JP4223296B2 - Optical pickup device and optical disk drive device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical pickup device such as an optical card device and an optical disk drive device.
[0002]
[Prior art]
FIG. 7 is a schematic diagram showing an optical system according to an optical pickup device of an optical disk drive device, where 1 is a semiconductor laser, 2 is a glass plate, 3 is a 3-beam generation formed on the surface of the glass plate 2 on the semiconductor laser 1 side. 4 is a hologram formed on the surface of the glass plate 2 opposite to the surface on which the grating 3 is formed, 5 is a holo pickup, 6 is a collimating lens, 7 is an objective lens, 8 is an optical disk, and 9 is a light receiving element. Show.
[0003]
FIG. 8 is a side view showing the internal configuration of the holo-pickup. A semiconductor laser 1 and a light receiving element 9 are mounted on a substrate, and a glass plate 2, a grating 3 and a hologram 4 are arranged facing the semiconductor laser 1. And unitized.
[0004]
The emitted light emitted from the semiconductor laser 1 as the light source is separated into a main beam (0th order light) and two sub beams (± first order light) by a grating 3 which is a diffraction grating for three beams, and then the hologram 4 To reach. Only the light (0th-order diffracted light) that passes through the hologram 4 is converted into parallel light by the collimating lens 6, passes through the objective lens 7, and is condensed on the optical disk 8. The return light reflected by the optical disk 8 passes through the objective lens 7 and the collimator lens 6 again together with the main beam and the sub beam, and is then guided to the hologram 4. In this case, only the light (first-order diffracted light) diffracted by the hologram 4 is incident on the light receiving element 9 to generate various signals.
[0005]
FIG. 9 is an explanatory view showing the state of the hologram 4 and the reflected light 10 from the optical disk 8 on the hologram 4. The hologram 4 is divided into three regions AB, C, and D by two dividing lines. A hatched portion in the figure of the reflected light 10 on the hologram 4 is a portion having a push-pull signal component. Details of the push-pull signal are described in Patent Document 1.
[0006]
FIG. 10 is an explanatory diagram showing the state of the light receiving element 9 and the reflected light 10 from the optical disk 8 on the light receiving element 9.
[0007]
The light receiving element 9 has eight light receiving surfaces a to h, and the relationship between the light beam diffracted in the three regions AB, C, and D in FIG. 2 and the light receiving surface to which the light beam reaches is as follows. .
The diffracted light of the main beam from AB is between the light receiving surface a and the light receiving surface b.
The diffracted light of the sub beam from AB is outside the light receiving surface a and the light receiving surface b (that is, not received),
The main beam diffracted light from C is incident on the light receiving surface c.
The sub-beam diffracted light from C is applied to the light receiving surface e and the light receiving surface g, respectively.
The diffracted light of the main beam from D is incident on the light receiving surface d.
The diffracted light of the sub beam from D is received by the light receiving surface f and the light receiving surface h, respectively.
[0008]
Here, when signals output from the light receiving surfaces a to h are expressed using the same symbols a to h,
Focus error signal (FES)
FES = a−b
The track error signal (TES) is
TES = (cd) −α ((e + g) − (f + h))
The track cross signal (TCS)
TCS = (c + d) −α ((e + g) + (f + h))
The lens position signal (LPS) is
LPS = (c−d) + α ((e + g) − (f + h))
Push-pull signal (PPS)
PPS = cd
The information reproduction signal (RFS) is
RFS = a + b + c + d
It can be expressed as.
[0009]
In the push-pull signal (PPS) indicated by the hatched portion in FIG. 9, the ratio of entering the regions C and D is 50% of the whole. Information such as an address obtained from the CD-R / RW pre-groove is detected from the push-pull signal. In the case of CD-R / RW, 50% of the total is sufficient.
