Optical information recording/reproducing apparatus and disk distinction method

An optical information recording/reproducing apparatus includes an optical source unit that emits an optical beam toward an optical information recording medium mounted on the apparatus, an optical receiving unit that receives a reflected beam of the optical beam reflected from the optical information recording medium or a transmitted beam of the optical beam transmitted through the optical information recording medium to output an output signal in response to the reflected beam or transmitted beam, and a distinction unit that discriminates whether the optical information recording medium is a hologram disk for recording information by using a holography or a reflection-type optical disk for reproducing information by virtue of the reflected beam, in accordance with the output signal output.

INCORPORATION BY REFERENCE

The present application claims priority from Japanese application JP-2007-256327 filed on Sep. 28, 2007, the content of which is hereby incorporated by reference into this application.

BACKGROUND OF THE INVENTION

The present invention relates to an apparatus and a method for recording and/or reproducing information in relation to an optical information recording medium by using a holography.

In the past, there have been an optical information recording and/or reproducing apparatus that records information in an information recording area (information recording surface) and/or reproduces the information from the area, of a reflection-based optical information recording medium (optical disk), such as CD (Compact Disk), DVD (Digital Versatile Disk), etc.

Recently, it is also possible to realize commercially available reflection-based disks having a recording density as large as 50 GB in consumer use, in accordance with the specifications of Blu-ray disk (hereinafter, referred to as BD) using a blue-violet semiconductor laser, HD DVD (High Definition DVD), etc. On the contrary, it is also desirable to realize an optical disk having a large storage capacity as large as 100 GB to 1 TB mostly equal to the storage capacity of HDD (Hard Disk Drive).

However, for a purpose of realizing the foregoing ultra-high density by the optical disk, it is necessary to realize a new storage technique different from the existing high density technique obtained from the traditional approach such that a wavelength is made short and NA of an objective lens is made high. Consequently, a holographic recording technique has attracted attention in these years such that digital information is recorded by using a holography. According to the holographic recording technique, it is effective to record and reproduce information in large volume and high speed since two-dimensional information can be recorded and reproduced simultaneously by one hologram, and plural pieces of page data can be written over the same area.

As an example of the holographic recording technique indicated above, there is an angle multiplex recording system, in which a signal beam is focused on a holographic optical disk (hereinafter, referred to as a hologram disk) by a lens, at the same time, a reference beam of a parallel pencil is irradiated thereon and interfered to record a hologram, and each piece of page data is displayed on a spatial light modulator to perform a multiple recording while an incidence angle of the reference beam toward the hologram disk is changed. The foregoing technique has been disclosed in JP-A-2004-272268.

WO2004-102542 has also proposed a holographic recording technique using a shift multiplexing, in which a beam from pixels inside one spatial light modulator is regarded as a signal beam, and a beam from pixels of orbicular zone shape outside the spatial light modulator is regarded as a reference beam, both the foregoing beams are then focused on the hologram disk by the same lens used for both the beams, and the signal beam and reference beam are made interference with each other in the vicinity at a focal plane of the lens to thereby record a hologram.

SUMMARY OF THE INVENTION

In the case of an optical information recording/reproducing apparatus adaptable to the hologram disk, it is desirable that information can also be recorded and reproduced in and from the existing reflection-type optical disk (referred to as an optical disk on which an optical beam is irradiated to reproduce information on the basis of a reflected beam) typically used as CD, DVD, BD, etc., from a point of view relative to compatibility with a high-order device. In this regard, since the recording/reproducing system of the reflection-type optical disk is quite different from that of the hologram disk, it is desirable that the optical information recording/reproducing apparatus is constituted such that an optical disk mounted on the apparatus is discriminated automatically whether it is the reflection-type optical disk or hologram disk, and information is recorded or reproduced by the recording/reproducing system adapted to the optical disk on the basis of a discriminated result.

In this way, the optical information recording/reproducing apparatus is constituted by the foregoing manner, so that a user can use the apparatus without regard to the type of mounting optical disk, in addition, usability of the apparatus can be enhanced.

The present invention is realized by considering the foregoing points, and an object of the invention is to provide an optical information recording/reproducing apparatus capable of enhancing usability.

In order to achieve the foregoing object of the invention, according to a first aspect of the invention, the optical information recording/reproducing apparatus records information in an optical information recording medium and reproduces the information recorded on the medium, and the apparatus includes: an optical source unit that emits an optical beam toward the optical information recording medium mounted on the apparatus; an optical receiving unit that receives a reflected beam of the optical beam reflected from the optical information recording medium or a transmitted beam of the optical beam transmitted through the optical information recording medium to output an output signal in response to the reflected beam or transmitted beam; and a distinction unit that discriminates whether the optical information recording medium is a hologram disk for recording information by using a holography or a reflection-type optical disk for reproducing information by virtue of the reflected beam, in accordance with the output signal output from the optical receiving unit.

According to a second aspect of the invention, a disk distinction method includes steps of recording information in an optical information recording medium and/or reproducing the information recorded on the medium in an optical information recording/reproducing apparatus, and the method further includes steps of: emitting an optical beam toward the optical information recording medium mounted on the apparatus; receiving a reflected beam of the optical beam reflected from the optical information recording medium or a transmitted beam of the optical beam transmitted through the optical information recording medium and outputting an output signal in response to the reflected beam or transmitted beam; and discriminating whether the optical information recording medium is a hologram disk for recording information by using a holography or a reflection-type optical disk for reproducing information by virtue of the reflected beam in accordance with the output signal, on the basis of the output signal.

According to the invention, the optical information recording/reproducing apparatus can be used by a user without regard to the type of mounting optical disk, so that usability of the apparatus can be enhanced.

DETAILED DESCRIPTION OF THE INVENTION

(1) First Embodiment

(1-1) Constitution of the Optical Information Recording/Reproducing Apparatus in the First Embodiment;

Referring toFIG. 1, a reference numeral1denotes an optical information recording/reproducing apparatus in the embodiment as a whole. The optical information recording/reproducing apparatus records and reproduces information in and from a hologram disk3in response to a request from a host device2, as well as in and from a reflection-type optical disk4.

