JPH02161625A - Protecting device for actuator - Google Patents

Abstract

PURPOSE:To prevent an objective lens or a galvanomirror from being moved excessively by providing a position sensor to detect the quantity of displacement of the objective lens or the galvanomirror from a balancing point, and opening the closed loop of a servo system when the output of the position sensor exceeds an allowable value. CONSTITUTION:An optical pickup 4 is loaded on a carriage 5, and it can be moved in the radius direction T of an optical disk 3 by a voice coil motor 6 as a carriage driving means to drive the carriage 5. And the position of the objective lens 13 is detected by the position sensor 28, and the output of the position sensor 28 is inputted to a lens actuator protection circuit 29. The output of the lens actuator protection circuit 29 is inputted to an adder 21, and the objective lens 13 set at a tracking state can be prevented from being moved excessively. In such a way, it is possible to prevent the movable mechanism of an actuator from being moved exceeding an allowable range.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention provides protection of the precision actuator by providing a means for detecting the position of the precision actuator, such as an objective lens, to prevent overloading of the precision actuator. Regarding equipment. [Prior art 1] In recent years, information has been optically recorded by condensing a light beam and irradiating it onto an optical recording medium (hereinafter referred to as optical ice cream) to form a row of pins or the like on an optical disk. There is also an optical recording/reproducing device (hereinafter referred to as an optical disk device) that can receive light returned from a recorded bit string or the like and reproduce recorded information. In the above-mentioned optical f-isk device, information is recorded in columns or the like on the pin 1 along the concentric or spiral i-rack of the optical disk. Therefore, when recording or reproducing information, it is necessary to follow the light spot irradiated onto the optical disc onto the track, and the tracking servo system is set in stage C. A focusing servo system is also provided to reduce the size of the light spot irradiated onto the optical disc and record information with high density. By the way, in Japanese Patent Publication No. 63-33207, in a tracking servo base, a current amplified by a C1 drive amplifier is passed through a drive coil to rotate a racking mirror, and the amplified output is manually input to a DC voltage detector. A conventional example is disclosed in which the obtained DC voltage is input to a window comparator, and when the voltage deviates from within two comparison voltages, the 1-racking 4 novolube is cut off. In this way, excessive force is prevented from being applied to the pivoting mechanism of the galvano mirror due to excessive swinging of the galvano mirror, thereby preventing damage to the galvano mirror. In other words, the aim is to detect the rotation angle of the galvanometer mirror and turn off the tracking servo when the rotation angle exceeds a predetermined angle. [Problems to be solved by the invention] Therefore, the tracking error signal is observed and the rotation angle of the galvanometer mirror is indirectly detected from the amplitude of this signal, but this value does not necessarily reflect this rotation angle. Not. The tracking servo group is controlled so that the tracking error signal becomes zero, but the position of the objective lens or galvanometer mirror to be controlled at this time is not fixed. Therefore, it is possible even if the track error signal is zero! I
It is not necessarily the center point (hereinafter also referred to as the equilibrium point) of the ll range. Ideally, the objective lens or galvanometer mirror should be tracking at this center point, but in reality it is often deviated from this point. This is due to electrical offsets in the electrical circuits that make up the servo system, dust, clumps, or scratches on the medium, or optical offsets caused by misalignment of the detection optical system or detector. It's for a reason. Accordingly, C1 in the above conventional example, the position of the galvano mirror is not determined and it is controlled to be zero.] - Rack error, but it deviates from zero by a certain value Because it detects the time (the amount of time has passed in history), depending on the case, it may be under-detected or over-detected (even if it does not exceed it, it is already at an excessive level, and the detection of one novel even bigger than Kone). . In addition, in a two-ton servo control system in which the tracking servo system is driven in