CN1205428A - Displacement sensor and method for producing target feature thereof - Google Patents
Displacement sensor and method for producing target feature thereof Download PDFInfo
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- CN1205428A CN1205428A CN 98105485 CN98105485A CN1205428A CN 1205428 A CN1205428 A CN 1205428A CN 98105485 CN98105485 CN 98105485 CN 98105485 A CN98105485 A CN 98105485A CN 1205428 A CN1205428 A CN 1205428A
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Abstract
A device for measuring the displacement of a movable object includes a stationary light source that produces an incident light beam. A target feature, attached to, or integral with, the object, reflects the incident light beam and forms a first image of the light source in close proximity of the target feature. An imaging lens receives the reflected light beam and reforms the first image of the light source as a second image on the photodetector. The photodetector, spaced from the object, receives the reflected light beam and, in response thereto, produces an electric signal having a characteristic (such as amplitude) which is proportional to a received location on the photodetector of the second image and which represents a position of the object. The target feature includes a curved surface that reflects the light beam such that a small, point-like or line-like first image of the light source is formed and reformed as a second image on the photodetector. The displacement sensor device is particularly useful in a disk drive servo system application.
Description
The application is that the series number of submitting to Dec 15 nineteen ninety-five is 08/573,170, is entitled as the part continuation application of the U.S. Patent application of " non-contacting position sensor ".
Generally speaking, but the present invention relates to be used for accurately measuring the optical devices of the micro-displacement of moving-target, more precisely, relate to the method that forms the target signature part that is applied in the optical devices.
But in many application, all be starved of the position of the one or more relatively desirable positions of monitoring moving-target.For example, the position of the rotatable desirable relatively known location of W head arm is accurately surveyed in hope in disc drive servo system, make head arm can be moved to disk on desirable radial track aligned in position so that the W head arm can be write on this position from this position sense data with data.Position transducer is to be the device of target so that this position sensing to be provided.Displacement transducer is a position sensing device of monitoring movable target location by the displacement that the repeated measurement target is left desired position.
The example of traditional displacement transducer comprises that electric capacity rule device, optical fiber are near (proximity) sensor with for example be generally used for the optical sensor of the interference sensor etc. of disc drive servo system.Many or can not reach the desired resolution of some application (for example disc drive servo system) (I location move) grade in the displacement transducer of prior art, perhaps require expensive and/or complicated circuit and hardware reaches this resolution.In order to reach high resolving power, but some displacement transducer for example require an accurate and powerful LASER Light Source or require sensing element and moving-target very approaching, make that this device is expensive and be difficult to realization.Like this, must between device performance and simple degree, average out.
The U.S. Patent No. 5,315,372 of Tsai is described the disc drive servo system of the prior art of having used optical displacement sensor.The Tsai device comprises a light source and a photodetector array, and they are installed on the rotating principal arm outside the disk drive, is in to leave position at interval.Reverberator is installed on the W head and the position between the arm rotation axis of rotating W head arm.At run duration, at first make accurately desirable radial track position on the aligning dish of principal arm with the interference device.Then, the position of head arm with respect to principal arm determined in displacement transducer work, so that head arm can be moved to and the principal arm positions aligning.
The light source of displacement transducer produces incident beam, and its device that is reflected reflexes to photodetector array.The relative radial position of magnetic head and principal arm is depended in the position that light beam reflexes on photo-detector.Each optical detector elements produces a kind of electric signal in the array, and its amplitude is directly proportional with the light intensity that is received.Like this, the signal that is produced by array has been represented the radial position of magnetic head and principal arm.Treatment circuit receives by the signal of array output and with its decoding, determines the position of relative head arm, and correspondingly controls motor and make the head arm rotation, suitably aims at up to it.
The disclosed device of the patent of Tsai has several shortcomings.Though the device of Tsai is structurally quite simple, and implement quite cheap, its troublesome poeration.The device of Tsai need be known each principal arm and relative head arm position in advance, so that explain the electric signal that is produced by photodetector array exactly.Also have, because at reverberator and the significant interval between the W head on the head arm, also because two rotation axiss of head arm and principal arm have been sacrificed the manipulation precision widely.In addition, the displacement transducer of Tsai is target with the monitoring head arm with respect to the moving radially of principal arm (by caused the moving of swaying).Because reverberator incident beam directly reflex to reverberator every photo-detector quite far away, so sensor is not only to the radius motion sensitive, also to the angle motion sensitive of reverberator.Like this, the accurate angular orientation of reverberator on head arm is vital for accurate operation.Reverberator moves the measurement that can make the mistake with respect to any angle of head arm.
General purpose of the present invention provides a kind of method that is applied in the target signature part on the simple but accurate optical displacement sensor that is used to form.
But one embodiment of the present of invention are the devices that are used to measure the displacement of moving-target at a kind of.In this device, static light source produces a branch of incident beam.Be installed in this incident beam of target signature partial reflection on the target, and nearby forming first of light source and resemble in target signature part.Imaging lens receives first and resembles, and resembles first and to form second of light source again resemble on photo-detector.The photo-detector that separates with target receives second and resembles, and it is responded, and produces electric signal, and it has second characteristic that resembles the position that is proportional on photo-detector to be received, and the position of target has been represented in this position.Be used in and mark a groove on the target and form the target signature part.
In one embodiment, target signature part groove is half garden cylindricality.
