JPH04330639A - Optical information reader - Google Patents

Abstract

PURPOSE:To reproduce R-CD in the middle of recording by compulsorily driving an information read beam so that crosses plural tracks, detecting the presence or absence of a recording signal in accordance with a signal waveform which is read from a disk and detecting the presence or absence of an RF signal without rotating the disk. CONSTITUTION:When a tracking servo loop is turned off(SW2 is turned off), a switch SW5 is turned on and an actuator is vibrated in a tracking direction, the information read beam is driven so that it crosses the plural tracks (having recorded part) on the disk 1. The laser beam is diffracted by a bit recorded on the crossed tracks and light/shade occur in a reflected beam. Since the difference of light/shade appears as the amplitude of the read RF signal, a level which is peak-held in a peak holding circuit P is large and a comparator 6 outputs H as an RF detection signal.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc reproducing apparatus, and more particularly to an optical information reading apparatus suitable for discriminating between a write-once recording disc and a read-only disc.

0002

2. Description of the Related Art Conventionally, apparatuses for reproducing optical discs called compact discs (CDs) with a diameter of 12 cm or 8 cm are known. As shown in FIG. 4, this compact disc has a lead-in area, a program area, and a lead-out area formed from the inner circumference of the disc. The recorded signal is EFM (Eight
to Fourteen Modulation)
It is a modulated digital signal, and includes sub-codes such as a time code (Q data) representing time information in addition to the main code.

[0003] In the lead-in area, there is a TOC (Table
Index information called ``of Contents'', ie, the total number of songs recorded in the program area of the disc, the total performance time, etc., are recorded as subcodes. In the program area, music information etc. are recorded as the main code, and the Q data of the subcode includes the track number (TNO) indicating the song number, the playing time from the start of the track (P-TIME), The total performance time (A-TIME) etc. measured from track number 1 are recorded. A lead-out code indicating that the area is a lead-out area is recorded in the lead-out area.

Compact discs with such a recording format are playback-only media, but in recent years write-once compact discs (write-once type compact discs) have been developed that use the same format as compact discs but allow additional information to be recorded.
R-CD: Recordable Compact D
isk) has been developed. Although the recording format of the R-CD conforms to the compact disc format, as shown in Fig.
ibration Area) area and PMA (Prog
A ram Memory Area) area is provided.

[0005] Further, a guide groove is formed in the recording track, and this guide groove transfers the 22.05 KHz carrier to data indicating absolute time information (ATIP).
Wobbling is performed at a frequency modulated by FM (Time In Pregroove). Then, by tracking the recording beam along the guide groove and controlling the rotation speed of the spindle motor so that the center frequency of wobbling is 22.05 KHz,
Tracking servo and spindle servo can be performed even on unrecorded discs.

[0006] The PCA area is an area where test recording is performed prior to a recording operation in order to make the laser power appropriate during recording. The PMA area is an area that stores the recording history of recorded information that is sequentially recorded in the program area, and the start address and end address of each track number recorded in the program area are stored in the TO in the lead-in area.
It is recorded in the same format as the C information.

[0007] This is a partially recorded disc (Par
This is because, in the case of a tial disk, there is a possibility that information may be subsequently added to the remaining program area, so TOC information cannot be recorded in the lead-in area until a final recording completion instruction is given. For this reason, it is necessary to temporarily record information on each track that has already been recorded. On the other hand, the TOC information and the lead-out signal are respectively recorded only when a recording completion instruction indicating that no further recording is to be performed is given by a user instruction or a command from the controller. In this way, the R-CD (Finalized
Disc) conforms to the compact disc format, so it can be played even on playback-only players.

FIG. 6 is a block diagram showing the configuration of an example of a conventional playback-only disc player. Information recorded on the disc 1 is read by an optical pickup 2. The optical pickup 2 supports an objective lens (not shown) for focusing a laser beam on the disk 1, and the objective lens is driven in the optical axis direction and the disk radial direction by a focus actuator and a tracking actuator (not shown). Further, the optical pickup 2 itself is configured to be movable in the radial direction of the disk by a thread mechanism 3.

