JPS595442A - Optical pickup device - Google Patents

Abstract

PURPOSE:To put a compact disk to practical use, by using a platelike member which is long in the direction orthogonal to a crossing direction of a recording track, and is parallel to a signal face of a disk, in the middle part of at least one arm member. CONSTITUTION:As for an arm member constituted of a damper 30 and a blade 32, the blade 32 which is long in the Y axis direction orthogonal to a crossing direction of a recording track of a signal face, and is parallel to a signal face of a disk is used. Accordingly, a range in which a side wall 26 and a bracket 29 move relatively in the Y axis direction is a deformed portion generated by shearing deformation of the damper 30. Therefore, a movement of a housing of an optical system in the Y axis direction becomes a minute extent that can be disregarded. Accordingly, it is possible to generate no offset in an optical spot for reading a signal, therefore, it is possible to put an optical pickup device to practical use to a compact disk having a small diameter of the innermost circumference of a recording track of an information signal.

Description

[Detailed description of the invention] Information signal σ from a recording medium such as a disc]
This has been done with the aim of providing an optical pickup device that can also perform endogeneity satisfactorily.

The light from the light source is projected as a minute light spot onto the signal surface of an I/- recording medium equipped with a signal surface on which information signals are recorded, and the light reflected from the signal surface is Optical information signal reproducing devices capable of reproducing information signals have not been put to practical use, for example, as so-called video disc players, and have recently been put into practical use as so-called compact disc players. As is well known, this is currently being offered.

By the way, in the optical information signal reproducing device described above, at
When reading the active information signal on the signal surface of the recording medium, so-called focus control is used to align the condenser lens with the normal to the signal surface of the recording medium so that the signal surface of the recording medium is always in focus. In order to drive the optical system for displacement in the direction of the recording trace, or to ensure that the spot of light for reading the information signal is always located at the center of the recording trace, so-called tracking control is used to move the optical system to the recording trace. Therefore, it is necessary to drive displacement in the transverse direction, and currently commercially available optical information signal reproducing devices also perform focus control and tracking control.

Various methods have been proposed in the past for the focus error detection method when performing focus control and the tracking error detection method when performing tracking control, but as the focus error detection method, The so-called astigmatism method is also used as a trasoking error detection method.
The so-called 3-bee method (twin-spot method) has been put into practical use as the most stable method with the fewest defects among the various conventional methods. = It has also been adopted in video disc players.

Now, the video disc to be played by the video disc player mentioned above has a diameter of 110 mm at the innermost recording track, and the diameter of the recording track on the innermost circumference is as large as 110 mm. The shape and dimensions of the entire optical system used in the compact disc are large, but the outer diameter of the compact disc is 120 cm, and the diameter of the recording track on the innermost circumference is 46 cm (the original information signal is not recorded). The innermost record trace diameter is 50 pieces)
As such, it is smaller than a conventional video disc, so this compact disc ambiguous device (compact disc player) is used in a conventional video disc player. Of course, it is not possible to directly apply the large optical pickup straddling device that was previously used in compact discs, and as mentioned above, the diameter of the 5e recording track on the innermost circumference is small and the curvature of each recording track is thick, so trunking is difficult. Error detection [When the three-beam method is adopted, the optical spot for reading the information signal is
For example, if the disk is offset from a predetermined diametrical position due to eccentricity of the disk, assembly error of the optical axis, or other causes, the detection gain of the tracking error signal may vary significantly due to the warp.

In addition, in compact disc players, it is necessary to downsize the entire optical system so that the tracking error detection system can also be housed within it, and to do this, the detector etc. must also be downsized. This compact optical system requires higher precision than conventional large optical systems.

The present invention solves the above-mentioned conventional problems and provides an optical pickup device chamber capable of satisfactorily reproducing information signals from compact discs.
Hereinafter, specific details of the optical binoquag device of the present invention will be explained in detail with reference to the accompanying drawings.

FIG. 1 is a diagram showing a schematic configuration of an optical system in an optical pickup device of the present invention. In FIG. 1, 1 is a casing of the optical system; All components of the optical system are fixedly provided. M1
2 is the AE recording medium (disc), 2a is the AT recording medium 2
This is the signal plane.

