JP2010055706A - Recording and reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make information recording precise, with respect to a recording and reproducing device. <P>SOLUTION: The recording and reproducing device includes a rotary drive means (motor) rotation-driving a recording medium 1 being multi-layers recordable, lenses 6, 7 for recording and reproducing and a lens 5 for address detection which are arranged oppositely to the recording medium 1 rotation-driven by this rotation-drive means, a light source 9 for recording and reproducing for supplying light for recording and reproducing to lenses 6, 7 for recording and reproducing, a light source 9 for address for supplying light for address to the lens 5 for address detection and a light source 38 for detecting position information for supplying light for detecting position information detecting position information of the lens 6 for recording and reproducing to the lens 6 for recording and reproducing and the lens 5 for address detection, wherein wavelength of the light source 9 for address is made same as wavelength of the light source 9 for recording and reproducing or shorter than wavelength of the light source 9 for recording and reproducing, and wavelength of the light source 38 for detecting position information is made longer than wavelength of the light source 9 for recording and reproducing and the light source 9 for address. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a recording / reproducing apparatus that performs recording and reproduction on a recording medium capable of multilayer recording.

  In recent years, recording media capable of multilayer recording have been proposed in order to increase the recording capacity.

  The configuration of the recording / reproducing apparatus that performs recording / reproducing on the recording medium is as follows.

That is, the conventional recording / reproducing apparatus has a rotation driving means for rotationally driving a recording medium capable of multi-layer recording, and a lens used for recording / reproduction and address detection arranged opposite to the recording medium rotationally driven by the rotation driving means. And a recording / reproducing light source for supplying recording / reproducing light to the lens and an address light source for supplying address light to the lens. As a document describing a technique related to a conventional recording / reproducing apparatus, for example, there is Patent Document 1.
JP 2002-150567 A

  In this recording / reproducing apparatus, the recording medium is irradiated with the addressing light from the addressing light source through the lens, and the recording / reproducing light from the recording / reproducing light source is obtained based on the obtained address. Is irradiated to a recording medium through a lens, thereby performing multilayer recording on the recording medium.

  The problem in the conventional example is that it is possible to record a large amount of information by increasing the recording density by performing multi-layer recording on the recording medium, but the conclusion is that the wavelength of the address light source is long. As a result, the recording density could not be increased.

  That is, in this type of recording / reproducing apparatus currently proposed, the address light source uses, for example, a red light source in response to the flow from the so-called DVD era. As a result, the address on the recording medium is subdivided. This can cause a decrease in recording density.

  To explain this point a little, it is considered that the recording / reproducing light source uses, for example, a blue or green light source, that is, an attempt to increase the recording density by using a light source having a sufficiently short wavelength. As described above, since the address that can be detected cannot be subdivided, even if the wavelength of the recording / reproducing light source is shortened and the recording density is increased, if the address is not subdivided, the recording density is further increased. As a result, the capacity cannot be increased.

  Therefore, the present invention aims to increase the recording density on a recording medium.

  In order to achieve this object, the present invention relates to a rotational driving means for rotationally driving a recording medium capable of multi-layer recording, a recording / reproducing lens and an address detection lens arranged opposite to the recording medium rotationally driven by the rotational driving means. A lens, a recording / reproducing light source for supplying recording / reproducing light to the recording / reproducing lens, an address light source for supplying address light to the address detecting lens, and position information detection for detecting position information of the recording / reproducing lens And a position information detecting light source for supplying the recording light to the recording / reproducing lens and the address detecting lens. The wavelength of the address light source is the same as the wavelength of the recording / reproducing light source or the wavelength of the recording / reproducing light source. However, the wavelength of the position information detecting light source is longer than that of the recording / reproducing light source and the addressing light source, thereby achieving the initial purpose. That.

  As described above, the present invention relates to a rotation driving unit that rotates a recording medium capable of multi-layer recording, a recording / reproduction lens and an address detection lens that are arranged to face the recording medium that is rotated by the rotation driving unit, and a recording / reproduction. A recording / reproducing light source for supplying recording / reproducing light to the recording lens, an address light source for supplying address light to the address detecting lens, and a position information detecting light for detecting position information of the recording / reproducing lens. A position information detection light source supplied toward a reproduction lens and an address detection lens, and the wavelength of the address light source is the same as or shorter than the wavelength of the recording / reproduction light source Therefore, since the addresses are sufficiently subdivided and recording / reproduction can be performed with a recording / reproduction light source based on the subdivided addresses, the recording density is increased. Are those so attained a large capacity.

  In the present invention, since the wavelength of the position information detection light source is longer than that of the recording / reproduction light source and the address light source, the position information of the recording / reproduction lens is correctly detected (without using ECLD). In addition to the address light source (LD), a general-purpose product can be used, thereby reducing costs.