The optical information recording/reproducing apparatus1in the embodiment provides with an optical pick-up11, a phase conjugate optical system12, a disk-cure optical system13, a disk rotation angle detecting optical pick-up14, a rotational motor16, and a microcomputer17for controlling the foregoing components. In this way, an optical disk (including the hologram disk3and reflection-type optical disk4) mounted on the apparatus in a predetermined condition is driven rotatably by the rotational motor16.

The optical pick-up11is constituted by a hologram optical system11A for recording/reproducing information in and from the hologram disk3and a reflection-type optical disk optical system11B for recording/reproducing information in and from the reflection-type optical disk4.

The hologram optical system11A emits a reference beam and a signal beam to the hologram disk3to serve as a recording of digital information by using a holography. At this time, an information signal to be recorded is generated by applying a predetermined signal processing to the digital information supplied from the host2to the microcomputer17in a hologram signal generation circuit18. On the basis of this information signal, the signal beam formed by a spatial light modulation of an optical beam is generated in the hologram optical system11A in the optical pick-up11. An irradiation time period of the reference beam and signal beam to be irradiated on the hologram disk3can be adjusted by controlling an open-close time period of an after-mentioned shutter42(referring toFIG. 3) in the optical pick-up11via a shutter control circuit (not shown) by the microcomputer17.

In the case of reproducing information recorded on the hologram disk3, a phase conjugate beam of the reference beam emitted from the hologram optical system11A is generated by the phase conjugate optical system12fitted on an opposite side of the hologram optical system11A as based on the hologram disk3. Here, the phase conjugate beam is a light wave which progresses toward a reverse direction while it keeps a wave surface identical with that of an input beam. A reproduced beam reproduced by the phase conjugate beam is detected by an after-mentioned optical detector62(referring toFIG. 3) in the hologram optical system11A to reproduce a signal by a hologram signal processing circuit19.

For a purpose of performing the foregoing recording/reproducing operation over an entire surface of the hologram disk3, the hologram disk3is rotated by the rotational motor16. In this case, it is desirable that the hologram disk3stands still on recording and reproducing information since a sufficient energy is required for stably recording information in the hologram disk3. Therefore, in this embodiment, the microcomputer17controls the drive of rotational motor16via a disk rotational motor control circuit20such that information is recorded or reproduced while the hologram disk3, in turn, stands still.

The disk-cure optical system13is used for generating an optical beam for purposes of a pre-cure and post-cure of the hologram disk3. Here, the pre-cure means a pre-process that irradiates a predetermined optical beam on a desired position before irradiating the reference beam and signal beam thereon when information is recorded in the desired position of the hologram disk3. Further, the post-cure means a post-process that irradiates a predetermined optical beam on the desired position to be set to a write inhibit, after the information is recorded on the desired position in the hologram disk3.

The disk rotation angle detecting optical pick-up14is an optical pick-up to detect a rotation angle of the hologram disk3, and has the same constitution as the reflection-type optical disk optical system11B in the after-mentioned optical pick-up11inFIG. 4. In this case of the embodiment, as shown inFIG. 2, a rotational angle control track3A having a sine-wave shape to be set a predetermined rotation angle of the hologram disk3to one cycle and a reflection layer are formed at one innermost circle on a surface of the hologram disk3that faced to the disk rotation angle detecting optical pick-up14, over one circle of the hologram disk3. The disk rotation angle detecting optical pick-up14irradiates a red optical beam on the rotation angle control track3A, on the basis of a reflected beam relative to the irradiation, a rotation angle detected signal is generated in response to the rotation angle of the hologram disk3, and the rotation angle detected signal is then sent to the microcomputer17. In this way, the microcomputer17controls the rotation angle of hologram disk3via the disk rotational motor control circuit20on the basis of the rotation angle detected signal.

In addition, a focusing (auto focus) of an optical spot in the optical beam on the hologram disk3is performed through a rotation angle detecting servo signal generation circuit21and a rotation angle detecting servo control circuit22. A positioning (tracking) on a track (guide groove) is also performed through the circuits21and22. Further, an existing-type disk detection circuit23has a function for generating a signal to discriminate whether a mounting optical disk, at this time, is the reflection-type optical disk4as an existing type, on the basis of a focusing error signal of a signal level corresponding to a defocusing amount of the optical beam relative to the optical disk, in which the focusing error signal is generated by the rotation angle detecting servo signal generation circuit21. A specific constitution of the existing-type disk detection circuit23will be described later.

The following components have an optical source for each: the hologram optical system11A and reflection-type optical disk optical system11B in the optical pick-up11; the disk-cure optical system13; and the disk rotation angle detecting optical pick-up14. These optical sources receive a predetermined optical source drive current from an optical source drive circuit24. In this way, these optical sources can emit optical beams of a predetermined amount of light, respectively.

Further, each of the optical pick-up11, phase conjugate optical system12and disk-cure optical system13has a slide mechanism to be able to slide its position in the radial direction of hologram disk3, so that a position control can be performed through an access control circuit25. Therefore, it is possible to record and reproduce information in and from the entire surface of the disk by the position control.

In addition, for a purpose of realizing downsizing for the optical information recording/reproducing apparatus1, the components such as optical pick-up11, phase conjugate optical system12, disk-cure optical system13and disk rotation angle detecting optical pick-up14, may be simplified to an optical construction including a few or all components. Further, since the recording technique using the holography is a technique to be able to record super-dense information, for example, there is a tendency for an allowable error to become extremely small in relation to an inclination and displacement of the hologram disk3. For this reason, a detection mechanism may be provided in the optical pick-up11to detect a displacement amount causing a small allowable error, such as inclination, displacement, etc. of the hologram disk3, a hologram servo signal generation circuit26may generate a signal to be used for the servo control, and a servo mechanism may be provided in the optical information recording/reproducing apparatus1to correct the displacement amount through a servo control circuit27.

On the contrary, the reflection-type optical disk optical system11B in the optical pick-up11emits the signal beam to the reflection-type optical disk4to serve as a recording of digital information. At this time, an information signal to be recorded is generated by applying a predetermined signal processing to the digital information supplied to the microcomputer17from the host2in a reflection-type optical disk signal generation circuit28. On the basis of the information signal, a modulated optical beam is emitted from the reflection-type optical disk optical system11B in the optical pick-up11and focused on the reflection-type optical disk4to record the information therein.