3 is a light source, and as this light source 3, for example, a semiconductor laser may be used. 3a in the figure indicates a light emitting point. 4 is a collimating lens, 5 is a diffraction grating, 6 is a polarizing prism, 7 is a condensing lens, 11 is a quarter wavelength plate, 12 is a right angle prism, 13.14 is a cylindrical lens, 15 is a light receiving element,
The light emitted from the light source 3 is made into parallel light by a collimating lens 4, and then split into a transmitted light (0-order diffracted light) and two 1st-order diffracted lights by a diffraction grating 5, and the above three lights are After being reflected by the polarizing prism 6, it passes through a quarter-wave plate 11 (λ/4 plate) and is not applied to the condensing lens 7. Three light spots 8 to 10 are formed on the signal surface 2a.

The reflected light from the signal surface 2a of the disk 2 is passed through the condenser lens 7.
The light is given to the polarizing prism 6 through the λ/4 plate 11, but since this light is linearly polarized light whose plane of polarization differs by 90° from the linearly polarized light incident on the polarizing prism 6 from the diffraction grating 5. Then, it passes through the polarizing prism 6 and is applied to the right angle prism 12, where it is reflected and transmitted to the cylindrical lens 13.14.
incident on . The light passing through the cylindrical lenses 13 and 14 illuminates the light receiving element 15. The cylindrical lenses 13 and 14 are used to detect focus errors as an addition to the astigmatism method.

The center σ of the three light spots 8 to 10 formed on the signal surface 2a of the disc 2] The light spot 8 is a light spot for reading information signals; The two light spots 9 and 10 on both sides of the figure are light spots for detecting a tracking error signal.

The three light spots 8 to 10 on the signal surface 2a of the front Me L disc 2 are the recording traces 1. on the signal surface. ．． For example, with respect to 12°t3, they are arranged as shown in FIG. The signal surface 2aK of the disc 2 has each recording trace t1゜j
2+t3 is formed at the Be recording interval p (track pitch P), and when the light spot 8 is reading the information signal of the recording trace t2, the light spots 8 to 1O are formed by the length of the recording trace t2. They are lined up on a straight line that is inclined by an angle of θ in the current direction, and the light beams 1-9 and 10 on both sides are separated by a distance t from the center light spot 8.

Therefore, for the light spot 8 whose center is located on the center line of the record trace t2, the light spots 9 and 10 on both sides have their centers located on the center line of the record trace t2. On the other hand, they exist on opposite sides and are separated by d=tθ.

In this way, for the halo e record t2VrC read by the central light spot 8, the light spots 9 on both sides
．． Since the IO is arranged symmetrically, when the optical system is driven and displaced in the transverse direction of the recording trace so that the magnitude of the signal generated by the reflected light from the light spots 9110 on both sides is equal, the central light spot 9110 Spot 8 corresponds correctly to the record trace to be read, and a good reproduction signal can be obtained from the ae record traces.

The technique for detecting the tracking error signal described above is such that the row of light spots generated by the diffraction grating 5 exists completely in a straight line, and the distance t between the light spots is This is true only if the recording trace on the signal surface of the disc can be regarded as a straight line with respect to the above-mentioned interval t (for example, t is 30 μm), but as mentioned above, compact discs The innermost diameter of the original information signal distribution trace is as small as 50, and the recording trace has a dog-shaped curvature, so the center of the spot is on the center line of the 8e recording trace. When the center of the central light spot 8 is on a predetermined radial line of the disc, the distance d, a + d,, a( Figure 3 (a
), the center of the central light spot 8 is on the center line of the recording trace, and the center of the central light spot 8 is at a position indicating an offset δ from the predetermined radius line m of the disk.
Figure 3 (Figure B1) and the state where the disk is stretched from the predetermined diameter line (1) to the position indicated by the offset -δ (Figure 3 (0)
Distance d, b + d2 b, between the center of the light spot 9.10 on both sides and the center line of the recorded trace in Figure 1)
d, c + d2c are very different.

FIG. 3(a) is an explanatory diagram when the center of the central light spot 8 is located on the center line of the recording trace and on the predetermined radial line m of the disc, and in this case, The distance between the center of the light spot 9 and the center line of the recorded trace in 9.10 is d, a, and the distance between the center of the light spot 1o and the center line of the recorded trace is d2a. There is a relationship of d, a) d2a.

In addition, in No. 31N(b) Ig, when the center of the central light spot 8 is located on the center line of the recording trace, an offset of δ occurs to the right from the predetermined radius line m of the disk. This is an explanatory diagram of the case, in which the distance d between the center of light spono on both sides) 9.10 and the center line of the trace 8c'
lb + d2b has the relationship d, b) d2b, and the distances d, a
.

d, a (d, b, d2a<d2b) with respect to d, b.

