JPS5936217A - Optical recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a small-sized, lightweight, and good-portability device which eliminates the need for a moving mechanism of complex constitution for an objective, by providing a movable transparent spacer in contact with a recording medium. CONSTITUTION:Laser light emitted by oscillation of a laser diode 31 is collimated by a collimator lens into parallel luminous flux, which is caused by a polarization beam splitter 34 to strike the objective 36 through a quarter-wavelength plate 35. This light is reduced to a specific beam diameter, passed through the transparent spacer 37, and focused on the recording layer 41 of the recording medium 43 to form a pit. Its reflected light travels backward through the same optical path to pass through the polarization beam splitter 34 and focused as reproduced information on a photodetector 39 through a condenser 38. This reproduced information is free of a focusing error due to the curvature and ruggedness of the recording medium 43 because the distance between the objective 36 and recording layer 41 is fixed through the transparent spacer 37, and aberrations of the objective 36 are compensated, so there is no deterioration of an image.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical recording and reproducing device that optically records and reproduces information, and in particular, focuses a laser beam onto an optical recording medium that rotates at a constant speed to write and read information. Relating to improvements in optical heads.

As is well known, an optical head in a conventional optical recording/reproducing apparatus is of a non-contact type with the surface of an optical recording medium. This is because, for reasons such as increasing the recording density of optical recording media, the beam diameter of the laser beam at the recording medium surface generally needs to be small, on the order of microns.
Therefore, the design of the objective lens system of the optical head that narrows down the laser beam and the setting of the distance between this objective lens and the surface of the recording medium must be strictly performed. However, the distance between the objective lens and the surface of the optical recording medium varies minutely due to warping, unevenness, etc. of the optical recording medium that rotates at a constant speed, and this causes a focusing error (focal shift).

Therefore, in the past, in order to correct this focus lens error, an objective lens moving mechanism was required to control the movement of the objective lens in the optical axis direction, and for this reason, the optical head was of a non-contact type.

Figures 1 and 2 show the optical head periphery and the objective lens moving mechanism (14 components) of the conventional optical recording/reproducing device mentioned above. Here we will briefly explain the operation of the conventional configuration.

In FIG. 1, the reference numeral I indicates a Ha-Ne laser or a radar oscillator such as a cow conductor radar, and the laser oscillator is turned on and off according to the recording signal by an electronic circuit (not shown). For reasons described later, dimming is controlled during playback.

The laser beam oscillated by the Rade oscillator 1 is passed through a magnifying lens (
The beam extension I')2VC is converted into a parallel beam of appropriate thickness, and is incident on the polarizing beam splitter 3. Since the Rede light incident on the polarizing beam splitter 3 has strong linear polarization, the S-polarized component is reflected,
The quarter wavelength plate 4 converts the light into a circularly polarized light beam. The Radhe light converted into a circularly polarized light beam passes through the reflection mirror 5, is given multi-position control by rotation of the tracking mirror 6, and is incident on the objective lens 7@The light beam from the tracking mirror 6 that is incident on the objective lens 7 is The radar light is narrowed down to a predetermined beam diameter and focused on the photosensitive surface of an optical disk 12, which is an optical recording medium, which is rotated at a constant speed by a drive source (not shown) such as a motor. As a result, a recording pattern of a series of short line segments called bits is formed on the photosensitive surface of the optical disc 12, and information is recorded.

To read out bit information, the radar light is appropriately attenuated during recording and continuously oscillated, and the light is focused onto the optical disk 12 through the same optical path as described above.

At this time, since the radar light is controlled to be moderately dimmed by the electronic circuit as described above, the bits will not be destroyed during the re-transmission.

The laser light focused on the photosensitive surface of the optical disc 12 in this way mainly changes in reflected light intensity depending on whether or not there is a bit in the focused area, and furthermore, the phase of the circularly polarized laser light is reversed. The light then enters the objective lens 7 again, travels backward along the optical path, and returns to the quarter-wave plate 4. Here, 1/4 wavelength plate 4
In this case, the reflected light from the optical disk 12 whose polarization phase is reversed is converted into P-polarized light, so that it is transmitted to the next polarizing beam splitter 3.
In this case, only reflected light is efficiently transmitted. The reflected light that has passed through the polarizing beam splitter 3 is passed through the condenser lens 8. A point image with large astigmatism is formed by the cylindrical lens 9 onto the four-part light receiving element 1θ. By electrically processing the output of the light receiving element 1o, the bit information of the light 7-' (block 12) and focusing error information are obtained, and based on this focusing error information, as shown in FIG. The objective lens moving mechanism shown in FIG.

In FIG. 2, the reference numeral 13 indicates the objective lens 7.
A lens holder 13 is used to fully hold the lens holder 13, and the lens holder 13 is integrated with the movable portion 14m of the voice coil. Also, reference numeral 15a.