conjunction with the coarse moving means, the response of the coarse moving means tends to be delayed, and in a transient manner, the galvanometer mirror is used to make the i-rack error signal zero. - may be swung excessively. In such cases as well, under-detection or over-detection may occur. In other words, in this conventional example, excessive rotation of the galvanomirror cannot be reliably prevented. The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an actuator protection device that can reliably prevent excessive movement of a galvanometer mirror. "Means and effects for solving the problem" In the present invention, an fff device sensor is provided to detect the displacement of the objective lens or galvano mirror from its equilibrium point, and when the output of this position sensor exceeds a permissible value, The closed loop of the servo system is opened <3'' to ensure that excessive translational or rotational movement of the objective lens or galvano mirror is prevented. . The present invention will be explained in detail with reference to the drawings below. Figures 1 to 11 relate to a first embodiment of the present invention, and Figure 1 is a configuration diagram of the first embodiment. , Fig. 2 (also a block diagram of an optical disk device equipped with the first embodiment, Fig. 3 is a lens arrangement)
Fig. 4 is an explanatory diagram of the rack access operation to l, Fig. 5 is a front view of the 11-position 1Y inner, Fig. 6 is an explanatory diagram of the operation of the position sensor, and Fig. 7 is an explanatory diagram of the operation of the position sensor. 6 Indicates that the position of the light spot changes with respect to Figure 6"?J
An explanatory diagram, Fig. 8 is a characteristic diagram showing the output characteristics of the Vincennes 1-no. The circuit diagram shown in FIG. 11 is a characteristic diagram showing the input/output characteristics of the window comparator. As shown in FIG. An optical pickup 4 is disposed opposite an optical disk 3 that is rotationally driven by a motor 2. The optical pickup 4 is mounted on a key 1r ridge 5,
A voice coil 6 serving as a carriage driving means for driving the carriage 5 is movable in the radial direction T of the optical disc 3. A light source and a laser diode 7 are housed in the optical pickup 4, and the laser light from the laser diode 7 is made into parallel light by a remeter lens 8 and then sent to a shaping prism 9. It is incident. After the cross-sectional shape of the light beam is shaped into a circle, the polarizing prism 11 is
It is incident as polarized light and is transmitted almost 100%. This transmitted light is made into circularly polarized light by a quarter-wave plate 12, and then enters an objective lens 13 and is irradiated onto an optical disc 3. The returned light from the optical disk 3 passes through the objective lens 13 and then passes through the quarter-wave plate 13, becomes S-polarized light, is almost 100% reflected by the polarizing prism 11, and passes through the critical angle prism 14.゛C, foot 7 - 4 placed in field position
The light is received by the split photodetector 15. Although FIG. 2 shows the critical angle prism 14 that is on the same plane as the polarizing prism 11, it is actually arranged in a direction perpendicular to the plane of the paper, that is, perpendicular to the radial direction T, with respect to the polarizing prism 11. . The objective lens 13 is the "lens 7" shown in FIG.
By applying a drive current to the ``no-okasing'' ile 17 and 1-silaking ``ile 18'' constituting the L-Y 1G, the optical disk can be moved in the distance direction perpendicular to the surface of the optical disk 3 and downward in the radial direction of the optical disk 3. Note that in FIGS. 1 and 2, only the tracking file 18 is shown. By passing through the operational circuit 20 to obtain the differential output of the four elements of the photodetector 15, which are divided by V-in (from the tangent of the rack), the 1-rack error can be detected. A signal TER is generated. The output of this arithmetic circuit 20 is inputted to an adder 21 via a switch S1, and the output t can be applied to a tracking port 18 via a phase compensation circuit 22 and a drive amplifier 23. It constitutes a racking rib system. Further, the output of this arithmetic circuit 20 can be supplied to a CM (voice coil motor) 6 via a switch S2 and a phase compensation circuit 24, and by driving the tracking coil 18 and this VCM 6, a two-stage ( (double) It is double-sided so that tracking servo can be performed. The movement of the carriage 5 by the VCM 6 is controlled by the external scale 25, which moves the position 11JL/to the ki side and outputs an external scale signal.