In one embodiment, target signature partly has the radius-of-curvature in the 0.2-5.0mm scope.
An alternative embodiment of the invention is at optic position sensor spare, and it is used to detect the position of the interior head arm of read driver with respect to principal arm.This device comprises and is installed in the light source that is used to produce incident beam on the principal arm.Be installed in the target signature partial reflection incident beam on the head arm, and nearby forming first of light source and resemble in target signature part.The imaging lens that is arranged on the light path between target signature part and the photo-detector receives reflected beams, and first of light source is resembled on photo-detector focusing again forms second and resemble.The photo-detector reception second that is installed on the principal arm resembles, and it is responded, and produces electric signal, and it has the characteristic of the position of reception second elephant that is proportional on photo-detector, and this electric signal has been represented the relative position of head arm.Form the target signature part by paddle-tumble on target.
An alternative embodiment of the invention is at the method that forms the target signature part on target; The displacement of targets that detects by displacement transducer; The displacement transducer that comprises light source and photo-detector, wherein light source produces the incident beam from the target signature partial reflection, and photo-detector receives resembling of the light source that partly produced by target signature.Described method comprises following step: the line surface of scoring tool is contacted with target surface; With under the situation of maintenance scoring tool, target signature is partly drawn target surface to target surface pressure.
In one embodiment, the step of line comprises the static step of maintenance target.
In another embodiment, the step of line comprises the step that the maintenance instrument is static.
Detailed description of the present invention below read in conjunction with the accompanying drawings, and according to the claim that invests this detailed description end just will appreciate that and knows the features and advantages of the present invention.
Fig. 1 is a block scheme of using the general embodiment of the target signature displacement transducer partly that forms according to the present invention;
Fig. 2 is the more detailed synoptic diagram of the specific embodiments of displacement transducer;
Fig. 3 is the electric signal that is produced is exported in explanation from two unit (bi-cell) photo-detector of sensor a curve map;
Fig. 4 is a more detailed block diagram of also using the disc drive servo system of the target signature part that forms according to the present invention;
Fig. 5 is the part-structure of explanation disc drive servo system work, the block scheme of partial function;
Fig. 6 A and 6B are the electrical block diagrams of the treatment circuit of disc drive servo system;
Fig. 7 is the detail drawing that is applied to a target signature embodiment partly of disc drive servo system;
Fig. 8 is shown in the target signature part of Fig. 7 and the side view of head arm end;
Fig. 9 is the more detailed schematic diagram of part of an embodiment of the application's displacement transducer.
Figure 10 is the sketch according to an embodiment of the instrument that can be used for marking the target signature part of the present invention
Figure 11 illustrates to come according to one embodiment of present invention modular construction, the component function sketch of drawing the target signature part;
Figure 12 illustrates to come according to one embodiment of present invention modular construction, the component function sketch of drawing the target signature part;
Figure 13 illustrates the sketch that can be used for drawing target signature speciality tool partly according to one embodiment of present invention; With
Figure 14 is the more detailed synoptic diagram on line surface of the instrument of Figure 13.
Fig. 1 is a general block scheme of using an embodiment of the target signature displacement transducer partly that forms according to the present invention.As shown, but this sensor comprises static light source 10 moving-targets 14, static imaging lens 26 and static photo-detector 20., target signature part 16 makes an integral body but but being fixed on the moving-target 14 or with moving-target 14.Target 14 is movable on the direction shown in the arrow X, and the displacement that displacement transducer leaves the reference position by measurement target 14 comes the position of monitoring objective 14.
Light source 10 produces incident beam 12, and the latter is become the light beam 18 that is reflected by the target signature partial reflection.By little curved reflective surface thereon, at the (not shown) that resembles of first point-like that has nearby formed light source 10 of target signature part 18 or wire.First resembles along with moving of target signature part and moves.Light beam 18 is focused on by lens 26, thus on the surface of photo-detector 20, form light source second as (with first resembling).Folded light beam 18 (with second resembling) is responded, photo-detector 20 produces electric signal, it has the characteristic (for example amplitude or frequency) of the position (promptly forming the place of second elephant) that is proportional to photo-detector 20 surfaces and receives folded light beam, thereby this signal is corresponding to the current location of target 14.Treatment circuit (its special embodiment will describe with reference to figure 6B below) can be connected to photo-detector so that receive the electric signal that photo-detector produces, and handles this signal so that determine the position of target and/or the displacement that target is left the known reference position.Described circuit both can comprise the signal processing circuit that also can comprise numeral of simulation.
As describing in detail in 90 minutes with reference to figure, target signature part 16 comprises curved surface 17, it is reflected into irradiating light beam 12, thereby near target signature part 18, formed the little of light source 10, preferably first of point-like or wire resemble, and on the surface of photo-detector 20, formed second again by lens 26 and resemble.When the size of elephant subtracts more for a short time, 20 pairs of less displacements of photo-detector are responsive more.Therefore, hope focuses on out little on the surface of photo-detector 20 again, and second of point-like or wire resembles.
As following will extremely describing in detail, the curved surface 17 of target signature part 16 can fall in or projection.Target signature part 16 can form with target 14 integral body, as described with reference to figure 10-13.For example, target signature part 16 can be included in formed curved surface on the part of target 14.Another kind of way is that the target signature part can be the discrete element that is fixed on the target 14.For example, target signature part 16 can be for example be fusion welded to, be brazed into, scolder is soldered to, screw is screwed on the target 14 or other ways are fixed to the such garden post element of for example pin on the target 14.If as discrete component and fixing, the curved surface 17 of target signature part 16 should be enough level and smooth, and preferably through the polishing, thereby be reflected into irradiating light beam effectively.
