JPH05217190A - Optical disk drive - Google Patents

Abstract

PURPOSE: To improve detection of the relative position of another component to a certain component in a device such as an optical disk drive. CONSTITUTION: A light beam emitted from a laser 20 is reflected by a turning prism 30 in the direction passing through an objective lens 31 for a mutual action focused with an optical disk 10. A detector 32 having one or above of LED generates a separate light beam reflected by one surface of the turning prism 30. After reflection, the beam emitted by the LED is light received by a pair of separated photodetectors. The intensity of the beam light received by the photodetector is changed according to the rotational position of the turning prism 30. A relative position error signal is generated from information supplied by the photodetector to be inputted to a coarse adjustment actuator for operating a fine adjustment tracking actuator and adjusting its operation.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to the relative positioning of a first component movably mounted on a second component. More specifically, the present invention relates to adjusting the operation of coarse and fine actuators, such as the coarse and fine actuators used in optical disk drives.

[0002]

Optical disc drives, including compact audio disc players and computer data storage devices, employ a collimated beam of light for writing and / or reading from a disc rotatably mounted therein. ing. Typically, this beam is produced by a laser and passes through a series of optical components before being focused on the disc. The beam is used to change one or more local properties there to write data to the disc. The beam is transmitted through the disc to read the data from the disc,
Alternatively, the characteristics of this passing or reflected beam, which is reflected from the disk, depends on the local characteristics of the area of the disk that interacts with the beam.

Data is typically placed on an optical disc in one of two configurations. The first configuration is a series of concentric circular tracks. A specific area of the disk (hence the
Random access to (specific data) refers to a radial seek that the light beam traverses the track until the desired track is located, followed by this desired track until it reaches a specific area of the disc. Is achieved by following and. The second configuration is a single spiral track. Random access to the spiral track is achieved in the same manner as for circular tracks. To locate a desired revolution of the spiral in the radial direction, the light beam seeks across the boundaries of the rotation of the adjacent spiral tracks, and follows this revolution until it reaches a specific area of the disc. .. In the following, the phrase "track" on the optical disc is
It also includes one revolution of a single spiral track.

The tracks on the optical disk are randomly accessed and tracked by a servo system that includes coarse and fine tracking actuators. An example of a coarse tracking actuator is a voice coil motor configured to controllably move certain optical components radially (across the track) with respect to the disc. The operation of the coarse actuator allows access to any track on the disc. A fine tracking actuator is a motor that is operably coupled to controllably move some of the optical components that are also moved by the coarse tracking actuator. For example, a light beam emitted by a laser passes through an objective lens by a mirror or prism,
Redirected to interaction with the focused optical disc. The coarse tracking actuator drives both the mirror / prism and the objective lens in the disk radial direction.
The fine adjustment actuator does not drive the mirror / prism, but simply drives the objective lens in the disk radial direction. Actuation of the fine adjustment actuator allows access to a particular track within a range of tracks. In other arrangements, the fine actuator instead pivots the mirror / prism controllably. The alignment of the light beam with respect to the track is detected optically after the beam has passed through or reflected from the disc, as described in US Pat. No. 4,745,588.

In a simple tracking servo system,
A fine tracking actuator compensates the track position deviation of the light beam. The misalignment occurs due to radial disc runout, for example. If the track position deviation of the coarse adjustment tracking actuator is quite large,
The light beam deviates far from its ideal path so that certain problems occur. As an example, the optical path of the light beam does not match within some tolerance with respect to the optical axis of the objective lens used to focus the beam on the disc. Objective lens size and performance specifications in optical disk drives are tailored to properly focus a properly positioned beam. If the offset or angle of the light beam with respect to the objective lens or other optical components becomes too large, drive performance will suffer. Therefore, the tracking servo system is most effective when the operation of the coarse and fine tracking actuators is adjusted to limit the magnitude of this offset / angle.

[0006]

By precisely following the fine tracking actuator to the coarse tracking actuator, the light beam is maintained in an almost ideal optical path through the optical components. Such adjustment requires accurate and stable sensing of the relative position of the optical components driven by the fine tracking actuator relative to the position of the components driven by the coarse tracking actuator. Requires precise adjustment of the relative position of. One technique for relative position detection is disclosed in US Pat. No. RE29,963. The sensing system measures the average current through the fine actuator motor coil. The average current is related to the displacement of the optical components and is also used to control the coarse tracking actuator. This approach is inexpensive but also inefficient and therefore cannot provide the bandwidth required for high performance optical disk drives.