Further, FIG. 3(C) shows that when the center of the central light spot 8 is located on the center line of the recording trace, the distance δ (one δ in the figure) is shown to the left from the predetermined radial plane of the disk. 9. This is an explanatory diagram of a case where an offset occurs, and in this case, there is a gap between the lights on both sides. , 10 and the center line of the recorded trace are in the relationship d, c) d2c, and the distance d in the case of Fig. 3 (Fig.
, a, d, b, d, a) d, c.

It has the size shown by the relationship d2 a) d2c.

In addition, in FIGS. 3A to 3C, R indicates the radius of the recording trace.

Previous MElr: The offset δ is caused by the installation error of the optical pickup device or the eccentricity of the disk, but the offset δ is caused by the former cause.The offset δ is caused by direct current, and the offset δ is caused by the latter cause. δ
is an exchange-like thing. And the offset δ of the previous ae
If this occurs, the distance between the center of the light spot 9.10 on both sides and the center line of the recording trace will change as described above, and the spot 9.10 of the light on both sides will change as described above.
The amount of superimposition between 10 and the recording trace changes, and the tracking signal detection gain changes accordingly, which adversely affects the stability of the tracking control system.

In Table 1, the central light spot 8 is the center line of the recorded trace.
In a state where the above-mentioned offset δ occurs, the CO7 Bact disc player's !・This table is provided as a document to explain how much influence it has on the ranking control system.This table 1 is based on the case where the radius R of the GE record is 25 mm and the distance between adjacent light spots. t
This is a numerical example in the case where is 30 μm.

(Table 1) In Table 1, the distance between each center of 9.10 (spora of light on both sides) and the center line of the e-recording is d,, d, (already mentioned in Figure 3 (a) - (C) In explanations of figures, subscripts a to C
However, when the above-mentioned interval is generally indicated, it is used without the subscript a''-c.), d,)
It is clear that there is a relationship of d2, and the interval d
1 and the distance d2 (a+a2) shows a constant value of 0036 μm regardless of the value of δ.

As mentioned above, in a state where the central light spot 8 is located on the center line of the 5C recording trace, that is, in a state where the central light spot 8 is correctly tracking the recording trace due to tracking control, the central light spot 8 on both sides The difference (d, -d
,,) always show a constant value, so there is always a constant difference between the outputs obtained by photoelectrically converting the reflected light from the light spots 9.10 on both sides mentioned above. be.

Then, by adding a bias corresponding to the value of (d+a2) mentioned above to the output signal that cannot be obtained from the reflected light from the light spot 10 [j], the central light spot 8 is aligned on the center line of the recording trace. It is necessary to ensure that the photoelectric conversion output value of the reflected light by the light spot 9-0 is the same when the light spot 9-0 is correctly positioned. What is necessary is to set the photoelectric conversion output value to be the maximum value when the reflected light from the filter is applied. In this way, the l racking signal (output gain is ((d, +a2
) is determined corresponding to +0.0361.

The values in the MdB column in Table 1 indicate that the offset δ is O
17) [(d, 10d2) + 0.0361
The values in the + (d, -1-d2) + 0.036 j column corresponding to each value of the offset δ are expressed in dB, with the column otw in OdB.

In order for a tracking control system to be stable, it is necessary that the gain fluctuation of the system be less than a few dB, and on the other hand, since the disk usually has eccentricity close to ±100 μm, it is difficult to use an optical pick. Since there is almost no tolerance for errors in the mounting position of the 7SOP device, the optical pickup device is mounted by adjusting it in the tangential direction of the recording trace so that the tracking error signal has a predetermined gain. Be done.

In addition to the above-mentioned trunking control operation, the Pink 7 Nop device also has an approximately ±
A focus control operation is also performed within the range of 1.0 mm, but if this focus control operation cannot be performed perpendicularly to the signal surface of the disk, a dynamic offset will occur as a result.

Generally, the movable part of an optical pick-up device is supported by an elastic body, so if there is a weight imbalance in the device, resonance may occur in the tangential direction of the ME' recording during focus control operation. However, the above operation (ail) is undesirable, so the optical pickup device of the present invention is constructed in a way that can suppress it, and this point will be made clear in the Be section below. ing.