  To explain this point a little, as described above, it is necessary to use an address light source having a short wavelength in order to detect a subdivided address. The demand for products that are concentrated on is currently a special product, which increases costs.

  Therefore, when trying to use a general-purpose product for cost reduction, the characteristic becomes a mountain-shaped characteristic including other wavelengths (frequencies). However, if an address light source using such a chevron characteristic is used as position information of a recording / reproducing lens, it becomes difficult to detect correct position information of the recording / reproducing lens. Therefore, in the present invention, a position information detecting light source having a wavelength longer than that of the address light source is separately provided.

  Light sources for position information detection with a long wavelength are supplied to the market even in current products, which are sufficiently concentrated on a specific frequency. Therefore, even if this position information detection light source is provided separately, the above-mentioned As a result, the cost can be reduced.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

(Embodiment)
FIG. 1 shows a recording / reproducing apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a multi-layer recordable recording medium formed of, for example, a photopolymer. It has a disk shape as shown in (a), and a through hole (2 in FIG. 3 (a)) is provided at the center. Then, the rotational drive shaft 4 of the motor 3 is inserted into the through-hole 2, and although not shown, chucking is performed in this state, whereby the recording medium 1 is rotationally driven. . That is, the motor 3 and the rotation drive shaft 4 constitute a rotation drive means.

  Returning to FIG. 1 again, the description will be continued. As shown in FIG. 1, an address detecting lens 5 and a recording / reproducing lens 6 are provided on one surface side (for example, the lower surface side) of the recording medium 1. 1 are arranged side by side facing one surface side. A recording / reproducing lens 7 is arranged on the recording / reproducing lens 6 so as to face the recording / reproducing lens 6 with the recording medium 1 interposed therebetween.

  Next, the address detection lens 5, the recording / reproducing lens 6, and the recording / reproducing lens 7 will be described with reference to FIG.

  First, as shown in FIG. 2, the recording medium 1 is capable of multi-layer recording in the thickness direction. As shown in FIG. Interference forms so-called interference fringes, which constitute a part of the digital signal, and the interference fringes are intermittently formed on one plane, so that video and audio are recorded as digital signals. It is.

  As will be described in detail later, as is clear from FIG. 2, by moving the focal points of the recording / reproducing lenses 6 and 7 to a plurality of recording surfaces in the thickness direction of the recording medium 1, Since the video and audio are recorded as digital signals and can be recorded in a plurality of layers, the recording capacity of the recording medium 1 is extremely large.

  For example, if the information of the monitoring camera is recorded on the recording medium 1, it is possible to record one year for the recording medium 1.

  The address detection lens 5 is provided to perform the recording using the recording / reproducing lenses 6 and 7 and the subsequent reproduction. That is, the address detection lens 5 reads the address 8 provided on the front surface side of the recording medium 1 as shown in FIG. 2, and uses the recording / reproducing lenses 6 and 7 described above based on the read address 8. Recording and subsequent playback are performed.

  Next, the description will be continued with reference to FIG. 1 again for the light source and the like for recording using the recording and reproducing lenses 6 and 7 and subsequent reproduction and reading the address information using the address detecting lens 5. .

  In the present embodiment, the recording on the recording medium 1 and the subsequent reproduction and reading of the address information using the address detection lens 5 are performed by one light source 9. That is, the light source 9 is constituted by a laser that emits blue light having one peak in the wavelength range of 402 to 408 nm.

  As described above, the light source 9 is composed of a laser that emits blue light having one peak in the wavelength range of 402 to 408 nm, and is currently in this range (402 to 408 nm). Those having a single peak are provided at low cost as commercial products.

  First, the blue light from the light source 9 is then subjected to the enlargement and rounding correction by the relay lens 10, then passes through the beam splitter 11, and then converted into parallel light by the collimator lens 12. Be changed. This parallel light is then converted into light having two polarization components (P-polarized light and S-polarized light) orthogonal to each other in the liquid crystal half-wave plate 13. The liquid crystal half-wave plate 13 can change the deflection state of light passing therethrough according to the voltage applied to the liquid crystal. When performing recording and reproduction on the recording medium 1 described above, an appropriate voltage is applied, and the liquid crystal half-wave plate 13 is used as a quarter-wave plate.

  Then, the P-polarized light in the converted light passes through the beam splitter 14, then passes through the quarter wavelength plate 15, passes through the beam splitter 16, passes through the quarter wavelength plate 17, Then, after passing through the address detection lens 5, the light is condensed to the address 8.

  The reflected light irradiated and reflected on the address 8 of the recording medium 1 is detected as address information, and this reflected light passes through the address detection lens 5 and then the quarter wavelength plate 17. , Enters the beam splitter 16, and then is reflected by 90 degrees by the beam splitter 16, and the reflected light passes through the hologram 18 and is collected by the astigmatism lens 19. The detection element 20 is reached.

