JPS58155536A - Optical disc pickup device - Google Patents

Abstract

PURPOSE:To miniaturize a device and to decrease the cost, by providing the 1st and the 2nd actuator sections for both surfaces of an optical disc respectively, and switching selectively an optical path between them and a main body at a switching section. CONSTITUTION:The upper side of the optical disc 8 is provided with an actuator 100a having a galvano-mirror 6a and an objective lens 7a, and the lower side is provided with an actuator 100b having an objective mirror 6b and an objective lens 7b, and the actuators are moved in the radial direction of the disc 8 with a prescribed interval to record or reproduce signals on an arbitrary track of the disc 8. A switching section 200 having a reflecting plate 21 turning the light in the direction orthogonal to the straight advancing line direction is provided between the actuators and the main body 300, and the optical path of the light from a semiconductor laser 1 is switched selectively so as to go the actuator 100a or 100b.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical disc pickup device, and more particularly to an optical disc pickup device that can record or reproduce signals on both sides of an optical disc.

FIG. 1 is a perspective view showing the principle of a conventional optical disc pickup.

Below, a conventional optical disc pickup device will be briefly explained using an example during playback. As is well known, a light emitting source, for example a semiconductor laser 1, is provided, which defines the starting point of the path of the light emitted therefrom.

A collimating lens 2 is first provided on the optical path from the semiconductor laser 1, and the light from the semiconductor laser 1 is made into a parallel beam by the collimating lens 2. A diffraction grating 3 is provided in front of this optical path in order to separate the parallel light beam from the collimator lens 2 into three beams. The three beams pass through a polarizing beam splitter 4 and a quarter wavelength plate 5, are directed in a 90'' direction by an objective mirror 6 such as a carbano mirror, pass through an objective lens 7, and reach an optical disk 8.Objective The beam that has passed through the lens 7 forms three focused spots on the surface of the optical disk 8. Although not shown, there are minute irregularities called bits on the surface of the optical disk 8. The optical disc 8 is rotating at high speed, so the beam irradiated onto the optical disc 8 is modulated by bits, reflected, and re-enters the objective lens 7.The beam reflected by the optical disc 8 The beams pass through the objective lens 7, are changed in direction by 90' by the objective mirror 6, and return along the optical path via the quarter-wave plate 5.The beams are each reflected and separated into two by the polarizing beam splitter 4. One of them is changed in direction by 90 degrees, passes through a convex lens 9 and a cylindrical lens 10 in order, and reaches a photodetector 11. The detector is divided into six parts and has two sensitive areas (■) and (2) sandwiched between them. The reflected beam is incident on the areas ■ and ■.More specifically, the reflected beam corresponding to the center spot of the three condensed spots on the eight surfaces of the recording disk is incident on the sensitive area group, thereby causing the RF (Radl
o Frequency) signal and A/F (Out.

l:ocuslng) signal is obtained. The RP signal is
The A/F signal is a signal representing information recorded on the optical disc 8, and the A/F signal is transmitted through the objective lens 7 in order to prevent the condensed spot from being defocused on the surface of the disc 8 due to surface wobbling of the optical disc 8. A mechanism that moves the up and down direction (
(usually referred to as an A/F actuator), such as a voice coil (not shown). In addition, the remaining two of the three focused spots on the eight surfaces of the optical disk enter the sensitive areas ■ and ■, respectively.
A/T (Auto Trac) from two areas n and m
king ) signal is obtained. This A/T signal is applied to a galvanometer mirror, which is an objective mirror 6, in order to move the spot in the radial direction of the optical disc 8 so that the focused spot always follows the track on the optical disc 8 even when the optical disc 8 is eccentric. is fed back to the rotation mechanism (usually referred to as an A/T actuator). In the following description, the part of the pickup device that includes a mechanism for correcting the focused light spot so that it focuses on the surface of the optical disc 8 and follows the track, that is, the A/F actuator and the A/T actuator, will be referred to as the part of the pickup device. It is called the 7 Kuchiyu Engineering Department,
Further, the portion including the light emitting source and the photodetector is referred to as the main body portion.