In the optical pickup device of the present invention, in order to downsize the player using the bow, the optical system is bent by using a right-angle prism 12 as shown in FIG. Although the structural members of the system are concentrated and the structural rigidity cannot be improved, the center of gravity of the optical system is inevitably moved to a position away from the optical axis of the condenser lens 7.

By the way, if the driving force for displacing the optical system is applied to the center of gravity of the optical system, the optical system exhibits ideal movement in that it is displaced only in the direction of the driving force. Even if the drive is modified, the dynamic offset described above does not occur.

Therefore, in order to ideally drive the displacement of the optical pink-up device that is connected to the optical system configured as shown in Figure 1, it is sufficient to install a drive coil at the center of gravity of the device. Of course, as mentioned above, the first
An optical system with the configuration shown in the figure is used
In the disc device, the drive coil installed corresponding to the center of gravity of the condensing lens 7, which is located away from the optical axis, allows the optical pink-up device to detect the recording traces on the innermost circumference of the disk. When the information signal cannot be read out, the drive coil is placed at the center of gravity of the optical pick amplifier because it overlaps with the space occupied by the motor installed to drive and rotate the disk. Installed on γ
In this case, the optical pink-up device cannot access the recording trace Vc7 on the innermost circumference of the disc.

However, in an optical pink-up device in which the optical system having the configuration shown in the first figure is used, the mounting position of the drive coil is located away from the center of gravity of the optical pickup device. , when the optical pickup device is driven by the drive coil, a twisting torque is applied to the device corresponding to the difference between the mounting position of the drive coil and the position of the center of gravity of the device. Although offset may occur, the optical pickup device of the present invention uses a special support structure as described below, which can effectively suppress undesirable movements that may occur due to the above reasons. It is solving a problem.

FIG. 4 is an exploded perspective view of an embodiment of the optical pickup device of the present invention, in which 1 is a housing of the optical system, 2
indicates the position of the disc for reference, and
The rectangular coordinate system of x, y, and z is used to explain the movement direction of each part and the configuration of each component, which will be described later.

In FIG. 4, the drive coils 20 and 21 fixed to the optical system housing 1 are driven by the electromagnetic force generated by the rich current flowing in the name and the DC magnetic field in the DC magnetic field generator. It is provided to displace the optical system housing l in a direction perpendicular to the signal surface of the disc 2 (Z-axis direction) by VC drive, and a focus control signal is supplied to the drive coils 20 and 21. Nero.

Reference numeral 23 is a direct current coil used in correspondence with the drive coil 20, and the above-mentioned DC current is applied to the E-shaped yoke 23a in the counter-clockwise magnetic gap formed between the center pole 23c and the permanent magnets 23b, 23b. The drive coil 2o is inserted into the groove, and this DC magnetic field generator 23
is fixed to the top plate of the case 27 as shown in the fifth figure.

The DC magnetic field generator 24 that cooperates with the drive coil 21 also has an E-shaped yoke 24a, a permanent magnet 24b5, a center hole 24c, and an E-shaped yoke 24a, similar to the DC magnetic field generator 23 described above. is fixed to the top plate of the case 27, the center pole 24c and the permanent magnet 24
The drive coil 21 is inserted into the magnetic gap formed between the

Reference numeral 22 denotes a diro drive coil fixed to the optical system housing 1, and when a tracking control signal is supplied to the drive coil 22, the DC magnetic field generator 25
Due to the electromagnetic force generated between the casing 1 of the optical system and the DC magnetic field in the In the state of being fixed to the side wall 26, it has a permanent six stones 25b.

In the magnetic gap between 25b and center pole 25c,
Allow the drive coil 22 to be inserted. Figure M5 shows the drive coil 20.22 and the DC magnetic field generator 23.2.
The relative positional relationship with 5 is not shown.

The bottom plate 1a of the optical system housing 1 is the tamper 28a to 28.
c (The individual tampers 28a to 28c are connected to the bottom surface 29a of the bracket 29 without distinction, and the vertical surface 29b of the L-shaped bracket 29 described above is connected to the bottom surface 29a of the tamper 3.
It is connected to the side wall 26 of the case 27 by a parallel spring mechanism consisting of a plurality of tiltable arm members constituted by a plate 32, a tamper 30, a column 31, etc., and is therefore connected to the side wall 26 of the optical system. 1 is supported so as to be movable both in the normal direction of the signal surface of disk 2 (Z-axis direction) and in the direction across the g-bee needle mark on the signal surface of disk 2 (X-axis direction). be.