Reference numeral 15b is a yoke constituting the fixed portion 14b of the voice coil, and a permanent magnet 16 is provided between the yokes 15a and 15b.

Reference numeral 17 indicates Danno 9-, and this damper 17 is connected to the lens holder 13, and the movable part 1 of the +j+' chair coil is connected to the lens holder 13.
4m and the fixed part 14b are supported with a certain degree of freedom.

In the above configuration, when a control current flows through the coil of the voice coil enable t114m based on the focal lens error information, a magnetic force is generated from the coil according to the magnitude of this control current, and the magnetic force of the movable part 141L and The movement of the objective lens 7 in the optical axis direction is controlled by interaction with the magnetic force of the fixed portion 14b generated by the permanent magnet 16, and forcing errors caused by the bending of the optical disk 12, H6, etc. are corrected.

Therefore, in the past, an objective lens moving mechanism was required to correct the forcing error, which forced the optical head to be of a non-contact type.

However, the conventional optical recording/reproducing apparatus has the following drawbacks due to the above-mentioned circumstances. That is, conventionally, in order to provide the objective lens with a certain working distance and a relatively large numerical aperture, the objective lens itself is large and a molded needle is also used.

How can I control the movement of such an objective lens so that it is held half-hollow? It is necessary to generate a strong magnetic force by passing a large current through the coil in the moving part of the chair coil, which has the disadvantage of consuming large amounts of power and making it unsuitable for battery operation.

However, since it requires a complicated objective lens movement mechanism, the device itself becomes large, and if such a device is made portable, it is easily affected by vibrations and tilting, making it difficult to control the force shifting servo. Another drawback was that the spot diameter of the objective lens was small, requiring high tracking accuracy.

The present invention has been made in order to eliminate the above-mentioned drawbacks, and provides an optical recording and reproducing device that consumes less power, does not require a complicated objective lens moving mechanism, is small and lightweight, and is suitable for being portable. The purpose is to

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

Figure 3 shows an embodiment of the optical recording and reproducing device according to the present invention. W4r diagram: This is a diagram showing the composition of the lens system of the Moto1 side.
1-J-3-i, -it lowering threshold A The reference numeral 31 indicates a laser diode, and the laser diode 31 is used for imaging during recording by an electronic circuit (not shown) as in the conventional example described above. The oscillation state of the laser beam is controlled according to the output of an element (not shown), and the laser beam is continuously oscillated during reproduction. It should be noted that during reproduction, the laser light continuously oscillated by the radar diode 31 is oscillated without being attenuated.

Further, the reference numeral 32 is a collimating lens that converts the Raded light oscillated by the Raded diode 31 into a parallel beam, and the reference numerals 3 and 3 convert the Raded light transmitted through the collimating lens 33 into elliptically polarized light during reproduction. 34 is a polarizing beam splitter, 3 is a cylindrical lens.
5 is a quarter wavelength plate. It should be noted that the cylindrical lens 33 can be inserted and removed so as to be removed from the optical path during recording.

Also, what is indicated by the reference numeral 36 is a polarizing beam splitter 34.
Reference numeral 37 is a transparent plate having optically flat characteristics, which is an objective lens for condensing the parallel light beam from the recording layer 4 onto the recording layer 4.

In other words, this transparent plate 37 is a parallel transparent plate that has neither polarization properties nor condensing properties with respect to the laser optical axis, and this transparent plate 37 is placed on the recording layer 41 of the recording medium 43 with the lubricant described later. The spatial distance between the objective lens 36 and the medium 43 is fixed by arranging them in pressure contact with each other through the layer 4°.

Further, although the objective lens 36 generally has negative spherical aberration, the transparent plate 37 has a positive spherical aberration number that cancels out this aberration.

The lubricating layer 4θ prevents wear and scratches between the transparent plate 37 and the recording layer 41 when the transparent plate 37 slides in pressure contact with the recording layer 41 during rotation of the recording medium 43, and is made of, for example, an ester-based synthetic lubricant. oil.

Polyα-olefin oil, fluorinated polyether, etc. are used and coated on the recording layer 41 or CVD (chem
ical vajor dejosiNon) with a thickness of 100X to 1 μm.

Further, in this embodiment, a low melting point material such as tellurium (To) or Bi-Te-As is used as the recording layer 41 of the recording medium 43, and this is placed on a flexible transparent substrate 42 such as polyethylene phthalate. information is recorded in the form of bits by the heat of the Rede light.

Therefore, in this embodiment, during recording, the Raded light oscillated by the Raded diode 31 is transmitted to the collimating lens 3.
2, it is converted into a parallel light beam by the polarizing beam slittor 34, passes through the quarter-wave plate 35, and enters the objective lens 3.
6. The 1/-de light incident on the objective lens 36 is focused to a predetermined beam diameter, passes through the transparent plate 37, and is focused on the recording layer 41 of the recording medium 43, forming pits.