[No. This external scale signal is sent to VCM6 via switch $3 and phase compensation circuit 24.
Coarse access can be performed by allowing input to Further, the outputs of the arithmetic circuit 20 are passed through a comparator 26 to Hun1-r! - The comparator 26 is manually inputted to the comparator 27.
Each part is controlled by determining the level of the rack error signal (R). The Y controller 27 turns on/off the switch S1, and the switch S via the switch S2 and the inverter 28.
3 on/off control. The position of the objective lens 13 is detected by a position sensor 1) 28, and the output of this position sensor 928 is input to a lens protector protection circuit 29. The output of the lens actuator protection circuit 29 is input to the adder 21, which functions to prevent excessive movement of the objective lens 13 in the tracking state. The operation of accessing the target 1-rack by the controller 27 for the parts other than the two functions of the lens actuator protection circuit will be described with reference to FIG. (In this case, the output of the arithmetic circuit 20 is the same as that input to the phase compensation circuit 22 via the switch S1, which is turned on and off at the turn 27.) 31: Access command signal 5J manually input to the J-Fun-D-Ra 27 from the outside, 32 (a speed control signal based on a scale signal, 33 a position control signal based on a speed control signal, 34 a scale signal, 35 a lens The tracking instruction signal, 336 is the 1st tracker signal, 37 is the main 11 tracker tracking instruction signal, and FIG. 4 shows the timing relationship between them. '4 (one of the command signals shown in Figure 2 Notice No. 38)
The switch 27 closes the switch S3 and opens the switch S2. At that point, V2V5 moves the carriage 5 based on the external scale signal output from the scale 25, and directs the light beam to the target of the optical disk 3 in the vicinity of the rack. During this time, the speed control and position control of V0V6 based on the scale offset are quickly performed at the timing according to the speed control signal and position control signal (Request No. 32 and 33 in FIG. 4). Next, the engine 1-[]-ra 27 receives a stable signal (Request No. 34 in Figure 4) which detects that V2V5 has come to rest with respect to the scale 25, and receives a stable signal (Request No. 34 in Figure 4). Switch S according to Figure 4 Request No. 35)
1 is tapped to operate the lens tracking servo loop. As a result, the objective 1 nons 13 is exposed to light] 2 A photodetector 15 that detects the returning light from the lens 3
And for a predetermined 1~lack by the 1~lack king level signal TER obtained by the operation Q circuit 2Of, 2.
) i-racking will be performed. On the other hand, due to the “C lens!” racking, the above 1.
- The signal level of the rack error signal TEf converges within a certain range (Request No. 36 in Figure 4). The track error signal T
' Comparator 2 such as a window comparator is used to detect the convergence of E R.
6, the dashed line 1-rem comparison level for the notification No. 36 in FIG. 4 is schematically shown. ) If it falls within a certain range, the 1-racking means detects that the person is in the 1-racking state, and outputs the 1-racking instruction signal (Request No. 37 in Figure 4). do. The instruction signal 3
7 followed by b, the second point []-ra 27 is the inverter 28.
After opening switch S3 and closing switch S2 via
- Carriage tracking (coarse tracking) control is based on the rack error signal TER. By the way, in this embodiment I°, the lens actuator 11-1
6, a position sensor 2 that detects the position of the objective lens 13;
8 is provided, and the output of this position sensor 28 is input to the lens acticoator maintenance circuit 29,
If it deviates from the allowable range of movement, the tracking servo system is turned off (in this embodiment, switch S1 is turned off) to prevent the objective lens 13 from being moved excessively.