[0010]
[Patent Document 1]
Japanese Patent Publication No. 4-3013 [Patent Document 2]
Japanese Patent Laid-Open No. 11-353698
[Problems to be solved by the invention]
However, in recent years, DVD + RW / + R has started to be widely used as a recording medium with a large capacity of CD-R / RW. DVD + RW / + R pregrooves are modulated at higher speeds than CD-R / RW with a phase modulation method and meander, and like CD-R / RW, information such as addresses written in the pregroove using push-pull signals. I'm reading. Since the groove pitch of DVD + RW / + R is only 0.74 μm while the groove pitch of CD-R / RW is 1.6 μm, this push-pull signal is much smaller than the conventional one. Since the modulation is fast and the signal itself is small, it is difficult to accurately read information such as addresses written in the pregroove by the same method as in the prior art.
[0012]
The present invention solves such problems, and in particular, provides an optical pickup device and an optical disc drive device that can accurately detect information such as an address written in a DVD + RW / + R pre-groove. With the goal.
[0013]
[Means for Solving the Problems]
In order to achieve the object, the invention according to claim 1 irradiates the optical disk with a light beam from a semiconductor laser through an objective lens, and receives reflected light from the optical disk through the objective lens and a light beam separation means. An optical pickup device that guides to an element and reproduces information on an optical disc, and includes two regions C and D for detecting a push-pull signal and a focus error signal as a light receiving region of the light beam separating means. one of a region AB, and consists of three straight lines and one curve dividing lines for dividing these three regions, shifting the position of the optical axis of the reflected light the area C, and D side, the light beam separation The dividing line at the center of the means is curved toward the regions C and D as the one curve, so that the sum of the amounts of light entering the regions C and D and the amount of light entering the region AB are substantially equal. Characterized in that it was. With such a configuration, the push-pull signal can be increased and information such as an address can be accurately detected. In addition, since the amounts of light entering the regions C and D and the region AB can be made substantially equal, it is possible to prevent the focus error signal from becoming undetectable.
[0016]
The invention according to claim 2 is the invention according to claim 1 , wherein the light beam separating means is a hologram element. With such a configuration, it is possible to provide an inexpensive optical pickup device by using a hologram element.
[0017]
According to a third aspect of the present invention, in the optical disk drive device, the optical pickup device according to the first or second aspect is mounted. Such a configuration makes it possible to provide a highly reliable optical disk drive device.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, detailed description was abbreviate | omitted by attaching | subjecting the same code | symbol about the member same as the member shown in FIG.
[0019]
FIG. 1 is an explanatory diagram showing a configuration of a hologram provided in an optical pickup device and a position of reflected light in Reference Example 1 of the present invention.
[0020]
In the apparatus of Reference Example 1 , the optical axis position of the reflected light 10 from the optical disc 8 with respect to the hologram 4 in the optical pickup apparatus shown in FIG. 7 is located on the two regions C and D sides for detecting the push-pull signal. It is a big shift. For this reason, in FIG. 9, the push-pull signal (PPS) is such that the intersection of the dividing line between the region AB and the regions C and D and the dividing line between the region C and the region D is at the optical axis center of the reflected light 10. Since the reflected light 10 is irradiated so as to substantially match, the reflected light 10 appears in the shaded portion, but the ratio of entering the regions C and D is about 50% of the whole. On the other hand, according to the reference example 1 shown in FIG. 1, the position of the center of the optical axis of the reflected light 10 is at the intersection of the dividing line between the region AB and the regions C and D and the dividing line between the region C and the region D. On the other hand, since it is biased toward the regions C and D, the ratio of entering the regions C and D is larger than 50% of the whole.
[0021]
With this configuration, it is possible to secure a light amount necessary for detecting the push-pull signal. In particular, by making the push-pull signal entering the areas C and D larger than 50% of the entire push-pull signal from the optical disc 8, information such as addresses written in the DVD + RW / + R pre-groove can be accurately detected. Is possible.
[0022]
By the way, when the reflected light 10 is irradiated onto the hologram 4 as shown in FIG. 1, the amount of light entering the regions C and D is large and the amount of light entering the region AB is small. As a result, there is a possibility that the operation of the conventional circuit for detecting signals may not be performed normally. For example, the amount of light entering the regions C and D is very large, the circuit that generates the push-pull signal is saturated, or the amount of light entering the region AB is very small and the focus error signal is small. It can happen. The second embodiment has been made in view of such problems.
