JPH04503585A - Optical data logger with dither operation - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Optical data logger with dither operation Technical field This invention is an optical device that utilizes a beam for writing data in an optical recording medium. This relates to data recording devices.

Background technology Recording of digital data on optical recording media involves marking or marking on the surface of a suitable recording medium. This has been accomplished using recording devices that create holes. Marks indicate reflectance, optical path length, and is a difference in light from the surrounding area of the recording surface, such as variations in optical contrast. It has scientific characteristics. Therefore, the mark may be more or less than the surrounding surface in reflective cases. It can be reflexive. One of the methods used to create these marks is laser A beam burns or melts the recording surface. Layout to create data stamps Recording devices that use laser beams typically focus the laser beam on a spot. laser When the beam is focused to a spot, an autofocus system typically To ensure that the beam remains focused to a spot at the recording surface used, otherwise the data mark may not be formed. For example, U.S. Patent No. 4,458.980 to Ohki et al. using a focused laser beam to record information in an optical recording medium; Teach an optical playback head. A focus servo control system keeps the beam in focus. It is used to keep it in good condition. For recording devices that use an autofocus system and a significant amount of energy is consumed by the autofocus circuitry and related hardware. used to design the Recording devices that use autofocus systems There is also an associated increase in both cost and complexity.

If the laser is of high enough power, the laser beam can be combined into a narrow beam. The recording device is focused where the beam impinges on the recording surface and heats it. Whenever such a situation arises, make a mark. The marks indicate ablation on the recording surface. created by pitting, pitting, or plastic deformation.

The data stamps made with this method have a diameter of less than 1 micron to several microns. have a law, and often the markings may not be uniform. formed around the edges Some marks have a high lip, and some do not. Recorded data and and control of the laser beam becomes difficult because the laser is turned on and off. This is because it must be pulsed. Yet another problem is from the mark. debris is deposited on the surface.

A high power laser that is pulsed on and off burns holes in the recording surface. will explode, scattering debris all over the surface.

The purpose of this invention is to ensure optimal focus and to prevent debris from being scattered on the recording surface. The objective is to devise a low-cost and simple data logger that allows

Disclosure of invention The above objective incorporates a relatively low power laser whose beam is optimally focused; A data logger that is dithered in an upward and downward direction about the recording surface. I'm satisfied. Optimal focus creates a small uniformity within the recording surface without forming debris. A spot with just enough energy density to melt a single pit. If The focused laser spot is initially above or below the plane of the recording surface and Therefore, it is out of focus at the recording plane. The focusing optics also flattens the recording surface. Electromagnetic and pressure through a range of motion moving a focused data spot through a surface Arranged either electrically or mechanically. Laser beam on recording surface The energy of the laser spot decreases as the diameter of the pot decreases and approaches the optimal focus. The Lugie density will be sufficient to form pits on the recording surface. dither The speed of operation of the laser is such that pitting occurs without debris formation. Coordinated with output.

There are various ways to generate the effect of dithering the laser beam spot. May be used depending on the light. In one embodiment, a laser diode and The focusing optics are incorporated into a housing that is attached to a flexure spring assembly. It will be done. Electromagnetic actuator drives about housing and spring assembly installed in position. The actuator is a unique feature of the optical device and spring assembly. Signal generation at frequencies below, the same as, or above the mechanical frequency driven by the device. Drive at a unique resonant frequency reduces the required electrical power Minimize. The stiffness and length of the flexure spring and the mass of the optical device assembly are Determine the resonant frequency. Actuator vibrates optics and spring assembly and thereby dither the focused laser spot. X,, Y The bull provides a relative displacement between the recording surface and the laser beam for further writing. It's okay. Such displacements may be applied to either the recording surface or the optics assembly. It's okay to be hit.

In other embodiments, the electromagnet is placed coaxially around the optics assembly. , where the assembly incorporates magnetic material. The signal generator consists of an optical device and a spring causing the assembly to vibrate and the focused laser spot to dither; Sends a drive signal to the electromagnet. Alternatively, the objective lens of the optics assembly may be The laser beam vibrates to cause the focused laser spot to dither. Requires. This is accomplished by an objective lens attached to the flexure spring assembly. or the objective lens may be vibrated alone in the voice coil array. Ru.