With reference to figure 1, when target 14 was mobile on the direction of arrow X, moved in the opposite direction the position that receives the light beam that is reflected on the surface of photo-detector 20, shown in arrow X '.This is responded, and photo-detector 20 produces electric signal, and wherein each signal has the position with the photo-detector surface that reflexes to, just the characteristic (being amplitude or frequency) that is directly proportional of the relative position of target 14.
When the size of the elephant of the light source that is reflected to the photo-detector surface reduced, the displacement resolution of sensor increased.In addition, when the intensity of incident beam increased, the displacement resolution of sensor increased.The light source that has reduced to reflex to the photo-detector surface because using the target signature part that curved surface is arranged widely resembles the size of (being resembling of point-like or wire), so, can loosen the requirement of efficient and expensive lasing light emitter for reaching high-grade displacement resolution.
Fig. 2 is the more detailed synoptic diagram of the specific embodiments of expression displacement transducer of the present invention.Like among Fig. 2 use with Fig. 1 in identical reference symbol represent.As shown in the figure, sensor comprises laser diode light source 22; Target 14, target signature part 16 or thereon attached or integrally form with it; With two unit light detectors 28.Also comprise graded index (GRIN) incident laser diode beam collimation lens 24 and folded light beam condenser lens 26.
As a rule produce incident beam 12 (being expressed as two laser beam of separating at Fig. 2) by laser diode 22, this light beam is sent to target signature part 16 by GRIN collimation lens 24.In laser diode 22, GRIN collimation lens 24 and the two unit light detector 28 each can be traditional element.Incoming laser beam 12 resembles (not shown) from curved surface 17 reflection of target signature part 16 in first of the little point-like that has nearby formed light source of target signature part or wire, and the target signature part is reflected into folded light beam 18 to incident beam 12.First of little point-like or wire resembles and formed second by lens 26 again on the upper surface 31 of two unit light detectors 28 and resemble 30.Lens 26 receiving beams 18 also are focused into second and resemble 30 on photo-detector 28.The curved surface 17 of target signature part 16 makes the little point-like of light source 22 or wire resemble 30 and can be focused on the surface 31 of photo-detector 28.
As will explaining in more detail below, under the situation of the garden cylindricality target signature part that forms on the target, first resembles in intersection or convergence from the light beam of target signature partial reflection and forms.In contrast to this, under target surface and situation about stretching from target surface, first resembles the virtual image that is actually in the target signature part, exhales folded light beam from this virtual image at garden cylindricality target signature partial fixing.
Because point-like first resembles the nearby formation in the target signature part, system is very insensitive to mobile (for example the moving radially) of target and target signature part, does not plan to be used for to measure.For example, if target 14 is rotated around the axle that forms in Y direction (longitudinal axis that is parallel to the target signature part) a little, just can not influence measurement.This is because the part of folded light beam 18 (with first resembling) on lens 16 surfaces will change, but second resembles 30 positions on photo-detector 31 and will can not become.Like this, system of the present invention moves radially insensitive to target little.
Two single-element detectors 28 comprise two by narrow with 32 detector unit A that separates and B.When target 14 was mobile on directions X, the surface 31 that point image 30 strides across two single-element detectors 28 moved on to unit B in X ' direction from unit A.Sensor can be calibrated to center when point image 30 between unit A and B be with on 32 the time be zero or reference position (is to be on the desirable position in target 14 on this position).
Each unit A of two single-element detectors 28 and B produce simulating signal, and their amplitude is decided by the position of point image 30 at cell surface.When each unit is in this unit surperficial fully at point image 30, produce the strongest electric signal.Ratio by monitoring (A-B)/(A+B), just can monitor the position of point image 30 on the surface of photo-detector 28, thereby also can monitor the position of target 14 (with respect to static light source and photo-detector), above-mentioned A and B represent the amplitude of the electric signal that the unit A and the B of detector 28 produced respectively.This is because point image 30 can be linearly in the position on the surface of photo-detector 28 interrelates with the relative position of target 14.(A-B)/(A+B) ratio can be monitored by means of the treatment circuit (seeing Fig. 6 B) that can be electrically connected with two single-element detector 28 output terminals.This circuit can comprise digital signal processing circuit, and the latter can be connected to the computing machine of display, thereby the user can easily use the position of eyes monitoring objective 14.
Described sensor is at Y, Y ', and the motion on Z or angle (around the Y-axis) direction is insensitive.In order to reduce the susceptibility of sensor to the vertical movement of target (leave or towards laser diode and photo-detector), must be basically and formed axis quadrature between the central point of unit A and unit B by incident beam 12 and folded light beam 18 formed planes, and basically be with 32 parallel.Like this, for example, if target 14 is from primary importance, for example be shown in the position among Fig. 2, vertically (leave or towards laser diode and photo-detector) moves on to the second place on the direction of arrow Z, and so, point image 30 will move on the direction of arrow Y ' on the surface of photo-detector 28, promptly move, and can not influence the electrical output signal of photo-detector perpendicular to direction X.
