JP3771945B2 - Optical information reproducing device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an optical information reproducing apparatus for reproducing information by irradiating light from a semiconductor laser onto a recording medium, and in particular, information is formed in a recording / reproducing data area where information can be rewritten and pits when the recording medium is manufactured. The present invention relates to a means for controlling a light emission amount of a semiconductor laser in an optical information reproducing apparatus for reproducing information of an optical recording medium in which a read-only data area in which information cannot be rewritten is mixed in one medium.
[0002]
[Prior art]
In an optical information reproducing apparatus that optically reproduces information, for example, an optical disc is used as a recording medium. Information can be recorded on the optical disc in advance, and information can be recorded and reproduced. There is.
[0003]
Among optical discs capable of both recording and reproducing information, a continuous groove type conforming to the ISO standard is a fully rewritable type (Fully Rewritable) having a data area capable of recording and reproducing information over the entire surface of the disc. ) And a data area in which information is formed by pits (holes) by molding at the time of manufacture of the disk and only data can be reproduced and a data area in which information can be recorded and reproduced are one disk. In general, a partially embossed disk is used.
[0004]
A plurality of tracks are formed on the recording surface of the optical disc, the data area of the disc is divided into a predetermined number of tracks, and each track is divided into a predetermined number of sectors. Each sector is provided with a header area in which information such as a start mark of the sector, a track number, and a sector number is formed by pits at the time of manufacturing the disk, and thereafter a data area in which data is recorded. As for the data area, in the case of a partially embossed disc, the information is recorded in pits as in the header area, and is a read-only data area where only information can be reproduced, or the information can be rewritten and reproduced by a magneto-optical method or the like. A recording / playback data area (hereinafter also referred to as a user data area) is provided.
[0005]
In the optical disk having such a configuration, in the case of a magneto-optical disk, information reproduction in the user data area where information can be recorded and reproduced is performed using the Kerr effect, but the reproduction signal is weak and C / N is not too high.
[0006]
In order to improve the C / N and accurately reproduce the information, we want to increase the power of the laser beam applied to the medium at the time of reproduction, but when the power is increased, the recorded information is emitted for information reproduction. Therefore, the appropriate range of the irradiation power of the semiconductor laser at the time of reproducing information in the user data area is very narrow.
[0007]
Semiconductor lasers have large initial variations in individual characteristics, and the characteristics change with temperature and time. Therefore, it is necessary to control the amount of light emitted to stably emit light with a predetermined power. As a light emission amount control circuit of a semiconductor laser, for example, as disclosed in Japanese Patent Application Laid-Open No. 62-281485, an actual light emission amount of a semiconductor laser is detected so that an error from a target light emission amount becomes zero. Various devices have been proposed, such as those that adjust the drive current of a semiconductor laser and control the semiconductor laser to emit light stably at a predetermined target power.
[0008]
By the way, in the case of an optical information reproducing apparatus, the information recording surface of the disc is irradiated with laser light, and the reflected light from the information recording surface is received by a photodetector to reproduce the information. It is known that if the laser beam returns to the semiconductor laser more than a predetermined amount, the light emission becomes unstable and the noise of the reproduction signal increases.
[0009]
In the case of an information recording / reproducing apparatus using a magneto-optical method, the information mark recorded on the optical disk is detected as the rotation of the polarization plane. Therefore, it is not possible to use an isolator optical system that prevents return light from the disk from returning to the semiconductor laser. Therefore, in order to solve the problem caused by the return light described above, for example, a semiconductor is used during information reproduction by means of reducing the influence of the return light by performing high-frequency superposition as disclosed in Japanese Patent Publication No. 59-9086. A method of canceling the interference between the emitted light and the returning light by superimposing a high frequency current on the laser driving current is employed.