Also, during playback, the Radhe light is transmitted through the collimating lens 32.
The light is transmitted through the cylindrical lens 33 and is converted into an elliptical beam by the cylindrical lens 33, and then condensed onto the recording layer 41 through the optical path described above. Here, since the Radhe light focused on the recording layer 41 is turned into an elliptical beam by the cylindrical lens 33, the luminous flux density is lower than during recording, so that the pits are not destroyed.

Then, the reflected light travels backward along the same optical path, passes through the polarizing beam splitter 34, and is sent to the light receiving element 3 by the condensing lens 38.
9 is focused as reproduction information.

The reproduced information obtained in this way does not have force errors caused by warping or unevenness of the medium because the distance between the objective lens 36 and the recording layer 41 is fixed by the transparent plate 37 as described above. Furthermore, since the aberration of the objective lens 36 is corrected, there is no image deterioration.

As is clear from the above, according to this embodiment, the objective lens moving mechanism can be omitted by bringing the transparent plate 37 into pressure contact with the recording layer 41 via the lubricating layer 42.

Note that the present invention is particularly effective when the device satisfies the following requirements.

(1) The disk diameter is small, about 50 to 100φ.

(2) The 7” isk is stored in a dustproof container such as a cassette.

(3) The disk should have the flexibility of a floppy disk.

Next, an example of application under the above conditions will be shown.

FIGS. 4 and 5 are diagrams showing a 70-piece disk cassette which is an embodiment of the present invention.

As shown in FIGS. 4 and 5, a floppy disk 55, which is a recording medium, is rotatably housed in a cassette 50. A head opening 5 is provided on the front surface of the cassette 50, and a dustproof plate 52 that is slidable in the radial direction of the disk 54 is provided in the head opening 5. A transparent spacer 53 similar to the transparent body 37 is integrally attached to the dustproof plate 52.

The floppy disk 55 is made of a flexible material, and by rotating the disk 54 from the outside at high speed using a drive source (not shown), it can be flattened and expanded in the plane perpendicular to the drive shaft within the cassette 50. Trying to grow. At this time, if the 53 transparent spacers are arranged so as to bite into the rotating surface of the disk, a part of the disk 55 will be pushed downward and pressed against it, as shown in FIG. . Therefore, the recording surface of the medium and the upper surface of the transparent spacer 53 can always maintain a constant distance. Therefore, if other members including the objective lens 36 can be placed on the transparent spacer 53 with high precision, stable recording and reproduction can be performed even without a force-shinging mechanism.

An example of this is shown in Figure 6.
The lower end of the lens holder 6θ that holds the lens holder 6
A ring-shaped magnetic material 61 made of soft iron or the like having a precisely finished plane perpendicular to the rotational axis of 0 is fixed with an adhesive or the like, and a coil 62 is wound around the outer circumference of the ring-shaped magnetic material 61 .

On the other hand, a circular plate 63 made of soft iron or the like having a precisely finished plane perpendicular to the axis of rotation is fixed to the transparent spacer 53 with an adhesive or the like.

Therefore, the lens holder 6 holding the objective lens 36
When the coil 62 is aligned with the minimum diameter of the conical protrusion provided concentrically with the rotation axis and a direct current is passed through the coil 62, the ring-shaped magnetic body 61 fixed to the lens holder 60 and a disc 6 fixed to a transparent spacer 53
3 is electromagnetically attracted to a conical hole and a conical protrusion each having an objective lens 36 and a transparent spacer 53. Fixed. In the case of detachment, the current may be turned off and the lens holder 60 may be moved back.

Regarding the centering, if the transparent plate 53 is a parallel plane plate in a small area near the optical axis, there is a great need for centering within that small area. Therefore, the alignment by the conical hole and the conical projection is not perfect, and even when the lens holder 60 and the transparent spacer 53 are in a fixed state, there may be a slight gap between the conical hole and the conical projection. .

Next, we will discuss how to access the optics in the track change direction.

Most simply, as shown in FIG.
A protrusion that fits with the optical head is provided on a part of the
There is a method in which the transparent spacer 53 is also driven together with the dustproof plate 52 when the head is driven by an external head actuator.

Regarding the fitting structure of the objective lens 36 and the transparent spacer 53, there is no need for alignment if the transparent spacer 53 is a parallel plane plate at least in a small area near the optical axis.

FIG. 7 shows another embodiment of the floppy disk cassette, and as shown in the same figure, a bag-shaped frame 56t with one end open is provided at both ends of the transparent spacer 53 in the moving direction of the arrow.
h and 56b are fixed, and ultrathin, lightweight leaf springs 57a and 57b wound in a spiral shape are housed in the frames 56h and 56b, respectively, and the spiral leaf spring 57a.