  Based on the detected address information, recording by the recording / reproducing lenses 6 and 7 described above and subsequent reproduction are performed.

  Here, the beam splitter 16 that reflects the reflected light from the recording medium 1 toward the address detection element 20 will be described in more detail.

  The beam splitter 16 separates light according to the rotation direction of circularly polarized light out of the polarization components of light. Particularly in this embodiment, the counterclockwise circularly polarized light passes through the beam splitter 16, and the clockwise circularly polarized light is reflected by the beam splitter 16.

  That is, the P-polarized light emitted from the light source 9 and passed through the beam splitter 14 passes through the quarter-wave plate 15 to become counterclockwise circularly polarized light and passes through the beam splitter 16. The counterclockwise circularly polarized light that has passed through the beam splitter 16 passes through the quarter-wave plate 17 and becomes S-polarized light, passes through the address detection lens 5, is condensed, and is reflected by the recording medium 1. The S-polarized light reflected by the recording medium 1 passes through the address detecting lens 5 and then passes through the quarter-wave plate 17 to become clockwise circularly polarized light. The reflected light from the recording medium 1 that has become clockwise circularly polarized light enters the beam splitter 16, is then reflected by 90 degrees at the beam splitter 16, and travels toward the address detection element 20.

  As described above, in this embodiment, by using the beam splitter 16 that separates the light according to the rotation direction of the circularly polarized light, the P-polarized light that is linearly polarized light emitted from the light source 9 and separated by the beam splitter 14 is converted to 1 / 4 wavelength plate 15 is passed through as circularly polarized light, and ¼ wavelength plate 17 is passed through twice, and when passing through ¼ wavelength plate 15, the direction of travel is as circularly polarized light that is reverse to that when passing through ¼ wavelength plate 15. Can be changed.

  In other words, by using the beam splitter 16 that separates the light according to the rotation direction of the circularly polarized light together with the quarter wavelength plates 15 and 17, it is possible to change the traveling direction of the linearly polarized light having a single wavelength. Become.

  In the present embodiment, as described above, recording by the recording / reproducing lenses 6 and 7 and subsequent reproduction are performed based on the address information detected by the address detection element 20.

  Specifically, the S-polarized light of the light that has passed through the liquid crystal half-wave plate 13 is reflected at right angles to the left side of FIG. 1 by the beam splitter 14 and then reflected again at right angles by the beam splitter 21. The light passes through the quarter-wave plate 22, passes through the spherical aberration correction element 23, and is then condensed in the recording medium 1 by the recording / reproducing lens 6, and then spreads from its focal point. Then, the light is converted again into parallel light by the recording / reproducing lens 7.

  The converted parallel light then passes through the quarter-wave plate 24, the spherical aberration correction element 25, and the shutter 26, and then proceeds to the retro-reflector 27. After being reflected by the retro-reflector 27, the shutter 26, The light passes through the spherical aberration correction element 25 and the quarter-wave plate 24 and is then focused by the recording / reproducing lens 7 to be focused in the recording medium 1 as shown in FIGS.

  As described above, interference fringes are formed in the recording medium 1 by interfering with the focal point of the recording / reproducing lens 6 and the focal point of the recording / reproducing lens 7 on the set recording surface in the recording medium 1. It is formed.

  The focus formation by the recording / reproducing lenses 6 and 7 will be described later in detail.

  Next, drive systems for the address detection lens 5, the recording / reproducing lens 6, and the recording / reproducing lens 7 will be described. That is, the address detection lens 5 needs to adjust the focal length with the recording medium 1 in order to appropriately read the address 8 of the recording medium 1, and the recording / reproducing lenses 6 and 7 are set. It is necessary to make adjustments so that the focal points of the recording surface are correctly formed on the recording surface, and these recording / reproducing lenses 6 and 7 need to perform multilayer recording in the thickness direction of the recording medium 1, That drive control is required.

  First, as can be understood from FIGS. 2 and 3B, the recording / reproducing lens 6 and the address detecting lens 5 are housed in a frame 28 to form a unit. 3A, the recording medium 1 is moved in the radial direction as shown in FIG. 3A by driving the screw shaft 29 with the motor 30 shown in FIG. .

  The quarter wavelength plate 17 is held on the frame 28 with a certain distance from the address detection lens 5, and the spherical aberration correction element 23 is kept at a certain distance from the recording / reproducing lens 6. Is held. For this reason, in the present embodiment, the position information of the address detecting lens 5 and the position information of the recording / reproducing lens 6 with respect to the recording medium 1 are obtained by using the quarter wavelength plate 17 and the spherical aberration correcting element 23. ing.

