JPS61199250A - Optical recording and reproducing device - Google Patents

Abstract

PURPOSE:To make precise alignment unnecessary to make an optical head and shorten the access time by providing a fiber which receives a laser light and transmits it to a recording medium and another fiber which receives a signal light from the irradiated part of the medium and guides it to a sensor. CONSTITUTION:The emitted laser light of a semiconductor laser element 10 is condensed on an incidence-side end face 14 of an optical fiber 12 for irradiated light transmission by a lens 15, and the laser light propagated in a fiber 12 is diffused from an exist-side end face 16 and is condensed on the recording surface of an optical recording medium by an objective lens 18. Meanwhile, the reflected light from the optical recording medium is received by an incident- side end face 22 of optical fibers 20 for reflected light transmission which are bundled around the fiber 12. These optical fibers 20 are branched into two, and the reflected light if guided to an optical sensor 28 for information signal detection and an optical sensor 30 for focusing and tracking signal detection from exit-side end faces 24 and 26.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an apparatus for recording or reproducing information using light from an optical recording medium such as an optical disk or a magneto-optical disk.

Prior Art A format in which, in order to record and reproduce information, a laser beam output from a laser light source is converged and irradiated onto an optical recording medium, and the reflected light from the irradiated part of the optical recording medium is detected by an optical sensor. An optical recording/reproducing device is known. This type of optical recording and reproducing device has a complex and precise structure that focuses laser light and irradiates it onto an optical recording medium, and uses an optical sensor to detect the reflected light from the irradiated part of the optical recording medium. It is equipped with an optical head. For example, as shown in FIG. 35, a laser beam output from a laser light source 200 is collimated by a collimator lens 202, passes through a polarizing beam splinter 204, a 1/4 wavelength plate 206, and is transferred to an optical recording medium by an objective lens 208. 210. The reflected light from the optical recording medium 210 is reflected by the objective lens 2.
After passing through the 08.1/4 wavelength plate 206, the light is reflected by the polarizing beam splinter 204, passes through a convex lens 212, a cylindrical lens 214, and enters an optical sensor 216.

The optical sensor 216 includes a plurality of photodetecting elements and outputs not only an information signal but also a tracking signal and a focusing signal. An objective lens optical axis direction driving device is provided that drives the objective lens 208 in the optical axis direction based on the focusing signal in order to cause the laser beam spot to follow the fluctuation in the optical axis direction of the recording surface of the optical recording medium 210.
Further, an objective lens optical axis vertical drive device or a tracking mirror and its drive device are provided to swing the laser beam spot so as to follow the track of the optical recording medium 210 based on a tracking signal.

Problems to be Solved by the Invention However, in such conventional devices, the optical head includes a laser light source, a collimator lens, a roof mirror or a polarizing beam splitter, a quarter-wave plate, an objective lens, a convex lens, and a cylindrical lens. , a highly rigid frame body that maintains various optical components such as optical sensors and their relative positions with high precision is installed, so the overall shape and weight of the optical head is large (which makes access time sufficiently small). Can not.

Furthermore, since there are many optical components, there is a drawback that the loss of light quantity increases and the efficiency decreases, and the apparatus becomes expensive because it is necessary to increase the precision of the optical components and their relative positions. This inconvenience becomes particularly noticeable when multiple types of laser light sources are used or when multiple locations on an optical recording medium are irradiated with laser light.

Means for Solving the Problems The present invention has been made against the background of the above circumstances.
The gist of this is that in order to record and reproduce information, laser light output from a laser light source is focused and irradiated onto an optical recording medium, and signal light from the irradiated part of the optical recording medium is sent to an optical sensor. An optical recording and reproducing device of the type that detects the optical recording medium, which (1) receives and transmits a laser beam output from the laser light source on one end surface, and emits the laser beam toward the optical recording medium from the other end surface. and (2) an optical fiber for transmitting signal light that receives signal light from the irradiated portion of the optical recording medium on one end surface and guides it to the optical sensor.