One end of the frame 57b protrudes from the respective openings of the frames 56a and 56b and is fixed to the outermost and innermost sides of the disk in the cassette case.

As the optical head moves, the transparent spacer 53
When moving to the left of the arrow (f" (in the outer peripheral direction), the leaf spring 57a increases the number of turns, and the leaf spring 57b decreases the number of turns. In the case of the opposite movement, the leaf spring 57b increases the number of turns. , 57m reduces the number of windings. Therefore, for the movement of the transparent 8A spacer 53 in the direction of the arrow, the leaf spring 57a
.

57b does not provide any resistance, but only changes the distance from the opening of the frames 56 & 56b to the respective fixing points depending on the position of the spacer 53. The leaf springs 57m and 57b that move as described above not only hold the spacer 53, but also serve to prevent dirt and dust from entering the disk surface through the head opening 51 of the cassette case. Note that for the transparent spacer 53, a lens may be used in addition to a parallel plane plate. FIG. 8 shows an example in which a lens 70 of a refractive index gradient type with end face focus is used in the spacer. In this case, it is naturally necessary to align the optical axes of the objective lens 36 and the spacer 53.

It is also possible to apply to hard type media with large disk diameters by adding a micro-range focus length mechanism.

In the present invention, the distance between the objective lens and the medium recording surface does not essentially change significantly. Therefore, in the case of a node disk, it is sufficient to add a forcing mechanism to correct the thickness unevenness of several microns that occurs in the protective layer covering the recording surface. If the objective position p+ is adjusted to this degree, there is no need to use a voice coil as described above, and force adjustment can be performed using a small, low power consumption member such as a bimorph element, for example.

Furthermore, if a gradual position adjustment mechanism such as a bimorph element is used, it becomes possible to adjust the offset of the initial position between the floppy optical disk housed in the cassette and the optical head as described above.

That is, in the engagement method of the head body and the transparent spacer, each time the cassette is attached to the device, the head body and the transparent spacer are engaged.

The departure is replaced. In this case, depending on how the locking mechanism is constructed, there is a possibility that a positional offset of several micrometers in the forcing direction may occur. A bimorph element can be used to correct this. In this process, when the cassette is loaded into the device, the head body is combined with the transparent spacer of the cassette.

At this time, a sensor detects the force shifting f% and obtains information regarding the shift of the force shifting, and based on this information, the voltage to be supplied to the bimorph element can be determined, and the just focus position can be selected.

The bimorph element can be attached by installing it between the transparent spacer 53 and the objective lens 36.

As is clear from the above description, according to the present invention, a lubricant layer is formed on the recording surface of a recording medium, and an optically transparent body having negative spherical aberration that is in pressure contact with the lubricant layer, and the negative spherical aberration By providing a lens system consisting of an objective lens that generates positive spherical aberration that cancels out the spherical aberration, we can create an optical recording and reproducing device that is small, lightweight, and consumes little power, without requiring any of the force and lens mechanisms that were previously required. Saru provided.

[Brief explanation of drawings]