That is, in FIG. 4, 16a to 16c are provided on the bottom plate 1a of the optical system housing l, and f, = tamper 28a.
~28c mounting hole,"! f -17a ~17
c is a mounting hole for the dampers 28a to 28c provided on the bottom surface 29a of the L-shaped bracket 29;
The damper 8a is mounted using the mounting holes 16a and 17a, the damper 28b is mounted using the mounting holes 16b and 17b, and the damper 28c is mounted using the mounting holes 16c and 17a.
Attach using 7c.

Also, the vertical surface 29b of the L-shaped bracket 29 and the side wall 2
A parallel spring mechanism consisting of a plurality of tiltable arm members provided as a support mechanism between the tamper 30, the plate 32, the column 31, etc. can be constructed as follows (see below). In the description, a plurality of dampers 30, 30
. . . and columns 31 and 31, etc., please add the letters alphabento to distinguish them from each other.)

In the fourth density, the vertical surface 29b of the L-shaped bracket 29
33-36 in K, 37-40 in side wall 26,
The holes 41 to 44 in the bracket 32, 45 to 48 in the column A31, etc. are the mounting holes for the damper 30, and the mounting holes 41 in the plate 32 and the L-shaped bracket 2
The damper 30 a is not attached to the attachment hole 33 of the vertical surface 29b of the 9, and the damper 3o is attached to the attachment holes 43 and 35.
C of the tamper 30 is not installed, and in the same manner, the tamper 30 B is installed in the mounting holes 42 and 37, and the tamper 3 is installed in the mounting holes 39 and 44.
0, d for the tags 34 and 45, e5 for the damper 30, f for the mounting holes 46 and 38, and f for the mounting holes 36 and 47 for the tamper 30.
The g of the tamper 30 and the h of the damper 30 in the mounting holes 48 and 40 are constituted by a parallel mechanism with a tiltable arm recess, and no support mechanism is provided. , the optical system housing 1 has a tamper path, as shown in FIG.
30, the bracket 29 and the column 31, the plate 32, etc. are elastically supported against the side wall 26.

Figures 5 and 6 show a neutral position in which the dampers 28, 30, etc. are in a non-strain state and are heavily wound. It is made to be located correctly at the center position in the magnetic gap in the generators 23-25.

The bottom plate 1a of the optical system housing 1 is shown in FIG.
Since it is fixed to the bottom surface 29a of the bracket 29 via the tamper 28, the housing 1 of the optical system is driven by the current from the drive coil 2HC, and the optical system housing 1 swings around the damper 28 as shown by the arrow in FIG. By swinging in the direction A, the optical axis of the condensing lens 7 also tilts, and the light spot moves in a direction that traverses the recording trace on the signal surface of the disc.

In the configuration example shown in FIG. 4, the bottom plate 1 of the optical system housing 1
The damper 28a='18c, which is interposed between the bottom surface 29a of the L-shaped bracket 29 and the damper 28a, is provided so that only the damper 28a is located on the swing center line Q-Q. , the other two dampers 28b and 28c are provided at positions seven distances apart from each other, not from the center line of oscillation.
f It is located offset from the center line of swing.
, l: This is to adjust the mechanical resonance frequency of the movable part to one that allows stable and good operation of the tracking control system by changing the spring constants of the returners 28b and 28c. Note that when the distance Xa between the tamper 28b and the damper 28c is increased, the spring constant of the tamper 28b and the tamper 28c increases.

As mentioned above, the tampers 28a to 28c are placed on the bottom surface 29a.
The housing 1 of the optical system is attached through the vertical surface 29b of the L-shaped platen plate 29 and the side wall 26, and there are tampers 30 a to d and a plate 32 below. The arm member and the tamper 30 e + f (!:
The arm member consisting of 1 of the column 31 and the g of the tamper 30
.

h and the flamm 31, each arm constitutes a flexible support that functions as a parallel spring mechanism, and the flexible support serves as an optical support. The L-shaped bracket 29 to which the system casing 1 is attached is supported so as to be moved only in the direction parallel to the side wall 26, as shown in FIG.