Further, in the case of reproducing the information recorded on the optical disk, a reflected beam from the reflection-type optical disk4is converted to an electric signal in the reflection-type optical disk optical system11B, and a predetermined signal processing is applied to the electric signal in a reflection-type optical disk signal processing circuit29to thereby obtain a reproduced signal. In this way, the reproduced signal obtained from the above is output to the host2via the microcomputer17. In the recording/reproducing operation described above, the focusing (auto focus) of an optical spot on the reflection-type optical disk4is performed through a reflection-type optical disk servo signal generation circuit30and a servo control circuit27, and the positioning (tracking) on the track (guide groove) is also performed through the circuits30and27.

For a purpose of performing the foregoing recording/reproducing operation over the entire surface of reflection-type optical disk4, the reflection-type optical disk4is rotated by the rotational motor16. In this case, for a purpose of obtaining a high speed transfer rate, such as several hundreds Mbps on recording/reproducing information in and from the reflection-type optical disk4, the microcomputer17controls the drive of rotational motor16via the disk rotational motor control circuit20such that the optical disk is rotated in high speed, such as several thousand revolutions per minute.

FIG. 3shows a specific constitution of the hologram optical system11A. In the case of the hologram optical system11A, the optical beam emitted from an optical source40is incident to the shutter42via a collimate lens41. When the shutter42is open, the optical beam passes through the shutter42, and is incident to a PBS prism44, after a polarizing direction is controlled such that a light amount ratio of P-polarization and S-polarization becomes a desirable ratio by an optical element43constituted by a half-wave plate etc., for example. A diameter of the optical beam transmitted through the PBS prism44is enlarged by beam expanders45, and then led into a spatial light modulator49via a phase mask46, relay lenses47and a PBS prism48. The spatial light modulator49applies a spatial light modulation to the optical beam on the basis of the information signal supplied from the hologram signal generation circuit18(FIG. 1). The signal beam obtained from the foregoing result is incident to an object lens52via a spatial filter51between relay lenses50to focus on the hologram disk3by the object lens52.

The optical beam reflected by the PBS prism44is set to a predetermined polarizing direction by a polarizing direction converting element53in response to either the time of recording or reproducing, and is then incident to a galvanometer mirror56via mirrors54and55. A reflected beam reflected as a reference beam by the galvanometer mirror56is therefore incident to the hologram disk3via a lens58and an object lens59. Here, the galvanometer mirror56is a mirror which can be rotated by an actuator57. In response to the rotation, an incident angle of the reference beam toward the hologram disk3can be set to a desirable angle.

In this way, the signal beam and reference beam are incident to the hologram disk3such that both the beams are overlapped with each other. An interference pattern is thereby formed on the hologram disk3, and written in an information recording area to record information. Further, the incident angle of the reference beam to be incident to the hologram disk3can be changed by rotating the galvanometer mirror52, so that it is possible to record the information by an angle multiplex recording system.

In the case of reproducing the information recorded on the hologram disk3, the reference beam alone is incident to the hologram disk3by closing the shutter42, and the optical beam transmitted through the hologram disk3is reflected by a galvanometer mirror60in the phase conjugate optical system12, so that a phase conjugate beam can be generated. In addition, the galvanometer mirror60is maintained rotatably by an actuator61. A reproduced optical beam reproduced by the phase conjugate beam is incident to the PBS prism48via the spatial filter51resided between the object lens52and relay lenses50, and is reflected by the PBS prism48to be incident to the optical detector62. In this way, the output of optical detector62is given to the hologram signal processing circuit19(FIG. 1) to be performed a reproducing processing.

On the contrary,FIG. 4shows a specific constitution of the reflection-type optical disk optical system11B. In the case of recording information on the reflection-type optical disk4in the reflection-type optical disk optical system11B, an optical beam modulated on the basis of the information signal supplied from the reflection-type optical disk signal generation circuit28(FIG. 1) is emitted from an optical source70, and incident to a polarizing direction converting element72via a collimate lens71. The polarizing direction converting element72controls a polarizing direction such that the polarization of optical beam to be incident from the element becomes the S-polarization. The optical beam to be incident to a PBS prism73is thereby reflected, and led into a light path of a beam expander74. Next, the optical beam passed through the beam expander74is incident to an object lens77with a circularly-polarized light formed via a mirror75and an optical element76constituted by a quarter-wave plate etc., for example, and focused by the object lens77on an information recording area (information recording surface) of the reflection-type optical disk4. In this way, the information is recorded on the reflection-type optical disk4by the optical beam.

Further, a reflected beam of the optical beam reflected from the reflection-type optical disk4is transmitted through the PBS prism73via the object lens77, optical element76, mirror75, and beam expander74. The optical beam transmitted through the PBS prism73is transmitted through a collimate lens78, then diffracted separately into a desired optical beam by a detection side diffraction grating79to detect an information signal, a desired servo signal, etc., and eventually focused on an optical receiving surface of an optical detector80. In this way, the output of optical detector80is given to the reflection-type optical disk servo signal generation circuit30(FIG. 1), and a tracking error signal and a focusing error signal are generated in the reflection-type optical disk servo signal generation circuit30on the basis of the output from the optical detector80. On the basis of the tracking error signal and focusing error signal, the tracking control and focusing control are performed through the servo control circuit27under the control of microcomputer17.

Furthermore, in the case of reproducing the information recorded on the reflection-type optical disk4, a certain optical source drive current is supplied from the optical source drive circuit24under the control of microcomputer17to emit an optical beam having a certain power from the optical source70. The optical beam is focused on an information recording surface of the reflection-type optical disk4, similarly to the foregoing recording operation, and a reflected beam of the optical beam is incident to the optical detector80, also similarly to the foregoing recording operation. The output of optical detector80is then given to the reflection-type optical disk signal processing circuit29(FIG. 1) to perform the reproducing processing therein. Further, the output of optical detector80is also given to the reflection-type optical disk servo signal generation circuit30. In this way, the tracking control and focusing control are performed on the basis of the output of optical detector80, similarly to the foregoing recording operation.