Figures 1 and 2 all show the configuration of a conventional optical recording/reproducing device. The cross-sectional view showing the structure and FIGS. 3 to 8 all explain the present invention in detail. 5 is a sectional view of FIG. 4, and FIG. 6 is a front view of the floppy disk cassette shown in FIG. 7 is a sectional view showing another example of a floppy disk cassette, and FIG. 8 is a perspective view showing a gradient index lens. Collimator lens, 33... Cylindrical lens, 34... Polarizing beam splitter, 35... 1/4 wavelength plate, 36...
...Objective lens, 37...Transparent plate, 38...Condensing lens, 39...Light receiving element, 40...Lubricating layer. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3, Figure 4 Figure 5 Figure 6 Figure 7 Figure 1 Figure 8 Commissioner of the Patent Office Kazuo Wakasugi 1. Patent application for indication of the case No. 57-147019 3 Relationship with famous case for amendment Name of patent applicant (037) Olympus Optical Industry Co., Ltd. 4, Agent 5, Voluntary amendment 6, Name of invention subject to amendment, Specification 7, Increased due to amendment 18. Contents of the amendment (1. The title of the invention is amended as follows. "Disc cassette and its disk power (2) The entire description is amended as attached. Description 1. The title of the invention is amended as follows. Title Disc cassette and recording/reproducing device using this disc cassette 2, Claims (11) A disc cassette for storing an optical information recording medium, characterized by having a transparent spacer movable in contact with the recording medium. (2) In a recording and reproducing apparatus that records and reproduces information using an optical information recording medium, a disk cassette having a transparent cover that is movable in contact with the recording medium; 3. Detailed Description of the Invention [Technical Field] The present invention relates to a disc cassette that stores an optical information recording medium and a recording and reproducing apparatus using this disc cassette, and particularly relates to a recording and reproducing apparatus that uses the disc cassette. optically record the
The present invention also relates to improvements in the optical head portion for reproduction. [Prior Art] In a conventional optical recording/reproducing device, an optical head is arranged to face a recording medium in a non-contact manner. In order to be able to record and reproduce information on a recording medium at a high recording density, the optical system is configured so that the recording medium is irradiated with a laser beam with a narrow beam diameter, usually on the order of microns. There is. However, if a recording medium that rotates at a constant speed is warped or uneven, there will be slight fluctuations in the facing distance between the objective lens of the optical head and the recording medium, resulting in so-called focus lens error. In order to correct this focus lens error, conventional devices require an objective lens moving mechanism that controls the movement of the objective lens in the optical axis direction. FIGS. 1 and 2 are diagrams showing the structure of the optical head periphery and the objective lens moving mechanism of the above-mentioned conventional optical recording/reproducing apparatus. The configuration and operation of the conventional device will be described below with reference to FIGS. 1 and 2. In FIG. 1, the reference numeral 1 indicates a laser oscillator such as a He--Ne laser or a semiconductor laser. This laser oscillator 1 is controlled on and off in response to a recording signal from an electronic circuit (not shown), and is controlled to be dimmed during reproduction for reasons described later. The laser beam oscillated by the laser oscillator 1 is passed through a magnifying lens (
The beam expander) 2 converts the beam into a parallel beam of appropriate thickness, and the beam is incident on the polarizing beam splitter 3. Since the Radhe light incident on the polarization beam sinter 3 has strong linear polarization, the S-polarized component is reflected and 1/4
The wave plate 4 converts the light into a circularly polarized light beam. The Radhe light that has been converted into a circularly polarized beam passes through a reflecting mirror 5, its position is controlled by the rotation of a tracking mirror 6, and it enters an objective lens 7. The laser beam from the tracking mirror 6 that is incident on the objective lens 7 is focused to a predetermined beam diameter,
The light is focused on the photosensitive surface of an optical disk 12, which is an optical information recording medium, which is rotated at a constant speed by a drive source (not shown) such as a motor. As a result, a recording pattern of a series of short line segments called bits is formed on the photosensitive surface of the optical disc 12, and information is recorded. To read out bit information, the laser beam is appropriately attenuated during recording and continuously oscillated, and the laser beam is focused onto the optical disk 12 through the same optical path as described above. At this time, since the laser beam is moderately dimmed and controlled by the electronic circuit as described above, the bits are not destroyed during regeneration. The intensity of the reflected light of the radar light thus focused on the photosensitive surface of the optical disc 12 changes depending on whether or not there is a bit in the focused area, and the phase of the circularly polarized laser light is also reversed. The light enters the objective lens 7 again, travels backward along the optical path, and returns to the quarter-wave plate 4. Here, 1/4 wavelength plate 4
In this case, the reflected light from the optical disk 12 whose polarization phase is reversed is converted into P-polarized light, so that it is transmitted to the next polarizing beam splitter 3.