To prevent the Lens Acrylic J-Y16 from becoming overloaded, 1. A protective covering is provided. The structure of the lens actuator 16 provided with the position sensor 28 will be explained below with reference to FIG. An objective 1 for irradiating a light spot onto the optical disc 3 is fitted into a support member 42 . The support member 42 is displaced in the focusing direction parallel to the optical axis of the objective lens 13 to converge the light spot onto the optical disk 3, and in the radial direction perpendicular to the information rack and optical axis of the optical disk 30. I-shoes 4-ng direction) Displace the information to the optical spora 1]-rack)D
In order to be able to follow the objective lens support member 42 (
It is connected to the base 43 via a support mechanism. This support mechanism 14 is composed of a pair of cussing plate springs 44a and 44b, a relay section vJ45, and a pair of tracking plate springs 462) and 46b. The leaf springs 44a and 44b are opposite to each other in the focusing direction F-; Supporting member 4 at the end
The grooves 42a and 42b formed on the side wall of 2 (the two grooves 45 formed in the relay member 45) and the grooves 45b are fitted and installed. -C is here. In addition, a pair of 1-racking leaf springs 46a and 46b
Now, while facing downward in the tracking direction with the child, the focusing direction ``and dragging direction 1''.
- If it melts, it will extend in the orthogonal direction so that each -・
The ends are fitted and attached to the left and right holes 45C and 45d formed on the relay member 45, and the other ends are fitted and attached to grooves formed on the bosses 47 and 48, respectively, formed integrally with the base 43. There is. - The relay member 45 of the pair of tracking leaf springs 46a and 46b mentioned above.

[The distance between one end of the springs 47 and 48 is longer than the distance between the other ends of J3, and these leaf springs 4 (321
and 46b, and the angle αG, 1, is preferably about 30° 1. In this way, the objective lens 13 is supported movably in the focusing direction F- and the tracking direction 1-. A pair of focusing coils 17a and 17b are fixed to the side surfaces of the support member 42 facing downward in the tracking direction, and a pair of tracking coils 18a and 18b are integrally formed on the outside of these focusing coils 17a and 17b. It is attached to. The focusing coils 17a and 17b have a ``figure 10'' shape when viewed in the focusing direction F, while the tracking coils 18a and 18b have a ``U'' shape when viewed in the focusing direction F. There is. A magnetic field generating member that generates a magnetic field in cooperation with these focusing wheels 17a, 17b and racking river 7'' wheels 18a, 18b consists of a pair of yokes 51 and 52 made of magnetic material, and a pair of yokes 51 and 52 on both sides of one yoke 51. Permanent magnets 53a and 63b are mounted along the legs 51 and 51b of the other yoke 520, and the legs 52a and 5 are mounted on both sides of the other yoke 520.
It is composed of permanent magnets 54a and 54 mounted along 2b. These arms 51 and 52 are fixed to the base 43 so that their central legs 51c and 52c are inserted into the focusing coils 17a and 17b, respectively. Focusing coil 1
7a, 17b and tracking m = ]il 18a, 18
Lead wire connected to b (only one is shown in section)
The holes 45e formed in the relay member 54 are made to extend almost along the rear leaf springs 44a, 44b, 46a, and 46b connected to the Q heights provided on the side surface of the support member 7'12, and the holes 45e formed in the relay member 54 are connected to the It is connected to a terminal of a printed circuit board 55 fixed to the base 43, and further connected to the drive amplifier 23 from here. On the other hand, a holding member 5G is erected on the base 43, facing the support member 42. This holding member 56 is formed in a plate shape, and the supporting member 4
A light-emitting cable 57 such as an LED and a light sensor +j58 are fixed on the side opposite to the light sensor 2. Also, a supporting member /! facing the light emitting element 57 and the optical sensor 58 is provided. An inverse) 1 plate 59 is fixed to the side surface of 2, and constitutes a position sensor 28 that detects the movement position of the objective lens 13 along the tracking direction T. - [The reflecting plate 59 is formed into a circular shape, for example, and reflects the light emitted by the light emitting cable 57 to form a circular light spot on the optical sensor 58. The optical sensor 58 includes two bin sensors 58a and 58b and a semiconductor position sensor (PS) as shown in FIG.