  In this case, the address detecting lens 5 is arranged on the upstream side of the recording medium 1 relative to the recording / reproducing lens 6. In this state, electromagnetic coils 31 for moving the frame 28 are provided at the four corners of the frame 28 in order to adjust the distances between the address detection lens 5 and the recording / reproducing lens 6 and the recording medium 1. .

  Further, in order to finely adjust individual distances between the recording medium 1, the address detection lens 5, and the recording / reproducing lens 6, electromagnetic coils are provided at the four corners of the address detecting lens 5 and the recording / reproducing lens 6, respectively. 32 and 33 are provided.

  On the other hand, the recording / reproducing lens 7 disposed above the recording medium 1 is driven in the radial direction of the recording medium 1 by driving the screw shaft 34 with a motor 35, as can be understood from FIGS. Driving is performed, and the distance to the recording medium 1 is adjusted by energizing the electromagnetic coil 36.

  In the above configuration, first, when the address 8 is detected by the address detection lens 5, the address detection lens 5 is placed in the electromagnetic coil 31 so that the focus on the address detection element 20 is most appropriate as described above. , 32, and so-called servo control is performed to read the correct address 8.

  Next, writing and reading of information to and from a specific inner layer of the recording medium 1, that is, adjusting the focal length of the recording and reproducing lenses 6 and 7 for recording and reproducing information.

  In this embodiment, in order to detect the position information of the recording / reproducing lens 6, as shown in FIGS. 1 and 4, a light source 38 is provided via a diffraction grating 37 in a direction orthogonal to the relay lens 10 of the beam splitter 11. Arranged.

  The light source 38 is used for detecting position information, and is a light source that emits red light having a wavelength of 650 nm, for example. Such a red light source 38 having a wavelength of 650 nm is provided as a commercial product at a low cost, and has a peak concentrated at a specific frequency (wavelength is 650 nm).

  The light source 38 is also used for recording and reproduction on a DVD, which will be described later with reference to FIG. When recording and reproducing on a DVD, a superimposing circuit is provided in a circuit for supplying power to the light source 38, and an electric signal for causing the light source 38 to emit light is superimposed so that red light emitted from the light source 38 is emitted. Is a mountain-shaped characteristic including other wavelengths (frequencies) other than 650 nm.

  Therefore, as described above, when the light source 38 is used for position information detection, the function of the superimposing circuit of the circuit that supplies power to the light source 38 is turned off, that is, superimposing from the circuit that supplies power to the light source 38 is performed. By simply removing the circuit electrically, the light source 38 can easily emit red light having a peak concentrated at a specific frequency (having a wavelength of 650 nm).

  As described above, red light having a peak concentrated at a specific frequency (wavelength is 650 nm) is emitted from the light source 38 as shown in FIG. 4 and reflected by the beam splitter 11 via the diffraction grating 37, which is reflected by the collimator. The light is adjusted to parallel light by the lens 12 and then converted into light having two mutually orthogonal polarization components (P-polarized light and S-polarized light) by the liquid crystal half-wave plate 13.

  In FIG. 4, the P-polarized light of the light that has entered the beam splitter 14 from the light source 38 travels straight, becomes circularly polarized light at the quarter-wave plate 15, and on the surface of the quarter-wave plate 17 on the beam splitter 16 side, A part of the reflected light is reflected, and the reflected light passes through the beam splitter 16 as shown in FIG. 4 and becomes S-polarized light by the quarter-wave plate 15, and this S-polarized light is reflected by the beam splitter 14, The light reaches the light receiving element 41 through the quarter wavelength plate 39 and the astigmatism lens 40.

  On the other hand, the S-polarized light traveling from the liquid crystal half-wave plate 13 to the beam splitter 14 is reflected by the beam splitter 21 toward the recording / reproducing lens 6 as shown in FIG. A part of the light is reflected on the surface, and this reflected light is reflected by the beam splitter 21 and then passes through the liquid crystal half-wave plate 42 to generate a P-polarized component, which is the beam splitter 14, The light reaches the light receiving element 41 through the quarter wavelength plate 39 and the astigmatism lens 40. Similarly to the liquid crystal half-wave plate 13 described above, the liquid crystal half-wave plate 42 used here can change the deflection state of light passing through the voltage applied to the liquid crystal. However, the liquid crystal half-wave plate 42 is used as a quarter-wave plate by applying an appropriate voltage when recording on the recording medium 1 described above. When reading, i.e., reproducing, an appropriate voltage different from that in the above-described recording is applied, and the liquid crystal half-wave plate 13 is used as a half-wave plate.

  Here, the reflected light from the quarter wavelength plate 17 and the reflected light from the quarter wavelength plate 22 reaching the light receiving element 41 are respectively relative to the optical axis connecting the center of the astigmatism lens 40 and the light receiving element 41. It is in a slightly tilted state.