Due to the electromagnetic force generated by the current flowing through the drive coil 20.21 and the DC magnetic field generated by the DC magnetic field generator 23.24, the optical system housing 1 is driven and displaced in the Z-axis direction. Now, the elifocus control operation is performed.
When performing this operation, the drive filter 20.
Even if there is a difference in the thrust generated by each of the two drive coils 20 and 21, the result is that even if the combined thrust of the thrust generated by the two drive coils 20 and 21 does not pass through the center of gravity of all movable bodies, The parallel spring mechanism configured as described above has an eighth support mechanism.
Having a parallel motion characteristic as shown in the figure [Eri,
The housing 1 of the optical system can perform correct movement for focus control within the Z-X plane.

In the embodiment shown in FIG. Since the plate 32 is elongated in the direction perpendicular to the transverse direction of the recorded trace on the disk surface and is parallel to the signal surface of the disk, the side wall 26 and the bracket 29 are aligned in the Y-axis direction. The range of relative movement is the deformation (9th
γ) in the figure. Furthermore, the range in which the optical system housing 1 moves relative to the bracket 29 in the Y-axis direction is also
Three tampers 28a and 28c cv not shown in the figure
This is only the deformation caused by shear deformation.

The displacement of the optical system casing 1 due to the shear deformation caused by the a-%-d of the tamper 30 and the damper 28a (Fig. This is extremely small compared to the amount of displacement of the optical system housing l caused by the deformation.

Well, when the optical system housing 1 is being driven in two axes, the force that causes the optical system housing 1 to be displaced in the Y-axis direction is the X@length direction thrust (or the Z direction thrust). This is caused by the thrust in the Y-axis direction (rho) or vibrations from the outside, which are extremely small.

Therefore, this small force in the Y-axis direction is applied to the tamper 30.
28 etc., almost no shearing deformation occurs in the tampers 30, 28, and therefore no shearing deformation occurs.
The amount of movement of the optical system housing 1 in the Y-axis direction is negligible.

In addition, neutral dampers provided on both sides of the plate 32,
As shown in FIGS. 10 and 11, when the optical system casing 1 is sheared in the opposite direction vertically, it is tilted, but since the amount of shearing deformation of the front damper is small, The amount of inclination of the optical system described above is also small, and therefore the movement of the optical axis in the Y-axis direction due to the inclination of the casing 1 of the optical system can be ignored.

Next, let us further explain the above-mentioned features of the support mechanism using the parallel spring mechanism. The radius of the tamper is r, the longitudinal elastic modulus of the tamper is E, and the spacing between the tampers is L.
(Refer to figure lE6), and the thickness of the tamper is Vt.
The spring constant of the tamper 30 in the Z direction is expressed by the following equation (1).

If the shear spring constant when the damper 30 undergoes shear deformation as shown in FIG. The ratio between the Z-direction spring constant and the shear spring constant expressed by equation (2) is expressed by the following equation (3).

Now, the distance between Tampa is 10. , the radius r of the tamper is 15W
nrl, then K/ = 0.135,
Kone corresponds to -17.4 dB. By the way, the crosstalk of the driving force in the 7-IY axis direction can usually be suppressed by -20 dBK by focus control, etc., so for example, if the housing 1 of the ERI optical system is displaced by ±1 for focus control, The amount of movement of the optical system housing 1 in the Y-axis direction is (-17,4aB)+(
-2 oag) = -374 an, ±13.5 μm.

The above-mentioned value of ±135 μm is shown in Table 1 [Also, since the value of offset δ, for example, is smaller than 0.1 tan Ic, the value of ±1 It can be seen that the movement in the Y-axis direction that occurs when the system housing 1 is driven and displaced in the Y-axis direction for focus control does not have a large adverse effect on the tracking control operation.

±1, the amount of offset based on the shear deformation of the tamper that occurs under the conditions shown in Figures 10 and 11 is as follows:
It is even smaller than the amount of movement obtained in the fc numerical example, and furthermore,
The amount of movement due to shear deformation in the Y-axis direction between the optical system casing 1 and the planar node 29 is also the same as in the numerical example-17 mentioned above.
It is expressed as 4 dB, which is 1/3 of the amount of movement, and does not pose any problem.

In the embodiment shown in FIG. 4, if the offset δ is approximately ±100 μm, including the eccentricity of the disk, the gain fluctuation of the tracking servo loop will be within several dB, and the tracking control operation will be stable. And, although it should be done well, it is fully possible to realize it even in terms of compact disc standards.

In addition to the fluctuations in the tracking loop gain due to eccentricity described above, fluctuations in the tracking loop gain also occur due to deformation of the recording trace on the signal surface of the disk and changes in the light intensity of the semiconductor laser. is the sum total of the amount of variation due to the various causes mentioned in 1 above, and its value cannot be ignored.