As shown in Figure 2, target signature part 16 can have the longitudinal axis, it is with parallel with folded light beam 18 formed planes (shown in dotted line) by incident beam 12, and be parallel to photo-detector 28 with 32 with perpendicular to the formed axle of the central point of each unit of crossing two single-element detectors, thereby sensor will be insensitive to little being displaced sideways (in Y or Y ' direction).
Described configuration causes target easily Z (making progress), Y or Y ' (by the side in incident beam and the formed plane of folded light beam) and mobile insensitive on (around at the formed axle of Y direction) direction radially.With a measurement target moving at directions X (perpendicular to by incident beam and the formed plane of folded light beam).
Fig. 3 represents when target 14 is moved poor (A-B) of the amplitude of signal A and B and the curve map of time relationship on arrow directions X (being shown in Fig. 2).In this example, suppose that the position of sd so when target 14 is zero in the time makes point image 30 be focused on to leave the position (arriving before the A surface, unit) on the surface 31 of two unit light detectors 28.Because target 14 is moved on directions X, point image 30 at first arrives the surface 31 of unit A, continues then to stride across and is with 32 to unit B.
When the point image (size that it is limited, and bigger than the gap between A and the B significantly) when 30 forward position arrives the edge of unit A (after the time 1), signal (A-B) begins to be in unit A fully when (in the time 2) from zero increase when resembling, and signal (A-B) arrives maximal value.When the forward position of point image arrives gap between A and the B (in the time 3), signal (A-B) begins to reduce, when resembling the center that is in the gap between A and the B and apart from unit A and B when equidistant, signal (A-B) is by zero bundle.When point image continue to arrive unit B, signal (A-B) continues to reduce, and is in unit B fully and arrives its minimum value when (in the time 4) when resembling.When point image moves apart unit B (in the time 5), signal (A-B) increases and gets back to zero point.Resembling when not only being in A but also being in B, (A-B) for the slope of a curve maximum of the position of elephant, and the value of this slope reduces along with the size of point image and increases, and but, the size of point image still is greater than the width in gap between unit A and the B.
Like this, just can see,, just can monitor the position of point image 30 on the surface 31 of two unit light detectors 28, also just can monitor the relative position of the target 14 of linear dependence with it by observation signal A-B.Similarly, just can the displacement of measurement target 14 between the primary importance and the second place.
The dynamic range of sensor (the target location scope that can accurately measure) drops on the linear zone of signal A-B curve, and this dynamic range is illustrated between the dotted line that is marked with DR of curve of Fig. 3 (greatly between time 2.5 and 3.5).In addition, there is the minimum capture scope in system, it be signal A-B minimum can accurately survey level.This capture range is represented with scope between the dotted line that is marked with CR.Signal A-B slope of a curve is corresponding to the responsiveness (or sensitivity) of two single-element detectors in linear dynamic range (at milliampere/microampere order of magnitude).When slope in this scope increased, the accessible resolution of sensor (detectable target least displacement) increased, but the dynamic range of sensor reduces.Therefore, will point out below, and, must between dynamic range and displacement resolution, average out for described sensor.
The amplitude of signal A+B (when point image 30 is focused on the surface 31 of two unit light detectors 28) can roughly be kept constant, thereby just just can finish the monitoring of contrast ratio A-B/A+B more simply by pilot signal A-B.Can be by control the intensity of input laser beam with automatic gain control (AGC) circuit (describing its embodiment below with reference to Fig. 6 A) that is electrically coupled to laser diode 22, it is constant to realize making signal A+B to keep.As described in following, agc circuit is pilot signal A+B when control is to the laser diode power supply.Like this, in order more to simplify monitoring, can use agc circuit by the required treatment circuit of output electric signal that two unit light detectors 28 produce.
Light source 10 can be any such light source, and it provides intensity to be enough to the incident beam that is detected by photo-detector, to satisfy the sensitivity requirement of application-specific.Light source can be for example laser diode, light emitting diode (LED), LED, tungsten light source.Or optical fiber source.If the application optical fiber source will be used a pair of optical fiber so, or be divided into two optical fiber and come reflection lasering beam is directed to photo-detector.In one embodiment, the power of light source is preferably in 0.1 milliwatt in the scope of 20 milliwatts.Also have, the intensity of incoming laser beam is preferably and approximates 1 milliwatt/100 μ greatly.
Various types of focusing optical elements can be used for guiding (direct) incident and folded light beam or laser beam.For example, can use traditional lens, sphere or garden cylindrical mirror, graded index (GRIN) lens or molded non-spherical lens.
Photo-detector can be any photo-detector that can produce the optics of the electric signal that such characteristic is arranged, and its characteristic (for example amplitude or frequency) is proportional to the position of receiving beam on the surface of detector.Photo-detector can be for example such position transducer, and the amplitude of the electric signal that it produces is proportional to the position of the sensor of receiving beam.Photo-detector preferably includes the photo-detector of a special arrangement, and it can produce one or more signals, can produce ratio (for example (A-B)/(A+B)) from these signals.For example, photo-detector can be two single-element detectors, four single-element detectors, ccd array or other device.
The advantage of described sensor is, by monitoring ratio (A-B)/(A+B), sensor is a bit insensitive to the sensitivity of the reflectivity of the intensity of light source, target signature part and photo-detector.