As described above, in the conventional pickup device, the actuator section is provided only on one side of the optical disk, and one main body section is required for one actuator section. Therefore, in order to reproduce signals from the other side of the optical disc, a mechanism must be provided to turn the optical disc over, or the entire pickup device that is the same as that provided on one side must be provided on the other side. Therefore, in the former case, a wide range of equipment is required to turn over the optical disc, and in the latter case, expensive semiconductor lasers, photodetectors, etc. are additionally required, which leads to miniaturization of the pickup device. However, there were drawbacks such as limitations on price reduction.

Therefore, the main object of the present invention is to provide an optical disc pickup device that eliminates the above-mentioned drawbacks.

In summary, the present invention provides a switching section having an optical path switching means between the first and second seven cutter sections provided on one side and the other side of the optical disk, respectively, and the main body section. This is an optical disc pickup device that can selectively form respective optical paths to record or reproduce signals on both sides of an optical disc.

The above objects and other objects and features of the present invention will become more apparent from the detailed description given below with reference to the drawings.

FIG. 2 is a schematic diagram showing the principle of an embodiment of a pickup device according to the present invention.

The principle of this embodiment will be briefly described with reference to FIG. 2. The switching unit 2 includes a rotary reflector 21 in the optical path switching means to switch the light between the straight direction and the orthogonal direction.
00 is provided, and the actuator parts 100a and 1oob provided on both sides of the optical disc 8 and the main body part 30
0, each optical path is selectively formed between the two.

Specifically, a first actuator section 100a and a second seven-actuator section 100b are provided on one side of the optical disc 8, such as the top surface, and on the other side, such as the bottom surface. Actuator parts 100a and 1
00b is the objective mirror 6 as described with reference to FIG.
a and 6b and objective lenses 7a and 7b, respectively.

The actuator parts 100a and 100b move in the radial direction of the optical disc 8 at a predetermined distance from the optical disc 8 in order to reproduce or record a signal on an arbitrary track of the optical disc. The aforementioned reflecting plate 21, which is a feature of this embodiment, is provided in front of the optical path of the quarter-wave plate 5.

As shown in the figure, the reflector 21 reflects the light emitted from the semiconductor laser 1 as a light emitting source by changing the 90' direction, and reflects the light from the actuator section 100a and the main body section 300 described above.
The light emitted from the semiconductor laser 1 is made to travel straight through a first shape 1t (shown as a two-point chain) forming an optical path between the actuator section 100b and the main body section 300, forming a dark optical path between the actuator section 100b and the main body section 300. It rotates so as to realize the 26th state (indicated by a dotted line). Further, the light reflected by the reflector 21 is further reflected so as to change the direction 9007J so as to form an optical path between the actuator part 100a and the main body part 300 when the reflector 21 is in the first state. A fixed mirror 22 is provided. In this example, the reflector 21 and the fixed mirror 2
2 constitute a switching section 200.

In this way, the optical system of the pickup device shown in FIG.

In addition, in the above description, the optical relative relationship of each part was described, but the l1llllI relative relationship of each part will be described later.

FIG. 3 is a perspective view showing an example of the optical path switching means used in the embodiment of FIG. 2.

Referring to FIG. 3, a mechanism for rotating the reflecting plate 21 in FIG. 2 will be explained. The reflecting plate 21 is pivotally supported by an rLJ-shaped support base 23 consisting of a vertical portion 23a in which a hole 27 is provided and a horizontal portion 23b. The reflecting plate 21 and the vertical portion 23a of the support base 23 are connected by a spring 24, and the spring 24 elastically biases the reflecting plate 21 clockwise in the figure. However, due to the contact between the convex portion 28 provided on the reflector 21 and the stopper 29 provided on the support base 23, the movable angle of the reflector 21 is preferably within the range of Oo to 45°. limited. Further, a magnetic body 25 is attached to the surface opposite to the reflective surface of the reflective plate 21, and an electromagnet 26 is provided on the horizontal portion 23b of the support base 23. The magnetic material 25 is preferably iron or nickel. Therefore, when the electromagnet 26 is energized, the magnetic body 25 is attracted to the electromagnet 26 by magnetic force, so the reflection plate 21 rotates counterclockwise against the spring 24 and becomes horizontal, and the above-mentioned second take a state. Therefore, the light emitted from the semiconductor laser 1 (FIG. 2) goes straight without being reflected by the reflecting plate 21 and advances to the actuator section 100b (FIG. 2). Also, when the electromagnet 26 is turned off, the magnetic force disappears, so
The reflecting plate 21 rotates clockwise due to the elasticity of the spring 24. Then, the reflection plate 21 takes the above-described first state because the above-described convex portion 28 and the stopper 29 come into contact with each other.

