JPS61260427A - Optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To shorten the settling time by switching a control loop of an objective lens or the like to eliminate shake of the lens or the like when a means which moves an optical beam roughly like a carriage is started or stopped. CONSTITUTION:When what is called the coarse control operation which moves the optical beam roughly is started, a switch 7 switches a servo loop by a loop selecting signal 102. That is, a controller 55 inputs a carriage control signal 101 and the loop selecting signal 102 to a switch 531 and the switch 7 respectively in accordance with a speed mode command signal 100, and a carriage 5 is moved in acceleration, uniform, and deceleration moving speeds, and the witch 7 switches the loop simultaneously, and an objective lens 2 is damped and is not oscillated, freely, and the lens is fixed in a mechanical center in accordance with the output signal of a detector 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application 1] The present invention relates to an optical information recording/reproducing apparatus that records, reproduces, or erases information as desired by irradiating a light beam onto an information recording medium. BACKGROUND OF THE INVENTION Optical information recording and reproducing devices generally include a light beam moving means for irradiating a light beam to a desired position on an information recording medium. For example, such a light beam moving means includes a light beam fine movement adjusting means for causing minute displacement by moving an objective lens that focuses and irradiates a light beam on an information recording medium, and the objective lens and its moving means. It is usually constructed by a coarse movement adjustment means for a light beam that moves the entire part to cause a coarse displacement (for example, Japanese Patent Application Laid-Open No. 59-1406
Publication No. 46). According to the above-mentioned prior art, when irradiating a light beam to a desired position on an information recording medium, the light beam is brought close to the target by the light beam coarse movement adjusting means, and then the light beam is brought close to the target. The beam fine movement adjustment means performs a tracking operation by performing so-called tracking control on a target (for example, a target track when the information recording medium is disk-shaped and has a track). [Problem to be Solved by the Invention 1] However, according to the above-mentioned prior art, when the light beam approaches the target, the coarse adjustment means moves coarsely and the fine adjustment means moves close to the target. For example, the objective lens constituting the fine adjustment means is shaken by the acceleration applied during acceleration and deceleration during the movement of the coarse adjustment means, and even after the coarse adjustment means stops when the coarse adjustment means reaches the vicinity of the target. The vibration of the objective lens cannot be easily suppressed. For this reason, a so-called waiting time is required until the fine adjustment means stabilizes and comes to a standstill, which is a waste of time. Alternatively, since the objective lens starts the so-called tracking control operation in a state shifted from its mechanical center (tilted state 7!S), a large shift occurs with respect to the target track. In addition, there is a problem in that it is sometimes necessary to perform the approach operation (so-called access) of the light beam to the target again. The present invention solves the problems of the prior art described above,
When accessing the target of the information recording medium with the light beam, there is no unnecessary tracking time, and it also has excellent high-speed performance that allows stable tracking control to the target.
Another object of the present invention is to provide a stable optical information recording/reproducing device. [Means for Solving the Problems] In order to achieve the above object, the present invention provides an information recording medium and a light beam to be irradiated onto the recording medium by finely moving it and irradiating it onto a desired position on the recording medium. In an optical information recording and reproducing apparatus, the optical information recording and reproducing apparatus has a light beam fine movement adjusting means for roughly moving the light beam onto the recording medium, and a light beam coarse movement adjusting means for roughly moving the light beam onto the recording medium. , a first controller that controls the movement of the fine adjustment means based on the detection signal.
a second light beam movement control loop that detects the return light of the light beam irradiated onto the recording medium and moves the fine movement adjustment means based on the detection signal; and the fine movement adjustment. a selection switch for selecting whether the means is to be driven by the first movement control loop or the second movement control loop; and a selection switch that detects the movement position of the coarse movement adjustment means, and uses the detection signal to control the coarse movement adjustment means. and a third light beam movement control loop for moving the light beam, and when the light beam is moved by the coarse movement adjustment means, the fine movement adjustment means is controlled by the fJS1 loop. Hereinafter, the present invention will be described in detail based on the drawings. FIG. 1 is a schematic block diagram showing the structure of the present invention. 1 is an information recording medium, which in the figure indicates a disk, and generally has concentric or spiral tracks. 11 is a spindle motor that rotates the disk l; 0 A light beam from a light source such as a semiconductor laser (not shown) passes through so-called optical members such as a polarizing prism and a quarter-wave plate (not shown). The light passes through the objective lens 2, which is a fine adjustment means, and is focused and irradiated onto the disk l. 3 is a pickup on which the objective lens 2 is mounted. The returning light from the disc 1 (in the figure, the solid thin line indicates the reflected light from the disc) enters the pickup 3 again via the objective lens 2 and is detected by the photodetector 4 which detects the returning light. , the pickup 3 is mounted on a carriage 5 constituting coarse movement means for moving in the radial direction of the disk l. Reference numeral 6 denotes a displacement detector for the objective lens 2, which supplies a lens drive signal to a tracking coil 9 that drives the objective lens 2 via a switch 7 and a servo amplifier 8, thereby forming a first light beam movement control loop. Moreover, the photodetector 4