[0023]
Figure 2 is an explanatory view showing the configuration and position of the reflected light of the hologram provided in the optical pickup device of the first embodiment of the present invention, apparatus of the first embodiment, in the optical pickup apparatus shown in FIG. 1 A hologram 21 shown in FIG. 2 is formed on the glass plate 2 instead of the hologram 4.
[0024]
The hologram 21 shown in FIG. 2 has a central portion of the hologram 4 shown in FIG. 1, that is, a part of the boundary line between the region AB and the regions C and D at the intersection of the two dividing lines. In the figure, the hatched area is curved so as not to become the area AB. That is, the dividing line for dividing the three regions is constituted by three straight lines and one curve.
[0025]
In the first embodiment configured as described above, the amount of light entering the region AB can be increased compared to the reference example 1 shown in FIG. It is possible to make the amount of incoming light substantially the same and increase only the push-pull signal. As a result, it can be prevented that the focus error signal cannot be detected due to insufficient light quantity.
[0026]
Figure 3 is an explanatory view showing the configuration and position of the reflected light of the hologram provided in the optical pickup apparatus in the second embodiment of the present invention, apparatus of the second embodiment, the first embodiment shown in FIG. 2 A hologram 22 shown in FIG. 3 is formed on the glass plate 2 instead of the hologram 21 in the optical pickup apparatus of the embodiment.
[0027]
The hologram 22 shown in FIG. 3 is rotated in the direction of the arrow in the drawing around the intersection of the curved portion and the straight portion of the dividing line dividing the region AB and the regions C and D in the hologram 21 shown in FIG. Is set at the position.
[0028]
With this configuration, it is possible to increase the area for detecting the push-pull signal as compared with the hologram 21 shown in FIG.
[0029]
Here, if the straight line portion is set so as to be a tangent to the hatched portion in the figure, or if it is set so as to pass through the contacts P and Q between the hatched region and the regions C and D, all the hatched regions are the regions C and D Thus, the push-pull signal can be detected satisfactorily and the amount of light entering the area AB can be secured.
[0030]
Figure 4 is an explanatory view showing the configuration and position of the reflected light of the hologram provided in the optical pickup apparatus in the reference example 2 of the present invention, apparatus of Reference Example 2, the reflected light 10 is irradiated as shown in FIG. 1 In place of the hologram 4, the hologram 23 shown in FIG.
[0031]
The hologram 23 is set such that the intersection point between the region AB and the regions C and D in the hologram 4 shown in FIG. 1 is deviated toward the regions C and D with respect to the optical axis of the reflected light 10. The dividing line as a straight line is divided so that the proportion of the hatched portion in the figure in the regions C and D is larger than 50% with respect to the whole shaded area in the drawing. The other two lines with respect to the dividing line are set in directions of angles θ1 and θ2 larger than 90 °.
[0032]
With this configuration, it becomes possible to increase the area for detecting the push-pull signal as compared with the hologram 4 shown in FIG. 1, and the dividing line is composed of only straight lines, but the same effect as in the case of FIG. Can be expected.
[0033]
Here, when the angles θ1 and θ2 are set so that the other two dividing lines are tangent to the hatched portion in the figure, the hatched regions are included in the regions C and D, and the push-pull signal is good. And the amount of light entering the area AB can be secured.
[0034]
As mentioned above, although embodiment of this invention has been described, embodiment based on this invention is not restricted to what was mentioned above. For example, in the embodiment described above, the hologram element is used as the light beam separating means, but an optical element such as a prism or a lens using refraction may be applied instead of the hologram element. In particular, the configurations shown in FIGS. 1 and 4 can easily use the prism because the dividing lines are formed only by straight lines.
[0035]
By the way, in recent years, a DVD (Digital Versatile Disc) is widely used as an optical disk for storing a large amount of information. DVD-RAM / WO, DVD-R, DVD + R and DVD-RAM, DVD-RW, DVD + RW discs are writable (recordable) DVDs. The former DVD-RAM / WO, DVD-R, and DVD + R are DVDs that can be written only once (also referred to as DVD Write Once). The latter DVD-RAM, DVD-RW, and DVD + RW are DVDs that can be written a plurality of times. Information is recorded / reproduced on these DVD + R and DVD + RW discs, that is, optical discs, by an optical disc drive apparatus as shown in FIG.