In this way, the light irradiated from the laser light source onto the recording surface of the optical recording medium is transmitted via the irradiation light transmission optical fiber, and the signal light from the optical recording medium, that is, the reflected light or The transmitted light is transmitted to the optical sensor via the signal light transmission optical fiber. Therefore, the objective lens moves the light source part such as a laser light source or collimator lens and the detection part such as a convex lens, cylindrical lens, or optical sensor while facing the optical recording medium and moves along the recording surface of the optical recording medium. Since the relative positional relationship with respect to the objective part such as The highly rigid frame is made smaller, and the optical head becomes smaller, lighter, and less expensive.

Furthermore, since the optical head is small and lightweight, the inertial weight is reduced and access time can be shortened.

In particular, if only the objective part of the optical head is made a movable head movable part, the inertial weight is further reduced and the access time can be significantly shortened. Furthermore, when the light source section and the detection section are on the same side with respect to the optical recording medium, a polarizing beam splitter for separating the irradiated light and the reflected light is provided.
Since the /4 wavelength plate and the like are not required and the number of parts is reduced, the optical head can be made more compact and has higher optical transmission efficiency.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a schematic diagram showing the main part configuration of an optical head of an optical recording/reproducing device.
The light is focused by a lens 15 on the incident side end face 14 of the irradiated light, thereby optically coupling the irradiated light transmission optical fiber 12 and the semiconductor laser element 10. The laser light propagated within the irradiation light transmission optical fiber 12 is diffused from its output side end face 16, but is focused by the objective lens 18 onto the recording surface of an optical recording medium (not shown). That is, when reading information recorded on an optical recording medium or recording information on the optical recording medium, a desired position of a track formed on the recording surface of the optical recording medium is irradiated with a laser beam spot. .

The reflected light from the optical recording medium is received by the incident side end face 22 of a large number of reflected light transmission optical fibers 20 bundled around the outer periphery of the irradiated light transmission optical fiber 12. The optical fiber 20 for transmitting reflected light is branched into two bundles, and the light transmitted within the optical fiber 20 for transmitting reflected light is transmitted from the output side end faces 24 and 26 of each bundle to a fixed position information a signal for detection. The light is guided to an optical sensor 28 and an optical sensor 30 for detecting focusing and tracking signals. In this embodiment, the fibers 20a bundled on the inner circumference side of the reflected light transmission optical fibers 20 are branched to the optical sensor 28 side, and the fibers 20b bundled on the outer circumference side are branched to the optical sensor 30 side. There is. Of the reflected light from the optical recording medium, the information signal representing the information signal travels in the opposite direction along substantially the same optical path as the irradiated light and enters the incident end face 22a of the optical fiber 20a for transmitting reflected light, but the reflected light from the optical recording medium Since the light used to detect focusing or tracking signals is diffracted light from pits or guide grooves on the optical recording medium, it enters the incident side end face 22b of the optical fiber 20b for transmitting reflected light. . By receiving the light at a position slightly away from the focal point of the objective lens 18 toward the outer periphery, the influence of changes in the amount of light corresponding to information signals is reduced, and the shift of the focal position in the optical axis direction and from the track are reduced. Changes in light intensity due to lateral displacement can be easily detected. Note that the optical sensor 28 includes a photodetecting element that receives laser light transmitted via the reflected light transmission optical fiber 20a and converts it into an electrical signal representing information. The optical sensor 30 includes a plurality of photodetecting elements that receive laser light transmitted through the reflected light transmission optical fiber 20b, convert it into an electrical signal representing focusing or tracking information, and output it to the controller 46. There is.