[0010]
In recent optical disk information reproducing apparatuses, the pickup apparatus has been reduced in size and weight in order to perform recording and reproduction of information at a higher speed. The objective lens, the objective lens can be moved in the vertical direction and the radial direction of the disk by an actuator, a prism and the like. It consists of a separate optical system that is separated into a movable part that is composed, an optical component that is composed of a semiconductor laser, a collimator lens, a prism, and the like, and a fixed part that is composed of a photodetector that extracts a signal from the return light. A pickup device is adopted. In the case where all the optical components are integrally arranged on the movable part, the distance between the semiconductor laser and the reflecting surface of the disk is constant, but in the separation optical system, the movable part is arranged in the radial direction of the disk. By moving, the distance between the semiconductor laser and the reflecting surface of the disk changes. Therefore, the separation optical system apparatus cannot completely cancel the interference between the return light and the outgoing light even if the high frequency superposition as described above is performed, and the header area where the information is recorded in the pits and the pits The amount of light returning to the semiconductor laser varies in a user data area where information can be recorded and reproduced by a magneto-optical method or the like in a land portion that does not exist. For this reason, even if the supply current to the semiconductor laser is controlled to be constant, the amount of light emitted from the semiconductor laser may change.
[0011]
FIG. 7 shows an example of the IP characteristic (driving current-emitted light quantity characteristic) of a semiconductor laser when measuring by changing the quantity of light returned to the semiconductor laser using an apparatus that actually interferes with the emitted light and the returned light. Shown in The slope of the I-P characteristic of the semiconductor laser changes as the return light quantity changes, and the laser emission light quantity when the laser drive current is constant Ic increases from P1 to P3 as the return light quantity increases. That is, in the semiconductor laser, the amount of emitted light may change according to the change in the amount of return light.
[0012]
The return light from the disk to the semiconductor laser is smaller in the header area where information is recorded in pits and in the user data area where recording / reproduction without pits is possible, because the header area is affected by diffraction, and is less than the user data area. In the user data area without pits, the return light increases.
[0013]
When the driving current supplied to the semiconductor laser is constant and the laser beam is irradiated with tracking servo applied to the magneto-optical disk, the semiconductor laser is shown in FIG. As shown in FIG. 8, the amount of emitted light changes due to the change in the amount of light returning to the laser. Therefore, as shown in FIG. 8, the amount of emitted light P of the semiconductor laser is greater in the header data area where the return light is larger. A lowering phenomenon may be observed.
[0014]
Therefore, in the case of Japanese Patent Application No. 5-275594, the present applicant detects the actual light emission amount of the semiconductor laser in order to control the light emission amount to keep the light emission amount of the semiconductor laser at a predetermined value. By detecting the light emission amount of the semiconductor laser, the light emission amount of the semiconductor laser is controlled not to be detected in the header area where information is recorded in pits but in the user data area for information recording / reproduction without pits. There has been proposed an optical information reproducing apparatus capable of controlling the light emission amount to be optimum in a user data area where information is rewritten and reproduced even when there is return light from the recording medium to the semiconductor laser.
[0015]
[Problems to be solved by the invention]
Consider a case where the above-described partially embossed optical disk is used in an optical information reproducing apparatus.
[0016]
FIG. 2 shows a schematic configuration example of each area on the recording surface of the partially embossed optical disk. The partially embossed optical disc 51 is provided with a plurality of tracks 52 on the recording surface and divided into a predetermined number of tracks. The optical disc 51 has a track area A in which information is recorded in pits and a read-only data area in which only information can be reproduced is formed, and a recording / reproduction data area in which information can be recorded and reproduced by a magneto-optical method or the like. The track area B is formed. In the track area A, in each sector on the track, a header area 53 in which information such as a sector mark and a sector number is formed in pits is provided at the head, and information is recorded in pits in the rear as in the header area. The read-only data area 54 is provided. In the track area B, in each sector on the track, a header area 53 in which information is formed by pits is provided at the head as in the track area A, and no pit is formed in the rear part to record information. A recording / playback data area (user data area) 55 that can be played back is provided.
[0017]
In the apparatus using the partially embossed optical disk having such a configuration, when the light emission amount control in Japanese Patent Application No. 5-275594 described above is applied, in the track region B where recording and reproduction are possible, the semiconductor laser The user data is calculated by detecting the amount of light emitted only in the user data area without pits or by calculating the amount of light emitted in the user data area by removing the data of the amount of light emitted that is assumed to be detected in the header area with pits. It is possible to accurately perform the light emission amount control for keeping the light emission amount of the semiconductor laser in the region at a predetermined value. Thereby, accurate and optimal light emission amount control can be performed in a user data area where high-precision light emission amount control is required, and data deterioration and erroneous reproduction can be prevented.