a second light for tracking control that detects the returning light and uses it as a so-called tracking error signal to supply a lens drive signal to the tracking coil 9 via the switch 7 and the servo amplifier 8 to make the light beam track the track; Configure the beam movement control loop. Reference numeral 51 denotes a scale means for detecting the moving position of the carriage 5 which carries the optical pickup 3 and roughly moves the entire carriage, a control circuit 52 that inputs the scale signal output from the scale means 51, a motor for moving the carriage 5, etc. The drive circuit 53 forms a third closed servo loop that roughly moves the light beam. [Function] In this device, when performing coarse control, which is the coarse movement of the light beam, the entire pickup 3 is roughly moved by the carriage 5 to position the light beam near the target track. This corresponds to, for example, a seek operation in which the carriage is moved at a constant speed or higher to move the light beam from a certain track position to another track relatively long distance away. On the other hand, during tracking control (fine control) in which the beam position is finely controlled to track a target track, the photodetector 4 detects the return light from the disk 1, uses it as a track error signal, and sends it to the servo amplifier 8. Tracking control is performed using a closed servo loop (the second movement control loop) that moves the objective lens 2 via the tracking coil 9. Now, assume that the fine control state is changed to the coarse control state. The optical pickup 3 is coarsely controlled by the carriage 5 and moved roughly to approach the target. - the force objective 2 is decoupled from the tracking control state according to the second movement control loop and is controlled by the first movement control loop by the output signal of the deflection detector 6 of the objective; That is, the switch 7 is switched so as to control the movement of the objective lens 2, and, for example, servo control is performed so that the objective lens 2 is fixed during this period. moreover,
When the coarse control operation is finished, the control of the light beam is returned to the tracking control by the second movement control loop to achieve a normal tracking operation state (so-called fine control operation). This serves to prevent the effect of acceleration due to carriage movement on the objective lens etc. that occurs during the above-mentioned coarse control operation, and to prevent so-called shaking of the objective lens. Note that, according to the above device, the first movement control loop can also function to fix the objective lens at a fixed position during the coarse control operation. In addition, the operation of the switch that switches from control by the second movement control loop to control by the first movement control loop is controlled within a predetermined range by comparing the carriage movement speed signal obtained from the scale signal with a preset reference signal. The operation may be performed by determining whether or not there is one. [Example] In the following explanation of the drawings, the same reference numerals are given to the members having the same functions as those shown in FIG. 1, and the explanation thereof will be omitted. FIG. 2 shows a block diagram of an optical information recording/reproducing apparatus according to an embodiment of the present invention. According to this embodiment, the output signal of the deflection detector 6 of the objective lens 2 is input to a processing circuit 61. For example, a sensor output corresponding to the displacement of the objective lens is converted into a voltage signal so that the objective lens 2 is correctly driven via a servo amplifier 8 of a servo loop. 10 is a semiconductor laser as a light source, 12 is a prism, and 13 is a mirror. Note that members such as a 1/4 wavelength plate, which are disposed at appropriate locations as necessary, are omitted from description. The output of the 2- or 4-split light detector 4 for detecting the returning light is input to an operational amplifier 41 and input to the switch 7 as a track error signal. The gear ridge 5 inputs a position detection signal via a scale 51 that detects the displacement of the carriage and a scale position detection sensor 511 to a control circuit 52, and performs feedback control by a carriage drive coil 54 via a servo amplifier 53 forming a part of the control circuit 52. and then moved. Reference numeral 55 is a controller such as a host CPU, which does not necessarily need to be built into the apparatus, but it supplies an instruction signal to the switch 7 during the seek operation, etc., and switches the servo control loop that controls the objective lens 2. Further, an instruction signal is input to the carriage drive circuit 53 via the switch 531 to control the movement of the carriage 5. Further, the target position is supplied as an analog signal via a D/A converter 521 to the detection signals of the scale means 51 and 511. The operation of this embodiment will be explained below with reference to FIG. During a so-called fine control operation in which the light beam is tracked to a track, the switch selects a servo loop according to the loop selection signal 102 of the controller 55, and the objective lens 2 performs tracking control using the returned light to direct the light beam to a predetermined track. - track the second time. On the other hand, when entering the so-called coarse control operation in which the light beam is roughly moved, the switch 7
switches the servo loop according to the loop selection signal 102. That is, the controller 55 receives the speed mode instruction signal 10.