In this way, depending on whether or not the electromagnet 26 is energized, the reflector 2
1 takes either the first or second state.

Note that a magnet may be used instead of the magnetic body 25 described above. In that case, by changing the polarity of the magnetic pole of the electromagnet 26, it becomes possible to rotate the reflecting plate 21 by the attractive force and repulsive force between the electromagnet 26 and the magnet without using the spring 24.

The operation will be explained with reference to FIG. For example, during reproduction, the light emitted from the semi-conductor laser 1 passes through the collimating lens 2, the diffraction grating 3, the polarizing beam splitter and the quarter-wave plate 5, as described above, and passes through the pickup device. The process moves from the main body section 300 to the switching section 200 (indicated by a dashed line). Switching section 20
0, the traveling direction of the light can be switched by the reflecting plate 21 taking two states as described above.

That is, when the reflection plate 21 takes the above-mentioned first state (indicated by the two-dot chain line), the direction of the light from the main body 300 is changed by 90 degrees by the reflection plate 21 (indicated by the two-dot chain line), If the vehicle takes the second state 11 (indicated by the dotted line), it will go straight (indicated by the dotted line). Light whose direction is changed by 90° by the reflector 21 (2
The dotted chain line) is further changed in direction by 90 degrees by the fixed mirror 22, advances to the actuator section 100a provided on the upper surface side of the optical disc 8, and is irradiated onto the upper surface of the optical disc 8. Therefore, when the reflector 21 is in the first state as an optical path switching means, an optical path is formed in the darkness between the actuator section 100a and the main body section 300, and as described with reference to FIG. The signal is played from the top.

On the other hand, due to the reflection plate 21 in the second state, the light (dotted line) traveling straight travels straight as it is and reaches the actuator section 100b provided on the lower surface side of the optical disc 8. Therefore, when the reflection plate 21 is in the second state, an optical path is formed between the actuator section 1oob and the main body section 300, and a signal is reproduced from the bottom surface of the optical disc 8. In this way, as a switching means, the reflecting plate 21 is used as the switching means, and the stone 316a
By setting the optical disc 8 to the first or twelfth state depending on the presence or absence of electricity (FIG. 3), it is possible to arbitrarily reproduce signals from the top or bottom surface of the optical disc 8, respectively.

FIG. 4 is a schematic diagram showing an example of the relative mechanical relationship between the actuator sections 100a and 100b, the switching section 200, and the main body section 300 of the embodiment shown in FIG.

In FIG. 4, actuator parts 100a and 10
0b moves on the upper surface side and the lower surface side of the optical disc 8, respectively, independently of the switching section 200 and the main body section 300. That is, actuator parts 100a and 1
00b are independent cases 50a and 50b, respectively.
It can be paid in

17) The cases 50a and 50b move in the radial direction of the optical disc 8 on the upper surface side and the lower surface side of the optical disc 8, respectively, by a sliding mechanism or the like.

On the other hand, the switching section 200 and the main body section 300 are preferably housed in a case 60 fixed to a base, and therefore do not move. Although cases 5(')a and bob are mechanically separated from case 60, cases 50a and 50b are connected from switching section 200 to actuator sections 100a and 100, respectively.
Since the actuator sections 100a and 100b move on the optical path (FIG. 2) leading to point b, the actuator sections 100a and 100b are always selectively and optically coupled to the switching section 200 housed in the case 60 and the main body section 300. It is in.

In the pickup device configured in this way, in order to move the seven actuator sections 100a and 100t onto any track on the optical disc 8, only the actuator sections 100a and 100b can be moved independently. Bye. Therefore, the movement can be performed using a motor with a smaller output than conventional ones.

Fig. ff15 is a schematic diagram showing an example of the principle of making the focused spot follow the track of the optical disk in response to the Δ/T signal.

In FIG. 5, the objective mirror provided in the actuator section 100 is a galvanometer mirror (FIG. 1) as in the conventional case.
Rather, it is a fixed mirror 16.