The signal read from the optical pickup 2 (read RF signal) is supplied to the EFM demodulator 5 via the reproducing amplifier 4, and is AC-coupled by the coupling capacitor C1, which is further composed of a diode D1 and a capacitor C2. A voltage corresponding to the RF signal level is generated in the peak hold circuit P, and this is applied to the comparator 6.
is supplied to one input terminal of The other input terminal of the comparator 6 has a predetermined threshold level voltage Vt.
As a result, the comparator 6 outputs an RF detection signal DRF of "H" or "L" depending on the presence or absence of the RF signal.

Further, a focus error signal FE and a tracking error signal TE are generated by the servo circuit 7, and each error signal FE and TE is generated by a switch SW1.
, SW2 to the focus actuator and tracking actuator to form a predetermined servo loop. Further, a low-frequency component of the tracking error signal TE is extracted by a low-pass filter 8, and a thread error signal SLE for moving the optical pickup 2 along the thread mechanism 3 is generated. The thread error signal SLE is supplied to the thread mechanism 3 via the switch SW3 to form a thread servo loop. Furthermore, from the EFM demodulator 5, for example, the reproduction E
A spindle error signal SPE is generated by detecting the phase difference between the reproduced clock extracted from the FM signal and the reference clock. Spindle error signal SPE is sent to switch SW4
is supplied to the spindle motor 9 via. The reproduced clock is generated by a PLL (phase locked loop) circuit (not shown) in the EFM demodulator 5, and a PLL lock detection signal DPL indicating the locked state of this PLL circuit is supplied to the controller 10. Each of these switches SW1
The switching of SW4 is controlled by the controller 10.

Each switch is connected to a drive signal source that not only turns the servo loop ON/OFF, but also forcibly drives a driven part controlled by the servo loop. For example, in order to make the tracking actuator jump in the disk radial direction in a tracking servo loop, the FW has a polarity that corresponds to that direction.
D (forward direction) voltage and REV (reverse direction) voltage are the switch S
In order to move the optical pickup in the disk radial direction at high speed in the thread servo loop, the FWD voltage and REV voltage of polarity corresponding to that direction are applied to the movable contact of switch SW3 to the movable contact of switch SW3, which accelerates the spindle motor in the spindle servo loop. FW to decelerate
The D voltage and the REV voltage are supplied to the movable contact of the switch SW4. Note that the level of the DC level generated by each drive signal source is controlled by the controller 10. For example, F given to the thread mechanism 3
If you change the voltage levels of the WD and REV signals,
The moving speed of the optical pickup 2 can be made variable.

In the player configured as described above, when the disc 1 is loaded by a disc loading mechanism (not shown), the optical pickup 2 is first moved to the lead-in area of the disc, and the focus servo is pulled in. Once the focus servo is retracted, the spindle motor 9 is then accelerated to rotate the disk 1. At this time, the tracking servo and spindle servo are pulled in. Spindle servo is EF
A PLL lock detection signal supplied from the M demodulator 5 detects that the servo is locked. When both the spindle servo and the tracking servo are pulled in, the TOC information recorded in the lead-in area is stored in a memory (not shown) and reproduction is started.

[0013]

[Problem to be Solved by the Invention] However, in an R-CD that has been partially recorded, since no information is recorded in the lead-in area as described above, it is difficult to accelerate and rotate the spindle motor in this area. However, the spindle servo does not lock and it runs out of control. Furthermore, even if it is attempted to perform spindle servo by detecting the wobbling frequency, it is impossible because conventional playback-only compact disc players are not equipped with means for detecting wobbling. For this reason, for example, first, a predetermined voltage is supplied to the spindle motor in order to rotate the disk at a predetermined angular velocity, and while the optical pickup is gradually moved forward (while the tracking actuator is jumping), an arbitrary track can be selected. It is conceivable to close the tracking servo at 1, monitor the presence or absence of an RF detection signal read on that track, and pull in the spindle servo when the RF signal is detected. However, it is necessary to add a mechanism to the conventional playback device to rotate the spindle motor at a constant angular speed.
This causes an increase in costs.