Another known technique for detecting the relative position described above is to physically monitor the movement of the fine tracking actuator servomotor. However, the cost and complexity associated with the additional electronics required are not practical. Yet another sensible yet another technique for the relative position sensing described above is disclosed in US Pat. No. 4,864,552. The reflected light beam from the disk passes through the objective lens driven by the fine tracking actuator in reverse, passes through the beam splitter, and is received by the split detector. The difference between the signals produced by each half of the split detector indicates the relative alignment of the objective lens with respect to the optical components driven by the coarse tracking actuator. This information is used to generate a drive signal, which is then provided to the coarse tracking actuator to coordinate the operation of the coarse and fine tracking actuators.

Two issues are associated with determining the relative position of optical components by sensing the light beam after it has been reflected from the disc. First,
An optical disc or similar scale calibration device must be present in the optical disc drive to align the optical components driven by the fine tracking actuator with those driven by the coarse tracking actuator. Second, the intensity of the light beam used for relative position sensing is attenuated during its propagation to and from the disc, and the intensity of the beam used for reading and tracking is reduced by the beam splitter. Attenuated by further,
This approach requires the use of an additional optical component, namely a lens that focuses the reflected light beam onto the split detector.

It is also known to determine the relative position of optical components by using secondary light beams. This secondary light beam is not used to read or write data. Instead, the secondary light beam is reflected from the pivoting mirror towards the split detector. The split detector is positioned so that the difference between the signal intensities detected by its optical elements indicates the rotational position of the mirror. The mirror position is set to properly direct the read / write light beam to the optical disc. Such an approach is described in US Pat. No. 4,564,75.
No. 7 and US Pat. No. 4,466,088. However, the S / N ratio is not the best because a single split detector is used to detect the secondary light beam. The use of one split detector also requires the presence of one or more collimating lenses.

US Pat. No. 4,425,043 describes S /
A similar approach is disclosed for relative position sensing to improve the N-ratio. The light beam is reflected from a beam splitter mounted on the objective lens mechanism. The beam splitter is a two-sided roof-shaped mirror used to split a light beam into two separate beams.
Two split detectors detect this separate beam, and one split detector is for each of the two separate beams. By comparing the signals detected by the split detectors, the position of the objective lens mechanism is determined. However, this approach is complicated due to the multi-faceted deformation of the objective mechanism. Nevertheless, in a manner similar to the two-sided roof mirror of this approach, the use of two sides of the pivoting prism is not practical in the enclosed space environment of an optical disk drive. The use of split detectors requires the presence of one or more lenses that again collimate.

From the above points, the main object of the present invention is to
It is to improve the relative position detection of one movably mounted component with respect to another.

Another object of the present invention is to improve an optical storage device.

Yet another object of the present invention is to improve the coordination of operation of coarse and fine tracking actuators in optical disk drives.

[0014]

In the optical disk drive according to the present invention, the detection of the position of the rotating prism driven by the fine tracking actuator is 1
The above separated light beams are used. Assuming the disc is loaded in an optical disc drive, the light beam emitted from the laser is reflected by the pivoting prism in the direction through the objective lens due to the focused interaction with the optical disc. One or more LEDs are used to generate a separate light beam that is reflected from one side of the rotating prism. After reflection, the beam emitted by the LED is received by a pair of separate photodetectors. The beam intensity received by the photodetector changes according to the rotational position of the rotating prism. The relative position error signal is generated from the information provided by the photodetector and is input to the coarse tracking actuator, whose operation is coordinated with that of the fine tracking actuator.

Several alternative embodiments of the invention will now be described. In the first embodiment, a single LED is located between a pair of photodetectors. In the second example, the photodetector is mounted on a single face of the pivoting prism. In the third and fourth embodiments, two LEDs are used in combination with a pair of photodetectors. The pair of photodetectors are attached to one surface of the rotating prism in the third experimental example, and are arranged apart from the surface in the fourth experimental example. In the fifth embodiment, a single LED
And shadow stripes are used with split detectors to achieve proper results. In the sixth embodiment, two LEDs and a pair of photodetectors are used, but the configuration is different from that in the third embodiment.