[0018]
On the other hand, in the track area A where only reproduction is possible, pits are continuously formed not only in the header area but also in the reproduction-only data area that follows the header area, and the light emission amount of the semiconductor laser is detected for light emission amount control. Since there is no user data area without pits, which is an area, it is impossible to detect the amount of light emitted from the semiconductor laser from the user data area without pits at least when the track area A dedicated to information reproduction is irradiated with laser light. For this reason, in the track area A, the same light emission amount control as that in the track area B cannot be performed.
[0019]
If the drive current value supplied to the semiconductor laser is not updated while the light emission amount detection operation of the semiconductor laser is stopped, the characteristics of the semiconductor laser will change when the temperature inside the device changes, and the amount of light emitted with respect to the drive current will change. Changes, and the output power cannot be maintained at a predetermined value. For this reason, even when the track area A that can only be reproduced is irradiated with a laser beam, the amount of light emitted from the semiconductor laser is detected every predetermined time so that the error from the target light amount becomes zero. It is necessary to increase / decrease the supply current.
[0020]
However, in the reproduction-only track area A, when the emission amount of the semiconductor laser is detected by avoiding only the header area as in the case of the recording / reproduction track area B, the reproduction-only data area in the track area A has the track area. Since the amount of light returning to the semiconductor laser is different from the user data area without pits in B, the value of the light emission quantity different from the light emission quantity in the user data area is detected. For this reason, when detecting the emission amount for controlling the emission amount of the semiconductor laser, if the emission amount of the semiconductor laser is detected in a read-only data area where information is formed by pits and the return light is reduced by diffraction, Even when the drive current is adjusted so that there is no error with respect to the target light emission amount by detecting the light emission amount in the user data area without pits, it is determined that the light emission amount is low.
[0021]
In this case, when the pickup is located in the reproduction-only track area A and the laser beam from the semiconductor laser is continuously irradiated onto the track in the track area A, the amount of current supplied to the semiconductor laser is determined based on the above determination. By increasing the light emission amount, the light emission amount is controlled so that an error from the target light emission amount in the track area A is reduced. However, when the pickup is moved from the track area A to the recording / reproducing track area B after increasing the amount of current supplied to the semiconductor laser in this way, the laser beam emitted from the semiconductor laser with the changed driving current quantity Is the optimal light emission amount in the header area with pits as in the track area A, but in the user data area in the land portion, the amount of return light increases due to the absence of diffraction by the pits, and the light emission quantity is a predetermined target value. The information recorded by the user may be deteriorated by the high-power beam.
[0022]
Contrary to the case of the above-described disk, in the case where the return light is larger in the area with pits than in the user data area without pits, the light emission amount detection is performed in the reproduction-only track area A. The amount of light emission is determined to be higher than the amount of light emission, and the amount of light emission is controlled so as to reduce the supply current to the semiconductor laser. The laser light emitted from the laser becomes lower than a predetermined target light emission amount in the user data area, and there is a possibility that the C / N deteriorates and information cannot be read.
[0023]
Further, when the emission amount is detected in the reproduction-only track area A and the supply current amount to the semiconductor laser is adjusted as described above, the changed semiconductor is moved after the pickup is moved to the recording / reproduction track area B. Control is required to return the amount of current supplied to the laser to an appropriate value in the user data area of the track area B and to correct it to an optimal light emission amount, but this requires a predetermined time, During the period of correcting the power of the semiconductor laser, a rotation waiting state in which a recording operation cannot be performed is entered. Therefore, there is a problem that the transfer rate is lowered due to this waiting time, and the operation performance of the apparatus is lowered.