In one embodiment, all there is the size of 0.6mm * 1.2mm each unit of two single-element detectors, and the gap between the unit (width with 32) approximate 10 μ m greatly.Resembling 30 width can be in the scope of 50 μ m-100 μ m.The normal sensibility of this photo-detector approximate greatly 0.4 the peace/watt.
In typical application, for example servo-drive system is used in (as will be described later), lens 26 can be placed between target signature part 16 and the photo-detector 28 with their equidistant positions on, 20mm apart respectively.Reflected light lens 26 have the focal length of 10mm usually.In one embodiment, the radius-of-curvature of the curved surface 17 of target signature part 16 is preferably in the scope of 0.5-5.0mm.
Fig. 4 is the synoptic diagram of another embodiment of expression, and wherein optical displacement sensor is used on the disc drive servo system.As shown, servo-drive system generally includes rotatable principal arm 40 (being in the outside of disk drive (not shown)) and W head arm 42 (being in the inside of disk drive).Principal arm 40 and head arm 42 boths rotate around common axle 44.The W head (not shown) is fixed to the upper surface of the end 54 of head arm 42 by sweep (flexure) (not shown).According to the present invention, the target signature part forms with head arm.Write and be in the top of head arm to it from the disk (not shown) of its sense data.
As (as is conventional in the generalized case of disc drive servo system ...), on the reference position of the radial track aligned in position that principal arm at first is transferred to and will writes or read.Then, by using optical displacement sensor of the present invention system, head arm is transferred to principal arm and aligns, thereby makes W head read or to write to it from the desirable radial track position of disk.Head arm and principal arm also can rotate in proper order with other, for example comprise in other mode till accurate aligning.
At first use the optical interference system to aim at principal arm.Interference system comprises lasing light emitter 46, (fold) mirror 48 of turning back, laser interference device 50, be fixed on the back reflection mirror 52 and the interferometer output signal detector 61 (being shown in Fig. 5) of the downside of principal arm 40.Principal arm VCM driving circuit 63 is coupling between interferometer output signal detector 61 and the voice coil motor (VCM) 65, the rotational motion of its control principal arm 40.
As it will be appreciated that, used the laser interference device first laser beam and reference laser beam decide the position (or displacement) of moving target, wherein first laser beam is the bundle that reflects from moving target (being back reflection mirror 52), and reference laser beam is then passed through the stroke of regular length.Lasing light emitter 46 produces laser beam, and the latter passes laser interference device 50 and arrives back reflection mirror 52 from mirror 48 reflections of turning back.This light beam is reversed catoptron 52 reflections, and interferometer 50 makes it and combines with reference to bundle.Interferometer 50 to detector 61 provide in conjunction with after light beam, detector 61 responds to this, determines the displacement (or position change) of principal arm 40.Then, detector 61 is sent the signal of expression change in location to driving circuit 63, and and then, driving circuit 63 provides signal to rotate principal arm 40 to VCM65, till it and selected radial track position alignment.
In case principal arm 40 is suitably aimed at, just utilize described displacement transducer to make head arm 42 aim at principal arm 40 then.Sensor comprises source module 56 (preferably including laser diode), reverberator 58 and detector module 60 (preferably including two unit light detectors), and all these is fixed on the upper surface of principal arm 40.Similar to the general embodiment of the described displacement transducer of reference Fig. 1 and 2, at run duration, laser diodes in the source module 56 produce incoming laser beam, and its device 58 that is reflected reflexes to that downside with the end 54 of head arm 42 forms or is attached to target signature part (not shown) under it.As mentioned above, this target signature partly has a curved surface, and incoming laser beam is formed resembling of light source by this camber reflection near the target signature part.Then, the laser beam that is reflected is reflexed to detector module 60 from reverberator 58.This resembles the photo-detector that is focused in the module 60.
Come calibration system like this, make when head arm 42 is suitably aimed at principal arm 40, little, 30 (see figure 2)s that resemble of point-like or wire are focused on the surface of the unit A of the interior two unit light detectors of module 60 and the dividing strip 32 between the B.Displacement transducer control and treatment circuit 67 (being shown in Fig. 5) is electrically connected to source module 56 and detector module 60 (Fig. 4), as will being described in greater detail below, circuit 67 comprises and is used to determine and the circuit of pilot signal A+B and A-B that this two signal has been represented the relative position of head arm and principal arm.Head arm VCM driving circuit 69 is coupling between displacement transducer control and treatment circuit 67 and the head arm VCM 71.Displacement transducer control and treatment circuit 67 provides a kind of digital output signal that reflects head arm and principal arm relative position to head arm VCM driving circuit 69, head arm VCM driving circuit 69 responds to this, send control signal to VCM71 and come rotational head arm 42, aim at principal arm 40 up to it.As will be below with reference to figure 6A described in detail in ten minutes, sensor also comprises agc circuit, it is coupling in, and to be used to keep signal A+B between photo-detector and the laser diode constant.
Fig. 6 A represents sensors A GC circuit with the form of block scheme.For convenience, this circuit table is shown as comprises two single-element detectors 62 (being included in the detector module 60) and laser diode 72 (being included in the source module 56).This circuit comprises traditional analog signal amplifier 64 and 66, and they are to connect like this,, receive output signal A and B from two single-element detectors 62 respectively that is. Analog signal amplifier 64 and 66 is amplified analog signal A and B respectively.Simulating signal A that is exaggerated and B are used as output and offer agc circuit 73.Agc circuit 73 comprises analog addition circuit 68 and laser power control circuit 70.Adding circuit 68 produces and signal A+B.Signal A+B is sent to laser power control circuit 70, the size of latter's monitoring and signal A+B, and the power that provides output signal to control laser diode 72 subsequently, and signal A+B is held substantial constant.The intensity that should be pointed out that the incoming laser beam that is produced by laser diode can change, for example when the reflectivity change of target, so that holding signal A+B is constant.