[0036]
FIG. 5 is a functional block diagram showing an example of the configuration of the main part of the optical disc drive. In the figure, 51 is an optical disk, 52 is a spindle motor, 53 is an optical pickup device, 54 is a motor driver, 55 is a read amplifier, 56 is servo means, 57 is a DVD decoder, 58 is an ADIP decoder, 59 is a laser controller, and 60 is DVD encoder, 61 DVD-ROM encoder, 62 buffer RAM, 63 buffer manager, 64 DVD-ROM decoder, 65 API / SCSI interface, 66 D / A converter, 67 ROM, 68 CPU, 69 Indicates RAM, LB indicates laser light, and Audio indicates an audio output signal.
[0037]
In FIG. 5, the arrows indicate the direction in which data mainly flows, and in order to simplify the diagram, the CPU 68 that controls each block in FIG. Omitted. The ROM 67 stores a control program written in a code readable by the CPU 68. When the power of the optical disk drive is turned on, the control program is loaded into a main memory (not shown), and the CPU 68 controls the operation of each unit described above according to the program and temporarily stores data necessary for the control. Save in the RAM 69.
[0038]
The configuration and operation of the optical disk drive apparatus are as follows.
[0039]
The optical disk 51 is rotationally driven by a spindle motor 52. The spindle motor 52 is controlled by a motor driver 54 and servo means 56 so that the linear velocity or angular velocity is constant. This linear velocity or angular velocity can be changed stepwise.
[0040]
The optical pickup device 53 includes the configuration shown in FIGS. 1 to 4, a focus actuator, a track actuator, a light receiving element 9 (see FIG. 7), and a position sensor, and irradiates the optical disc 51 with a laser beam LB. Further, the optical pickup device 53 can be moved in the sledge direction by a seek motor. These focus actuator, track actuator, and seek motor are positioned at a target location on the optical disk 51 by the motor driver 54 and the servo means 56 based on signals obtained from the light receiving element and the position sensor. To be controlled.
[0041]
At the time of reading, the reproduction signal obtained by the optical pickup device 53 is amplified by the read amplifier 55 and binarized, and then input to the DVD decoder 57. The input binarized data is demodulated 8/16 in the DVD decoder 57. Note that the recording data is modulated in units of 8 bits and modulated (8/16 modulation). In this modulation, 8 bits are converted to 16 bits. In this case, the combined bits are attached so that the number of previous “1” s and “0” s are equal on average. This is called “DC component suppression”, and the slice level fluctuation of the DC-cut reproduction signal is suppressed.
[0042]
The demodulated data is subjected to deinterleaving and error correction. Thereafter, this data is input to the DVD-ROM decoder 64, and further error correction processing is performed in order to improve the reliability of the data. The data that has been subjected to the error correction processing twice as described above is temporarily stored in the buffer RAM 62 by the buffer manager 63, and is arranged as sector data to the host computer (not shown) via the ATAPI / SCSI interface 65. It is transferred at a stretch. In the case of music data, the data output from the DVD decoder 57 is input to the D / A converter 66 and extracted as an analog audio output signal Audio.
[0043]
At the time of writing, the data sent from the host computer through the ATAPI / SCSI interface 65 is temporarily stored in the buffer RAM 62 by the buffer manager 63. Thereafter, the write operation is started. In this case, it is necessary to position the laser spot at the write start point before that. In the case of DVD + RW / + R, this point is obtained by a wobble signal that is previously engraved on the optical disc 51 by meandering tracks.
[0044]
Note that the above points are obtained by land pre-pits instead of wobble signals in DVD-RW / -R, and by pre-pits in DVD-RAM / RAM / WO.
[0045]
The wobble signal in the DVD + RW / + R disc includes address information called ADIP (ADress In Pre-groove), and this information is extracted by the ADIP decoder 58. The synchronization signal generated by the ADIP decoder 58 is input to the DVD encoder 60 so that data can be written at an accurate position on the optical disc 51. Data in the buffer RAM 62 is added to the error correction code and interleaved by the DVD-ROM encoder 61 and the DVD encoder 60, and is recorded on the optical disk 51 via the laser controller 59 and the optical pickup 53.