  For this reason, a shift occurs in the position where these two reflected lights reach the light receiving element 41. However, when two lights are irradiated on substantially the same portion, interference between the two lights occurs. In FIG. 5, when the relative position between the recording / reproducing lens 6 and the address detecting lens 5 changes, a light and dark stripe that changes with time is created.

  In order to confirm position information by forming such bright and dark stripes, it is important that the light source 38 is light having a peak concentrated at a specific frequency. However, regarding this point, the light source 9 has a peak at any frequency within a certain range in the present embodiment, and this is not suitable for use in position information confirmation.

  As described above, the number of layers in the recording medium 1 to be recorded or the number of layers to be read depends on how the distance between the recording / reproducing lens 6 and the recording medium 1 is set. It is important that the position of the recording / reproducing lens 6 can be set by counting the number of times of light intensity based on the change in interference fringes that changes with time in the light receiving element 41 ( In this case, the position of the address detection lens 5 constitutes a reference point).

  In the above description, the beam splitter 16 that separates the light according to the rotation direction of the circularly polarized light out of the polarization components of the light is used as the beam splitter 16, but the recording medium 1 is specified as in the present embodiment. When the red light is used for adjusting the focal length of the recording / reproducing lenses 6 and 7 for recording or reading on the inner layer, the incident light is separated by the wavelength of the incident light, that is, the incident light is separated according to the wavelength. It is also possible to use a beam splitter 16 that has a wavelength selectivity for transmitting or reflecting (similar to the beam splitter 11) and also has a polarization selectivity for separating light by its polarization component for light of a specific wavelength. It can be implemented. An embodiment in this case will be described in detail below.

  When the beam splitter 16 having wavelength selectivity and polarization selectivity is used, the red light emitted from the light source 38 is transmitted regardless of the polarization component, and the S-polarized light is reflected from the blue light emitted from the light source 9. In addition, a beam splitter 16 having a polarization selectivity for separating the light by the polarization component of the blue light, which transmits the P-polarized light among the blue light emitted from the light source 9, is used. Further, the quarter wavelength plate 15 is not provided.

  Of the red light emitted from the light source 38 and converted into light having P-polarized light and S-polarized light by the liquid crystal half-wave plate 13, the light receiving element follows the same path as described with reference to FIG. 4. 41 is not described here.

  On the other hand, of the red light converted into light having P-polarized light and S-polarized light by the liquid crystal half-wave plate 13, the P-polarized light is not provided with the quarter-wave plate 15 as described above. By using the beam splitter 16 having the property and the polarization selectivity, the beam splitter 14 goes straight and passes through the beam splitter 16, and then a part thereof enters the quarter wavelength plate 17. The light is reflected from the inner surface of the wave plate 17 on the address detection lens 5 side and travels toward the beam splitter 16 again. Since the red light traveling toward the beam splitter 16 passes through the quarter-wave plate 17 twice, it is S-polarized light. The S-polarized light is reflected by the beam splitter 14 and then reaches the light receiving element 41 via the quarter-wave plate 39 and the astigmatism lens 40.

  The reflected light from the quarter-wave plate 17 and the quarter-wave plate 22 are used as the beam splitter 16, as in the case of using the polarization component of the light that separates the light according to the rotational direction of the circularly polarized light. The reflected light from the light reaches the light receiving element 41, and includes an address detection lens 5 provided integrally with the quarter-wave plate 17 and a recording / reproducing lens 6 provided integrally with the quarter-wave plate 22. Bright and dark stripes that change with time when a change occurs in the relative position are formed on the light receiving element 41. By counting the number of times of the light intensity, the position of the address detection lens 5 is used as a reference. The position of the recording / reproducing lens 6 can be set.

  The reading of address information using the address detection lens 5 is performed as follows when a beam splitter 16 having wavelength selectivity and polarization selectivity is used and the quarter wavelength plate 15 is not provided. Is called.

  Blue light emitted from the light source 9 is converted into light having two mutually orthogonal polarization components in the liquid crystal half-wave plate 13, and P-polarized light among them is transmitted through the beam splitter 14. The beam splitter 16 reflects S-polarized light in the blue light emitted from the light source 9 and transmits P-polarized light in the blue light emitted from the light source 9, so that the P-polarized light that has passed through the beam splitter 14 The light passes through the splitter 16, passes through the quarter-wave plate 17, becomes circularly polarized light, and then passes through the address detection lens 5, and then is condensed to the address 8.

  The reflected light that is irradiated and reflected on the address 8 of the recording medium 1 is detected as address information. The reflected light passes through the address detection lens 5 and then the quarter-wave plate 17. After becoming S-polarized light, it enters the beam splitter 16 and is then reflected by 90 degrees by the beam splitter 16, and the reflected light passes through the hologram 18 and is collected by the astigmatism lens 19. The emitted light reaches the address detection element 20 and the address information is read.