As described above, the optical pick-up11changes over (selects) whether the optical beam is emitted from the optical source40or from the optical source70, so that the information can be recorded and reproduced in and from the hologram disk3or reflection-type optical disk4.

FIG. 5toFIG. 7show recording/reproducing operation flows in the optical information recording/reproducing apparatus1. Here, an operation associated with the recording and reproducing relative to the hologram disk3will specifically described below.

FIG. 5shows a recording/reproducing provision processing flow from when the optical disk is set into the optical information recording/reproducing apparatus1to when a recording or reproducing provision is completed.FIG. 6shows a recording processing flow from when a provision completed condition to when information is recorded on the optical disk.FIG. 7shows a reproducing processing flow from when the provision completed condition to when the information recorded on the optical disk is reproduced.

As shown inFIG. 5, the optical disk is set to the apparatus (step SP1). The optical information recording/reproducing apparatus1discriminates the setting optical disk whether it is used for an optical disk (hologram disk3) for recording or reproducing digital information by using the holography (step SP2).

From a result of the disk discrimination, if the process discriminates that the setting optical disk is the hologram disk3, the optical information recording/reproducing apparatus1reads out control data provided on the hologram disk3to obtain information relative to the optical disk and information relative to various setting conditions at a time of the recording or reproducing (step SP3).

The optical information recording/reproducing apparatus1completes the reading of the control data to perform various adjustments in response to the control data and a learning processing relative to the optical pick-up11(step SP4), and the provision for the recording or reproducing is completed (step SP5).

The operation flow from the provision completed condition to the recording of information is shown inFIG. 6. That is, the optical information recording/reproducing apparatus1receives data to be recorded to then send information corresponding to the data to the foregoing spatial light modulator49of the hologram optical system11A (FIG. 3) in the optical pick-up11(step SP10).

After that, the optical information recording/reproducing apparatus1performs the various learning processings in advance, as required, to be able to record high quality information in the hologram disk3(step SP11), and allocates positions of the optical pick-up11and disk-cure optical system13to predetermined positions of the hologram disk3while repeating a seeking operation and an address regeneration (steps SP12and SP13).

Subsequently, the optical information recording/reproducing apparatus1performs a pre-cure processing to apply a pre-cure to a predetermined area by using the optical beam emitted from the disk-cure optical system13(step SP14), after that, records the data by using the reference beam and signal beam emitted from the hologram optical system11A in the optical pick-up11(step SP15).

After recording the data, the optical information recording/reproducing apparatus1verifies the data, as required (step SP16), and performs a post-cure processing to apply a post-cure to the data recording area by using the optical beam emitted from the disk-cure optical system13(step SP17).

The operation flow from the provision completed condition to the reproducing of information is shown inFIG. 7. That is, the optical information recording/reproducing apparatus1performs the various learning processings, as required, to be able to reproduce the high quality information from the hologram disk3(step SP20). After that, the optical information recording/reproducing apparatus1allocates positions of the optical pick-up11and phase conjugate optical system12to predetermined positions of the hologram disk3while repeating the seeking operation and the address regeneration (steps SP21and SP22).

The optical information recording/reproducing apparatus1then makes the hologram optical system11A in the optical pick-up11emit the reference beam, and reads out the information recorded on the hologram disk3(step SP23).

(2-1) Disk Distinction Method in the Embodiment;

Next, a specific method of a disk distinction processing to be performed at the step SP2inFIG. 5will be described below.

FIGS. 8A to 8Cshow amplitude variations of a focusing error signal S1. This focusing error signal is generated by the rotation angle detecting servo signal generation circuit21on the basis of a reflected beam of the optical beam reflected from the optical disk, by emitting the optical beam to the optical disk from the disk rotation angle detecting optical pick-up14while an object lens (not shown) on the pick-up14is moved in an axial direction of the optical disk.

In this case, when the optical disk is not mounted on the optical information recording/reproducing apparatus1, the amplitude of focusing error signal S1is always maintained at a constant value “0” since the optical beam emitted from the disk rotation angle detecting optical pick-up14is not reflected from the optical disk. Further, when the hologram disk3is mounted on the optical information recording/reproducing apparatus1, the amplitude of focusing error signal S1is varied slightly by the reflected beam as shown inFIG. 8B, since the optical beam is reflected from the surface of hologram disk3.

Therefore, a threshold value (hereinafter, this is referred to as a first threshold value voltage Vth1) is set between the signal level of focusing error signal S1inFIG. 8Aand the peak level of focusing error signal S1inFIG. 8B. It is judged whether the variation of focusing error signal S1is greater than the first threshold value voltage Vth1in the case where the optical beam is emitted from the disk rotation angle detecting optical pick-up14, while the focusing position is changed toward the optical disk as described above, so that it can be judged whether the optical disk is mounted on the optical information recording/reproducing apparatus1.

On the other hand, when the reflection-type optical disk4is mounted on the optical information recording/reproducing apparatus1, the amplitude of focusing error signal S1is varied by the reflected beam, as shown inFIG. 8C, since the optical beam emitted from the disk rotation angle detecting optical pick-up14is reflected from the surface of the reflection-type optical disk4and the reflection layer thereof. In this case, since the optical beam is reflected from the reflection layer much more than from the surface of reflection-type optical disk4, the amplitude of focusing error signal S1becomes greater than the variation (the left side variation inFIG. 8C) caused by the reflected beam from the surface of reflection-type optical disk4than the variation (the right side variation inFIG. 8C) caused by the reflected beam from the reflection layer.

Therefore, a threshold value (hereinafter, this is referred to as a second threshold value voltage Vth2) is set between the peak level of focusing error signal S1on the basis of the reflected beam from the surface of reflection-type optical disk4and the peak level of focusing error signal S1on the basis of the reflected beam from the reflection layer of the existing-type disk4. It is then judged whether the variation of focusing error signal S1is greater than the second threshold value voltage Vth2in the case where the optical beam is emitted from the disk rotation angle detecting optical pick-up14, while the focusing position is changed toward the optical disk, so that it is judged whether the mounting optical disk on the optical information recording/reproducing apparatus1is the hologram disk3.