[0016]

DETAILED DESCRIPTION OF THE INVENTION As will be described in more detail with reference to the drawings, like reference numbers indicate like features and components in the various figures. The present invention is described as embodied in an optical disc drive. In the preferred embodiment, the optical disk drive is a rewritable magneto-optical disk drive. The figures depict such drives only to the extent necessary to explain the invention. Other features of optical disk drives, including additional optical and electronic components and their operation, are irrelevant to such descriptions or are well known. Further description of some of these mechanisms may be found in US patent application Ser. No. 07 / 589,7
10 are mentioned. Other applicable optical disc drive aspects are read-only (ROM) or write-once (WO), and known recording techniques such as fused or phase change recording may be used.

Referring to FIG. 1, a portion of an optical disc 10 mounted in an optical disc drive is shown. Hub 1 for easily loading a disk 10 onto a spindle 12 that is rotatably driven by a spindle motor 13.
Has 1. Laser (including associated optical components)
20 is coherent and emits a collimated light beam. The optical path is generally indicated by the reference numeral 21 as it travels toward the disc 10 (upward or to the right as shown). When emitted by the laser 20, the beam 21
Passes through the beam splitter 22. Then, the beam 21 is reflected by the rotating prism 30, passes through the objective lens 31, and is focused on the disc 10. Detector 32
Will be described later. The detector 32 has a 2
The intensities of the individual light beams are detected. The relative intensity of these light beams is determined by the rotation prism 30 about the axis 37.
Depends on the rotational position of. The differential amplifier is a rotating prism 30.
Used to determine the rotational position of the. To eliminate the variations caused by the LED power levels, the output of the differential amplifier is normalized by the total signal level of detector 32. The result is output to a set of relative position error (RPE) circuits 70. Based on this result, the RPE circuit 70 sends a signal for adjusting the position of the carriage 36 to the coarse adjustment tracking actuator 33. The coarse tracking actuator 33 includes a carriage 36 (a rotating prism 30, an objective lens 31, and a fine tracking actuator 3) in the radial direction of the disk 10.
4) (including a linear voice coil motor).

The optical path of the light beam after reflection from the disk 10 is distinguished by the dashed line indicated by reference numeral 24 (going down or to the left, as shown). Beam 24 reflects off pivot prism 30 and is directed back towards beam splitter 22 and another beam splitter 23. Beam splitters 22 and 23 are optically adjusted to reflect a portion of beam 24 towards two detectors 26 and 27.

The detector 26 is a data read detector and actually has several components (not shown for convenience). For example, a beam splitter, a pair of polarizers and a photodetector, and a differential amplifier can be used. The beam splitter splits the beam into two equal intensity beams. The first beam output by the beam splitter is directed to the first polarizer and the photodetector, and the second beam emitted by the beam splitter is directed to the second polarizer and the photodetector. The first polarizer is the first 2
It is set to pass only light that is rotated when the optical path reflects from a spot on the disc 10 having a progressive orientation. The light passing through the first polarizer is received by the first photodetector. The second polarizer is set to pass only light that is rotated when the optical path reflects from a spot on the disk 10 having a second binary orientation. The light passing through the second polarizer is received by the second photodetector. The signals generated by the photodetectors are output to the differential amplifiers, respectively. Then, this amplifier gives an output difference signal representing the data recorded on the disk 10 to the set of data circuits 50. The data circuit 50 has circuits for format control, error detection, correction and the like. The output of the data circuit 50 is transmitted directly to the host processor via a suitable bus.