0, the carriage control signal lO1 and the loop selection signal 102 are input to the switch 531 and the switch 7, respectively, and the carriage 5 changes the moving speed of acceleration, constant speed, and deceleration (
103) in FIG.
switches the loop (102), and the objective lens 2 is braked so that free vibration does not occur, and the lens is fixed at the mechanical center according to the output signal of the detector 6. When the carriage 5 reaches the vicinity of the target, the switch 7 is the loop selection signal 102
In response to the return of the light, the servo loop is switched to perform fine control operation using the original returning light. In the explanation of the above embodiment, switching of the switch 7 etc. is performed by the loop selection signal 102 in accordance with the speed mode instruction signal 100 of the controller 55, but the seek start signal 104 and the operation of the carriage 5 are generated prior to the start of the operation of the carriage 5. Seek completion signal 105 which is a delayed signal after stopping
The loop selection signal 106 may also be used. The loop selection signal can also be obtained by detecting the moving speed 103 of the carriage and comparing it with a preset reference level. FIGS. 4(A) and 4(CB) are configuration diagrams showing an embodiment of an objective lens deflection detector and its peripheral circuit. Figure 4 (A)
is a configuration diagram of the objective lens 2 as seen from an example of the optical axis, 61 is a magnet, 62 is a central electrode which is also a lens frame, 63a,
63b, 63c, and 63d are parallel electrodes that constitute a capacitive circuit. 64 is a lens drive coil, and the objective lens 2 moves in the direction of the arrow in the figure. Figure 4 (B
), 65 is a differential amplifier, 67 is an oscillator, and 68 is an analog switch. 63b via electrodes 63a and 62
Let the capacitance between the electrodes 63c and 63a via the electrodes 63c and 62 be Ccd. A balanced bridge circuit is constituted by resistors R1 and R2, variable capacitance capacitors CI and C2, and the capacitors 1kCab and Ccd. Figure 4 (C),
CD) is an operation explanatory diagram for explaining the operation of the above embodiment. The operation of the above embodiment will be explained below with reference to FIG. 4(C), CD). When objective lens 2 is located at the mechanical center, R+ X (C2+ Ccd) = R2X
Adjust C1, C2 as much as possible to (C1+Cab). As a result, the output of the bridge circuit (Fig. 4 (B) 681)
becomes zero (72 in FIG. 4(D)), and positive and negative outputs are generated corresponding to the amount of deviation of the objective lens 2. 7144 (C) shows the relationship with the horizontal axis representing the amount of deviation and the vertical axis representing the DC output voltage through the filter circuit constituted by R3 and C3. That is, since the lens is located at the neutral point (72 in FIG. 4(D)), the center electrode 62 is
When biased to example b, Cab changes to a large value and Ccd changes to a small value, and a positive output is obtained at the bridge circuit output 681 (FIG. 4(D) 71). In the opposite case, the output is negative (FIG. 4 CD) 73). Note that the analog switch 68 outputs the output signal 70 of the oscillator 67.
It is rectified in synchronization with the Therefore, according to this embodiment, a DC output corresponding to the deflection of the objective lens can be easily obtained. [Effects of the Invention] According to the present invention, when the means for roughly moving the light beam, such as the carriage, is operated or stopped, the control loop of the objective lens, etc. can be switched to eliminate the fluctuation of the lens, etc.
This has the effect of shortening settling time. Furthermore, it is possible to prevent free vibration of the lens due to the resonance effect caused by external vibrations applied to the entire device, and to provide a stable optical information recording/reproducing device with excellent high-speed response.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing the configuration of the present invention, FIG. 2 is a configuration diagram showing an embodiment of the present invention, FIG. 3 is a waveform diagram for explaining operation, and FIGS. 4 (A) and (B). (C) and (D) are diagrams illustrating the configuration of a deflection detector and its operation. l...Disk 2...Objective lens 3...Pickup 4...Photodetector 5...Carriage 6...Deflection detector 7...Switch 8...Servo amplifier 9... - Tracking coil 51...Scale means 52...Control circuit 53...Drive circuit Patent applicant Olympus Optical Industry Co., Ltd. 1, disk 2, objective lens 4, photodetector 5, carriage 6,! i-position detector 51, scale means 52, control circuit 53, drive circuit Fig. 3 Fig. 4 (A) Fig. 4 (B)

Claims (1)

[Claims] (1) An information recording medium, a light beam fine adjustment means for finely moving a light beam to irradiate the recording medium to a desired position on the recording medium, and a light beam fine adjustment means for finely moving the light beam to irradiate the recording medium to a desired position; In an optical information recording and reproducing apparatus, the first light beam detects the deviation of the fine movement adjusting means and controls the movement of the fine movement adjusting means based on the detection signal. a beam movement control loop; a second light beam movement control loop that detects the return light of the light beam irradiated to the recording medium and drives the fine movement adjustment means based on the detection signal; A selection switch for selecting whether driving is to be performed by the first movement control loop or the second movement control loop, and a movement position of the coarse movement adjustment means are detected, and the coarse movement adjustment means is moved based on the detection signal. and a third light beam movement control loop, wherein the fine movement adjustment means is controlled by the first loop when the light beam is moved by the coarse movement adjustment means. Recording and playback device.