Consequently, in the optical information recording/reproducing apparatus1of the embodiment, it is judged whether the signal level of focusing error signal S1is greater than the foregoing first threshold value voltage Vth1or second threshold value voltage Vth2, as shown inFIGS. 8A to 8C, in the reflection-type optical disk detection circuit23, on the basis of the focusing error signal S1generated in the rotation angle detecting servo signal generation circuit21, so that it can be judged whether the optical disk is mounted, and judged whether the optical disk is the hologram disk3or reflection-type optical disk4, when the optical disk is mounted on the apparatus.

FIG. 9shows a specific constitution of the reflection-type disk detection circuit23having the foregoing function. As is apparent fromFIG. 9, outputs from a first optical receiving area81A and a third optical receiving area81C in a four-segmented optical detector81provided in the disk rotation angle detecting optical pick-up14, are given to a first adding circuit83A via a first IV amplifier82A and a third IV amplifier82C provided in the rotation angle detecting servo signal generation circuit21, and is added therein to be given as a first added signal to a positive input terminal of a subtracting circuit84. Further, outputs from a second light receiving area81B and a fourth light receiving area81D in the four-segmented light detector81, are given to a second adding circuit83B via a second IV amplifier82B and a fourth IV amplifier82D provided respectively in the rotation angle detecting servo signal generation circuit21, and is added therein to be given as a second added signal to a negative input terminal of the subtracting circuit84.

The subtracting circuit84subtracts the second added signal from the first added signal to obtain a focusing error signal and send it to the microcomputer17. In this way, the microcomputer17controls the disk rotation angle detecting optical pick-up14via the rotation angle detecting servo control circuit22on the basis of the focusing error signal, such that the optical beam emitted from the disk rotation angle detecting optical pick-up14is focused correctly on the optical disk, as described above.

Further, the focusing error signal output from the subtracting circuit84is also given to positive input terminals of a first subtracting circuit85A and a second subtracting circuit85B in the reflection-type disk detection circuit23. The foregoing first threshold value voltage Vth1is then given to a negative input terminal of the first subtracting circuit85A from a first threshold value voltage output circuit86A under the control of microcomputer17on the disk distinction processing at the step SP2inFIG. 5. In this way, the first subtracting circuit85A subtracts the first threshold value voltage Vth1from the signal level of the focusing error signal to output a difference voltage between the focusing error signal and the first threshold value voltage Vth1, as a first judged signal, to the microcomputer17.

Likewise, the foregoing second threshold value voltage Vth2is given to a negative input terminal of the second subtracting circuit85B from a second threshold value voltage output circuit86B under the control of microcomputer17on the disk distinction processing at the step SP2inFIG. 5. In this way, a second subtracting circuit84B subtracts the second threshold value voltage Vth2from the signal level of the focusing error signal to output a difference voltage between the focusing error signal and the second threshold value voltage Vth2, as a second judged signal, to the microcomputer17.

The microcomputer17then judges whether the optical disk is mounted, and whether the optical disk is the hologram disk3or reflection-type optical disk4in the case where the optical disk is mounted, on the basis of the first and second judged signals given from the reflection-type disk detection circuit23. Further, the microcomputer17performs various setting processings on the basis of judged results.

FIG. 10is a flowchart showing specific processing contents of the microcomputer17in relation to the foregoing disk distinction processing. The microcomputer17executes the disk distinction processing shown inFIG. 10on the basis of a control program stored in an internal memory (not shown).

That is, the microcomputer17executes the step SP2of the foregoing recording/reproducing provision processing inFIG. 5to then start the disk distinction processing. First, the disk rotation angle detecting optical pick-up14is moved up to a position where it is faced to a predetermined position on the optical disk in the case where the optical disk is mounted on the apparatus, by driving a slide mechanism (not shown) used for the disk rotation angle detecting optical pick-up14(step SP30).

Subsequently, the microcomputer17controls the optical source drive circuit24(FIG. 1) to supply a power source drive current to the optical source in the disk rotation angle detecting optical pick-up14and emit the optical beam (red optical beam) from the pick-up14(step SP31).

After that, the microcomputer17drives a biaxial actuator (not shown) which holds an object lens (not shown) in the disk rotation angle detecting optical pick-up14to make the object lens move to the farthest position from the optical disk, in the case where the optical disk is mounted on the apparatus (step SP32).

The microcomputer17then drives the biaxial actuator to start the movement of the object lens in the focusing direction (step SP33), and then obtains peak values of the respective signal levels of the first and second judged signals given from the reflection-type disk detection circuit23(step SP34).

Subsequently, the microcomputer17judges whether the peak value of the focusing error signal exceeds the first threshold value voltage Vth1on the basis of the peak value of the first judged signal obtained at the step SP34(step SP35). The microcomputer17then obtains a negation result from the judgment at the step SP35to judge that the optical disk is not mounted on the apparatus (step SP39), and the disk distinction processing is completed.

On the other hand, the microcomputer17obtains an affirmation result in the judgment at the step SP35to judge whether the peak value of the focusing error signal exceeds the second threshold value voltage Vth2(whether the peak value of the second judged signal is a positive value), on the basis of the peak value of second judged signal obtained at the step SP34(step SP36).

The microcomputer17obtains the negation result at the step SP36to judge that the mounting optical disk is the hologram disk3(step SP37). In contrast, the microcomputer17obtains the affirmation result to judge that the mounting optical disk is the reflection-type optical disk4(step SP38), and the disk distinction processing is then completed.

(1-3) Advantages of the Embodiment

As described above, in the case of the optical information recording/reproducing apparatus1, a user can use the optical information recording/reproducing apparatus1without regard to the type of optical disk mounting on the apparatus1since the optical beam is irradiated on the optical disk, and the type (hologram disk3or reflection-type optical disk4) of optical disk being mounted is discriminated on the basis of a reflected beam. This enables the optical information recording/reproducing apparatus1to enhance usability.