  As described above, when red light is used for adjusting the focal length of the recording / reproducing lenses 6 and 7, the beam splitter 16 is conventionally used without using a special one that separates the light according to the rotation direction of the circularly polarized light. Therefore, it is possible to reduce the cost of the optical element and thus the recording / reproducing apparatus.

  Further, since it is not necessary to provide the above-described quarter-wave plate 15, the number of parts can be reduced, the cost of the recording / reproducing apparatus can be further reduced, and the recording / reproducing apparatus can be miniaturized. Become.

  Next, control for causing the focal points of the recording / reproducing lenses 6 and 7 to interfere with each other will be described.

  As described above, recording on a specific inner layer of the recording medium 1 is formed by interference fringes by the recording and reproducing lenses 6 and 7.

  As shown in FIG. 5, when performing recording on a specific inner layer of the recording medium 1, the blue light emitted from the light source 9 is converted into the relay lens 10, the beam splitter 11, the collimator lens 12, and the liquid crystal half-wave plate 13. The S-polarized light generated by the liquid crystal half-wave plate 13 functioning as the quarter-wave plate is reflected by the beam splitter 14 and travels with the liquid crystal half-wave plate 42. The liquid crystal half-wave plate 42 that functions as a four-wave plate generates P-polarized light in addition to S-polarized light.

  The focal point in the recording medium 1 by the recording / reproducing lens 7 is formed by S-polarized light generated by the liquid crystal half-wave plate 42.

  Specifically, as shown in FIG. 5, the S-polarized light is reflected by the beam splitter 21, and then the quarter-wave plate 22, the spherical aberration correcting element 23, the recording / reproducing lens 6, the recording medium 1, the recording The image is inverted by a retroreflector 27 via the reproduction lens 7, the quarter wavelength plate 24, the spherical aberration correction element 25, and the shutter 26, and after passing through the shutter 26, the spherical aberration correction element 25, and the quarter wavelength plate 24, recording is performed. A focal point is formed in the recording medium 1 through the reproduction lens 7.

  On the other hand, the focal point in the recording medium 1 by the recording / reproducing lens 6 is formed by P-polarized light generated by the liquid crystal half-wave plate 42.

  Specifically, as shown in FIG. 5, this P-polarized light passes through the beam splitter 21, becomes circularly polarized light by the first quarter-wave plate 43, and then is reflected by the first reflector 44. Again, it is circularly polarized by the first quarter-wave plate 43 to become S-polarized light, and then this S-polarized light is reflected by the beam splitter 21 and then becomes circularly polarized by the second quarter-wave plate 45. Then, the light is reflected by the second reflector 46 and becomes P-polarized light again by the second quarter-wave plate 45. The P-polarized light forms a focal point in the recording medium 1 via the quarter-wave plate 22, the spherical aberration correction element 23, and the recording / reproducing lens 6.

  In this case, what is important is that the beam is reflected by the beam splitter 21 shown in FIG. 5, and the distance to the focal point formed in the recording medium 1 by the recording / reproducing lens 7 and the beam splitter 21 are passed through the recording / reproducing lens. 6 is to make the optical distance to the focal point formed in the recording medium 1 the same. Therefore, in this embodiment, the 1st reflector 44 and the 2nd reflector 46 were provided.

  More specifically, a beam splitter 21 is provided between the recording / reproducing light source 9 and the recording / reproducing lens 6, and the reflected light from the beam splitter 21 travels toward the recording / reproducing lens 7. The passing light is reflected by the first reflector 44 through the first quarter-wave plate 43, travels again to the beam splitter 21 through the first quarter-wave plate 43, and then This beam splitter 21 reflects the recording / reproducing lens 6 to the opposite side, and then reflects it by the second reflector 46 via the second quarter-wave plate 45, and again the second 1/1 The beam splitter 21 is allowed to pass through the four-wavelength plate 45 and travel toward the recording / reproducing lens 6 side.

  In order to adjust the focal position of the light from above and below in FIG. 5 in the recording medium 1 and to adjust the recording and reading depth in the recording medium 1, not only the recording / reproducing lenses 6 and 7, At least one of the first reflector 44 and the second reflector 46 is provided with driving means (not shown) that can change the distance from the beam splitter 21.

  6 reads out the address 8 by the address detecting lens 5 described above and performs the previous focusing, the focus servo of the address detecting lens 5 and the recording / reproducing lens 6, and recording on the recording medium 1. The route is described collectively.

  When reading (reproducing) information recorded on the recording medium 1 in a multilayer manner, the liquid crystal half-wave plate 13 is used as a half-wave plate, unlike the case of recording.

  Thus, the focal length of the recording / reproducing lenses 6 and 7 is adjusted using the red light emitted from the light source 38, and at the same time, the information from the specific inner layer of the recording medium 1 is used using the blue light emitted from the light source 9. Reading can be performed.