Therefore, in order to make the C1 focused spot follow the track, the actuator section 1oo is moved in the horizontal direction. In the pickup device according to the present invention, as shown in FIG. 4, the actuator section 100 can be uniquely moved by a small-output motor or the like. In this example, the actuator section is moved in the radial direction of the optical disk.
A slide mechanism etc. that can be used as an A/T actuator can be used as an A/T actuator, thus eliminating the need for a dedicated A/T actuator.

FIG. 6 is a schematic diagram showing another example of the relative mechanical relationship between the actuator parts 100a and 100b, the switching part 200, and the main body part 300 of the embodiment shown in FIG.

In the example of FIG. 6, seven cutter parts 100a and 10
0b, the switching section 200, and the main body section 300 are configured to be coupled into one structure. That is, the actuator parts 100a and 1 are placed in a U-shaped case 7o.
oob, a switching section 200, and a main body section 300. The case 70 sandwiches the optical disc 8 and moves am in the radial direction of the optical disc 8 using a slide mechanism or the like. Therefore, the actuator sections 100a and 1oob attached to the case 7o on the upper surface side and the lower surface side of the optical disk 8, respectively, can reproduce signals from any one rack on each surface of the optical disk 8.

In the pickup device configured in this way, the actuator sections 100a and 100b and the switching section 20
0 and the main body 300 are both connected to the case 70, and their relative position 11 does not change due to vibrations, etc., so the optical path is always stable and there are fewer malfunctions during signal reproduction or recording. .

FIG. 7 is a schematic diagram showing another example of the principle of causing a focused spot to follow a track of an optical disk in response to A/T (No. 1).

In the example shown in FIG. 7, the condensed spot is moved by rotating the galvanomirror 26 to change the angle and direction of the light incident on the objective lens 7, as in the prior art. therefore,? Without the actuator section 100 moving,
A light spot is made to follow the track using a galvano mirror or the like. In this method, as described with reference to FIG.
0 and the main body 300 (preferably configured) to move together.

FIG. 8 is a schematic diagram showing the principle of another embodiment of the optical disc pickup' device according to the present invention.

In FIG. 8, this embodiment differs only in the structure of the switching section from the embodiment shown in 2nd @l.

That is, in this example, the optical path switching means is provided with a deflection element 41 preferably made of a well-known acousto-optic material or an electro-optic material. As is well known, the optical properties of acousto-optic materials and electro-optic materials, such as refractive index, change upon application of a sound field and an electric field, respectively. Therefore, the deflection element 41 has its refractive index changed by the method described above and directs the light M(2) to the actuator section 100a.
A first state in which an optical path (indicated by dotted lines) is formed to the actuator section 100b, and a second state in which an optical path (indicated by dotted lines) to the actuator section 100b is formed. In this way, when the deflection element 41 is in the first state, the light incident on the deflection element 41 exits at an upward angle in the figure. Then the light is transferred to the switching section 4
The light is sequentially reflected by fixed mirrors 42a and 43a provided on the optical disk 8, and advances to the actuator section 100a provided on the upper surface side of the optical disk 8, and is irradiated onto the surface of the optical disk 8. Therefore, the main body part 300 and the acti IN-)'1 part 1
An optical path is formed between the optical disc 00a and the signal is reproduced from the upper surface of the optical disc 8.

Furthermore, if the deflection element 41 is in the second state, the signal is reproduced from the lower surface of the optical disk 8 (the optical path is shown by a dotted line) in the same manner as in the above case.

In this way, if the above-mentioned acousto-optic material or electro-optic material is used as the optical path switching means for switching the optical path, since these materials do not operate mechanically, vibrations will not occur when switching the optical path. .

Hereinafter, as shown in F, according to the present invention, the first and second actuator parts and the main body part, which are arranged on one side and the other side of the optical disc, respectively, are connected by a switching part having an optical path switching means. Each optical path can be selectively formed between the two. Therefore, actuator sections are provided on both sides of the optical disk, and two
Since only one main body is required for each actuator, a compact and inexpensive optical disk pickup device capable of double-sided reproduction or recording can be obtained.

In addition, although the above explanation has been about a pickup device that reproduces signals recorded on an optical disk, it goes without saying that this optical disk pickup device can also be used when recording signals on an optical disk. .