[0014] In order to overcome such conventional drawbacks, the present invention
The presence or absence of an RF signal is detected without rotating the disk, and if the RF signal is not present, the optical pickup is moved to an area where the RF signal is present, and then the spindle motor is rotated to perform a reproduction operation, It is an object of the present invention to provide an optical information reading device that makes it possible to play back an R-CD in the middle of recording by using the functions of a conventional playback-only player.

[0015]

[Means for Solving the Problems] In order to solve the above problems, the invention as set forth in claim 1 of the present invention provides that a guide groove for information recording is formed in a spiral shape from the inner circumference to the outer circumference of the optical disc. An optical information reading device that reads information from an optical disk on which information can be written additionally, the device comprising: condensing an information reading light beam on the optical disk to read information stored on the optical disk; An optical pickup that has an objective lens capable of condensing a reflected light beam in which the information reading light beam is reflected by the optical disk, converts the reflected light beam into an electrical signal, and outputs a read signal from the electrical signal. tracking servo signal generating means for generating a tracking servo signal for servo-controlling the objective lens in the radial direction of the optical disk in response to the electrical signal; When the tracking servo loop, which includes an actuator means capable of driving in the radial direction of the disc, the optical pickup means, the tracking servo signal generating means, and the actuator means, is not closed, the information is read. drive signal generating means for generating a drive signal for forcibly driving the information reading light beam to cross the plurality of guide grooves in the radial direction of the optical disc; When the optical disc is forcibly driven to cross the plurality of guide grooves, whether or not information is recorded on a portion of the optical disc that is irradiated with the information reading light beam based on the waveform of the read signal. and a detection means for detecting the detection signal and outputting a detection signal.

According to a second aspect of the invention, in the optical information reading device according to the first aspect, the drive signal generating means comprises:
The circuit is configured to be an oscillating circuit that oscillates at a single frequency. According to a third aspect of the invention, in the optical information reading device according to the first aspect, the drive signal is configured to be supplied to the actuator means. According to a fourth aspect of the invention, in the optical information reading device according to the first aspect, the drive signal is transmitted to a sled that supports the optical pickup means and the actuator means and is movable freely in the radial direction of the optical disk. configured to be supplied to the mechanism.

[0017]

[Operation] According to the optical information reading device having the above-mentioned structure, the information reading beam irradiated onto the write-once recording disk in the non-rotating state is forcibly driven in the tracking direction by the drive signal. . Thereby, the detection means can detect the presence or absence of a recording signal based on the signal waveform read from the disk without rotating the disk.

According to the optical information reading device according to the second aspect of the invention, the information reading beam is vibrated in the tracking direction by the oscillation output generated by the oscillation circuit. Therefore, the probability of detecting the presence or absence of recorded information can be increased compared to the case of one-way movement. According to the optical information reading device according to the third aspect, the drive signal is supplied to the actuator that drives the information reading beam in the tracking direction, whereby the actuator vibrates and forcibly drives the information reading beam in the tracking direction. Therefore, by utilizing the tracking servo system, it is possible to easily move the information reading beam across a plurality of tracks compared to a conventional read-only CD player.

