity of each spot scan position, promptly also signal 208a ' to 208f's ' with signal waveform.The 227th, the expression signal waveform that 225 whens scanning were detected along the spot scan position, the 228th, the signal waveform that detects at scanning position 226, the 229th, the signal waveform of detection when scanning position is consistent with the code track center line.In the past, the tracking of the servo mode of taking a sample detects, be that (2 light spot positions of representing with arrow among Figure 25) detection signal is used as the sampling spot signal constantly, the difference according to these 2 sampling spot detected signal value detects tracking error signal again by sampling hole groove 222 and 223 at luminous point, aforementioned tracing error signal detector 211 ', carry out detecting identical signal Processing, detect signal TE1 and TE2 as the 1st and the 2nd tracking error signal with the tracking of its servo mode of sampling in the past.
Below, detection describes to the disc tilt degree.Figure 26 (a) is the result who the waveform modelling of tracking error signal is handled by numerical evaluation (b), the waveform when the no CD of Figure 26 (a) expression tilts, the waveform of Figure 26 (b) expression CD when radial direction has 0.6 degree to tilt.Design conditions are: the wavelength of light source is 660nm, the object lens opening number is 0.6, the substrate thickness of CD is 0.6mm, the code track spacing is 1.2 μ m, sampling hole slot length and width are 0.4 μ m, and the width of the code track direction that is subjected to optical arena 208e and 208f shown in Figure 20 and the diameter ratio of beam profile 206 are 0.25.
At Figure 26 (a), 230 is the 1st tracking error signal TE1, and 231 is the 2nd tracking error signals, and 232 are to use all 208a ' to 208f ' and tracking error signal input.232 is identical with the tracking error signal of in the past the servo mode of sampling, so be referred to as tracking error signal in the past.Again, in figure, transverse axis is represented the position of luminous point from the code track center, and Tp represents the code track spacing.3 waveforms are all represented when light spot position is consistent with the code track center and waveform that transverse axis intersects.
At Figure 26 (b), 233 expressions the 1st tracking error signal TE2,234 expressions the 2nd tracking error signal TE2, the waveform of the aforementioned tracking error signal in the past of 235 expressions.Different with Figure 26 (a), expression is here, in each waveform generation phase deviation, at the position of runout information track center and the crossing waveform of transverse axis.The size of this phase deviation is a maximum with the waveform 233 of the 1st tracking error signal TE1, secondly is the waveform 235 of tracking error signal in the past, is the wave system 234 of the 2nd tracking error signal TE2 subsequently.
Therefore, with the 2nd tracking error signal TE2, do bit comparison mutually, can detect the disc tilt degree with the 1st tracking error signal TE1 or aforementioned in the past tracking error signal.Produce the reason of phase deviation between each signal, with the same with Figure 21 narration in the explanation of example 6, when luminous point is cheated on the groove by sampling, the light intensity distributions of the light beam that detects is owing to the influence of the comatic aberration that disc tilt produces forms asymmetric distribution, in aforementioned the 1st field and the 2nd field, its amount that contains asymmetrical light intensity distributions is different.
The optical head of this example, the tracking that is the servo mode of sampling detects, so, use detected signal with the input tracking error signal, even move, in tracking error signal, can not produce skew at the direction object lens vertical with code track yet, again, because will the aforementioned the 1st and the shape in the 2nd field be done so that the shape that the direction length vertical with code track is grown than the diameter of the light beam that detects, so, even light beam moves, the light intensity distributions in each field does not change yet.Therefore, can detect the disc tilt degree that is not subjected to the influence that object lens move.
Again, the 2nd tracking error signal TE2 is because the phase deviation that disc tilt causes is little, so, carry out tracking Control with this signal, in tracking Control, by detecting the 1st tracking error signal TE1 or aforementioned in the past the value of tracking error signal, can detect the disc tilt degree.Like this, by tracking Control, luminous point is fixed in code track, so the flip-flop similar detection method of employing and detection signal can compare the phase place of 2 signals.
As mentioned above, according to this example, at the optical head of the servo mode of sampling,, the detection that the disc tilt degree detects special-purpose detecting device, is not subjected to the stable disc tilt degree of object lens moving influence can be set by comparing the phase place of the 1st tracking error signal and the 2nd tracking error signal.