(2) Second Embodiment

FIG. 11shows a constitution of an optical information recording/reproducing apparatus90in a second embodiment, and the same element shown inFIG. 1is indicated by the same reference numeral inFIG. 11. The optical information recording/reproducing apparatus90does not use the optical beam, used for the disk rotation angle detection, emitted from the disk rotation angle detecting optical pick-up14, but uses the optical beam (red optical beam), used for recording/reproducing information in and from CD, emitted from the reflection-type optical disk optical system11B in the optical pick-up11. The foregoing constitution is the same as the optical information recording/reproducing apparatus1in the first embodiment, except for the distinction of whether the mounting optical disk is the hologram disk3.

Practically, in the case of optical information recording/reproducing apparatus90, the focusing error signal generated in the reflection-type optical disk servo signal generation circuit30is given to a reflection-type optical disk detection circuit91. The detection circuit91has the same constitution as the reflection-type disk detection circuit23(FIG. 1) in the first embodiment, and sends the same first and second judged signals in the first embodiment to a microcomputer92.

The microcomputer92judges whether the optical disk is mounted on the apparatus, and whether the mounting optical disk is the hologram disk3in the case where the optical disk is mounted, on the basis of the first and second judged signals given from the reflection-type optical disk detection circuit91. In addition, a description for processing steps of the disk distinction processing by the microcomputer92on the basis of the first and second judged signals is omitted since it is the same as the foregoing disk distinction processing inFIG. 10.

As described above, in the case of optical information recording/reproducing apparatus90in the embodiment, the user can use the optical information recording/reproducing apparatus90without regard to the type of optical disk mounting on the apparatus1, similarly to the first embodiment, since the type of optical disk is discriminated by using the red optical beam for recording/reproducing information in and from CD. This enables the optical information recording/reproducing apparatus90to enhance usability.

FIG. 12shows a constitution of an optical information recording/reproducing apparatus100in a third embodiment, and the same element shown inFIG. 1is indicated by the same reference numeral inFIG. 12. The optical information recording/reproducing apparatus100has the same constitution as the optical information recording/reproducing apparatus1in the first embodiment, except that the type of optical disk is discriminated on the basis of a transmitted beam through the optical disk, and that it is judged whether the optical disk is present or absent on the basis of a stationary rotation speed of the rotational motor16.

That is, in the case of the first and second embodiments, it is judged whether the optical disk is present or absent on the apparatus by irradiating the optical beam on the optical disk and on the basis of a light amount of the reflected beam from the optical disk. Besides, the type of optical disk is discriminated when the optical disk is mounted on the apparatus.

However, in consideration of the hologram disk3which is an optically transmitted type optical disk without having a reflection layer and the reflection-type optical disk4, such as CD, DVD, BD, etc., which is a reflection-type optical disk4with the reflection layer, the optical disk through which the optical beam is transmitted can be discriminated to the hologram disk3, and the optical beam is not transmitted can be discriminated to the reflection-type optical disk4.

Consequently, in the case of the optical information recording/reproducing apparatus100in the embodiment, the reference beam is irradiated on the optical disk from the hologram optical system11A at the step SP2inFIG. 5, the transmitted beam thereof is received by a phase conjugate optical system101, and it is then judged whether the mounting optical disk is the hologram disk3on the basis of a received light amount of the transmitted beam.

FIG. 13shows a specific constitution of a part associated with the disk distinction function in the optical information recording/reproducing apparatus in the embodiment, and the same element shown inFIG. 3is indicated by the same reference numeral inFIG. 13. In this case, the phase conjugate optical system101in the optical information recording/reproducing apparatus100provides with a reflection-type optical disk detection circuit103in addition to a verification judgment circuit102for performing the foregoing verification at the step SP16inFIG. 6.

An optical detector110in the phase conjugate optical system101receives the reference beam transmitted through the optical disk, among the reference beams emitted from the hologram optical system11A on the disk distinction processing at the step SP2inFIG. 5. At this time, the output of optical detector110, as a received signal, is sent to the reflection-type optical disk detection circuit103via an IV amplifier111.

The reflection-type optical disk detection circuit103is constituted by a threshold value voltage output circuit112and a subtracting circuit113to supply the received signal given from the phase conjugate optical system103to a positive side input terminal of the subtracting circuit113. On the disk distinction processing, the threshold value voltage output circuit112outputs, to a negative side input terminal of the subtracting circuit113, a predetermined voltage (hereinafter, this voltage is referred to as threshold value voltage Vth3) which is lower than the signal level of received signal output from the optical detector110receiving the reference beam transmitted through the hologram disk3, and higher than the signal level of received signal output from the optical detector110when the reference beam is blocked by the reflection-type optical disk4, under control of a microcomputer104.

In this way, the subtracting circuit113subtracts the threshold value voltage Vth3from the output voltage of optical detector110to send a subtracted result, as a discriminated signal, to the microcomputer104. The microcomputer104then judges whether the mounting optical disk is the hologram disk3on the basis of the discriminated signal given from the subtracting circuit113.

In addition, when the type of optical disk is discriminated on the basis of the transmitted beam through the optical disk as described above, it is required to pay attention to the optical disk position on which the reference beam is irradiated such that the reference beam irradiated on the optical disk is adversely affected to the information recorded on the hologram disk3.

That is, a photopolymer constituting a recording layer of the hologram disk3has a characteristic indicating that it hardly absorbs an energy at an initial condition (information is hardly recorded), and it becomes a condition where the energy is easily absorbed after absorbing to some extent of the energy (information is easily recorded), but it becomes a condition where the energy is hardly absorbed after absorbing a predetermined amount of the energy, as shown inFIG. 14.

Consequently, when information is recorded on the hologram disk3in general, the pre-cure processing (the step SP14inFIG. 6, and time t1to time t2inFIG. 14) is applied to an area portion on which the information is recorded in the hologram disk3. After the recording of the information is completed, the post-cure processing (time t3to time t4inFIG. 14) is applied to the area portion to place the information firmly thereon. Referring toFIG. 14, TH3denotes an energy threshold value to be given to the area portion on which the information is recorded on the pre-cure processing, and TH4denotes an energy threshold value to be given to the area portion on which the information is recorded on the post-cure processing.

Therefore, when the type of optical disk is discriminated on the basis of the transmitted beam through the optical disk, it is necessary to select a non-recorded area before which the pre-cure processing is applied, or an area after which the post-cure processing is applied.