A head movable section 32 that is driven along a direction intersecting the tracks of an optical recording medium (not shown) is provided with the objective lens 18 and connected to the end of the fiber 12.20, so that the movable section is small and It is considered lightweight. For example, as shown in FIG.
A moving coil 40 is fixed to 8, and the moving coil 40
receives a driving force from the magnetic field formed by permanent magnets 42,44. A head movable section 32 is fixed to the movable plate 38, and by controlling the excitation state of the moving coil 40, the head movable section 32 is positioned and a track is selected.

The head movable section 32 is equipped with a focusing mechanism that moves the objective lens 18 in the optical axis direction and a tracking mechanism that moves the objective lens 18 in a direction perpendicular to the optical axis, and the controller 46 controls the focusing mechanism and the tracking mechanism. Through this control, a laser beam spot of an optimal size is formed on the track of the optical recording medium, regardless of variations in the distance between the optical recording medium and the objective lens 18 and variations in the track position. . That is, as shown in FIG.
A movable member 5 supported movably in the optical axis direction by 6.
8 via a leaf spring 60, and the objective lens 18 is supported so as to be movable in the optical axis direction and in a direction perpendicular to the optical axis (a direction intersecting the tracks of the optical recording medium). Focusing coil 62 fixed to movable member 5B
A magnetic field of a permanent magnet is applied to the focusing coil 62, and the position of the objective lens 18 in the optical axis direction is controlled in accordance with the current supplied from the controller 46 to the focusing coil 62. The magnetic field of the permanent magnet 68 is also applied to a frame-shaped magnetic member 66 that directly supports the objective lens 18, and the objective lens 18 is illuminated in response to the current supplied from the controller 46 to the tracking coil 72. The position perpendicular to the axis is controlled. The tracking coil 72 is arranged so that the magnetic force acting on the magnetic member 66 is changed by the magnetic field of the permanent magnet 68. The ends of the optical fiber 12 for transmitting the irradiated light and the optical fiber 20 for transmitting the reflected light are fixed in a cylindrical fiber holder 70, and the optical fiber 12 for transmitting the irradiated light substantially coincides with the optical axis of the objective lens 18. The fiber holder 70 is fixed to the head movable section 32 so that the fiber holder 70 is fixed.

According to the device configured as described above, the light source section consisting of the semiconductor laser element 10, the lens 15, etc., and the detection section consisting of the information signal detection optical sensor 28 and the focusing or tracking signal detection optical sensor 30 are fixed in position. Further, an objective section including an objective lens 18 and the like is provided on a head movable section 32 that is driven along the recording surface of the optical recording medium in a direction perpendicular to the track.

Therefore, compared to the conventional case in which the light source section, detection section, and objective section of the optical head are integrally fixed while maintaining a certain mutual positional accuracy, the irradiation light and the reflected light are Polarizing beam splitter, 1/
Since optical parts such as a four-wavelength plate are not required and the number of parts is reduced, the light transmission efficiency of the optical head is increased and the size of the optical head is reduced.

In addition, since the light source section such as the laser element 10 and the collimator lens 15, and the detection section such as the convex lens, cylindrical lens, and optical sensor can be arranged independently of the objective section, the light source section and the detection section can be arranged independently. Positioning with the objective part is no longer necessary, and a highly rigid frame body for maintaining relative positional accuracy between parts is reduced, making the head movable part 32 smaller, lighter, and less expensive. Furthermore, since the optical head is small and lightweight, the inertial weight is reduced, and access time can be significantly shortened.

In this embodiment, the head movable section 32 is composed of only the objective section, but even if the head movable section 32 is provided with a light source section and a detection section, the effects of the present invention can still be obtained.

Next, another embodiment of the present invention will be described. In the following description, parts common to those of the previously described embodiments are denoted by the same reference numerals, and the description thereof will be omitted.