According to the optical information reading device according to the fourth aspect of the present invention, the drive signal is supplied to the sled mechanism that moves the optical pickup in the radial direction of the disk, thereby forcibly driving the information reading beam in the tracking direction. Therefore, by utilizing the thread servo system, the information reading beam can be easily moved across a plurality of tracks compared to a conventional read-only CD player.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. First Embodiment FIG. 1 is a block diagram showing the configuration of a first embodiment of the optical information reading device of the present invention. Parts corresponding to those in the conventional explanation are given the same reference numerals, and the explanation thereof will be omitted as appropriate. do. Figure 1
An oscillation circuit 11 that oscillates at a single frequency is provided as a drive signal supply source, and the oscillation output of the oscillation circuit 11 is connected to be mixed into the tracking servo loop via a switch SW5. switch SW
5 is switched and controlled by the controller 10. Turn off the tracking servo loop (turn off SW2)
), when the switch SW5 is turned on, the oscillation output of the oscillation circuit 11 is supplied during the tracking servo loop, so that the tracking actuator (not shown) of the optical pickup 2 vibrates in the tracking direction (disk radial direction) at the frequency of the oscillation output. By setting the amplitude of the oscillation output at this time to an appropriate level, the information reading beam is driven to cross a plurality of tracks on the disk 1. Generally, the driving range of a tracking actuator is several hundred μm.
If the track pitch is 1.6 μm, then 100
You will be crossing more tracks than a book.

Next, the waveform of the read RF signal reproduced by the optical pickup 2 when the information read beam crosses the track as described above will be explained. First, when the actuator is vibrated in the tracking direction in the unrecorded area and crosses multiple recording tracks, the R-CD
Depending on the presence or absence of guide grooves formed on the disk, the reading RF
Strength and weakness appear in the signal waveform. This is called radial contrast (contrast in the disk radial direction). The amplitude of the radial contrast is determined by the depth of the guide groove, the wavelength of the beam, and the track pitch, but is generally at an extremely small level. Therefore, the output level peak-held by the peak-hold circuit P also becomes an extremely small level, so the comparator 6 outputs "L" as the RF detection signal.

On the other hand, when the actuator is vibrated in the tracking direction in the recorded area, the laser beam is diffracted by pits recorded on the track that it traverses, causing brightness and darkness in the amount of reflected beam. In other words, the RF signal obtained during normal playback is based on the principle that the laser beam is diffracted by pits existing in the direction tangential to the track, causing brightness and darkness in the reflected beam. Even if the beam is moved in the direction (that is, in the radial direction of the disk), there are pits in the tracks that it traverses, so brightness and darkness of the same amount of light occur, although the frequency bands are different. This difference in brightness appears as the amplitude of the read RF signal, so the output level peak-held by the peak-hold circuit P becomes a large level, and the comparator 6 outputs an "H" signal as an RF detection signal.
” is output.

FIG. 2 shows the waveform of such an RF signal. At time t1, the focus servo is pulled in, and from time t2, the thread servo begins to be moved in the FWD direction while vibrating the actuator. From time t2 to time t3, the RF signal in the lead-in area of the disc is shown, and a waveform with minute amplitude due to radial contrast is obtained. Next, when entering the recorded program area at time t3,
RF is detected by the brightness and darkness caused by the diffraction phenomenon of the pits of each track.
The amplitude of the signal increases. When the unrecorded area is reached at time t4, the waveform again becomes a small amplitude waveform due to radial contrast. Note that time t5 is the time when the vibration of the actuator is stopped.

Since the RF signal that fluctuates in this way is AC-coupled by the capacitor C1 and the DC component is removed, the peak hold circuit P ends up holding the peak value from the center value of the amplitude of the RF signal. . The RF signal is detected by comparing this hold voltage with an appropriate threshold level Vth by the comparator 6.

[0025] In this way, the RF in the lead-in area
By determining the "H" or "L" state of the detection signal DRF, it is determined whether the disc is a compact disc, a recorded R-CD, or a partially recorded R-CD. . In this case, if the RF detection signal DRF is "H", the disc is a compact disc or an R-CD on which recording has been completed, so the TOC information is read and corrected in the same way as when playing a conventional compact disc. After that, shift to playback of the program area. When the RF detection signal DRF is "L", the thread mechanism 3 gradually moves the pickup 2 in the radial direction until the RF signal is detected. This is switch SW3
The FWD signal may be supplied to. When the program area is reached and an RF signal is detected, the movement of the thread mechanism 3 is stopped, SW5 is turned off, and the vibration of the actuator is stopped. Next, the spindle motor 9 is rotated to pull in the spindle servo and the tracking servo to start reproducing information. Therefore, by doing this, it is possible to detect whether information is recorded without rotating the disc.