The optic and spring assembly also rotate when the cam is rotated. vibrated by mechanical means such as a multifaceted cam that deflects the device and spring assembly. You may be

A vibrating lever is also used in the mechanical system to provide the necessary dithering movement. May be used. Additionally, the piezoelectric exciter dithers the laser beam spot. The required mechanical vibrations may be applied.

Centering of the dithering movement of the laser beam spot about the recording plane is driven Processing a laser feedback signal indicating a duty cycle in relation to the signal may be found and maintained by Drive frequency is laser feedback Optimization may be achieved by exploiting the difference in phase between the signal and the drive signal.

While it is shown that only the optical device vibrates to produce the dithering effect , the recording surface is vibrated by the same means used to vibrate the optical device. Alternatively, dither operation may be used. In other words, used to vibrate optical devices Electromagnetic, piezoelectric, and mechanical means are used to direct the focused laser beam spot. can be used to vibrate the recording surface.

The advantage of this invention is the lower cost of not using an autofocus system. faster and lower complexity.

Since the focused beam always passes through the plane of the recording surface, writing is accurate. It becomes fruit. Additionally, low power lasers can be used without the need for on and off outputs. It is Noh.

Brief description of the drawing Figure 1 shows the development of the optical device and spring dither assembly in the data logger of this invention. FIG.

FIG. 2 is a perspective view of a data logger using an electromagnetic actuator according to the present invention. .

3-5 are plan views of a storage medium and a laser beam, illustrating the operation of the present invention. It is.

FIG. 6 is an exploded perspective view of a data logger using coaxial electromagnets according to the present invention.

Figure 7 shows a variation of the data logger in Figure 6 in which a coaxial electromagnet is attached to the housing. FIG.

FIG. 8 is a plan view of the data logger of FIG. 7 taken along line 8-8 in FIG. be.

FIG. 9 is a perspective view of a data logger using a multifaceted cam according to the present invention.

FIG. 10 is a perspective view of a data logger using a lever according to the present invention.

FIG. 11 is a series of plots of amplitude versus time for the dither assembly of the present invention. Ru.

FIG. 12 is a block diagram for the automatic centering circuit.

FIG. 13 is a schematic diagram showing an embodiment of the circuit shown in FIG. 12.

Best mode to implement invention 1 and 2, an optical device and spring dither assembly of the present invention 10 includes a laser diode package 14, a collimating lens 16, and and an objective lens 18, all of which are located within the optical device housing 2. It can be placed within 4. Lenses 16 and 18 may be any combination utilized in this invention. It also represents a focusing device. The lens used to focus the laser beam is Conventional spherical multi-element design, aspherical design, gradient coefficient ) design or a combination of the three types are possible. The beam is also in focus as long as the focal point can be oscillated around the surface of interest. The choice is not important. The optical device housing 24 is located within the optical device housing. It is attached to the flexure spring 20 such that the central axis is perpendicular to the longitudinal axis of the flexure spring. Deflection The springs are attached to the mounting block 22 such that the springs are parallel to each other. Record The recording surface or plane 12 can be any laser recording material that is supported from below.

For example, U.S. Pat. Reflective laser recording material on cards of the type shown in No. 4,544°835 is preferred. Delicious. Power is supplied to the laser diode package via power wire 34. Ru.

The optic and spring assembly 10 has a length and stiffness of the spring and an optic spring assembly. It has a unique resonant frequency determined by the mass of the assembly. Magnetic actuator in Figure 2 ducator 28 receives a drive signal from a signal generator 32 through wire 30. Aku To minimize power consumption and performance requirements of the tuator, the drive signal is should be at the resonant frequency of the spring assembly. However, the drive signal The frequency may be below or far above the resonant frequency and still be as desired. causes vibration.