In order to suppress fluctuations in the tracking loop gain, add the signal outputs of the light spots 9, 101C, l: on both sides using an adder 40, as shown in FIG. , calculate the difference between the output of the adder 40 in the previous section 5e and the constant C using the subtracter 43, and calculate the difference between the output of the adder 40 in the previous step 5e and the constant C, and also calculate the difference between the output of the adder 40 in the previous section 5e and the subtractor 43 on both sides.
10 is output from the subtracter 41, the output from the 5 subtracter 41 is given to the automatic gain control circuit 42vc, and the gain of the automatic gain control circuit 42 described by Ail is applied to the output signal from the subtracter 43 described above. It should be controlled by Jl.

In the embodiment shown in FIG. 4, only the lower arm member or plate 32 is used, and the upper arm member is made of a tamper 30 and a flamm 31. However, in carrying out the present invention, the upper arm member may be composed of a tamper 30 and a plate 32, and may be made up of a single piece, similar to the lower arm member. Compared to the embodiment shown in FIG. 4, the offset amount can be Y 1/2 vc.

In addition, as mentioned above, the plate 32 can also be used as an upper arm member.
The first thing you want to do is to use the following:
The installation of the direct current magnetic field generator 24 must be different from that in the embodiment shown in FIG.

FIG. 12 is a diagram showing another embodiment of the optical pickup device of the present invention, and in the embodiment shown in FIG. A tamper 28 is provided between the optical system housing 1 and the plate 27a.

In the device of the embodiment shown in the twelfth figure, since the bracket 29 does not move up and down, the advantage of reducing the mass of the movable part during the focus control operation cannot be obtained.

As is clear from the above detailed explanation, the optical pickup device of the present invention includes two or more tiltable arm members connected to a movable member including a housing of an optical system. 2, wherein at least one of the arm members in the parallel spring mechanism is substantially tiltable only in a direction transverse to the recording needle track on the signal surface of the disc. ), an elastic body is connected to at least the four corners of the plate-like section, which is long in the middle part in a direction perpendicular to the transverse direction of the 5e record and parallel to the signal surface of the disc. The support mechanism has a structure that includes an optical system housing that is movable in the normal direction of the signal surface of the disk and in the direction that traverses the recording trace on the signal surface of the disk. Since the movable part including the disc is supported, when the movable part is driven and displaced in the normal direction of the signal surface of the disk for focus control, it is offset to the light spot for signal reading. This makes it possible to use the three-beam method with the highest tracking error detection sensitivity in the optical pick Z-tub device, and also eliminates the offset of the light spot, which is the weak point of the three-beam method. Since fluctuations in the tracking signal detection gain cannot be suppressed, the diameter of the innermost circumference of the information signal recording trace is set to 50. , l, the optical pick 7 device of the present invention is cantilevered with respect to the center of the disk, opposite the supported side of the optical system housing l. Since an empty space is formed on the side, a light spot for signal reading can be easily accessed to the recording trace on the innermost circumference of the disk. To provide a substantially compact optical pickup. becomes possible.

Further, since the optical pickup device of the present invention has a structure in which the housing of the optical system is supported such that its longitudinal direction is in the direction in which the recorded traces of the disc extend, the outermost peripheral part of the disc The dimension from the center of the disk to the outside of the optical pickup device when reading the information signal from the recorded trace is small, and therefore a compact information signal reproducing device can be constructed.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an optical information signal reproducing device including an optical pickup device of the present invention, and FIG. 2 is a plan view showing the positional relationship between a recording trace on a disk and three light spots. Figures 3 (a) to (C) are diagrams showing the positional relationship between the three light spots and the recording trace depending on whether or not the reading light spot is offset, and Figure 4 is an optical pick of the present invention. 5 and 6 are partial sectional views of the optical pickup device of the present invention, and FIGS. A side view showing the state of the system casing and tamper; Figure 8 is a partial side view of the support mechanism during focus control operation;
Figure 9 is a plan view showing the displacement of the tamper in the Y-axis direction;
Figure 0 is a side view of the plate to show the movement of the support mechanism that causes an offset from the rotation VC of the optical system housing around the X axis, Figure 11 is a side view of the same, and Figure 12 is the optical pink of the present invention. FIG. 4 is a cross-sectional view of another embodiment of the up device. 199. Optical system housing, 2...recording medium (disc)
, 2a... Signal surface, 7 - Condensing lens, 8 to 10...
・Spot of light, 20-22. Drive coil, 23-25
...DC magnetic field generator, 26...side wall, 27...
・Case, 28a-28c, 30 Tampa, 29...
・L-shaped placket, 31...column, 32...plate, patent applicant: Victor Japan Co., Ltd.