D (abbreviation) 58c is integrally formed. In other words, the two-divided bin sensors 58a and 58b have a shape in which a semicircle is divided into two on the left and right (in the first ranking direction T), and a semicircular PSD sensor 58c is formed adjacent to this semicircle. Therefore, when the support member 42 to which the objective lens 13 is attached moves from the neutral point shown by the solid line in the tracking direction 1 as shown by the dotted line as shown in FIG.
As shown in FIG. 7, the irradiation spot irradiated onto the light receiving surface moves from the solid line to the dotted line. Therefore, the objective lens 13 is
It is possible to detect movement of the object from its neutral point. This 2
Position detection using the differential outputs of the divided bin sensors 58a and 58b is limited to a relatively narrow range. In other words, this 2 minutes A
As shown in FIG. 8(a), the linearity of the differential output of the No. 11 bins 58a and 58b decreases at about 200 [μ], for example. Therefore, the two-divided bin sensors 58a, 58
b is used for lens dumping to set the objective lens 13 at a neutral point. That is, in FIG. 1, the two divided bin sensors 58a, 58
By inputting the output through the differential amplifier 61 of B to the adder 21 via the switch S4, a lens dump signal Y-! is sent to the tracking coil 18 to set the objective lens 13 at the center point. can be applied. On the other hand, the sensor output of the PSD tton+j58G is within a wide area (for example, 1000 μm) as shown in Figure 8(b).
1). ．．
Therefore, this PSD sensor 8G is used to detect the limit of the movable range of the objective lens 13 and prevent it from moving excessively. This PSD sensor 58G has a structure as shown in FIG. In FIG. 9, one layer 65 is formed on the surface of the flat silicon.
It consists of N1M66 on the back surface and a high-resistance insulating layer 67 made of a silicon substrate between these layers. Thus, electrodes 65a and 65b for position detection are provided at both ends of the second layer 65 in the longitudinal direction of the sensor, while a bias electrode 68 is provided at the center of the N layer 66 for blood loss. When the first layer 65 is irradiated with incident light in the form of a spot, a charge proportional to the light energy is generated at the incident position, which becomes a photocurrent that passes through the resistive layer forming the second layer 65, causing each 6N4i65 a, 65 Ai comes out from b
,, +: 0)! ;j, the resistance layer is uniform and
/, C is formed to have a resistance M+ tl, and the photocurrent (,1′ city Mi 65 a, 65 b kTj
1 to be output in inverse proportion to rf [resistance value], for example, Wl[e2L-,
The current taken out from each electrode ('35a, 65b is 11
゜ [2. If the photocurrent is written as io (=11 + - 12), then if the center position of PSD ton υ58c is the hematemesis, then 11 = Io (L-X) / (2m). 12 = Io (L+X)/<21) or (12-11>/(It + I2)=X
/L. 11/12 = (1--X)/(L+X). Here, Cx represents the distance (coordinates) from the original g:1 to the spora 1-irradiation position of the input 0'' light. Therefore, by measuring the current flowing through the picture electrodes 65a and 65b, it is possible to detect the position of the spot light irradiated on the PSD (photo sensor 58G) and the displacement pattern of the 94-object lens 13. As shown in FIG. ”The output of the PSD sensor +j 58C is connected to the low-pass filter 71 via the switch S5.
After high frequency components such as noise are removed, the signal is input to the window comparator 73 via the DC cut circuit 72, where it is compared with an allowable level, and the comparison output connects the AND circuit 74 to turn on the switch S1. /Off system TL
applied to lE. Note that a tracking start signal as a control signal from the roller 27 is input to the controller 1 to the other input terminal of the AND circuit 74. In addition, the DC cup 1-
The circuit 72 is provided to remove a direct current offset caused by the tilt of the objective lens 13. The specific circuit configuration of the low-pass filter 71, the DC cut circuit 72, and the window comparator 74 is shown in FIG. The wind inverter 73 is composed of a blocking capacitor C2 and a resistor R2.The wind inverter 73 includes two inverters 76a and 76b, and an AND circuit 7 connected to the output terminals of the inverters 76a and 76b.