[0046]
Moreover, the structure which acquires address information from a land prepit or a prepit may be sufficient.
[0047]
FIG. 6 is a schematic diagram of an information processing apparatus using an optical disk drive. The information processing apparatus includes a main control device 70, an interface 71, a recording device 72, an input device 73, a display device 74, an optical disk drive device 75 configured as shown in FIG. The main controller 70 includes a CPU, a microcomputer, a main memory, and the like, and controls the entire information processing apparatus.
[0048]
The interface 71 is a bidirectional communication interface with the optical disc drive device 75 and conforms to a standard interface such as ATAPI and SCSI. The interface 71 is connected to the interface 65 of the optical disk drive device shown in FIG. The connection form between the interfaces may be not only a cable connection using a communication line such as a communication cable (for example, a SCSI cable) but also a wireless connection using infrared rays.
[0049]
A recording device 72 such as a hard disk drive (HDD) stores a program written in a code readable by the microcomputer of the main controller 70. When the drive power supply of the information processing apparatus is turned on, the program is loaded into the main memory of the main controller 70.
[0050]
The display device 74 includes a display unit (not shown) such as a CRT, a liquid crystal display (LCD), or a plasma display panel (PDP), and displays various types of information from the main control device 70.
[0051]
The input device 73 includes at least one input medium (not shown) such as a keyboard, a mouse, and a pointing device, for example, and notifies the main controller 70 of various information input by the user. Note that information from the input medium may be input in a wireless manner. Further, as an integrated display device 74 and input device 73, for example, there is a CRT with a touch panel.
[0052]
The information processing apparatus is equipped with an operating system (OS). It is assumed that all devices constituting the information processing apparatus are managed by the OS.
[0053]
【The invention's effect】
As described above, according to the present invention configured as described above, it becomes possible to secure a light amount necessary for detecting a push-pull signal, for example, an address written in a DVD + RW / + R pre-groove. It is possible to accurately detect the information. In addition, since the amounts of light entering the regions C and D and the region AB can be made substantially equal, it is possible to prevent the focus error signal from becoming undetectable.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a configuration of a hologram provided in an optical pickup device and a position of reflected light in Reference Example 1 of the invention. FIG. 2 is a diagram of a hologram provided in an optical pickup device in a first embodiment of the invention. reference example configuration and explanatory view showing the configuration and position of the reflected light of the hologram provided in the optical pickup apparatus in a second embodiment of illustration the present invention; FIG indicating the position of the reflected light the present invention; FIG for illustration Figure 5. the optical disk drive showing the configuration and the position of the reflected light of the hologram provided in the optical pickup apparatus in 2, a functional block diagram showing an example of the main configuration [6] the information processing using an optical disk drive Schematic diagram of the device [FIG. 7] Schematic diagram showing the optical system of the optical pickup device of the optical disk drive device [FIG. 8] FIG. 9 is a side view showing the configuration. FIG. 9 is an explanatory view showing the state of light reflected from the optical disk on the hologram. FIG. 10 is an explanatory view showing the state of reflected light from the optical disc on the light receiving element. Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Semiconductor laser 2 Glass plate 3 Grating 4, 21, 22, 23 Hologram 5 Holo pick-up 6 Collimating lens 7 Objective lens 8 Optical disk 9 Light receiving element 10 Reflected light

Claims (3)

An optical pickup device that irradiates a light beam from a semiconductor laser onto an optical disk via an objective lens, guides reflected light from the optical disk to a light receiving element via an objective lens and a light beam separation means, and reproduces information on the optical disk. And
As the light receiving area of the light beam separating means, two areas C and D for detecting a push-pull signal and one area AB for detecting a focus error signal are provided, and the three areas are divided. The line is constituted by three straight lines and one curve, the optical axis position of the reflected light is shifted to the areas C and D, and the dividing line at the central portion of the light beam separating means is defined as the one curve in the area C. , D, and the amount of light entering the regions C and D is substantially equal to the amount of light entering the region AB . 2. The optical pickup device according to claim 1, wherein the light beam separating means is a hologram element . 3. An optical disk drive device, wherein the optical pickup device according to claim 1 is mounted .

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