Consequently, in the embodiment, a disk distinction-purposed area including the non-recorded area which is not used for recording information before the pre-cure processing and a ROM area after the post-cure processing, is provided on a predetermined radial position of the hologram disk3in advance. In this way, the reference beam is irradiated on the disk distinction-purposed area on the disk distinction processing to discriminate the type of optical disk.

On one hand, in the case where a certain drive voltage V1as shown inFIG. 15Ais applied to the rotational motor16for example in the optical information recording/reproducing apparatus1, the rotation speed of rotational motor16varies as indicated by a curve K1inFIG. 15Bwhen the optical disk is not mounted on the apparatus. On the other hand, when the optical disk is mounted on the apparatus, the rotation speed of rotational motor16decreases by causing an amount of weight as indicated by curves K2and K3inFIG. 15B, compared with a condition where the optical disk is not mounted. In addition, one of the curves K2and K3is a rotation characteristic of the rotational motor16in the case of mounting the hologram disk3and the other thereof is a rotation characteristic in the case of mounting the reflection-type optical disk4.

In the case of optical information recording/reproducing apparatus100in the embodiment, it is judged whether the optical disk is mounted on the apparatus on the basis of the rotation speed of rotational motor16on the disk distinction processing executed at the step SP2inFIG. 5.

Specifically, as shown inFIG. 12, in the case of optical information recording/reproducing apparatus100, a high-frequency generator (not shown), such as a rotary encoder to output a pulse in response to a rotating condition of the rotational motor16, is fitted on the rotational motor16to give an output from the high-frequency generator to a rotation speed detection circuit105. The detection circuit105then detects the rotation speed of rotational motor16on the basis of the output of high-frequency generator to send a detected result as a rotation speed detected signal to the microcomputer104.

At this time, the microcomputer104has a predetermined value (hereinafter, this value referred to as a rotation speed threshold value) Rth, in advance, which is smaller than the stationary rotation speed of rotational motor16when the optical disk having a previously set rotation speed of the rotational motor16is not mounted, and larger than the stationary rotation speed thereof when the optical disk is mounted. The microcomputer104then compares the rotation speed of rotational motor16recognized on the basis of the rotation speed detected signal give from the rotation speed detection circuit105with the rotation speed threshold value to thereby judge whether the optical disk is mounted.

FIG. 16is a flowchart showing specific processing contents relative to the disk distinction processing executed by the microcomputer104. The microcomputer104performs the disk distinction processing shown inFIG. 16on the basis of a control program stored in an internal memory (not shown).

That is, the microcomputer104starts the disk distinction processing when the foregoing recording/reproducing provision processing progresses at the step SP2inFIG. 5. First, the disk rotational motor control circuit20is controlled to drive the rotational motor16by a predetermined voltage (step SP40). After that, it is judged whether the stationary rotation speed of rotational motor16is greater than the previously set foregoing rotation speed threshold value Rth, on the basis of the rotation speed detected signal given from the rotation speed detection circuit105(step SP41).

The microcomputer104then obtains an affirmation result from the step SP41to thereby judge that the optical disk is not mounted on the apparatus (step SP47), and the disk distinction processing is completed.

On the contrary, the microcomputer104obtains a negation result by the judgment at the step SP41to move the optical pick-up11to a predetermined radial position of the optical disk by driving a slide mechanism (not shown) (step SP42). After that, the optical source drive circuit24(FIG. 12) is controlled to drive the optical source40(FIG. 13) on the hologram optical system11A in the optical pick-up11, so that the reference beam is irradiated on the disk distinction-purposed area of the optical disk (step SP43).

Subsequently, the microcomputer104judges whether the output voltage from optical detector110is greater than the threshold value voltage Vth3output from the threshold value voltage output circuit112in the reflection-type optical disk detection circuit103, on the basis of the discriminated signal given from the reflection-type optical disk detection circuit103(step SP44).

The microcomputer104then obtains the negation result at the step SP44to judge that the mounting optical disk is the hologram disk3(step SP45). After that, the disk distinction processing is completed. Further, the microcomputer104obtains the affirmation result at the step SP44to judge that the mounting optical disk is the reflection-type optical disk4(step SP46), and the disk distinction processing is then completed.

As described with the embodiment above, since the type of optical disk is discriminated on the basis of the transmitted beam through the optical disk in the optical information recording/reproducing apparatus100, the user can use the optical information recording/reproducing apparatus100without regard to the type of optical disk to be mounted, similarly to the first embodiment. This enables the optical information recording/reproducing apparatus100to enhance usability.

FIG. 17shows a constitution of an optical information recording/reproducing apparatus120in a fourth embodiment, and the same element shown inFIG. 12is indicated by the same reference numeral inFIG. 17. The optical information recording/reproducing apparatus120has the same constitution as the optical information recording/reproducing apparatus100in the third embodiment, except that a red optical beam emitted from the disk rotation angle detecting optical pick-up14is used as an optical beam to be irradiated on the optical disk, and the constitution of a phase conjugate optical system121is different from the previously described ones, on the disk distinction processing at the step SP2inFIG. 5.

FIG. 18shows a specific constitution of the optical information recording/reproducing apparatus120in the embodiment in relation to the disk distinction function, and the same element shown inFIG. 13is indicated by the same reference numeral inFIG. 18. Referring toFIG. 18, the disk rotation angle detecting optical pick-up14provides with an optical source130which emits a red beam. On recording/reproducing information in and from the hologram disk3in the disk rotation angle detecting optical pick-up14, the optical beam emitted from the optical source130is converted to a parallel beam by a collimate lens131, and the parallel beam is then incident to an object lens134via a polarizing beam splitter132and a mirror133to be focused by the object lens134on the rotation angle control track3A (FIG. 2) of the hologram disk3.

A reflected beam of the foregoing optical beam reflected from the hologram disk3is incident to the collimate lens135via the object lens134, mirror133and polarizing beam splitter132, and converted to a converged beam by the collimate lens135to focus on a light receiving surface of an optical detector136. In this way, a tracking error signal and a focusing error signal are generated in the rotation angle detection-purposed servo control circuit22on the basis of a received signal output from the optical detector136. On the basis of the tracking error signal and focusing error signal, a tracking control and a focusing control are performed by the microcomputer123via the rotation angle detecting servo control circuit22(FIG. 17).