  Further, when reading the information recorded in the multilayer on the recording medium 1, the reflected light from the recording / reproducing lens 7 is prevented from returning to the light receiving element 41. Therefore, at the time of reproduction, the shutter 26 provided in front of the retroreflector 27 is closed so that the reflected light does not return through the recording / reproducing lens 7, so that noise components are mixed in the reproduction data. It was set as the structure which suppresses. In addition to the method of closing the shutter 26, the screw shaft 34 described with reference to FIGS. 2 and 3 is driven by a motor 35 so that the recording / reproducing lens 7 disposed above the recording medium 1 can be used for recording / reproducing. By moving the lens 6 to a position that does not face the lens 6, it is possible to prevent the reflected light from returning via the recording / reproducing lens 7. That is, if the radial position of the recording medium 1 between the recording / reproducing lens 6 and the recording / reproducing lens 7 is shifted, the reflected light is prevented from returning through the recording / reproducing lens 7 without providing the shutter 26. It is possible to suppress noise components from being mixed in the reproduction data.

  In this embodiment, as described above, in addition to the recording medium 1 capable of multi-layer recording, compatibility for performing writing and reading to a so-called CD or DVD is also provided.

  Specifically, as shown in FIG. 1, a light source 38 capable of emitting infrared light for CD and red light for DVD is provided in a direction orthogonal to the relay lens 10 of the beam splitter 11.

  This compatibility will be briefly described. First, when recording or reproducing a CD, infrared light is emitted from the light source 38 as shown in FIG. Further, when recording or reproducing a DVD, red light is emitted from the light source 38 as shown in FIG. Of course, at this time, a CD or DVD is mounted on the rotational drive shaft 4 of FIG. The light source 9 stops emitting light.

  When these CDs or DVDs are loaded, the light emitted from the light source 38 then travels to the beam splitter 11 via the diffraction grating 37.

  Here, the diffraction grating 37 is for splitting the infrared light for CD emitted from the light source 38 and the red light for DVD into three lights, respectively. By separating the light emitted from the light source 38, the servo control of the recording / reproducing lens 6 can be performed with high accuracy, and the recording / reproducing quality can be improved.

  FIG. 7 shows a state in which the CD 47 is mounted on the rotary drive shaft 4 instead of the recording medium 1, and recording or reproduction can be performed in this state. At this time, since the amount of information contained in the CD 47 is not so large, infrared light is emitted from the light source 38 and is provided near the upper surface in the thickness direction of the CD 47 through the path of the arrow shown in FIG. Data 48 is written on this recording surface, or this data 48 is read. That is, the CD 47, the DVD shown in FIG. 8, and the BD (Blu-ray Disc) shown in FIG. 9 have address information in the data 48, 50, and 52, respectively. Reading can be performed simultaneously. The read data at the time of reproduction is supplied to the light receiving element 41.

  FIG. 8 shows recording / reproduction on the DVD 49, which is different from the CD 47 in FIG. 7 in that red light is emitted from the light source 38 and data is recorded on the recording surface provided near the intermediate surface in the thickness direction of the DVD 49. 50 is written or this data 50 is read, and the writing of the data 50 to the DVD 49 and the reading detection of the data 50 by the light receiving element 41 have the same path.

  FIG. 9 shows recording / reproduction of data 52 to / from the BD 51. At this time, the blue light emitted from the light source 9 is recorded on the recording surface provided near the lower surface in the thickness direction through the address detection lens 5 as shown in FIG. The recorded data 52 is read out through the address detecting lens 5 and detected through the address detecting element 20. That is, in the present embodiment, the information that can be recorded and read from the recording medium 1 capable of multi-layer recording can be recorded and reproduced on the CD 47, the DVD 49, and the BD 51.

  As described above, since the recording / reproducing apparatus of the present invention can record and reproduce extremely dense and large-capacity information, it can be widely used in various fields that require a large recording capacity. It will be used. In addition, if the recording and reproduction can be performed precisely and with a large capacity, there is no need to replace the recording medium, and it becomes extremely convenient.

  Further, since the cost can be reduced, it can be provided to the market at a low cost.