At this time, it is difficult to start playback from the exact starting point of the program area, but in the program area, a 2-second pause area is formed just before the actual song starts, so the pause area If you start playback from within, the beginning of the song will not be cut off. In compact disc format, the inner circumference is approximately 60
Since it rotates at 0 rotations/minute, it rotates approximately 20 times in 2 seconds. That is, a pause area of about 20 tracks is formed. Therefore, even if the point at which the detection of the RF signal is completed is when the point is deep into the program area, it is possible to repeatedly jump back, for example, about 10 tracks, and then switch to playback mode when the pause area is reached. In other words, the beginning of the song is never cut off.

[0027] If the disk is rotated immediately when an RF signal is detected, an unrecorded portion (lead-in area) may be located again in the area where the information reading beam is located due to eccentricity of the disk. . Therefore, even if the RF detection signal DRF becomes "H", the unrecorded area is detected by the pickup 2, taking into consideration the eccentricity of the disc.
It is desirable to move the optical pickup 2 to a position that does not reach the position , and then turn on the spindle servo and the tracking servo and pull it in.

In this case, if the tracking servo is pulled in first and then the spindle servo is pulled in, the above-mentioned problem will not occur because the information reading beam will follow the track even if the disk is eccentric. However, when the disk is stopped or rotating at low speed, for example, in the case of tracking servo using the conventional three-beam method, there are pits at the leading beam position and no pits at the trailing beam position. There may be situations in which an offset occurs in the tracking error signal. Therefore, even if the spindle motor is rotated from this state, the tracking servo cannot be pulled in accurately.

Generally, after the spindle motor is rotated, a tracking error waveform in an open loop caused by eccentricity of the disk is monitored, and the tracking servo loop is closed when the frequency decreases. Therefore, if the beam crosses an unrecorded area due to eccentricity, and if the tracking servo is turned on at this position, there is a risk that the spindle servo will run out of control because the reproduced clock will not be extracted. Therefore, the RF detection signal DRF is obtained, and the pickup 2 at that time
At a position where the lead-in area does not reach the position due to eccentricity, the spindle servo is turned on to rotate the disk, and the tracking servo is closed.

Second Embodiment FIG. 3 is a block diagram showing the configuration of a second embodiment of the present invention. This experimental example differs from the first example shown in FIG.
The oscillation circuit 11 is configured to provide an oscillation output into the thread servo loop via the switch SW5. That is, with this configuration, by turning off the tracking servo loop and supplying the oscillation output to the thread servo loop, as in the case of the first embodiment shown in FIG.
The information reading beam will be vibrated in the radial direction of the disk. At this time, if SW3 is switched so that the FWD signal is supplied, the optical pickup 2 will gradually move in the FWD direction while vibrating in the disk radial direction.

In the first and second embodiments described above, the information reading beam was vibrated using the oscillation circuit 11, but this was caused by the FW supplied to SW2 and SW3.
Exactly the same effect can be achieved by switching and connecting the D and REV signals at a predetermined period. In this case, the oscillation circuit can be omitted and this can be realized by software support by the controller 10, and the FWD signal and REV signal in each servo loop act as drive signal generating means.

Note that in the case of an R-CD (virgin disc) in which no information is recorded in the program area, no RF signal is obtained even if the information reading beam is vibrated in the radial direction. Therefore, for example, a position sensor is provided at a position around the center of the program area of the disk, and even if the pickup 2 moves to this position, the RF detection signal DR is
If F cannot be obtained, it may be determined that the disc is a virgin disc.

[0033] Furthermore, even without providing a sensor, the R
If no F detection signal is obtained, it may be determined that the disk is a virgin disk, and in this case, this can be realized only by adjusting the software of the controller. In addition,
In the first and second embodiments described above, the optical pickup 2 corresponds to an optical pickup means, the servo circuit 7 corresponds to a tracking servo signal generation means, and the controller 10 corresponds to a tracking servo signal generation means.
The oscillation circuit 11 corresponds to drive signal generation means, and the peak hold circuit P corresponds to detection means.