In operation, the optics enclosed in the optics housing 24 include a laser diode. The laser beam emitted by the card 14 is focused onto a spot 26, which is an optical recording medium. The frequency of the dither operation is adjusted to form pits or spots on the recording surface 12. In terms of numbers, it has a sufficiently high energy density. First, the focused laser beam The beam spot is above or clearly below the recording surface. optical equipment and The spring assembly 10 is vibrated by an electromagnetic actuator 28 so that the laser The beam spot is dithered about the recording surface. The laser beam spot is displayed. When moving through the plane of the surface, pits or plastic deformations are formed within the surface.

When the laser beam is out of focus at the recording surface, i.e. When the spot is above or below the plane, the beam will be pitted at the surface. does not have enough energy density to form. The laser beam spot is always Optimum focus of the laser beam is always guaranteed as it moves through the recording plane be done. The photodetector diode in the laser diode package 14 is a pit may be used to detect the presence of Planar recording surface allows for continuous writing. so that it is moved in the XSY plane generally perpendicular to the beam, or the beam is moved relative to the recording surface.

Referring to FIGS. 3-5, a plurality of focused laser beam positions are shown. If When the focused laser beam spot 26 is dithered about the recording plane 12 , the area of the laser beam in the recording plane is the focused laser beam spot 26 decreases as it approaches the recording plane. The energy density of the laser beam is is inversely proportional to the cross-sectional area of the beam. The laser beam spot is placed on the recording surface for a suitable period of time. When present, the energy density is sufficient to form pits 52 at the surface. High enough. As the laser spot moves away from the recording plane, the Since the area of the beam increases, the energy density is not sufficient to form a pit. stomach. In FIG. 3, the focused laser beam spot 26 is above the recording plane 12. It is in. In FIG. 4, the laser beam spot is within the recording plane and the pit 5 2 is formed. Figure 5 shows a record that appears to be focused below the recording surface. shows the laser beam spot, but in reality there is a reflected laser beam spot above the surface. It is focused at pot 26. The events shown in Figure 4 can be It's a tree.

Referring to FIG. 6, the data logger shown here is similar to that of FIG. Figure 6 In this logger, the electromagnet 36 is an optical device housing that incorporates a permanent magnet 38. 24 in a coaxial direction. The magnet is attached to the optical device housing. may also be embedded within the housing or contents of the optical device hardware. You may be Alternatively, the electromagnet 36 is as shown in FIGS. 7 and 8. attached to the optical device housing 24 and the external magnet 38 used. Good too. In this case, the permanent magnet 38 is supported by the mounting block 22 and is stationary. the electrical device that is held in the The magnet 36 vibrates. In another embodiment, not shown, a vibrating optical Having only the objective lens 18 in the device housing and the laser diode package The lens 14 and collimating lens 16 remain stationary and the optical system It is believed that this reduces the vibrating mass. It will be done.

In FIG. 9, the optical device and spring assembly 10 are shown in the direction indicated by arrow A. It is caused to vibrate by a multifaceted cam 40 which is shown to rotate. Drive rod 4 2 is drive-related to the multifaceted cam and the drive source 44. When the multifaceted cam rotates, The surface is such that the laser beam spot 26 moves upwardly and downwardly or dithers. deflecting the optical device and spring assembly to cause the Change from surface to surface With this, the laser beam spot will be focused twice at the recording plane. .

Referring to FIG. 10, the optical device and spring assembly 10 is drive-related to a drive source 44. and is connected via pivot 50 to the optical device and spring assembly. , can be seen to include a piston rod 46. The piston rod 46 extends upwardly. When moving downward, the optic and spring assembly vibrate, thereby causing the laser to The beam spot 26 is dithered. The drive source 44 may be a piezoelectric transducer. stomach.

In FIG. 11, several plots are shown that illustrate the operation of the invention. plot A is for an ideal drive signal. The frequency is determined by the optics and spring assembly. at a resonant frequency. Plot B is centered at resonance and about the recording surface. It shows the movement of the laser beam focus spot when the laser beam is focused. The laser beam is 90 In focus at ° and 270°. Detail of the spot where the laser beam is focused When the laser motion is centered above and below the recording surface, plot C The feedback signal. Feedback signal is fed into the laser Result of backing up laser energy causing more effective laser operation . Is the optical detector incorporated in the laser diode package the recording surface? Observe the feedback laser energy reflected from the generates a lock signal.