The end face shape of the fiber 12.20 is shown in FIGS. 4, 5,
As shown in FIG. 6, it may be a flat surface, a convex surface, or a concave surface.
In addition, in order to focus the laser beam emitted from the end face of the fiber 12 onto the optical recording medium 76, FIGS.
It may be configured as shown in FIGS. In the apparatus shown in FIG. 7, the laser beam is made parallel by one convex lens 78 and then focused onto the optical recording medium 76 by the other convex lens 80. The apparatus shown in FIG. 8 focuses laser light onto an optical recording medium 76 using a light focusing waveguide 82 such as a SELFOC lens. In the apparatus shown in FIG. 9, the end surface of the optical fiber 12 for transmitting irradiated light is formed into a convex shape, and the laser beam is focused onto the optical recording medium 76 by the convex lens action of the convex surface.

The branching method of the reflected light transmission optical fiber 20 is as follows.
As shown in the figure, the cross section may be branched into a fan-shaped cross section along a straight line in the radial direction, or may be branched randomly. Further, as shown in FIG. 11, a photodiode array 84 in which a large number of light detection elements are arranged is used to detect the laser light transmitted through the individual fibers constituting the reflected light transmission optical fiber 20. You can do it like this.

As shown in FIG. 12, an optical sensor 2 is provided between the optical sensor 28 and the optical fiber 20a for transmitting reflected light, and between the optical sensor 30 and the optical fiber 20b for transmitting reflected light.
a convex lens 86 that focuses the laser beam onto the photodetector element 8;
, and optical components such as a convex lens 88 and a cylindrical lens 90 that converge laser light on the photodetecting element of the optical sensor 30 may be provided, respectively.

The optical fiber 20 for transmitting reflected light may be suitably constituted by a multi-core optical fiber used for a so-called image guide, but as shown in FIG. 13, the optical fiber 1 for transmitting irradiated light
Alternatively, as shown in FIG. 14, a plurality of single-core optical fibers may be arranged around the irradiation light transmission optical fiber 12. It can also be configured by bundling 94.

Additionally, the fibers 12.20.92.94 are generally made of quartz, but may also be made of plastic to reduce weight. In this case, the head movable section 32 becomes even lighter. Fiber 12.20.92.94 may also be constructed from polarization maintaining fiber. In this case, if the optical recording medium 76 is a magneto-optical disk, the information stored therein can be read out using the polarization plane of the fiber.

Furthermore, since information can be reproduced by detecting transmitted light instead of reflected light from the optical recording medium 76, as shown in FIG. A transmitted light transmission optical fiber 96 configured in the same manner as the reflected light transmission optical fiber 20, and a convex lens 98 that focuses the transmitted light from the optical recording medium 76 on the end face of the transmitted light transmission optical fiber 96, It may be provided on the opposite side to the objective lens 18.

Next, an example will be described in which laser light of two different wavelengths is used or two irradiation locations are irradiated with laser light.

In FIG. 16, laser beams of different wavelengths emitted from semiconductor laser elements 100 and 102 for information recording and information reproduction are transmitted to incident side end faces 108 and 110 of single-core irradiation light transmission optical fibers 104 and 106, respectively.
The light is focused by lenses 112 and 114, respectively, to the optical fibers 104 and 10 for transmitting the irradiated light.
6 and semiconductor laser elements 100 and 102 are optically coupled. The laser light propagated within the irradiation light transmission optical fibers 104 and 106 is transmitted to the output side end face 116.
and 118, but is focused by the objective lens 18 onto the recording surface of the optical recording medium. That is, when reading information recorded on an optical recording medium or recording information on the optical recording medium, as shown in FIG. A laser beam spot 122 for information output and a laser beam spot 124 for information recording, each having a different wavelength, are irradiated to the position simultaneously or alternatively.