The detector 27 actually includes a four-division detector having four light-receiving elements and a divided far-field detector having two light-receiving elements. The focus of the beam 21 on the disk 10 is maintained by comparing the relative intensities detected by the four light receiving elements of the quadrant detector. Such comparison is performed by a set of focus error signal circuits coupled to the focus actuator to form the focus servo. For convenience, the focus detector, circuit and focus actuator are
Not shown in FIG. The tracking of the beam 21 on the disk 10 is performed by a set of tracking error signals (TE
S) maintained by comparing and amplifying the difference between the relative intensities detected by the two light receiving elements of the split far field detector in circuit 60. The intensities detected by the four light receiving elements are output to the TES circuit 60 for comparison. A differential amplifier is then used to determine the position of beam 21 with respect to the track on disk 10. T
The ES circuit 60 is coupled to the fine tracking actuator 14 which uses the amplified difference to align the beam 21 with the track centerline. The tracks on disk 10 may be formed by lands, grooves or other known methods. The components described above operate under the control of one or more microprocessors 80. The microprocessor 80 detects the rotational position of the spindle 12, controls the spindle motor 13 to rotate the spindle 12 at a desired speed, and controls access to the data segment on the disk 10.
It is connected to the spindle 12 and the spindle motor 13. The microprocessor 80 is coupled to the data circuit 50 to control the data read operation, and receives a command therefrom to write data to the disk 10 or read data from the disk 10. Combined with. The microprocessor 80
Coupled with the TES circuit 60 and the RPE circuit 70, the servo operation is monitored and controlled.

The optical paths in FIG. 1 are merely exemplary. At least one beam from a light source other than the laser 20 is transmitted to the carriage 3.
It will be appreciated by those skilled in the art that the optical path, if used to detect the relative position of the prism 6 and the prism 30 on the coarse actuator 33, may be physically configured differently than that shown. Also, in alternative implementations, different optical components than those shown may be used. For example, the rotating prism 30 may be a rotating mirror.

The fine adjustment tracking actuator 34 will be described with reference to FIG. The rotating prism 30 and the two magnets 38 are integrated and are rotatably attached to the shaft 37. One or more electric coils 39 are T
Energized by ES circuit 60 to interact with magnet 38. This interaction causes prism 30 to rotate about its axis. The direction of the reflected beam 21 from the rotating prism 30 can be adjusted together with the entire tracking servo. The direction of the reflected beam from the rotating prism 30 is controlled to seek and / or follow tracks on the disk 10.

The relationship between the rotating prism 30 and the objective lens 31 will be described with reference to FIG. The fine tracking actuator 34 is not shown. The objective lens 31 is supported in a lens support tube 40 that is slidably (or flexibly) attached to a cylinder 41. The beam 21 is reflected by the rotating prism 30, passes through the center of the cylinder 41, and then the objective lens 3
Directed through 1. By controlling the focus actuator motor coil 42, the lens support tube 40, and thus the objective lens 31, is moved to the disk 1.
It is moved linearly toward or away from 0. The beam 21 is maintained in focus on the active layer of the disk 10 with the overall focus servo.

The interaction between the TES circuit 60 and the RPE circuit 70 will be described with reference to FIG. It should be noted that FIG. 4 is a schematic and is not intended to show a functional circuit that is not related to the present invention. The position of the beam 21 with respect to the track depends on the position of the rotating prism 30 and the carriage 36, which is detected by the detector 27 which outputs a signal to the TES circuit 60. The TES circuit 60 has a compensator 61 and an amplifier 62. The position of the rotating prism 30 with respect to the carriage 36 is detected by the detector 32. The detector 32 subtracts the signal from the other photodetector from the signal from one photodetector, and outputs the signal to the RPE circuit 70. The RPE circuit 70 includes a compensator 71 and an amplifier 72.
Have. Compensators 61 and 71 provide phase margin within their respective servo loops. Amplifiers 62 and 72
Drives actuators 34 and 33, respectively. Therefore, the position of beam 21 with respect to the desired track is used to adjust the input to fine tracking actuator 34. The position of the rotating prism 30 with respect to the carriage 36 is used to adjust the input to the coarse tracking actuator 33. In this way, the operation of the coarse and fine tracking actuators is adjusted to maintain the beam offset / angle with respect to the desired track within an acceptable range.

Now referring to FIGS. 5-10, the detector 32
Various embodiments will be described. The detector 32 is actually one or more light emitting diode (LED) light sources and a photodetector (PD), as shown. Each example is represented by a different configuration of LED and PD of detector 32. For convenience, the mounting of LEDs and PDs on the circuit board or to other devices, the circuits contained in such devices, and the connections to the RPE circuit 70 are not shown. Such a configuration is well known. For the sake of convenience, reference numeral 32
Are not used in FIGS. 5-10, but represent LEDs and PDs. In this example, reference numeral 43 is used to represent all LEDs and reference numeral 44 is used to represent all PDs, regardless of their respective numbers.