(example 8)
This example to the optical head of in the past 3 pencil tracing modes, owing to be suitable for the present invention, become and solves the example that the disc tilt degree detects problem.
Figure 27 is the pie graph of the optical head of example 8 of the present invention.
For the inscape same with Figure 19, be with same symbol, explanation is omitted.The 236th, be the diffraction element of main beam and 2 auxiliary beams along separate routes with light, the 237th, carry out the signal calculation portion that signal amplifies, calculates, the 246th, tracing error signal detector.
Figure 28 is explanation each light receiving unit of infrared rays receiver 237 and the figure of signal calculation portion 238, and 239 and 241 is 3 to cut apart light receiving unit, 239a to 239c, 241a to 241c represent 3 cut apart light receiving unit respectively be subjected to optical arena.240 is 4 to cut apart light receiving unit, and 242 and 244 is auxiliary beams, the 243rd, main beam, the 245th, 245a to 245f is an amplifier, 238a ' to 238d ' be each signal from the output of signal calculation portion.
Action to the optical head of this example with such formation describes below.
The light that light source 201 sends through diffraction element 236 diffraction, is generated 2 bundle auxiliary beams as the 1st and the 2nd auxiliary beam of the main beam of 0 diffraction light and conduct+1 time and-1 diffraction light.These 3 light beams, transmitted beam resolver together, through object lens 204 by light harvesting in CD 205, on the optical axis 202 of optical head, form the luminous point of main beam, leaving the luminous point that forms 2 auxiliary beams on optical axis 202, the accompanying drawing above-below direction.
From the folded light beam of each luminous point that reflects with CD 205,,, incide relay lens 206 through 203 reflections of light beam resolver together once more by object lens 204.For example with the focus detection mode as non-some aberration mode, relay lens 206, refracting power with the cylindrical lens that makes non-some aberration generation, light beam is imported infrared rays receiver 237, as shown in figure 28, main beam incides 4 to be cut apart light receiving unit 240, the 1 auxiliary beams and incides 3 and cut apart 239, the 2 auxiliary beams of light receiving unit and incide 3 and cut apart light receiving unit 241.Incide 4 main beams 243 of cutting apart light receiving unit 240 and cut apart by 4 and be subjected to light, the calculation that the tie lines by as shown carries out, detection signal F1, F2.
Again, light receiving unit 239 and 241 respectively be subjected to optical arena, dispose equally with aforementioned example 6 and 7, the the 1st and the 2nd field that the light beam of incident can be divided into is subjected to light, and aforementioned the 1st auxiliary beam is cut apart by 3, is subjected to optical arena 239b that the light in aforementioned the 1st field is subjected to light, be subjected to optical arena 239a, 239c that the light in aforementioned the 2nd field is subjected to light, aforementioned the 2nd auxiliary beam cut apart by 3, is subjected to optical arena 241b that the light in aforementioned the 1st field is subjected to light, is subjected to optical arena 241a, 241c that the light in aforementioned the 2nd field is subjected to light.
Calculation and amplifier 245a, 245b, 245e and 245f that tie lines by as shown carries out, detectable signal 238a ' is to 238d '.238a ' be the 1st auxiliary beam the 1st field be subjected to light signal, 238b ' be the 1st auxiliary beam the 2nd field be subjected to light signal, 238d ' be the 2nd auxiliary beam the 1st field be subjected to light signal, 238c ' be the 2nd auxiliary beam the 2nd field be subjected to light signal.
Tracing error signal detector 246 in formation, uses 238a ' and signal 238d ', detection is used 238b ' and signal 238c ' as the signal TE1 of the 1st tracking error signal, detects the signal TE2 as the 2nd tracking error signal, so, signal TE1, TE2 can represent by following formula.
TE1=238a '-238d ' (several 22)
TE2=238b '-238c ' (several 23)
Disc tilt degree pick-up unit 212 by to comparing as the signal TE1 of the 1st and the 2nd tracking error signal and the phase place of TE2, detects the disc tilt degree.
Below, detection elaborates to the disc tilt degree.Figure 29 is the figure how luminous point of expression main beam and auxiliary beam disposes code track, as shown in the figure, the luminous point of main beam relatively, the luminous point of 2 auxiliary beams on the direction vertical with code track according to 1/4 track pitch configured separate.