Similar to the embodiment shown in FIG. 1, the reflected light from the optical recording medium is transmitted to the incident side end face 132 of a large number of reflected light transmission optical fibers 130 bundled around the outer periphery of the irradiation light transmission optical fiber 104.1O6. Uke is accepted. Therefore, among the reflected light from the optical recording medium, the information signal representing the information signal travels in the opposite direction along substantially the same optical path as the irradiated light, enters the incident side end face 132a of the reflected light transmission optical fiber 130a, and reaches the optical sensor 126. However, the reflected light from the optical recording medium that is used to detect focusing or tracking signals is the diffracted light from the bits and guide grooves on the optical recording medium, so an optical fiber for transmitting reflected light is used. Incidence side end surface 1 of 130b
32b and is transmitted to the optical sensor 128. The optical sensor 126 and the optical sensor 128 are each equipped with a dichroic mirror (not shown), detect only light of a required wavelength, and output an information signal, a tracking signal, and a focusing signal, respectively.

A fiber holder 70 is fixed to one end of the single-core optical fibers 104, 106 and the multi-core optical fibers 130 bundled around their outer peripheries, as in the previous embodiment, and this fiber holder 70 is shown in FIG. It is attached to a movable head 32 similar to that shown in FIG. The fiber holder 70 is provided with a flange portion 136 in which an arc-shaped elongated hole 134 is formed as shown in FIG. 18, and is inserted into the movable head 32 so as to be rotatable around an axis. A screw 138 is fastened to the movable head 32 through an elongated hole 134 to prevent the fiber holder 70 from coming off and to limit rotation around the axis within a certain range. The flange portion 136 has a protrusion 14 protruding toward the outer circumference.
0 is provided, and its protrusion 140 is provided with a pair of positioning screws 14 that are screwed together in opposite directions on the movable head 32.
It is locked between the two.

According to this embodiment, as in the previous embodiment, the light source section and the detection section are provided in fixed positions, and the head movable section 32, which is the objective section, is movable. A polarizing beam splitter that is compact and has a reduced inertial weight, and that separates irradiated light and reflected light;
Since optical parts such as a quarter-wave plate are no longer necessary and the number of parts is reduced, the light transmission efficiency of the optical head is improved.

In addition, since the relative positional relationship between the light source section, the detection section, and the objective section can be arranged independently, there is no need to align the light source section, the detection section, and the objective section, and the relative positional accuracy between the parts is maintained. The high-rigidity frame for this purpose is made smaller, the head movable section 32 becomes smaller, lighter, and less expensive, and the optical head becomes smaller and lighter, which reduces the inertial weight and significantly shortens the access time.

Furthermore, according to this embodiment, since the rotational position of the fiber holder 70 around the axis is adjusted, the parallelism between the line connecting the laser beam spots 122 and 124 and the track 120 can be adjusted very easily. Moreover, since the ends of the optical fibers 104 and 106 for transmitting the irradiated light are fixed to each other, there is an advantage that there is no need to adjust the interval between the laser beam spots 122 and 124. - The end faces of the fibers 104, 106 and 130 may be flat, convex or concave as shown in FIGS. 19, 20 and 21.
The ends of 04.106 may be spaced apart as necessary, as shown in FIG. 22, or three or more fibers for irradiation light transmission may be provided as necessary, as shown in FIG. 23. Therefore, on the track 120 of the optical recording medium 76, for example, when there are three single-core irradiation light transmission optical fibers as shown in FIG. 23, there are three optical fibers as shown in FIG. 24 or FIG. A laser beam spot is formed. In the case of FIG. 25, three laser beam spots are formed on a straight line obliquely intersecting the track 120 for three-beam tracking.

Further, the plurality of laser beam spots may be formed one by one on adjacent tracks 120 as shown in FIG. 26, or the plurality of laser beam spots may be formed on adjacent tracks 120 as shown in FIG. A plurality of them may be formed.

Further, in order to focus the laser light emitted from the end faces of the fibers 104 and 106 onto the optical recording medium 76, a configuration as shown in FIGS. 28 and 29 may be used. 28th
The illustrated device focuses laser light onto an optical recording medium 76 with a light focusing waveguide 144 such as a Selfoc lens. In the apparatus shown in FIG. 29, the end surfaces of the optical fibers 104 and 106 for transmitting irradiated light are formed into convex surfaces, and the laser beams are focused on the optical recording medium 76 by the action of convex lenses on the end surfaces.