In this case, only reflected light is efficiently transmitted. The reflected light that has passed through the polarizing beam splitter 3 is passed through the condenser lens 8. A point image with large astigmatism is formed on a four-part light receiving element 10 by a cylindrical lens 9. By electrically processing the output of the light receiving element 1o, it is possible to read the bit information of the optical disk 12 and obtain focusing error information, and based on this focusing error information, the objective lens is moved as shown in FIG. The mechanism is driven and controlled. Note that reference numeral 11 in FIG. 1 is a feed screw for moving the optical head in the radial direction of the optical disk 12. In FIG. 2, reference numeral 13 is a lens holder that holds the objective lens 7, and this lens holder 13 is integrated with the flexible portion 24& of the voice coil. Further, reference numerals 15a and 15b are yokes constituting the fixed portion 14b of the disco tile, and a permanent magnet 16 is provided between the yokes 15g and 15b. Reference numeral 17 is a damper provided to connect the fixed portion 14b of the voice coil and the lens holder 13;
The movable portion 14g of the voice coil is supported by the damper 17 with a predetermined degree of freedom relative to the fixed portion 14b. Therefore, when a control current based on the focusing error information flows through the coil of the voice coil movable portion 14m, a magnetic force is generated from the coil in accordance with the magnitude of this control current. Then, the objective lens 7 is controlled to move in the optical axis direction due to the interaction between the magnetic force of the movable part 14th and the magnetic force of the fixed part 14b generated by the permanent magnet 16, and the warpage of the optical disk 12 is caused by force twisting caused by unevenness, etc. Errors are corrected. The conventional device having the above configuration has the following drawbacks. That is, in order to correct the focusing error, a complicated objective lens moving mechanism is required, which increases the size of the apparatus. Furthermore, since the objective lens 7 needs to have a certain working distance and a relatively large numerical aperture, the objective lens itself is large (l), and N and t are also large. In order to control the movement of the objective lens 7 while holding it partially in the air, it is necessary to generate a strong magnetic force by passing a large current through the coil of the voice coil movable part 14a, which consumes a lot of power and requires a battery drive. The disadvantage was that it was not suitable for Furthermore, when such a device is made portable, it is easily affected by vibrations, tilting, etc., and there is a risk that the force pulling servo control will not work. Another disadvantage is that tracking accuracy must be increased because the spot diameter of the objective lens is small. [Object] The first object of the present invention is to provide a disk cassette with a new configuration to eliminate the drawbacks of the conventional device as described above, and the second object is to provide a disk cassette with a new structure that eliminates the drawbacks of the conventional device as described above. [Summary] In order to achieve the first object described above, the present invention provides a disk cassette that accommodates an optical information recording medium, which does not require a complicated objective lens moving mechanism. The feature is that a movable transparent spacer is attached. Further, in order to achieve the above object @2, the present invention provides a recording and reproducing apparatus that records and reproduces information using an optical information recording medium, which is coupled to a transparent spacer of the disk cassette to form an optical system. (It is characterized by having an optical member.) [Embodiment] FIG. 3 is a diagram showing the main parts of the recording and reproducing apparatus of the present invention, and reference numerals 31 to 36 and 38 and 39 are recording and reproducing optical members that are combined with the transparent spacer 37 to form an optical system. That is, the reference numeral 31 denotes a laser diode, and the laser diode 31 controls the oscillation state of laser light according to the output of an image sensor (not shown) during recording by an electronic circuit (not shown), as in the conventional example described above. , a laser beam is continuously oscillated during reproduction. Note that during reproduction, the laser light continuously oscillated from the laser diode 3 is oscillated without being attenuated. Further, reference numeral 32 is a collimating lens that converts the laser beam oscillated by the radar diode 3 into a parallel beam.
Reference numeral 33 denotes a cylindrical lens that converts the laser beam transmitted through the collimating lens 32 into elliptically polarized light during reproduction;
Reference numeral 34 is a polarizing beam snoritter, and reference numeral 35 is a quarter wavelength plate. The cylindrical lens 33 is removable so that it is removed from the optical path during recording. Also, what is indicated by the reference numeral 36 is a polarizing beam splitter 34.
This is an objective lens for condensing a parallel light beam from the recording layer 4 onto the recording layer 4, and reference numeral 37 is a transparent spacer having optically flat characteristics. In other words, the transparent spacer 37 is a parallel transparent plate that has neither polarization properties nor light focusing properties with respect to the laser optical axis. Furthermore, although the objective lens 36 generally has negative spherical aberration, the transparent spacer 37 has positive spherical aberration that cancels out this aberration. The transparent spacer 37 is placed in pressure contact with the recording layer 41 of the recording medium 43 via the lubricant layer 40, and the spatial distance between the transparent spacer 37 and the objective lens 36 is fixed. Lubricant layer 4
0 is for preventing wear and scratches between the transparent spacer 37 and the recording layer 41 when the transparent spacer 37 slides in pressure contact with the recording layer 4 due to the rotation of the recording medium 43, and the lubricant is, for example, Ester-based synthetic oil, polyα-olefin oil, fluorinated ether, etc. are used to form the recording layer 41.
On top is a layer of cloth or C'V D (chemical va
100X~ by jor dejosition)
It is formed with a thickness of 1 μm. Further, in this embodiment, as the recording layer 4 of the recording medium 43,
Te/I/ /l/ (Te), B1-Te-A