Claims (1)

[Claims] l Light from a light source is projected as a minute light spot onto the signal surface of a recording medium equipped with a signal surface on which an information signal is recorded, and the reflected light from the signal surface is An optical pickup device for an information signal reproducing device which reproduces an information signal based on the information signal, and includes a condenser lens for forming a light spot Y on a signal surface of a recording medium. The housing of the optical system is flexibly supported so as to be movable in the normal direction of the signal surface of the recording medium and in the direction across the recording trace on the signal surface of the recording medium. As a support mechanism that flexibly supports the optical system casing in a movable direction normal to the signal surface of the recording medium, two or more members connected to the movable member including the optical system casing a parallel spring mechanism having tiltable arm members, wherein at least one arm member of the arm members in said parallel spring mechanism is tiltable substantially only in a direction transverse to a recording trace in a signal plane of a recording medium; As shown in the figure, an elastic body is connected to at least four corners of a plate-like member that is long in the direction perpendicular to the transverse direction of the recording trace in the middle part of the recording medium and is provided parallel to the signal surface of the recording medium. An optical pick-up device 2 is used in which the light from the light source is transmitted to the signal surface of the GE recording medium, which is equipped with a signal surface on which information signals are recorded. An optical pink-up device for an information signal internal generation device that projects as a spot and reproduces the information signal based on the reflected light from the signal surface, the device comprising:
It is composed of a condensing lens to form a light spora (Y) on the signal surface of the recording medium, and the casing of the optical system is
An optical system that is flexibly supported so as to be movable in the normal direction of the signal surface of the e-recording medium and in the direction that traverses the recording trace on the signal surface of the recording medium. The support mechanism that flexibly supports the casing in a manner movable in the normal direction of the signal surface of the recording medium includes a fixed part that is arranged parallel to the direction in which the recording traces extend on the signal surface of the recording medium. and one side of an L-shaped planknod, the parallel spring mechanism having two or more tiltable arm members disposed between the arm member and one side of the L-shaped plank, the arm member of the parallel spring mechanism having at least one tiltable arm member. The arm member has a shape elongated in the direction perpendicular to the transverse direction of the recording trace at the middle part of the rib so that the arm member can be substantially tilted only in the transverse direction of the Me recording trace on the signal surface of the recording medium, and The plate-shaped member is provided parallel to the signal surface of the recording medium, and the elastic body is connected to at least the four corners of the plate-shaped member. , the other surface of the L-shaped bracket and the bottom surface of the optical system casing so that the casing of the optical system can swing around a line parallel to the direction in which Se recording traces extend on the signal surface of the recording medium. and an optical pickup device 3 connected by an elastic body arranged in the required manner between the two.With respect to the signal surface of a recording medium having a signal surface on which an information signal is not recorded, An optical pickup device for an information signal reproducing device that projects light from a light source as a minute light spot and reproduces an information signal based on the reflected light from a signal surface, and is a recording medium. Form a spot of light on the signal surface of the recording medium The casing of the optical system, which includes a condensing lens, is aligned in the normal direction of the signal surface of the recording medium and in the direction that crosses the recording trace on the signal surface of the recording medium. In a device configured to be flexibly supported so as to be movable, the support mechanism that flexibly supports the housing of the optical system so as to be movable in the normal direction of the signal surface of the recording medium is: A parallel spring mechanism comprising two or more tiltable arm members provided between a wall surface of a housing of an optical system and one surface of an L-shaped bracket, wherein the arm members of the parallel spring mechanism include: At least one arm member has a shape elongated in the direction orthogonal to the transverse direction of the recording trace in the middle part of the seventh arm so that it can be substantially tilted only in the transverse direction of the recording trace on the signal surface of the 8e recording medium. and a plate-like member provided parallel to the signal surface of the ME' recording medium, with elastic bodies connected to at least four corners of the plate-like member. In addition, the movable member including the optical system casing swings about a line parallel to the extending direction of the recording trace on the signal surface of the recording medium. an optical pickup device in which a fixing member is arranged between the two in a desired arrangement manner and connected by an elastic body.