It consists of 7. 2. The ten limit value VU and the lower limit value Vl- are input to the two comparators 76a and 76b, respectively, and as shown in FIG.
becomes '1('', and misses this range111'2-!J-
Then, it becomes 11 L 11, which is J two sea urchins. The switch 81 is turned on when it is set to 'H' and turned off when it is set to 'L.'Therefore, while the switch S1 is turned on and the tracking servo system is operating, the PSD
(When the output of J-58G exceeds 1 bell,
The output of the window comparator 73 becomes LIT, and the tracking control is stopped by pressing the switch S1. Note that, as shown in FIG.
In addition to the on/off control of the switch S5, the on/off control of the switch S5 can be performed. The output of the circuit 74 becomes "[°", the switch S1 is off, and the differential output of the two-divided bin sensor output 58a.
The signal is input to the tracking coil 18 via the phase compensation circuit 22 and the drive amplifier 23. This keeps the objective lens 13 at a neutral point. However, when the dragging start signal becomes 'H' after the seek operation is completed, the switch 84 is turned off and the switch S5 is turned on.In this case, the output of the window comparator 73 is normally 11.
HT! Therefore, the output through the AND circuit 74 turns on the switch S1. That is, the track error signal '; 3 T E R is the track error signal passed through the arithmetic circuit 20 of the photodetector 15.
, the j-racking servo operation is applied to the tracking coil 18 via the drive amplifier 23. During this operation, if the output of the PSD sensor 58c deviates from the lower limit value or the upper limit value, the window comparator 7
The output of 3 becomes "L11", the switch S1 is set to A--, and the lagging servo system becomes inactive, protecting the tracking actuator. FIG. 12 shows a lens actuator according to a second embodiment of the present invention. A protection circuit 81 is shown.In this second embodiment, for example, a lens actuator 82 is used in addition to that shown in FIG.
4, of this magnetic piece 84 - racking direction T
Due to the magnetic field of the permanent magnet 15 disposed facing a plane perpendicular to the plane and the magnetic field generated by energizing the coil 86, the objective lens 83 is can be moved in the tracking direction T. Two electrode pieces 89 and 89 are attached between the magnetic pieces 84 facing the permanent magnet 85 via an electrode mounting base 88, and the electrode pieces 89 and the magnetic piece 84 facing the electrode pieces 89 form a capacitor. is formed. This capacitor is connected to the magnetic piece 84 and thus to the objective lens 8.
3 moves down in the tracking direction and changes, so
This capacitor forms a position sensor 90 that detects the position of the objective lens 83. Note that this lens actuator 82 is supported by a disk-shaped leaf spring 91 so that it can also move in the focusing direction F. In addition, a part that is moved by this leaf spring 91,
Electrode pieces 92 and 92 are respectively disposed on the fixed portion that faces this and is not moved, so that the position in the 7-occasing direction F can be detected from the capacitance of this capacitor. (This is described in detail in Japanese Patent Application Laid-Open No. 61-224143.) In this embodiment, the lens limit of the objective lens 83 is performed using the position sensor 90 with a configuration as shown in FIG. At the same time, lens dumping is also performed from the output of this position sensor 90. The lens actuator protection circuit 81 shown in FIG.
The output of the position sensor 90 is passed through the switch S5 to the LPF7.
1 and is also input to the lens dump generation circuit 91. The output of this lens dump generation circuit 91 is input to the adder 21 via the switch S4. ] The tracking roller 2 controls the ON/OFF state of the switch S1 via the AND circuit 74 using the tracking start signal as in the first embodiment. On the other hand, the switch S4 is turned on by the seek start signal and turned off by the tracking IJfl start signal. Further, the switch 85 is turned on by the i~ racking start signal. In addition to this, it is also possible to enable independent on/off control, and simultaneously instruct locking of the objective lens 13 by, for example, lens limit operation or lens dump. This embodiment is characterized in that the output of the position sensor 90 performs a lens limit function and a lens dump function. Although each of the above-mentioned switches Sl, S4, and 35 can be independently controlled on/off, the switches 84 and 85 may be controlled on/off by the tracking start signal as in the first embodiment. . In addition, as shown in the modified example of FIG. 14, when the roller 27 turns on the switch S1 via the AND circuit 74 with the tracking start signal, it turns on the switch 85 with the start signal. , switch S4 is connected to inverter 95. It can be turned off via the AA circuit 96 to perform lens limiting during tracking servo operation, and the output of the window energizer 73 is 111.