For each embodiment, the perspective view is aligned with the axis about which the pivot prism 30 as represented by the dashed line rotates. Each embodiment includes two separate light beams used for relative position sensing. The path of such a light beam is represented by one or more arrows in at least one of the perspective views. 5-9 include two arrows, each of which is a light beam. FIG. 10 includes a single arrow in the presented perspective because only one single of the two light beams is actually visible.

The first embodiment will be described below with reference to FIG. In this embodiment, the detector 32 is a single L
It has an ED 43a and a pair of separate single elements (ie, not split detectors) PDs 44a and 44b. The LED 43a is located between the PDs 44a and 44b. The intensity of the light beam received by PDs 44a and 44b is a function of rotation about axis 37,
It depends on the angle of reflection to / from the rotating prism 30. The distance between the rotating prism 30 and the LED / PD, and the LED / P
The lateral movement of D does not affect the quantitative signal input to the RPE circuit 70. In this embodiment, since the PDs 44a and 44b are separated, the S / N ratio is improved more than that of the known split detector, and it is easy to realize. This embodiment is not suitable for a simple rotating mirror that relies on the space constraints of an optical disk drive, but it is compact. The use of a single LED reduces cost and also
It eliminates the susceptibility of the detector 32 to the effects of the varying deterioration of the plurality of light sources.

The second embodiment will be described below with reference to FIG. In this embodiment as well, the detector 32 has a single LE.
D43a and a pair of separate single elements PD44a and 44b. The LED 43a includes PDs 44a and 4
Positioned vertically (as shown) between 4b, but now PDs 44a and 44b are attached to pivot prism 30. The intensity of the light beam received by PDs 44a and 44b depends on the angle of such light reception, which is a function of rotation about axis 37. Rotating prism 3
The distance between 0 and the LED / PD and the lateral movement of the LED / PD do not affect the quantitative signal input to the RPE circuit 70. Similar to the previous embodiment, this embodiment uses S
It is easy to realize while improving the / N ratio. This embodiment is not suitable for a simple rotating mirror that relies on the space constraints of an optical disk drive, but it is compact. The additional weight and wiring of the PD on / to the pivoting prism 30 detracts from the superiority of this embodiment compared to that of FIG. The use of a single LED reduces cost,
In addition, the influence of the deterioration with variations of the plurality of light sources on the detector 3
Remove that 2 is susceptible.

The third embodiment will be described below with reference to FIG. In this embodiment, the detector 32 comprises a pair of L
ED 43a and 43b and a pair of separate single elements P
D44a and 44b. LEDs 43a and 4
3b is located vertically (as shown) between PDs 44a and 44b. The intensity of the light beam received by PDs 44a and 44b depends on the angle of reflection to / from pivoting prism 30, which is a function of rotation about axis 37. The distance between the rotating prism 30 and the LED / PD and the lateral movement of the LED / PD do not affect the quantitative signal input to the RPE circuit 70. Similar to the embodiment described above, this embodiment improves the S / N ratio and is easy to implement. This embodiment is not suitable for a simple rotating mirror that relies on the space constraints of an optical disk drive, but it is compact.

The fourth embodiment will be described below with reference to FIG. In this embodiment, similar to the previous embodiment,
The detector 32 has a pair of LEDs 43a and 43b and a pair of separate single elements PD44a and 44b. LEDs 43a and 43b are PDs 44a and 4
Positioned vertically (as shown) between 4b, but now PDs 44a and 44b are attached to pivot prism 30. The intensity of the light beam received by PDs 44a and 44b depends on the angle of such light reception, which is a function of rotation about axis 37. Rotating prism 3
The distance between 0 and the LED / PD and the lateral movement of the LED / PD do not affect the quantitative signal input to the RPE circuit 70. Again, this embodiment improves S / N ratio and is easy to implement. This embodiment is not suitable for a simple rotating mirror that relies on the space constraints of an optical disk drive, but it is compact. The additional weight and wiring of the PD on / to the pivoting prism 30 detracts from the superiority of this embodiment compared to that of FIG.