By forming this material on a flexible transparent substrate 42 such as polyethylene phthalate, information can be recorded in the form of bits using the heat of laser light. Therefore, in this embodiment, the laser beam oscillated by the laser diode 31 during recording is transmitted through the collimating lens 3.
2, it is converted into a parallel beam by the polarizing beam splitter 34, passes through the 1/4 wavelength plate 35, and passes through the objective lens 3.
6. The laser beam incident on the objective lens 36 is focused to a predetermined beam diameter, passes through the transparent spacer 37, and is focused on the recording layer 4 of the recording medium 43, thereby forming a bit. In addition, the laser beam during reproduction is transmitted through a collimating lens 32.
The light passes through the cylindrical lens 33 and is converted into an elliptical beam by the cylindrical lens 33, and then condensed onto the recording layer 4 through the optical path described above. Here, since the laser beam focused on the recording layer 4 is turned into an elliptical beam by the cylindrical lens 33, the luminous flux density is lower than during recording. Therefore, the bits will not be destroyed. Then, the reflected light travels backward along the same optical path, passes through the polarizing beam splitter 34, and is sent to the light receiving element 3 by the condensing lens 38.
9 is focused as reproduction information. Since the reproduction information obtained in this way is fixed in the distance between the objective lens 36 and the recording layer 41 via the transparent spacer 37 as described above, focus lens errors due to warping or unevenness of the recording medium 43 does not occur. Also,
Since the aberration of the objective lens 36 is corrected, there is no image deterioration. In this way, in this embodiment, the transparent spacer 37 is brought into pressure contact with the recording medium 43, and the spatial distance between the transparent spacer 37 and the objective lens 36 is fixed, so that the objective lens moving mechanism can be omitted. . Note that the present invention is particularly effective when the recording medium 43 satisfies the following conditions. (1) The disk diameter is small, about 50 to 100φ. (2) The disc is stored in the cassette. (3) The disk has the flexibility of a floppy disk. FIGS. 4 and 55 are diagrams showing a floppy disk cassette equipped with the above-mentioned .phi. As shown in FIGS. 4 and 5, a floppy disk 55, which is a recording medium, is rotatably housed in a cassette 50. A head opening 51 is provided in the front surface of the cassette 50, and a dustproof plate 52 that is slidable in the radial direction of the disk 55 is provided in the head opening 51. A transparent spacer 53 similar to the transparent spacer 37 is integrated with this dustproof plate 52. The floppy disk 55 is made of a flexible material, and by rotating the disk hub 54 at high speed from an external drive source (not shown), it attempts to spread flatly within the cassette 50 in a plane perpendicular to the drive axis. . At this time,
When the transparent spacer 53 engages the rotating surface of the disk, a portion of the disk 55 is pushed downward and pressed into contact with the disk. Therefore, the recording surface of the medium and the upper surface of the transparent spacer 53 can always maintain a constant distance. Therefore, if the recording and reproducing optical member including the objective lens 36 can be placed on the transparent spacer 53 with high precision, stable recording and reproducing can be performed even without a focus length mechanism. FIG. 6 is a diagram showing an example thereof. Holder 600 for holding recording/reproducing optical members such as objective lens 36) A ring-shaped magnetic material 6 made of soft iron or the like with an accurately finished flat surface perpendicular to the axis of rotation of holder 60 is attached to the outer periphery of the tip using an adhesive or the like. A coil 62 is wound around the outer periphery of the coil 62. On the other hand, on the outer periphery of the transparent spacer 53 is a magnetic disk 63 made of soft iron or the like having a precisely finished plane perpendicular to the axis of rotation.
is fixed with adhesive or the like. Therefore, the holder 60 that holds the objective lens 36 etc. has a maximum diameter of a conical hole provided concentrically with the rotational axis of the holder 60 and a minimum diameter of a conical protrusion provided concentrically with the rotational axis of the transparent spacer 53. When the coils 62 are aligned and brought close to each other within the difference, and a direct current is applied to the coil 62, the magnetic disc 63 fixed to the transparent spacer 53 is magnetically attracted to the ring-shaped magnetic body 61 fixed to the holder 60. Ru. As a result, the objective lens 36 and the transparent spacer 53 move centripetally in a circular-axis manner due to the conical hole and conical protrusion, and are fixed at a predetermined constant distance. In order to separate the two, the current may be cut off and the lens holder 60 may be moved backward. Note that if the small area near the optical axis of the transparent spacer 530 is a parallel plane plate, there is no need for the above-mentioned centering within the range of the small area. Therefore, in this case, even if the centering by the conical hole and conical protrusion is not perfect, +
In addition, there is no problem even if there is a slight gap between the conical hole and the conical protrusion in the state where the lens holder 60 and the transparent spacer 53 are combined. When accessing the optical head in the track width direction,
As shown in Figure 6, transparent spacer 5.7 and objective lens 3
The holder 60 may be driven by an external head actuator in a state in which the holder 60 is integrated with a recording/reproducing optical member such as 6 or the like. By doing this, the transparent spacer 53 also moves together with the dustproof plate 52. FIG. 7 is a diagram showing another embodiment of the floppy disk cassette. As shown in the same figure (=both ends of the transparent spacer 53 in the direction of arrow movement (second is a bag-shaped frame 56 with one end open)
a and 56b are fixed. Inside these frames 56L and 56b are ultra-thin lightweight plates/gunes wound in a spiral shape, 5
7 a and 57b are stored, and the spiral plate/gune 5