[0034]

As described above, according to the first aspect of the present invention, there is provided a driving signal generating means for forcibly driving an information reading beam across a plurality of tracks, and a drive signal generating means for forcibly driving an information reading beam across a plurality of tracks, and Since a detection means for detecting the presence or absence of a recorded signal is provided accordingly, it is possible to detect the presence or absence of recorded information without rotating the disk. Therefore, by simply adding a simple configuration such as an oscillator to a conventional playback-only CD player or changing the software of the controller, it is possible to play a partially recorded R-CD without a lead-in area. This makes it possible to prevent the spindle motor from running out of control even when
It becomes possible to start reproduction only at a position where recorded information exists. In addition, the FWD signal and R
EV signals are also used in conventional playback-only CD players, so if these signals are supplied appropriately and the information reading beam is forcibly driven across multiple tracks, an oscillator is not required. First, a partially recorded R-CD can be played back on a playback-only CD player only by software support.

According to the second aspect of the present invention, since the drive signal supply source is an oscillation circuit that oscillates at a single frequency, the information reading beam reciprocates (vibrates) across a plurality of tracks. Therefore, the probability of detecting the presence or absence of recorded information can be increased compared to one-way movement. Further, according to the third aspect of the present invention, since the drive signal is supplied to the actuator, by utilizing the tracking servo system, it is possible to easily direct the information reading beam to multiple tracks in a conventional playback-only CD player. can be moved across.

Further, according to the fourth aspect of the present invention, since the drive signal is supplied to the thread mechanism, by utilizing the thread servo system, the conventional playback-only CD
The information reading beam can be easily moved across a plurality of tracks with respect to the player.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a first embodiment of an optical information reading device of the present invention.

FIG. 2 is a diagram showing a signal waveform of an RF detection signal in FIG. 1;

FIG. 3 is a block diagram showing the configuration of a second embodiment of the optical information reading device of the present invention.

FIG. 4 is a diagram showing a recording format of a compact disc.

FIG. 5 is a diagram showing a recording format of an R-CD.

FIG. 6 is a block diagram showing an example of a conventional playback-only compact disc player.

[Explanation of symbols]

1...Disk 2...Optical pickup 3...Thread mechanism 6...Comparator 9...Spindle motor 10...Controller 11...Oscillation circuit

Claims (4)

[Claims] 1. An optical information reading device for reading information from an optical disk in which information recording guide grooves are formed in a spiral shape from the inner circumference to the outer circumference of the optical disk and on which information can be written additionally, comprising: An information reading light beam for reading information stored on an optical disk can be focused on the optical disk, and a reflected light beam that is reflected by the information reading light beam by the optical disk can be focused. an optical pickup means having an objective lens for converting the reflected light beam into an electric signal and outputting a read signal from the electric signal; tracking servo signal generating means for generating a tracking servo signal to be controlled; actuator means capable of driving the objective lens in a radial direction of the optical disk according to the tracking servo signal; the optical pickup means and the tracking servo signal. Forcing the information reading light beam to cross the plurality of guide grooves in the radial direction of the optical disc when the tracking servo loop comprising the generating means and the actuator means is not closed. a drive signal generating means for generating a drive signal for driving; and a waveform of the read signal when the information reading light beam is forcibly driven to cross the plurality of guide grooves in the radial direction of the optical disk. On the basis of the,
An optical information reading device comprising: detection means for detecting whether or not information is recorded on a portion of the optical disc irradiated with the information reading light beam and outputting a detection signal. . 2. The optical information reading device according to claim 1, wherein the drive signal generating means is an oscillation circuit that oscillates at a single frequency. 3. The optical information reading device according to claim 1, wherein the drive signal is supplied to the actuator means. 4. The optical system according to claim 1, wherein the drive signal is supplied to a sled mechanism that supports the optical pickup means and the actuator means and is movable freely in the radial direction of the optical disc. Expression information reading device.