Fig. 6 B represents the head arm control and treatment circuit 69 of control head arm VCM 71 with the form of block scheme.As shown, signal A and B are comprised amplifier, are used to produce the addition of signal A-B and A+B and the square frame 74 of subtraction circuit receives.Signal A-B is sent to analog to digital converter (ADC) 76, and it converts simulating signal A-B to digital signal.This digital signal is sent to traditional impact damper 78, and the latter provides the numeral output of representation signal A-B.
Signal A+B is sent to comparer 80, and it compares signal A+B and reference signal (minimum threshold level (promptly zero)), and a state carry-out bit is provided, to represent that whether signal A+B is greater than the minimum threshold level.Circuit 69 control VCM71 come rotational head arm 42, A-B equals zero up to signal, and decision, the point of this zero passage (point of signal A-B) is corresponding to such point, and this moment, point image was focused being with (representing that head arm 42 aligns with principal arm 40) between each unit of two single-element detectors.Should be understood that (discussing with reference to figure 3 as top), when point image is not in any unit surperficial of two single-element detectors (expression head arm 42 does not seriously line up with principal arm 40), signal A-B also has null value.The circuit decision is by reaching suitable zero passage with comparer 80 pilot signal A+B.With reference to figure 3, should be pointed out that when signal A-B equal zero and signal A+B much larger than zero the time, just reach the suitable zero crossing of signal A-B.When comparer 80 decision signal A+B greater than zero the time, just export a mode bit.Like this, the digital output signal that provides by impact damper 78 and represent together by the mode bit that comparer 80 provides when head arm 42 suitably aligns with principal arm 40.
Fig. 7 illustrates in greater detail the end 54 of head arm 42.The basal surface that head arm 42 is shown makes eye bright and marks characteristic 86.Slide block (slider) sweep (flexure) 84 is fixed on the upper surface of head arm 42 with the method for welding.Represented solder joint 82 among the figure.Slide block (slider) and W head (not shown) are connected to the end of sweep (flexure) 84.The structure of such sweep, slide block and W head is traditional structure.
In one embodiment of the invention, target signature part 86 forms with the end 54 of head arm 42.As described in greater detail below, can advance the end 54 of head arm 42 to target signature part " drawing " with scoring tool, generation preferably has the target signature part of the curved surface longitudinal axis of the longitudinal axis that is parallel to head arm.The target signature part for example can be the indenture 88 of the garden cylindricality on head arm 42.The indenture 88 of garden cylindricality has the curved surface of the target signature part 86 of reflection incoming laser beam.In this embodiment, the radius-of-curvature of curved surface is preferably in the scope of 0.5-5.0mm.
Fig. 8 is the side view of the end 54 of head arm 42, and its expression slide block (slider) 92 is fixed on sweep (flexure) 84.As shown, slide block 92 be in target signature part 86 below, approximately along identical vertical some place of head arm 42.Also represented shoulder 90, it makes the remainder of target signature part 86 a little higher than head arms 42.
Fig. 9 is the component function of the part of system (similar and Fig. 1 and 2), the block scheme of modular construction, and it illustrates the formation of light source first and second elephants.In Fig. 9, only show the part of system.Shown part comprises target signature part 16, imaging lens 26 and detector 20.
Two positions of target signature part 16 have been shown: the primary importance (position of representing the target signature part with solid line) and the second place (being represented by dotted lines the position of target signature part) among Fig. 9.The second place is represented the target signature part of primary importance after side direction X moves from it, and its displacement is exactly the object that system of the present invention will measure.
As shown, incident beam 12 becomes folded light beam 18 from curved surface 17 reflection of target signature part 16.Form the little of light source near target signature part 16, point-like first resembles 100A.When target signature part 16 from its primary importance (A represents with the position) to its second place when (B represents with the position), first punctiform images also moves on to its second place (representing with 100B) from its primary importance (representing with 100A) with target signature part 16.
In each position, the part of folded light beam 18 is received by imaging lens 26, and focuses on the surface of photo-detector 20.For position A, on the surface of photo-detector 20, form second and resemble 100A '.For position B, on the surface of photo-detector 20, form second and resemble 100B '.Such as can be seen, target signature part 16 moves on to position B from position A on side direction X, and second punctiform images moves on to position 100B ' (it resembles 30 moving on X ' direction corresponding to the surface 31 of the photo-detector 20 of Fig. 2) from position 100A '.Should be pointed out that second resembles 100A ' (and 100B ') and resemble 30 corresponding to second of Fig. 2.
In the embodiment of servo-drive system, (be shown in Fig. 4), have only around rotatablely move (it is corresponding to the motion on the directions X of target 14 at Fig. 2) of the head arm of axle 44 measured.System can not detect target signature part with respect to the radial motion (corresponding to the rotation of Fig. 2 target 14) of head arm around axle Y, head arm vertically leaves or near any the motion in the motion on formed two directions of the longitudinal axis of head arm (corresponding to the motion of Fig. 2 on the Y direction) of the motion of principal arm (corresponding to Fig. 2 in the motion on the axle Z direction) or target signature part.