The fifth embodiment will be described below with reference to FIG. In this embodiment, the detector 32 is a single L
It has an ED 43a and a pair of PDs 44a and 44b.
Since the PDs 44a and 44b are located integrally, they can be realized as a single split detector. Rotating prism 30
The reflective surface of the has a dark, shadow stripe 46.
The shadow of stripe 46 is projected on both PDs 44a and 44b and centered on their boundaries. P
The intensity of the light beam received by D44a and 44b depends on the angle of reflection to / from the rotating prism 30, which is a function of rotation about the axis 37. Rotation of the prism 30 causes the stripes 46 to move vertically (as shown) so that their shadows are PD44a and 44b.
Move back and forth across. Rotating prism 30 and L
The distance between the ED / PD and the lateral movement of the LED / PD do not affect the quantitative signal input to the RPE circuit 70. As described above, the stripe 46 improves the signal-to-noise ratio even though the split detector is used, and thereby can be realized more easily than the above-described embodiment. This embodiment is compact, the use of a single LED reduces cost, and also the effects of variable degradation of multiple light sources on the detector 32.
Eliminates susceptibility to heat.

The sixth embodiment will be described below with reference to FIG. In this embodiment, similar to the embodiment shown in FIG. 7, the detector 32 has a pair of LEDs 43a and 43b and a pair of separate single elements PD44a and 44b. However, PD4 of LED43a
The relative position with respect to 4a and the relative position with respect to PD44b of LED43b are rotated 90 degrees with respect to the Example of FIG. The intensity of the light beam received by the PDs 44a and 44b no longer depends on the angle of reflection to / from the rotating prism 30, but instead is also a function of the rotation about the axis 37. 30 and LED
Depends on the distance between / PD. LED in a certain direction /
The angular alignment of the rotating prism 30 with respect to the PD does not affect the quantitative signal input to the RPE circuit 70. For best signal-to-noise ratio, LEDs 43a and 43b and PDs 44a and 44b are positioned vertically (as shown) to be as close as possible to the edge of pivot prism 30. In this embodiment, the S / N
It improves the ratio and is easy to realize.

In operation, the detector 32 and RPE circuit 7
0 is used with or without the disk 10. The configuration described is for initializing the positions of the coarse actuator 33 and the carriage 36.
Used in the optical disk drive without the disk 10,
As a result, there is no offset / angle of the beam 21 with respect to the objective lens 31. Such initialization is particularly useful during the manufacture of optical disc drives. The configuration described is
Used with the disc 10 loaded in the optical disc drive to maintain the offset / angle of the beam 21 with respect to the objective lens 31 within acceptable tolerances during writing and / or reading of the disc 10.

Although the present invention has been described with reference to the preferred embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit, scope and teaching of the present invention. .. For example, although the present invention has been described as being realized for an optical disk drive,
It can also be employed in other devices, including other types of optical storage devices.

[0035]

The present invention has several advantages over other approaches for adjusting the operation of coarse and fine tracking actuators in optical disk drives. The invention is inexpensive and simple to implement.
Also, the present invention does not require the presence of an optical disc in the drive to align the components driven by the coarse and fine tracking actuators. In addition, relative position sensing does not include the optical path of the laser, thus reducing problems associated with beam attenuation. And, the present invention achieves coordination of the operation of coarse and fine tracking actuators with sufficient bandwidth for practical use in modern high performance optical storage devices.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an optical disk drive according to the present invention.

2 is an enlarged isometric view of a rotating prism and fine adjustment tracking actuator of the optical disc drive of FIG. 1. FIG.

FIG. 3 is an enlarged isometric view of a rotating prism, an objective lens and a focus actuator of the optical disc drive of FIG.

4 is a TES and RP of the optical disk drive of FIG.
FIG. 6 is a schematic block diagram of the interaction of an E circuit.

FIG. 5 is a front view, a plane view, and a side view of a rotating prism 30 and a detector 32 in the first embodiment.

FIG. 6 is a front view, a plane view, and a side view of a rotating prism 30 and a detector 32 in a second embodiment.

FIG. 7 is a front view, a plane view, and a side view of a rotating prism 30 and a detector 32 in a third embodiment.

FIG. 8 is a front view, a plane view, and a side view of a rotating prism 30 and a detector 32 according to a fourth embodiment.

FIG. 9 is a front view, a plane view, and a side view of a rotating prism 30 and a detector 32 in a fifth embodiment.

FIG. 10 is a front view, a plane view, and a side view of a rotating prism 30 and a detector 32 in a sixth embodiment.