Typically, the recording surface and optical assembly are moved at a constant speed during continuous writing. moved in relation to each other. Plots D and E pull apart the dither assembly Mainly when the optical element is too close to the recording surface Shows the laser feedback signal when the laser is too close or too far away.

As shown, the nonuniformly spaced laser feedback signal Corresponds to the location where the mark will be recorded. This non-uniform spacing method is Due to the problem it would cause when the is to be read back to successive writes to It is harmful. Without a uniform spacing method, the reading system will look for data marks. You're going to have a difficult time deciding where to go. For this problem One strategy is to use a laser feed to focus the dither oscillations on the recording surface. It is thought that it is to use a back signal. Another strategy is to The data will be written under focused conditions. This strategy reduces data writing speed This results in uniform spacing of data marks and eliminates the need for Simplify the electronics equipment used.

Plots F and G show the dynamics when the drive frequency is too low or too high. The assembly drive signal's result is a phase error, and the write event affect the predictability of Data feedback signal phase and duty cycle Optimized frequency and offset by comparing cycle to drive signal Or a spacing method for dithering can be achieved.

Referring to FIGS. 12 and 13, the monitor diode D1 is a laser diode door. It is a part of the assembly and gives a signal proportional to the laser diode output power power. . Due to the nature of laser diode laser operation and the optical arrangement used, a significant amount is in the laser diode D2 when the energy is focused in the optical system. and likewise fed back into the monitor diode. This allows the laser die to The laser operation of the ode becomes more effective and as a result the monitor diode D1 resulting in an increase in output. The output of monitor diode D1 is based on the baseline output power. Detecting such an increase in laser diode output power over signal v1 and detecting this A circuit C1 is supplied which converts the signal into a binary quantity. This signal $4 is a laser It is called a feedback signal (LFS). As shown in FIG. Path C1 includes an operational amplifier AI with a barb string of diodes D3. LFS is lens acti It is supplied to the phase detector circuit C2 together with the signal S3 that drives the tuator. phase detection The output circuit C2 includes two parallel NOR gates N1 and N2 and an inverter 11. and an operational amplifier subtractor circuit A2. As input to NOR gate N1, The actuator signal S3 is inverted by an inverter 11. phase detector times The output of channel C2 is a low frequency signal S2 that is proportional to the amount and direction of the focus error. A multi-pass filter F1 is provided. This signal S2 is a focus error signal (FES) It is called. Filter F1 consists of an operational amplifier A2 and a resistor/capacitor network. Including. The FES is fed into a circuit not shown, and that circuit is used to focus the lens. the lens actuator in a manner that maintains the center of vibration with respect to the surface to be drive The laser exposure time is determined by the exposure control circuit C3 and the laser feedback signal S4. , and data write signal S1. Laser feedback signal S 4 and data write signal S1 are gated together through an AND" logic circuit Gl. It will be done. The output of G1 controls one-shot multivibrator circuit M1. exposure The output of control circuit C3 is used to turn on the laser diode and A laser diode drive circuit C used to maintain a fixed average level of output. Connected to 4. The average level of the output is determined by the series voltage level at ■1. be done. The circuit shown in FIG. 13 is shown by way of example only and may be implemented in accordance with the invention. It does not limit the circuits shown.

In this application, the words "above" and "below" simply refer to relative directions. and does not imply an absolute direction.