Can utilize process of the present invention that target signature part and target (use if promptly be used in disc drive servo system, be fixed on the E piece on the head arm exactly) are integrally formed.This process comprises with the instrument that the line part is arranged partly draws the into surface of target to target signature.
Figure 10 illustrates an embodiment of scoring tool, and it can be used for drawing the target signature part according to the present invention.As shown, scoring tool 200 comprises shank portion 202 and line part 204.Shank portion 202 and can have the cross section of Any shape normally longitudinally, comprises rectangle (as shown), square, octagon, garden shape or other shapes.With suitable way line part 204 is fixed on the end of shank portion 202, for example mechanical fixation, bonding is fixing or additive method.Line part 204 can be firmly held in the end of shank portion 202, makes that (tight) tolerance is close in the interface existence between line part 204 and shank portion 202.
The least significant end that is preferably in line part 204 has line surface 206.Line surface 206 is garden shapes in one embodiment, so that the target signature of half garden cylindricality is partly drawn the into surface of target.In an illustrated embodiment, line part 204 has preferably flat face 212.From face 212 extend back and probably above surface 206 (leaving end) be the surface 208 of line part 204.
Figure 11 illustrates the modular construction and the component function figure of the technological process that can mark the target signature part.What be shown in Figure 11 is scoring tool 200 and target 220.Target 220 comprises the surface 222 that will mark the target signature part thereon.Instrument 200 represents that with side view it comprises handle 202 and line part 204.Plane 212 is facing to such direction, and promptly this direction is exactly to draw the longitudinal axis of wanting paddle-tumble on target signature part institute edge, and is as will be described in greater detail below such.Because be side view, Figure 11 does not illustrate the garden shape on line surface 206.
In this technological process, make the surface 206 of scoring tool 200 contact with the surface 222 of target 200.This can move and/or target 220 is moved to the surface 206 of instrument 200 with direction Y2 to surface 222 with direction Y1 by making instrument 200, and the longitudinal axis that preferably keeps handle 202 simultaneously is perpendicular to surface 222.When line surface 206 is moved to when contact with the surface 222 of target 200, line surperficial 206 will be in position S.Then, an increment △ is further moved on line surface 206 on direction Y1.This can realize by instrument 200 being moved with direction Y1 and/or target 220 being moved with direction Y2.In this, the surface 222 of target 220 will be injected in surface 206, and will be in the position of surface 222 following S-△.In most preferred embodiment of the present invention, △ is in the scope of 0.02-0.05mm.
The first motion that line surface 206 is moved and contacted with it to the surface 222 of target 220 occurs in starting point d, the desirable starting point of target signature part (one of end points) that this point will be rule exactly.Then, mark the target signature part by instrument 200 being moved with direction X1 and/or making target 220 reach a D+d with direction X2 displacement D, this D+d is exactly the desirable end points of target signature part that will draw.In this step, keep with the Y1 direction being added on the instrument 200 and/or being added to pressure on the target 220, thereby surface 206 is maintained on the level of S+ △, and institute is marked the target signature part groove that comes and will be had from the degree of depth of surperficial 222 following △ with the Y2 direction.Preferably, the longitudinal axis that keeps handle 202 is perpendicular to surface 222, with the symmetry of the groove that guarantees to be marked.The groove that is marked will be half garden cylindricality, and the radius on the line surface 206 that approximates the garden greatly will be arranged.Described radius is preferably in the scope of 0.2-5.0mm.
When the surface 206 reaches end points D+d, then instrument 200 on the Y2 direction and/or target 220 on the Y1 direction, move, disengage up to surface 206 and surface 222, like this, just finished the operation that marks flute profile target signature part.
When moving target 200, can keep instrument 200 static.Another kind of way is to keep target 220 static.Can provide confining force with bench vice.This process can be finished by hand also can be by machine, and for example milling machine is finished, and on milling machine, target is by the clamping of milling machine platform, and instrument vertically is installed on the milling machine.
The half garden cylindrical groove 224 that Figure 12 explanation is marked on the surface 222 of target 200 by the line surface 206 of line part 204.
Figure 13 represents another best scoring tool 300, and it comprises handle 302 and line part 304.
The line part 304 of scoring tool 300 is illustrated in Figure 14 in more detail, and it comprises the trailing edge 308 of line surface 306, plane 312 and taper.The interface of line part 304 and handle 302 is in 310.Can be from joslyn hi-voltage (Cleveland, E.C.Kitzel ﹠amp Ohio); Sons, a kind of like this instrument has been bought with the ProductName of the natural golden guiding principle lapicide tool of 1135-020 by company.
Through the description to a minimum illustrative embodiment of the present invention, the professional and technical personnel just can propose various changes, modification and improvement.For example, come the position of monitoring objective on one dimension (or direction), should point out, the invention is not restricted to this though sensor of the present invention is described as with two single-element detectors.By using four single-element detectors, sensor can be distinguished the position of monitoring objective on two dimension.To be grouped into a kind of like this change, modification and improvement in the spirit and scope of the present invention.Correspondingly, top description just is not intended as restriction as an example.The present invention only is subjected to the restriction of defined and equivalent with it content of following claims.