Figure 30 is to carrying out Simulation result perpendicular to the signal waveform the during scanning of the 1st subsidiary beam spot on the vertical direction of code track by numerical evaluation.The 247th, the waveform of signal 238a ', the 248th, the waveform of signal 238b ', the 249th, signal 238a ' and 238b ' and waveform signal.Design conditions are: the object lens opening number is 0.6, and the wavelength of light source is 660nm, and the code track spacing is 1.2 μ m, is 0.4 μ m as the succeeding vat width of cloth of code track, and groove depth is 1/8 wavelength, and the disc tilt degree is 0.6 degree at radial direction.
Because code track narrow width, when CD does not tilt, each signal waveform should present the waveform of tool minimum value when light spot position is in the code track center, but in Figure 30, because disc tilt phase deviation occurs in each signal waveform, phase deviation increases according to the order of waveform 247, waveform 249, waveform 248.Here, so-called light spot position refers to the light intensity peak of luminous point.
As can be seen from Figure 29, the luminous point of the 2nd auxiliary beam, the luminous point of relative the 1st auxiliary beam has the offset of 1/2 track pitch, so, each signal of the 2nd auxiliary beam, the signal of relative the 1st auxiliary beam all has the phase differential of 1/2 track pitch.But, the phase deviation of the signal that takes place by disc tilt, its reason comes from the asymmetry of the light intensity distributions that detects light beam, so the signal of the auxiliary beam to the 1st and the 2nd equally takes place.
Therefore, the 2nd tracking error signal TE2 that uses the signal 238c ' of the 1st tracking error signal TE1 that the signal 238d ' of the signal 238a ' of the 1st auxiliary beam and the 2nd auxiliary beam detects and signal 238b ' that uses the 1st auxiliary beam and the 2nd auxiliary beam to detect, identical with the waveform 219 and 220 of 2 tracking error signals of example 6 among Figure 22 (b), become the signal that produces phase differential corresponding to disc tilt.Like this, by the signal TE1 of the 1st and the 2nd tracking error signal and the phase place of signal TE2 are compared, can detect the disc tilt degree.
In addition, in the above description, the 1st tracking error signal is to use the signal 238a ' that detects in the 1st field and signal 238d ' to detect, and as shown in figure 30, waveform 249 has phase differential with respect to waveform 248, therefore, the signal that use detects in the 1st and the 2nd field and signal, promptly also, use signal 238a ' and signal 238b ' with signal, and signal 238ac ' and signal 238d's ' and signal, the 1st tracking error signal can be detected, the disc tilt degree can be detected too.
Again, the tracking of 3 pencil tracing modes detects, utilize auxiliary beam to be carried out input by light intensity modulation at code track, therefore, even object lens move in the direction perpendicular to code track, can not produce skew in the tracking error signal yet, again, the shape of cutting apart the 1st and the 2nd field of detecting light beam is made into perpendicular to the length of the direction of the code track shape greater than the diameter that detects light beam, so, even light beam moves, the light intensity distributions in each field does not change yet.Like this, not detected by the disc tilt degree of object lens moving influence.
As mentioned above, according to this example, at the optical head of 3 pencil tracing modes, by the 1st tracking error signal and the 2nd tracking error signal are carried out the phase bit comparison, disc tilt degree detecting device that need not be special-purpose can not be subjected to the detection of the stable disc tilt degree of object lens moving influence.
(example 9)
This example is to make the signal of the disc tilt degree correspondence that detects in the optical head of aforementioned each example have an example of the signal Processing of better characteristics of signals.The explanation of this signal processing apparatus comprises respectively constituting of aforementioned optical head, for example, and the content of the inside of the disc tilt degree pick-up unit 212 among Figure 23.
The detection of disc tilt degree is undertaken by the phase differential of measuring aforementioned the 1st tracking error signal TE1 and the 2nd tracking error signal TE2.With Figure 26 (b) this measuring difference of phases is described.At Figure 26 (b), waveform 233 expression signal TE1, waveform 234 is signal TE2, and waveform 235 is signal TE1 and TE2's and signal, still, waveform 234, if the waveform 233 when intersecting with transverse axis or the signal of waveform 235 are measured, so, corresponding to the direction of the phase differential of waveform 234 relatively, positive and negative variation takes place in aforementioned signal value, and this mensuration becomes one of measuring difference of phases method.