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Claims (23)

[Claims] 1. used to create digital data spots in optical recording media a data logger comprising: a light source providing a collimated beam of light; and a light source associated with the light source. energy density sufficient to form pits on a planar optical recording surface. optical means for focusing a light beam within an optimal beam region having said optimal beam region; The beam area is relatively above or below the plane of the planar optical recording surface. means for imparting oscillations in said focused beam so as to cause said beam to be displaced; imparts a relative linear motion between the beam and the optical recording surface, thereby creating a new recording surface. and means for bringing a surface area into the path of the beam. 2. to receive light from the collimated beam after impact with the recording surface; 2. The data logger of claim 1, further comprising a photodetector located at. 3. for centering the oscillations of the optimal beam area about the plane of the recording surface; 3. The data logger of claim 2, further comprising means for. 4. The means for applying vibration is an electromagnetic actuator linked to a signal generator. The data logger according to claim 1. 5. said means for applying vibrations coaxially with said optical means and an electrical signal generator; an electromagnet placed in conjunction with said optical means having an associated magnetic field; Data logger for requirement 1. 6. the vibrations are provided by a multifaceted cam associated with a drive rod and a drive source; The data logger according to claim 1. 7. 2. The data logger of claim 1, wherein said vibration is provided by a piezoelectric vibration source. 8. Said means for relative linear movement between the light beam and the recording surface is a lead strip. 2. The data logger of claim 1 provided by a clew assembly. 9. A data recorder used to record digital data on optical recording media. It's a moth, a laser diode generating a laser light beam and having at least one photodetector; a planar optical recorder associated with the laser diode package; Optimal beam area with sufficient energy density to form pits at the surface and optical means for focusing a laser beam on a region, said focused beam comprising: , when the optimal beam area is not within the plane, the recording surface is does not have sufficient energy density in the plane of the beam region is displaced above and below the plane of the planar optical recording surface; means for applying vibration of the optimum beam area to the recording surface so as to means for centering said oscillations of the optimal beam area about the plane of the recording surface; , imparts a relative linear motion between the light beam and the optical recording surface, thereby creating a new record. and means for bringing a recording surface area into the path of the beam. 10. an electromagnetic actuator in which said means for relative vibration is coupled to a signal generator; 10. The data logger of claim 9, given by. 11. said optical means for relative vibration, said means having an associated magnetic field; 10. The data logger of claim 9 provided by axially related electromagnets. 12. Said means for relative vibration is a multifaceted cover associated with the drive rod and the drive source. 10. The data logger of claim 9, provided by a system. 13. 10. The method of claim 9, wherein said means for relative vibration is provided by a piezoelectric vibration source. data logger. 14. Said means for relative linear interlocking is provided by a lead screw assembly. 10. The data logger of claim 9, provided. 15. Data used to record digital data on optical recording media A logger that is associated with a laser diode package and generates a laser light beam. and a laser diode package having at least one photodetector; The highest energy density that has sufficient energy density to form pits in the optical recording surface. optical means for focusing the laser beam within a suitable beam region; a housing surrounding the optical means and the laser diode package; The housing is supported by a flexure spring; The optimal beam area of the laser beam is displaced above and below the optical recording surface means for vibrating the housing to cause the housing to vibrate; and means for providing relative interlocking between the laser beam and the optical recording surface. -Taroga. 16. means for centering said displacement of the optimal beam area with respect to the recording surface; 16. The data logger of claim 15, further comprising: 17. an electromagnetic actuator in which the means for imparting vibration is linked to a signal generator The data logger according to claim 15. 18. Said means for applying vibrations are arranged coaxially with the housing and are electrically connected. an electromagnet associated with a signal generator, the housing having an associated magnetic field; , The data logger according to claim 15. 19. The means for imparting vibration is a multifaceted cam associated with a drive rod having a drive source. The data logger according to claim 15. 20. A means for imparting relative motion between the light beam and the recording surface is provided on the recording surface. 16. The data logger of claim 15, provided by an associated X,Y table. 21. 16. The data storage device of claim 15, wherein the means for applying vibration is a piezoelectric vibration drive source. Ga. 22. A method for data logging using a focused light beam, the method comprising: When the focus area passes through the plane of the recording surface, the focus area is above the plane of the recording surface. and downward to the optical recording surface to form a data spot. dithering the focal region of the light beam across the dithering direction; , displacing the optical storage surface with respect to the beam in a linear manner. A method of writing on a planar optical recording surface. 23. 23. The method of claim 22, wherein the dithering operation of a focal region with respect to a plane of a recording surface. further including centering.