7a. One end of the frame 57b comes out from the opening of each of the frames 56a and 56b and is fixed to the outermost and innermost sides of the disk in the cassette case. As the optical head moves, the transparent spacer 53
When moving to the left of the arrow (toward the outer circumference of the disk), the leaf spring 57a increases the number of turns, and the number of turns of the leaf spring 57b decreases. In the case of movement in the opposite direction to the above, the leaf spring 57b increases the number of turns, and the leaf spring 578 decreases the number of turns. Therefore, against the movement of 53 in the direction of the arrow, 56
The distances from the openings a and 56b to the respective fixed points are changed. Note that the plate springs 57a and 57b are made of the transparent spacer 5 as described above.
3, and also functions as a dustproof plate to prevent dirt and dust from entering the disk surface through the head opening 5 of the cassette case. Further, as the transparent spacer 53, in addition to a parallel plane plate, one having a lens function may be used. Figure 8 shows a gradient index lens 7 with edge focus as a transparent spacer.
This is an example using θ. In this case, it is naturally necessary to align the optical axes of the objective lens 36 and the spacer 53. The present invention can also be applied to hard type media with large disk diameters by adding a micro-range focusing lens mechanism. In the present invention, the distance between the objective lens and the recording surface of the recording medium does not essentially change significantly. Therefore, in the case of a hard disk, it is only necessary to add an alignment mechanism for correcting the thickness unevenness of several microns that occurs in the protective N covering the recording surface. If this level of objective position adjustment is desired, there is no need to use a voice coil as described above, and forcing adjustment can be performed using a small, low power consumption displacement means such as a bimorph element, for example. Furthermore, by using a minute displacement adjustment mechanism such as a bimorph element, it becomes possible to adjust the offset of the initial position between the floppy optical disk housed in the cassette and the optical head as described above. In other words, in the coupling method of the recording/reproducing optical member and the transparent spacer, each time a cassette is loaded into the device, the recording/reproducing optical member and the transparent spacer are repeatedly coupled and separated. There is a possibility that an offset due to a positional shift in the direction of force twisting on the order of μm may occur. In order to correct this, a bimorph element is installed between the transparent spacer 53 and the objective lens, and when the transparent spacer of the cassette and the recording/reproducing optical member on the device main body side are combined when loading the cassette, the focus lens information is Detection sensor. Information on the deviation of the Kufour force is detected, and based on this information on the deviation, the voltage to be supplied to the two pimol elements is determined, and the just focus position is selected. [Effects of the Invention] According to the present invention, a transparent spacer movable in contact with the recording medium is attached to the disk cassette that stores the optical information recording medium, so that an objective lens moving mechanism etc. is unnecessary. We can provide a new disc cassette that closes the disc. Further, according to the present invention, a recording and reproducing apparatus for recording and reproducing information using an optical information recording medium is provided with a recording and reproducing optical member that is coupled to the transparent spacer of the disk cassette to form an optical system. By using the disk cassette described above, it is possible to provide a recording and reproducing apparatus that does not require a complicated objective lens moving mechanism, consumes less power, and is suitable as a small, lightweight, and portable type. 1. Brief explanation of the drawings Figures 1 to 2 all show the configuration of a conventional optical recording/reproducing device. Figure 1 is a configuration diagram showing the configuration of a conventional optical head, and Figure 2 is A sectional view showing the structure of the objective lens moving mechanism, and FIGS. 3 to 6 are all views showing an embodiment of the present invention. FIG. Figure 4 is a front view of the floppy disk cassette in the same embodiment, Figure 5 is a schematic sectional view of Figure 4, and Figure 6 is a schematic cross-sectional view of Figure 4.
The figure is a partial sectional view showing a state in which the transparent spacer of the floppy disk cassette and the recording/reproducing optical member on the side of the main body of the apparatus are integrally combined, and FIGS. 7 and 8 are views showing other embodiments of the present invention. FIG. 7 is a sectional view showing another example of a floppy disk cassette, and FIG. 8 is a perspective view showing a transparent spacer made of a gradient index lens. 3... Laser diode, 32... Collimating lens, 33... Cylindrical lens, 34... Polarizing beam splitter, 35... 1/4 wavelength plate, 36...
...Objective lens, 37...Transparent spacer, 38...
Condensing lens, 39... Light receiving element, 40... Lubricating layer,
43... Recording medium, 50... Disc cassette, 5
3... Transparent spacer, 65... Floppy disk, 57a, 57b... Lightweight plate spring, 60... Holder, 6... Ring-shaped magnetic body, 63... Magnetic disc, 7
0...Gradient refractive index lens. Applicant's agent Patent attorney Atsushi Tsuboi 115-

Claims (1)

[Claims] (1) In an optical recording and reproducing device that records and reproduces information by focusing Raded light on a disk-shaped recording medium that rotates at a constant speed, a lubricant layer is formed on the recording surface of the recording medium, and this lubricant layer An optical recording/reproducing device comprising a lens system comprising an optical transparent body having negative spherical aberration that is in pressure contact with the object, and an objective lens having positive spherical aberration that cancels out the negative spherical aberration. Optical recording and playback device.