Be shown in Figure 31 calculating the signal value suitable and the relational result of disc tilt amount with the phase differential of measuring like this.The calculating of design conditions and Figure 26 is same.Transverse axis is represented the disc tilt amount, and the longitudinal axis is represented aforementioned signal value, considers mapping ratio, allows the suitable coefficient of signal value band.250 expression aforementioned signal values original result of calculations, 251 expressions are pressed aforementioned signal value the result of calculation after the amplitude normalization of signal TE1.Because the disc tilt degree, signal TE1 correspondence lowers amplitude, visual curve 250 linear bad, and by pressing the amplitude normalization of signal TE1, the linearity of visual curve 251 can improve.In addition, the normalized concrete device for the aforementioned signal value of realizing carrying out with amplitude can adopt general electric signal treating apparatus, and explanation is omitted.
As mentioned above, signal TE2, the signal value of the signal TE1 when mensuration intersects with reference voltage is owing to make disc tilt degree detection signal with this signal value with the normalized signal of the amplitude of signal TE1, so, can obtain disc tilt degree detection signal at the good linearity of disc tilt amount.
(example 10)
This example, an example that is to use the 1st and the 2nd tracking error signal that detects with the optical head of aforementioned each example 6 to 9 and disc tilt degree detection signal to carry out generating in the tracking Control optical head of suitable control signal.
Figure 32 is the pie graph of optical head of expression example 10 of the present invention, with the common same symbol of inscape band of aforementioned each example, again, except the part of mandatory declaration, all the other all economize substantial pie graph.The 252nd, object lens mobile device, the 253rd, tracking control signal generating apparatus, the 254th, follow-up control apparatus.Disc tilt degree pick-up unit 212, signal TE1, the TE2 of output disc tilt degree detection signal TLT, the 1st and the 2nd tracking error signal.These 3 signals are transfused to tracking control signal generating apparatus 253, perform calculations there, and as tracking control signal TE output, signal TE, the control signal that is used as follow-up control apparatus 254 is used.Follow-up control apparatus 254 drives object lens mobile device 252, and the position of object lens 204 is controlled, and makes luminous point can follow the center of code track.
Figure 33 is the pie graph of explanation tracking control signal generating apparatus 253, the 255th, make the attenuator of the amplitude fading of signal, and the 256th, differential amplifier.Attenuator 255 can be adjusted the attenuation rate of input signal according to the size of signal TLT, changes the amplitude of signal TE1 according to this, and differential amplifier 256 carries out difference and output signal TE from signal TE2 with amplitude signal TE1 after changing.
With reference to Figure 26 (b) this example with above formation is described.Waveform 233 is signal TE1, and waveform 234 is signal TE2, because there is phase differential in 2 waveforms, can remove waveform 233 from waveform 234, can generate the signal waveform that waveform 234 is moved to the left.,, remove for this reason, phase change arbitrarily can be added to the waveform after the calculation from waveform 234 if adjust the amplitude of waveform 233.
That is, adjust with the amplitude of 255 couples of signal TE1 of attenuator, remove from signal TE2, can generate the signal TE that relative signal TE2 has random phase difference with differential amplifier 256 according to signal TLT.Like this, the point that the waveform of signal TE and reference voltage intersect, can at random be set in the code track center around, therefore, carry out tracking Control by using this signal TE, can set the tracking Control position arbitrarily.
Therefore, suitably adjust by the attenuation rate to the attenuator 255 adjusted by signal TLT in advance, the light spot position and the offset at code track center that can use signal TLT revisal to produce by disc tilt, the line trace of going forward side by side is controlled.
As mentioned above, according to the optical head of this example, the disc tilt degree of detection radius direction adopts this disc tilt degree detection signal, and revisal can realize high-precision tracking Control by the code track center of disc tilt generation and the skew of light spot position.
Again, the adjustment of tracking Control position in the past, by adding that at tracking control signal direct current biasing carries out, so, there is the unsettled problem of control system, according to this example, need not add direct current biasing,, adjust the control position by the phase place of offset control signal, so, can realize stable tracking Control.
Generate the occasion of tracking control signal, as technology in the past again,, use is subjected to the occasion of signal in the full field of light, the revisal degree of carrying out with radial skew, than the occasion of the disc tilt degree that obtains based on aforementioned example, can carry out bigger correction.
(example 11)
This example is an example that applies the present invention to carry out the optical head that the degree of tilt of CD wiring direction detects.