Claims (9)
1. device that is used to measure movable displacement of targets is characterized in that comprising:
Static light source, it produces incident beam;
Be fixed on the target signature part on the target, it is reflected into irradiating light beam, and nearby forms first of light source in target signature part and resemble;
Imaging lens, its receives first and resembles, and resembles first on photo-detector and form second of light source again and resemble; With
With the photo-detector that target separates, it receives second and resembles, and this is responded, and produces such electric signal, and its characteristic is proportional to the position of second elephant of photo-detector reception, and this characteristic has been represented the position of target;
Wherein the target signature part forms by paddle-tumble on target.
2. the device of claim 1, it is characterized in that: described target signature part groove is half garden cylindricality.
3. the device of claim 1, it is characterized in that: described target signature partly has the radius-of-curvature in the 0.2-5.0mm scope.
4. optic position sensor spare, it is used to detect W head arm on disk drive with respect to the position of principal arm position, it is characterized in that described device comprises:
Be fixed on the light source of principal arm, it produces incident beam;
Be fixed on the target signature part on the head arm, it is reflected into irradiating light beam, and nearby forms first of light source in target signature part and resemble;
Be in the imaging lens on the light path between target signature part and the photo-detector, it receives beam reflected, and first of light source resembled focuses on the photo-detector again and form second and resemble; With
Be fixed on the photo-detector on the principal arm, it receives second and resembles, and this is responded, and produces such electric signal, and its characteristic is proportional to the position of second elephant of photo-detector reception, and this characteristic has been represented the relative position of head arm;
Wherein the target signature part forms by paddle-tumble on head arm
5. the device of claim 4, it is characterized in that: described target signature part groove is half garden cylindricality.
6. the device of claim 4, it is characterized in that: described target signature partly has the radius-of-curvature in the 0.2-5.0mm scope.
A method that on target, forms the target signature part, utilize the displacement of targets that displacement transducer detects, the displacement transducer that comprises light source and photo-detector, wherein light source produces the incident beam from the target signature partial reflection, and photo-detector is characterized in that described method comprises following step from by the resembling of the light-receiving light source of target signature partial reflection:
Make the line surface of scoring tool contact with target surface; With
Keeping under the situation of scoring tool to target surface pressure target signature partly being drawn target surface.
8. the method for claim 7 is characterized in that: the step of described line comprises and keeps the static step of target.
9. the method for claim 7, it is characterized in that: the step of described line comprises the step that the maintenance instrument is static.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 98105485 CN1205428A (en) | 1997-06-10 | 1998-03-10 | Displacement sensor and method for producing target feature thereof |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US872,607 | 1997-06-10 | ||
| CN 98105485 CN1205428A (en) | 1997-06-10 | 1998-03-10 | Displacement sensor and method for producing target feature thereof |
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| CN1205428A true CN1205428A (en) | 1999-01-20 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 98105485 Pending CN1205428A (en) | 1997-06-10 | 1998-03-10 | Displacement sensor and method for producing target feature thereof |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102192709A (en) * | 2010-01-22 | 2011-09-21 | 佳能株式会社 | Displacement measuring apparatus and velocity measuring apparatus |
| CN103727880A (en) * | 2012-10-12 | 2014-04-16 | 横河电机株式会社 | Displacement sensor, spectral characteristic measuring apparatus and method, color measuring apparatus and method, planar measured object quality monitoring apparatus and displacement measuring method |
| CN105841609A (en) * | 2016-03-22 | 2016-08-10 | 哈尔滨工业大学 | Beam scanning detection-based combined cantilever beam probe sensing device and sensing method |
| CN105841608A (en) * | 2016-03-22 | 2016-08-10 | 哈尔滨工业大学 | Optical fiber emergent light collimation detection-based combined cantilever beam probe sensing device and sensing method thereof |
| CN108387250A (en) * | 2018-03-28 | 2018-08-10 | 中铁十局集团第二工程有限公司 | Two-dimentional micrometer device and system |
-
1998
- 1998-03-10 CN CN 98105485 patent/CN1205428A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102192709A (en) * | 2010-01-22 | 2011-09-21 | 佳能株式会社 | Displacement measuring apparatus and velocity measuring apparatus |
| US8760635B2 (en) | 2010-01-22 | 2014-06-24 | Canon Kabushiki Kaisha | Displacement measuring apparatus and velocity measuring apparatus which measure displacement amount of moving object |
| CN103727880A (en) * | 2012-10-12 | 2014-04-16 | 横河电机株式会社 | Displacement sensor, spectral characteristic measuring apparatus and method, color measuring apparatus and method, planar measured object quality monitoring apparatus and displacement measuring method |
| CN105841609A (en) * | 2016-03-22 | 2016-08-10 | 哈尔滨工业大学 | Beam scanning detection-based combined cantilever beam probe sensing device and sensing method |
| CN105841608A (en) * | 2016-03-22 | 2016-08-10 | 哈尔滨工业大学 | Optical fiber emergent light collimation detection-based combined cantilever beam probe sensing device and sensing method thereof |
| CN105841609B (en) * | 2016-03-22 | 2018-04-24 | 哈尔滨工业大学 | A kind of combination socle beam probe sensing device and method for sensing based on light beam scanning probe |
| CN108387250A (en) * | 2018-03-28 | 2018-08-10 | 中铁十局集团第二工程有限公司 | Two-dimentional micrometer device and system |
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