On the disk distinction processing at the step SP2inFIG. 5, the disk rotation angle detecting optical pick-up14is moved to the foregoing disk distinction-purposed area provided on the optical disk, and the optical source130in the disk rotation angle detecting optical pick-up14is driven and turned on at the disk distinction-purposed area.

At this time, the optical beam emitted from the optical source130in the disk rotation angle detecting optical pick-up14is focused on the information recording surface of the optical disk, similarly to the foregoing operation. However, in the case where the optical disk is the hologram disk3, the optical beam is transmitted through the optical disk and incident to the optical detector110via a lens137and a polarizing beam splitter138in the phase conjugate optical system121. The optical detector110is used for performing the verification processing at the step SP16inFIG. 6. However, in the case of this embodiment, the optical detector110is used for both the verification processing and disk distinction processing, as a feature of this embodiment. The output voltage of optical detector110is then given to a reflection-type optical disk detection circuit122via the IV amplifier111.

The reflection-type optical disk detection circuit122is constituted by the same constitution as the reflection-type optical disk detection circuit103(FIG. 12) in the third embodiment, except for the case that the threshold value voltage Vth4outputted from the threshold value voltage output circuit124is changed into a predetermined voltage (this is referred to as a threshold value voltage Vth4) that is lower than the output voltage from the optical detector110which receives the optical beam emitted from the optical source130in the disk rotation angle detecting optical pick-up14and transmitted through the hologram disk3, and higher than the output voltage of optical detector110at a time of blocking the optical beam by the reflection-type optical disk4.

In this way, the reflection-type optical disk detection circuit122calculates, in the subtracting circuit113, a difference between the output voltage of optical detector110in the phase conjugate optical system121and the threshold value voltage Vth4output from the threshold value voltage output circuit124, and a calculated result, as a discriminated signal, is output to the microcomputer123. The microcomputer123then discriminates the type of optical disk which is mounted on the apparatus at this time on the basis of the discriminated signal.

FIG. 9is a flowchart showing specific processing contents relative to the foregoing disk distinction processing to be executed by the microcomputer123. The microcomputer123executes the disk distinction processing in accordance with a control program stored in an internal memory (not shown).

That is, the microcomputer123starts the disk distinction processing when the foregoing recording/reproducing provision processing progresses at the step SP2inFIG. 5. First, it is judged whether the stationary rotation speed of rotational motor16is greater than the predetermined rotation speed threshold value Rth (steps SP50, SP51), similarly to the steps SP40and SP41inFIG. 16.

The microcomputer123obtains the affirmation result in the judgment at the step SP51to thereby judge that the optical disk is not mounted on the apparatus (step SP57), and the disk distinction processing is then completed.

On the contrary, the microcomputer123obtains the negation result in the judgment at the step SP51to drive a slide mechanism (not shown) and move the disk rotation angle detecting optical pick-up14to a predetermined radial position on the optical disk (step SP52). After that, the optical source130(FIG. 18) on the disk rotation angle detecting optical pick-up14is driven by controlling the optical source drive circuit24(FIG. 12) such that the optical beam is irradiated toward the disk distinction-purposed area on the optical disk (step SP53).

Subsequently, the microcomputer123judges whether the output voltage of optical detector110is greater than the threshold value voltage Vth4output from the threshold value voltage output circuit112in the reflection-type optical disk detection circuit103on the basis of the discriminated signal given from the circuit103(step SP54).

The microcomputer123then obtains the affirmation result at the step SP54to judge that the mounting optical disk is the hologram disk3(step SP55). After that, the foregoing disk distinction processing is completed. Further, the microcomputer123obtains the negation result at the step SP54to judge that the mounting optical disk is the reflection-type optical disk4(step SP56), and the disk distinction processing is then completed.

As described above, in the case of the optical information recording/reproducing apparatus120in the embodiment, since the type of optical disk is discriminated on the basis of the transmitted beam through the optical disk, the user can use the optical information recording/reproducing apparatus120without regard to the type of optical disk to be mounted, similarly to the first embodiment. This enables the optical information recording/reproducing apparatus120to enhance usability.

(5) Other Embodiments

In addition, the first to fourth embodiments have been described with such that the optical source unit to emit the optical beam toward the mounting optical disk and the optical receiving unit to receive the reflected beam of the optical beam or transmitted beam through the optical disk and output the output signal corresponding to the reflected beam or transmitted beam, are constituted by the disk rotation angle detecting optical pick-up14(first embodiment), the reflection-type optical disk optical system11B in the optical pick-up11(second embodiment), the hologram optical system11A and phase conjugate optical system101in the optical pick-up11(third embodiment), or the disk rotation angle detecting optical pick-up14and phase conjugate optical system121(fourth embodiment). However, the invention is not limited to the foregoing constitutions. The optical source unit and light receiving unit may be provided separately from the pick-up14, the optical system11B in the optical pick-up11, the optical system11A and optical system101in the optical pick-up11, or the optical pick-up14and optical system121.

Further, the first to fourth embodiments have been described with such that the discrimination unit for discriminating whether the optical disk is the hologram disk3or reflection-type optical disk4on the basis of the output signal output from the optical receiving unit, is constituted by the reflection-type disk detection circuit23,91,103or122and the microcomputer17,92,104or123. However, the invention is not limited to the foregoing constitution. For example, the microcomputer17,92,104or123may have the function of the reflection-type disk detection circuit23,91,103or122, by removing these circuits. Besides, various constitutions may widely be applicable.

Further, the first to fourth embodiments have been described with such that the reflection-type disk detection circuits23,91,103and122are constituted by the threshold value voltage output circuits85A,85B,112and124as the threshold value voltage output unit and the subtracting circuit83,84A,84B and113as the difference voltage output unit, respectively. However, the invention is not limited to the foregoing constitution, and various constitutions may widely be applicable.

Further, in the case of the first and second embodiments, the focusing error signal is used for detecting the presence or absence of the optical disk, however, the rotation speed of the rotational motor16may also be used for that purpose, similarly to the third and fourth embodiments. In this case, the difference calculation circuit relative to the first threshold value voltage Vth1can be omitted in the first and second embodiments.