Figure 34 is the pie graph of the optical head of the invention process form 11.For the inscape identical with aforementioned example, be with same symbol, again,, give province in fact at this because focus detection device and tracing error signal detector are identical with aforementioned each example.The 257th, infrared rays receiver, the 258th, signal calculation portion, the 259th, disc tilt degree pick-up unit.The light that light source 1 sends is through CD 205 reflections, and the explanation that this light is imported into before the infrared rays receiver 257 is identical with aforementioned each example, gives province in fact at this.Again, CD adopts its code track to form the type of hole groove.
Figure 35 is the figure of explanation infrared rays receiver 257 and signal calculation portion 258.The 256th, the profile of incident beam, 257a to 257c be infrared rays receiver 257 respectively be subjected to optical arena, 258a, 258b are amplifiers, S1, S2 are the signals of signal calculation portion 258 outputs.Infrared rays receiver 257 be subjected to optical arena, be divided into as being parallel on the direction of code track long and be positioned at being subjected to optical arena 257b and being subjected to optical arena 257a and 257c of the 1st field of light beam central portion as the 2nd field in the field beyond the 1st field by 3, respectively be subjected to light signal pass through tie lines phase adduction through amplifier 258a, 258b as signal S1, S2 output.Signal S1 is made of the light signal that is subjected in aforementioned the 1st field, and signal S2 is made of the light signal that is subjected in aforementioned the 2nd field.
Figure 36 is tilt when there is the wiring direction in the CD oscillogram of the signal that (containing the disc tilt that the normal of CD in the plane of wiring of the optical axis of object lens and code track contains) time point detects when cheating groove of expression.The 260th, aforementioned signal S1, the 261st, the waveform of aforementioned signal S2.There is the skew of wave trough position in signal S1 relative signal S2, and its reason that phase deviation occurs is the comatic aberration that disc tilt takes place.With the light intensity distributions of CD in the light beam that the degree of tilt of wiring direction detects, present such as shown in figure 21 asymmetric distribution at luminous point during by the hole groove, such asymmetric distribution occurs on the direction parallel with code track.
The 1st field of this example and the 2nd field are long shape on the direction parallel with code track, so in the 1st and the 2nd field, aforementioned asymmetrical light intensity distributions content is different, cause signal S1 and signal S2 that phase differential takes place.Again, when disc tilt was contrary direction, the phase deviation of signal also was created on the contrary direction, and this is the same with aforementioned example.Therefore, disc tilt degree pick-up unit 259 by the phase differential of detection signal S1 and S2, can detect the disc tilt degree.
Figure 37 is the figure that is used for illustrating one of the method example of detection signal S1 and S2.Waveform 262 is differentiated waveforms of signal S1, and waveform 263 is differentiated waveforms of signal S2, the 264th, and reference voltage.Waveform 262 and waveform 263, it is the almost symmetrical signal that changes on the positive negative direction that with reference voltage 264 center, so, the signal value of the waveform 262 when intersecting with reference voltage 264 by measuring waveform 263 can obtain taking place according to the phase differential direction of 2 differentiated waveforms the signal of positive and negative variation.The phase differential of these differentiated waveforms is corresponding with the phase differential of signal S1 and signal S2, and therefore, this signal is exactly a disc tilt degree detection signal.
As mentioned above, according to this example, for the CD that forms the hole groove, when luminous point during by the hole groove, the phase place that sees through the detection signal in the detection signal in the 1st field and the 2nd field compares, and can detect the degree of tilt of CD on the wiring direction.
Again, this example forms code track with the hole groove, but also can with the CD that succeeding vat and hole groove form.Mainly be that code track whole or one one can with hole flute profile achievement.
Again, if compoundization of tilt detection with the wiring direction of the CD of the optical head formation of expression in the tilt detection of the radial direction of the optical head of example of the present invention 6 to 8 expressions and the example 11, then not be used in the disc tilt degree detecting device of the outer setting special use of optical head, just can detect the disc tilt degree of all directions.
Again, the invention is not restricted to the formation of aforementioned example, be divided into the 1st field of aforementioned such shape and the optical head that the 2nd field is subjected to the formation of light, can easily use the present invention for the infrared rays receiver that the detection tracking error signal can be used.