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the principle of a conventional optical disc pickup device. FIG. 2 is a schematic diagram showing the principle of an embodiment of an optical disc pickup device according to the present invention. FIG. 3 is a perspective view showing an example of the optical path switching means used in the embodiment of FIG. 2. FIG. 4 is a schematic diagram showing an example of the relative mechanical relationship between the actuator section, the switching section, and the main body section of the embodiment shown in FIG. 2. FIG. 5 is a schematic diagram showing an example of the principle of causing a focused spot to follow a track of an optical disk in response to an A/T signal. FIG. 6 is a schematic diagram showing another example of the mechanical relative relationship between the actuator section, the switching section, and the main body section of the embodiment shown in FIG. 2. FIG. 7 is a schematic diagram showing another example of the principle of causing a focused spot to follow a track of an optical disk in response to an A/T signal. FIG. 8 is a schematic diagram showing the principle of another embodiment of the pickup device according to the present invention. In the figure, 1 is a semiconductor laser, 8 is an optical disk, and 11 is a semiconductor laser.
is a photodetector, 21 is a reflector, 41 is a deflection element, 100a
, 100b is an actuator section, 200.400 is a switching section, and 300 is a main body section. Agent: Mr. Kuzuno (
Other 1 name) Kuzu 3 Figure 2 I 5 Figure 8 I Figure Atsushi 4 Figure Kuzu 6 Figure 100 α ;00 JqO00b Procedural amendment (spontaneous) Patent Office 12 Offices 1, Display of 1G Patent application 1984-38491i
No. 1, No. 2, Name of the invention: Optical Disc Pickup Device 3, hli+l: Detailed Description of the Invention in the Specification and Drawing 6, Contents of Amendment (1) Page 3, Line 18 of the Specification Corrected "objective mirror like F galvano mirror" to "R galvano mirror". (2) "Objective mirror" on page 4, line 9 of the specification was corrected to "r galvano mirror." (3) In the fourth part of the specification, lines 11 and 12, "Each is reflected and separated into two parts, and one of them is reflected by J.
” was corrected. (4) On page 5, lines 18 to 19 of the specification, "of the galvano mirror which is the objective mirror 6" was corrected to "of the r galvano mirror 6." (5) "Objective mirror" on page 8, line 9 of the specification was corrected to "galvano mirror." (6) "Objective mirror" in line 6 of page 15 of the specification was corrected to "mirror." (7) [Actuator unit 1] on line 9 of member 15 of the specification
00” was corrected to “Objective lens 7”. (8) Delete "In this example," to "Unnecessary." in Lines 13 to 17 of Part 15 of the specification. (9) “26” on line 6 of member 17 of the specification was corrected to “6”. (10) Comes with 1m! ll[I's fifth! ll and Figure 7 have been corrected as shown in the attached sheet. that's all

Claims (6)

[Claims] (1) It is movably provided on one side of the optical disc,
a first actuator section for forming a condensed spot on one side of the optical disk; and a first actuator section that is movable on the other side of the optical disk and for forming a condensed spot on the other side of the optical disk. A second actuator section, a main body section including a light emitting source and a photodetector, and a first or second actuator section, respectively, to selectively form an optical path between the first or second actuator section and the main body section. and a switching section including an optical path switching means that assumes a state, wherein the first or second state of the optical path switching means causes the main body section and the optical disc to be connected via the first or second actuator section, respectively. An optical disc pickup device in which an optical path is selectively formed between one side or the other side. (2) The first and second seven-unit processor sections are independent from the switching section and the main body section, and are characterized in that they are located on one side and the other side of the optical disc, respectively. The optical disc pickup device according to item 1. (3) The optical disk pickup device according to claim 1, wherein the first and second actuator sections, together with the switching section and the main body section, are located on one side and the other side of the optical disk, respectively. . (4) The optical disk pickup device according to any one of claims 1 to 3, wherein the optical path switching means includes a rotatable reflector. (5) The optical disc pickup according to any one of claims 1 to 3, wherein the optical path switching means includes an electro-optic material. (6) The optical disc pickup puller L according to any one of claims 1 to 3, wherein the optical path switching means includes an acousto-optic material.