[Explanation of symbols]

 10 Disk 20 Laser 22 Beam Splitter 23 Beam Splitter 26 Detector 27 Detector 30 Rotating Prism 32 Detector 33 Coarse Tracking Actuator 34 Fine Tracking Actuator 50 Data Circuit 60 Tracking Error Signal Circuit 70 Relative Position Error Circuit 80 Microprocessor

 ─────────────────────────────────────────────────── ————————————————————————————————————— Inventor Reed Alan Hancook West Orange Wood Drive 3860, Tucson, Arizona, USA 3860

Claims (10)

[Claims] 1. A system for measuring the relative displacement of a first component relative to a second component movably mounted to rotate about an axis, the system comprising: Means for emitting a first beam directed to a first region of the surface in the direction of the surface of the first component and a second beam directed to a second region of the surface; First mounted to detect the first beam
Detector and a second beam mounted to detect the second beam
Detector and means for comparing the outputs of the first and second detectors to determine the relative displacement of the first component with respect to the second component. 2. The system of claim 1, wherein the first component is a rotating prism. 3. The system of claim 1, wherein the emitting means comprises an LED and is mounted on the second component. 4. The emitting means is a single LED mounted remotely from the first component, and the first and second detectors are first and first mounted remotely from the first component. Second photodetector, wherein the first photodetector is separate from the second photodetector, and the first photodetector is after the first beam is reflected from the first region. Is received by the second photodetector after being reflected by the second region, and the first and second regions are symmetrical with respect to the axis. The system of claim 1, wherein the system is located. 5. The emitting means is a single LED mounted remotely from the first component, the first detector being the first LED.
Mounted in a first region on a face of the component of the
The second photodetector is mounted in the second region on the surface of the first component, the first photodetector being the second photodetector and the second photodetector being the second photodetector. The system of claim 1, separate from the photodetector and wherein the first and second regions are symmetrically arranged about an axis. 6. The emission means are first and second LEDs mounted remotely from the first component, and first and second detectors are mounted remotely from the first component. A first and a second photodetector, the first photodetector being separated from the second photodetector;
Beam is reflected from the first region and then received by the first photodetector, and the second beam is reflected from the second region and then received by the second photodetector. The system of claim 1, wherein the first and second regions are symmetrically arranged about an axis. 7. The emitting means are first and second LEDs mounted remotely from the first component, the first detector being in a first region on the face of the first component. A first photodetector mounted, the second detector being a second photodetector mounted in a second region on a surface of the first component, the first photodetector The system of claim 1, wherein the container is separate from the second photodetector and the first and second regions are symmetrically arranged about an axis. 8. A first LE, wherein the emitting means is mounted remote from the first component and emits a first beam.
D, mounted away from the first component,
A second LED emitting a second beam, the first and second detectors being a first and a second photodetector mounted remotely from the first component, wherein The first photodetector is separated from the second photodetector, the first beam is received by the first photodetector after being reflected from the first region, and the second beam is The second photodetector receives light from the second region, and the first and second regions are symmetrically arranged with respect to the axis. First
Photodetectors are substantially equidistant from the axis, and the second L
The system of claim 1, wherein the ED and the second photodetector are substantially equidistant from the axis. 9. The emission means is a single LED mounted remotely from the first component and the first and second detectors are first and first mounted remotely from the first component. 2 photodetectors, the dark stripes on the surface separating the first region from the second region,
Beam is reflected by the first region and then received by the first photodetector, the second beam is reflected by the second region and then received by the second photodetector, and The system of claim 1, wherein the two regions are arranged symmetrically about an axis. 10. An optical disk drive for reading data on a loaded disk, comprising: an objective lens, a fine tracking actuator, a coarse tracking actuator, a carriage coupled to the coarse actuator, and a shaft. An optical component rotatably mounted on the carriage and coupled to the fine adjustment actuator, and a controlled interaction of the disc with the optical component and the objective lens. Means for emitting a first light beam directed to do so, means for sensing the first light beam after interaction with the disc and reading data thereon, said optical means Emitting second and third light beams in the direction of the surface of the component, directing the second beam toward a first region of the surface, and Means for directing the third beam to a second region of the surface; a first detector mounted to detect the second beam and output a first signal; A second detector mounted to detect the beam of the second detector and output a second signal, the first detector and the second detector being coupled to compare the first and second signals. And an optical disk drive comprising means for adjusting the coarse adjustment actuator according to the result.