Again, at aforementioned example 1 to 5, object lens 4 are equivalent to light collecting device of the present invention, infrared rays receiver 8,30,47,54 is equivalent to infrared rays receiver of the present invention, tracing error signal detector 9,55 and 58 are equivalent to tracking error detecting device of the present invention, and optical devices 6,6 ' are equivalent to attenuating device of the present invention.
Again, the optical function field 11 in the optical devices 6 is equivalent to dim light of the present invention field, and other part is equivalent to non-dim light field, and optical devices 6 ' are equivalent to branch apparatus of the present invention.Again, the light receiving unit in the infrared rays receiver 30 34 to 37 the 1st son that is equivalent to light receiving unit of the present invention is subjected to the optical arena part.Again, light receiving unit 34 to 37 is equivalent to make the light of auxiliary beam of the present invention to be subjected to the part of light.Again, light receiving unit 31,33 the 2nd son that is equivalent to light receiving unit of the present invention is subjected to optical arena.Again, light receiving unit 31,33 is equivalent to make the light of main beam of the present invention to be subjected to the part of light.
Again, cut apart the part that light that light receiving unit 49 is equivalent to make the main beam of light receiving unit of the present invention is subjected to light at infrared rays receiver 47,4,3 cut apart the part that light that light receiving unit 48,50 is equivalent to the auxiliary beam of light receiving unit of the present invention is subjected to light.Again, be subjected to optical arena 48b, 50b to be equivalent to the 1st son of the present invention and be subjected to optical arena, be subjected to optical arena 48a, 48c, 50a, 50c to be equivalent to the 2nd son of the present invention and be subjected to optical arena.
Again, at light receiving unit 54, the 1st son that light receiving unit 72,73a, 81a, 81b, 82a, 82b, 83a, 83b are equivalent to light receiving unit of the present invention is subjected to the optical arena part.Again, light receiving unit 70,73b, 73c, 80a, 80b, 83c, 83d, 83e, 83f the 2nd son that is equivalent to light receiving unit of the present invention is subjected to the part of optical arena.
Again, profile of tooth mark 107 and 108 is equivalent to a pair of mark of the present invention.
Again, position A in Figure 41, sampling spot signal S, be equivalent to the aforementioned light signal that is subjected to that is used, obtains from a pair of mark one side's folded light beam by the 10th tracing error signal detector of the present invention, position B in Figure 41, sampling spot signal S is equivalent to the aforementioned light signal that is subjected to that is used, obtains from a pair of mark the opposing party's folded light beam by the 10th tracing error signal detector of the present invention.
Again, at infrared rays receiver 54, light receiving unit 56a, 56b are subjected to the light signal that is subjected to of light, and light receiving unit 80a, 81a, 82a are subjected to the light signal that is subjected to of light, and light receiving unit 83a, 83c, 83e be subjected to light be subjected to light signal to be equivalent to the 1st son of the present invention to be subjected to light signal, light receiving unit 56c, 56d are subjected to the light signal that is subjected to of light, and light receiving unit 80b, 81b, 82b, light receiving unit 83b, 83d, 83f be subjected to light be subjected to light signal to be equivalent to the 2nd son of the present invention to be subjected to light signal.
At aforementioned example 6 to 11, object lens 204 are equivalent to light collecting device of the present invention, infrared rays receiver 208,237,257 is equivalent to infrared rays receiver of the present invention, tracing error signal detector 211,211 ' is equivalent to tracking error detecting device of the present invention, and disc tilt degree pick-up unit 212,259 is equivalent to disc tilt degree pick-up unit of the present invention.
Again,, be subjected to optical arena 208f and 208e to be equivalent to the 1st son of the present invention and be subjected to optical arena, be subjected to optical arena 208a, 208b, 208c, 208d to be equivalent to the 2nd son of the present invention and be subjected to optical arena at infrared rays receiver 208.
Again,, be subjected to optical arena 239b and 241b to be equivalent to the 1st son of the present invention and be subjected to optical arena, be subjected to optical arena 239a, 239c, 241a, 241c to be equivalent to the 2nd son of the present invention and be subjected to optical arena at infrared rays receiver 237.
Again,, be subjected to optical arena 257b to be equivalent to the 1st son of the present invention and be subjected to optical arena, be subjected to optical arena 257a, 257c to be equivalent to the 2nd son of the present invention and be subjected to optical arena at infrared rays receiver 257.