1 is a block diagram of a recording / reproducing apparatus according to an embodiment of the present invention. Enlarged view of the main part (A) Enlarged perspective view of the main part (b) Enlarged plan view of the main part Block diagram for explaining the operation Block diagram for explaining the operation Block diagram for explaining the operation Block diagram for explaining the operation Block diagram for explaining the operation Block diagram for explaining the operation

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording medium 2 Through-hole 3 Motor 4 Rotation drive shaft 5 Address detection lens 6 Recording / reproducing lens 7 Recording / reproducing lens 8 Address 9 Light source 10 Relay lens 11 Beam splitter 12 Collimator lens 13 Liquid crystal half wave plate 14 Beam splitter 15 1/4 wavelength plate 16 Beam splitter 17 1/4 wavelength plate 18 Hologram 19 Astigmatism lens 20 Address detection element 21 Beam splitter 22 1/4 wavelength plate 23 Spherical aberration correction element 24 1/4 wavelength plate 25 Spherical aberration correction Element 26 Shutter 27 Retroreflector 28 Frame 29 Screw shaft 30 Motor 31 Electromagnetic coil 32 Electromagnetic coil 33 Electromagnetic coil 34 Screw shaft 35 Motor 36 Electromagnetic coil 37 Diffraction grating 38 Light source 39 1/4 wavelength plate 40 Non Point aberration lens 41 Light receiving element 42 Liquid crystal half wave plate 43 1/4 wave plate 44 Reflector 45 1/4 wave plate 46 Reflector 47 CD
48 data 49 DVD
50 data 51 BD
52 data

Claims (18)

Rotation drive means for rotating a recording medium capable of multilayer recording;
A recording / playback lens and an address detection lens disposed opposite to the recording medium rotated by the rotation driving means;
A recording / reproducing light source for supplying recording / reproducing light to the recording / reproducing lens;
An address light source for supplying address light to the address detection lens;
A position information detecting light source for supplying position information detecting light for detecting position information of the recording / reproducing lens toward the recording / reproducing lens and the address detecting lens;
The wavelength of the address light source is the same as the wavelength of the recording / reproducing light source or shorter than the wavelength of the recording / reproducing light source,
The recording / reproducing apparatus in which the wavelength of the position information detecting light source is longer than that of the recording / reproducing light source and the addressing light source. The recording / reproducing apparatus according to claim 1, wherein the address light source is a blue light source. The recording / reproducing apparatus according to claim 1, wherein the recording / reproducing light source is a blue or green light source. The recording / reproducing apparatus according to claim 1, wherein the position information detection light source is a red light source. 5. The recording / reproducing apparatus according to claim 1, wherein the recording / reproducing light source and the address light source are shared. The recording / reproducing lens includes a first recording / reproducing lens provided on the address detection lens side of the recording medium, and a second recording / reproducing lens disposed opposite to the first recording / reproducing lens via the recording medium. 6. The recording / reproducing apparatus according to claim 1, wherein the recording / reproducing lens is used. 7. The recording / reproducing apparatus according to claim 1, wherein the address detecting lens and the recording / reproducing lens are arranged side by side upstream and downstream of a track-like address of the recording medium. The recording / reproducing apparatus according to claim 1, wherein the address detection lens is disposed upstream of the recording / reproducing lens. 9. The recording / reproducing apparatus according to claim 1, wherein the address detecting lens and the recording / reproducing lens arranged on one surface side of the recording medium are unitized. 10. The recording / reproducing apparatus according to claim 9, wherein the address detecting lens and the recording / reproducing lens have means for varying a distance from one side of the recording medium. The recording / reproducing apparatus according to claim 6, wherein the recording / reproducing lens is optically connected to a light receiving element that detects a defocus between the first recording / reproducing lens and the second recording / reproducing lens. The reflection element for reflecting the light from the position information detection light source is disposed on the light input side from the position information detection light source of the recording / reproducing lens and the address detection lens. The recording / reproducing apparatus according to claim 11. The recording / reproducing apparatus according to claim 12, further comprising a light receiving element to which light from the reflecting element is input. A beam splitter is provided between the recording / reproducing light source and the recording / reproducing lens, and light reflected by the beam splitter travels to the recording / reproducing lens side. The light is reflected by the first reflector through the four-wave plate, and again travels to the beam splitter through the first quarter-wave plate. Reflected on the opposite side, then reflected by the second reflector through the second quarter-wave plate, and again passed through the beam splitter through the second quarter-wave plate. The recording / reproducing apparatus according to any one of claims 1 to 13, wherein the recording / reproducing apparatus advances toward the recording / reproducing lens side. 15. The recording / reproducing apparatus according to claim 14, wherein at least one of the first reflector and the second reflector is provided with a drive unit that varies a distance from the beam splitter. The recording / reproducing lens includes a first recording / reproducing lens provided on the address detection lens side of the recording medium, and a second recording / reproducing lens disposed opposite to the first recording / reproducing lens via the recording medium. And a retroreflector is provided on the opposite side of the second recording / reproducing lens from the recording medium, and the retroreflector and the second recording / reproducing lens are integrally provided. The recording / reproducing apparatus according to any one of claims 1 to 15. When the position information detection light source is a red light source,
The recording / reproducing apparatus according to any one of claims 1 to 16, wherein a high-frequency superimposing circuit in a circuit for supplying power to a red light source is not used. 18. The recording / reproducing apparatus according to claim 1, wherein security information is supplied to the recording / reproducing light source.

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