In FIG. 16, two semiconductor laser elements 100 and 102 with different wavelengths are used, but these elements may output laser beams of the same wavelength, or as shown in FIG. 30. The laser beam output from the single element 146 may be branched to each of the irradiation light transmission optical fibers 104 and 106 using a demultiplexer 148.

Further, the optical fiber 130 for transmitting reflected light may be suitably constituted by a multi-core optical fiber used for a so-called image guide, but as shown in FIG. It may be configured by arranging a plurality of single-core optical fibers 150, and
As shown in FIG. 32, an optical fiber 104 for transmitting irradiated light
and multi-core optical fibers 152 and 15 around 106
It can also be constructed by bundling 4 pieces together. Further, as shown in FIG. 33, the irradiation light transmission optical fibers 104 and 106 can be arranged between a plurality of bundles of multi-core optical fibers 156.

In addition, when reproducing information by detecting transmitted light instead of reflected light from the optical recording medium 76, as shown in FIG. An optical fiber 157 for transmitting transmitted light having the same structure as the optical fiber 20 for transmitting reflected light, and a convex lens 158 that focuses the transmitted light from the optical recording medium 76 on the end face of the optical fiber 157 for transmitting transmitted light are connected to an objective. lens 18
It may be provided on the opposite side.

Note that the above-mentioned embodiment is merely one embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 and FIG. 16 are schematic diagrams showing the configuration of an embodiment of the present invention, respectively. FIG. 2 is a perspective view showing how the front and back movable parts of FIG. 1 or FIG. 16 are attached. Third
This figure is a cross-sectional view showing the configuration of the head movable section in FIG. 1. 4 to 6 and 19 to 21 are diagrams showing other examples of end face shapes of the irradiated light transmission optical fiber and the reflected light transmission optical fiber, respectively. Figures 7 to 9
28 and 29 are diagrams respectively showing other configuration examples for irradiating an optical recording medium from an optical fiber for transmitting irradiated light. FIGS. 10 and 11 are diagrams respectively showing other branching structures of the optical fiber for transmitting reflected light. FIG. 12 is a diagram showing another method in which a light sensor receives light emitted from a reflected light transmission optical fiber. Figures 13 and 14
31 to 33 are diagrams respectively showing other configuration examples of the optical fiber for transmitting reflected light. FIG. 15 and FIG. 34 are diagrams each showing an example in which transmitted light is detected instead of reflected light. FIG. 17 is a diagram showing the formation state of the laser beam spot in the embodiment of FIG. 16. 18th
This figure is a perspective view showing how the head movable part and the optical fiber of FIG. 2 are attached. FIGS. 22 and 23 are diagrams showing other examples of optical fibers for transmitting irradiated light, respectively. FIGS. 24 to 27 are views corresponding to FIG. 17 showing other formation states of the laser beam spot, respectively. FIG. 30 is a diagram showing another example of the light source device for transmitting laser light to two irradiation light transmission optical fibers in the embodiment of FIG. 16. FIG. 35 is a schematic diagram showing the configuration of an optical head of a conventional optical recording/reproducing device. 76: Optical recording medium

Claims (1)

[Claims] In order to record and reproduce information, laser light output from a laser light source is focused and irradiated onto an optical recording medium, and signal light from the irradiated part of the optical recording medium is sent to an optical sensor. An optical recording and reproducing device of the type that detects the optical recording medium by receiving and transmitting a laser beam output from the laser light source on one end surface, and emitting the laser beam toward the optical recording medium from the other end surface. An optical recording and reproducing apparatus comprising: an optical fiber; and an optical fiber for transmitting signal light that receives signal light from the irradiated part of the optical recording medium at one end surface and guides it to the optical sensor.