Again, in infrared rays receiver 237 and 257,3 cut apart light receiving unit 239 and 241 is equivalent to make light infrared rays receiver of the present invention, 2 auxiliary beams to be subjected to the part of light, and 4 cut apart light receiving unit 240 is equivalent to make light infrared rays receiver of the present invention, at least 2 auxiliary beams to be subjected to the part of light.
Again, groove 222 and 223 one group is cheated in sampling, is an example of a pair of mark of the present invention.
Again, at example 7, at the detection signal of cheating the moment sampling spot of groove 222 by sampling, become an aforementioned example that is subjected to light signal of the present invention, that obtain from a side's of a pair of mark folded light beam of the 21st, at the detection signal of the moment sampling spot by sampling hole groove 223, become an aforementioned example that is subjected to light signal of the present invention, that obtain from the opposing party's of a pair of mark folded light beam of the 21st.
Again, signal 208a ', 208e ', signal 208d ' are the examples that the 1st son of the present invention is subjected to light signal, and signal 208b ', 208f ', signal 208c ' are the examples that the 2nd son of the present invention is subjected to light signal.
Again, tracking control signal generating apparatus 253 is examples of tracking control signal generating apparatus of the present invention, and follow-up control apparatus 234 is examples of follow-up control apparatus of the present invention.
Again, the present invention also can realize as the optical disc recording apparatus that has optical head of the present invention, recorded information is used in CD.
Again, the present invention also can realize as the optical disk reproducing apparatus that has optical head of the present invention, regenerating information is used from CD.
Again, the present invention, also can realize as have optical head of the present invention, record or the optical disc recording/reproducing apparatus used of regenerating information in CD.
Again, CD of the present invention carries out recording of information or regeneration with optical devices, but is not restriction with its formation and pattern, also can enumerate examples such as CD, CD-R, CD-RW, DVD, DVD-R, DVD-RW, DVD-ROM.
As mentioned above,, can suppress the phase deviation of the tracking error signal of disc tilt generation, realize the extra high optical head of tracking Control precision according to the present invention.
According to the present invention, can realize need not be special-purpose disc tilt degree detecting device, be not subject to the influence that object lens move, the degree of tilt of high-precision CD radial direction or wiring direction detects.Even optical disc shapes there are differences, also can not can lower accuracy of detection ground and carry out stable detection again.
Claims (7)
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000190893 | 2000-06-26 | ||
| JP2000190893 | 2000-06-26 | ||
| JP2000214050 | 2000-07-14 |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB01814621XA Division CN1235205C (en) | 2000-06-26 | 2001-06-22 | Optical head |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1725318A CN1725318A (en) | 2006-01-25 |
| CN100336120C true CN100336120C (en) | 2007-09-05 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB200510081466XA Expired - Fee Related CN100336120C (en) | 2000-06-26 | 2001-06-22 | Optical head |
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| Country | Link |
|---|---|
| CN (1) | CN100336120C (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61158044A (en) * | 1984-12-28 | 1986-07-17 | Nec Home Electronics Ltd | Tracking error detecting device |
| US4748609A (en) * | 1985-03-29 | 1988-05-31 | Hitachi, Ltd. | Method and apparatus for composite tracking servo system with track offset correction and rotary optical disc having at least one correction mark for correcting track offset |
| US4855991A (en) * | 1982-07-21 | 1989-08-08 | Hitachi, Ltd. | Optical disk having track offset detection areas |
| CN1204414A (en) * | 1995-10-27 | 1999-01-06 | 松下电器产业株式会社 | Optical head |
-
2001
- 2001-06-22 CN CNB200510081466XA patent/CN100336120C/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4855991A (en) * | 1982-07-21 | 1989-08-08 | Hitachi, Ltd. | Optical disk having track offset detection areas |
| JPS61158044A (en) * | 1984-12-28 | 1986-07-17 | Nec Home Electronics Ltd | Tracking error detecting device |
| US4748609A (en) * | 1985-03-29 | 1988-05-31 | Hitachi, Ltd. | Method and apparatus for composite tracking servo system with track offset correction and rotary optical disc having at least one correction mark for correcting track offset |
| CN1204414A (en) * | 1995-10-27 | 1999-01-06 | 松下电器产业株式会社 | Optical head |
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| CN1725318A (en) | 2006-01-25 |
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