In the event of an error, the switch S4 may be turned on via the A circuit 96 in synchronization with the turning off of the switch S1 to dump the lens. The boxed portions in FIG. 14 have the same configuration as in FIG. 12. According to this modification, the lens dump i- functions to l.
If the racking servo becomes inactive, objective lens 1
3 moves to the neutral point. Therefore, it is possible to reliably prevent the objective lens 13 from moving beyond the allowable range of movement. In each of the above-mentioned embodiments, the objective lens is prevented from moving beyond the allowable range of movement; The same applies. It is also possible to detect the position of A in the focusing direction and prevent it from moving beyond a permissible level, and protect the object from dirt and the like. [Effects of the Invention] As described above, according to the present invention, since the iJ movement mechanism of the j7 Kubuyuator is prevented from moving 1J beyond the allowable range, the actuator is prevented from being overloaded. Prevents negative effects such as getting wet before.

[Brief explanation of the drawing]

1 to 11 relate to a first embodiment of the present invention, FIG. 1 is a configuration diagram of the first embodiment, FIG. 2 is a configuration diagram of an optical disc necking equipped with the first embodiment, and FIG. Figure t is an exploded perspective view showing the structure of the lens actuator, Figure 4 is an explanatory diagram of the track access movement collar, Figure 5 is a front view of the position sensor, Figure 6
The figure is an explanatory diagram of the operation of the position sensor. , Fig. 9 is a sectional view showing the structure of the semiconductor body sensor, Fig. 10 is a circuit diagram showing the structure of the !:]-bus filter, etc., and Fig. 11 is a sectional view showing the human output characteristics of the window comparator. Figure 12 shows the second embodiment of the present invention.
FIG. 13 is a block diagram showing the configuration of the embodiment, FIG. 13 is a schematic configuration diagram of the lens actuator Y-ta in the second embodiment, and FIG. 14 is a block diagram showing one main part of a modification of the second embodiment. This is a zero diagram. 58c...Semiconductor digital sensor 73...Window comparator 74...AND circuit Sl, 84. S5... Switch '1... Optical disk device 3... Optical disk 4...
...Optical pickup 7...Laser diode 13
...Objective lens 15...Photodetector 18...
Troughing coil 20... Performance circuit 21... Adder 27...
- Controller 28...Position sensor 29...Lens acticoator protection circuit 57...Light emitting element 58...Light t! Sensors 58Δ, 58b... (2-split) Vin sensor Fig. 4 Fig. 6 Fig. Sr Fig. 8 (a) (b) Fig. 12 E! ~ To Tomisaku Diagram Liu Yu Rome Figure 10 Figure 13 Figure 14 Diagram 7 To Sl Kazan "Kurehachi"

Claims (1)

[Claims] a tracking actuator that is displaceable to control the radial position of a scanning spot that scans a recording track on a recording surface of a recording medium; and an error signal that represents the amount of radial deviation of the scanning spot with respect to the recording track. a tracking servo means comprising an error signal generating means, a driving means for displacing the tracking actuator to reduce the amount of deviation in response to the error signal, and detecting the position of the objective lens or galvanometer mirror. an optical information reproducing device that reads information on a recording track by scanning the recording track with the scanning spot,
When the output of the position detection means deviates from the permissible range,
A protection device for an actuator, characterized in that a means for disabling the tracking servo means is formed.