[0024]
On the other hand, if the emission amount control is performed by detecting the emission amount in the reproduction-only track area A, the above-mentioned problems occur. Therefore, when the track area A is irradiated with laser light, the semiconductor laser emits light. Stop the amount detection, monitor the temperature change inside the device, and if the temperature change more than a predetermined value is detected or if the predetermined time has passed, move the pickup to the track area B for recording / reproduction Then, it is conceivable to control the light emission amount of the semiconductor laser by detecting the light emission amount in the user data area. In this case, the semiconductor laser does not have an inappropriate power in the user data area immediately after the pickup is moved from the track area A to the track area B.
[0025]
However, such control requires an operation of moving the pickup between the reproduction-only track area A and the recording / reproduction track area B, and a predetermined waiting time that was originally unnecessary for this operation is required. Since additional time is required, there is still a problem that the transfer rate is lowered and the operation performance of the apparatus is lowered.
[0026]
The present invention has been made in view of these circumstances, and includes one recording / reproduction data area in which information can be rewritten and one reproduction-only data area in which information is formed in pits during recording medium production and information cannot be rewritten. When the optical recording medium mixed in the medium is used, the correct reproduction power is obtained in the user data area where information can be recorded / reproduced even if there is a return light from the recording medium to the semiconductor laser. Light emission control is possible, the power of the semiconductor laser can be increased to prevent the recorded data from being deteriorated, and the power can be prevented from being accidentally reproduced due to the reduced power. It is an object of the present invention to provide an optical information reproducing apparatus that can prevent the operation performance of the apparatus from deteriorating.
[0027]
[Means for Solving the Problems]
  The first optical information reproducing apparatus according to the present invention can record and reproduce information without a header area and pits in which information such as sector start marks, track numbers, and sector numbers are formed by pits when the medium is manufactured. 1 is a rewritable recording / reproducing track area composed of various data areas, and a reproduction-only track area in which information in the data area is formed by pits when the medium is manufactured and information cannot be rewritten together with the header area. In an optical information reproducing apparatus that reproduces information from optical recording media mixed in a single sheet, the target value of the amount of light emitted from the semiconductor laser during information reproduction is set to high frequency before the focus servo operation at the initial setting. It is set on the condition that a current is supplied to the semiconductor laser, and the semiconductor laser is irradiated when the recording / reproducing track area is irradiated. For the emission amount of the target value so as to set the test area, Bei the semiconductor laser output control means for performing light emission amount control for maintaining the light emission amount of the semiconductor laser at a predetermined valueThe semiconductor laser output control means sets the target value of the light emission amount of the semiconductor laser when irradiating the recording / reproducing track area to a predetermined value corresponding to the mounted medium, and the reproduction-only track area The target value of the light emission amount of the semiconductor laser when irradiating the laser beam is the same as the drive current supplied to the semiconductor laser before the optical head starts moving after the optical head is moved from the recording / reproducing track area to the reproducing-only track area. A light emission amount of the semiconductor laser is detected in a state where a driving current having a value is supplied to the semiconductor laser, and the value is set based on the detection result.
Further, the second optical information reproducing apparatus of the present invention is the first optical information reproducing apparatus, wherein the semiconductor laser output control means moves the optical head from a recording / reproducing track area to a reproducing-only track area. The detection of the light emission amount of the semiconductor laser after the movement is performed a predetermined time after reproducing the information in the header area of the reproduction-only track area.
[0029]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
FIGS. 1 to 5 relate to a first embodiment of the present invention, FIG. 1 is a block diagram showing the configuration of output control means of a semiconductor laser in an optical information reproducing apparatus, and FIG. 2 is a portion used in the apparatus of this embodiment. FIG. 3 is an explanatory diagram showing a schematic configuration of each area on the recording surface of an embossed optical disc, FIG. 3 is a configuration explanatory diagram showing a configuration of a pickup unit, and FIG. 4 is an operation description showing a light emission amount detection state when performing a track jump operation. FIGS. 5 and 5 are operation explanatory views showing the light emission amounts of the semiconductor lasers in the track area B where recording and reproduction are possible and the track area A where reproduction is possible.
[0030]
The optical information reproducing apparatus according to the present embodiment uses a semiconductor laser (also referred to as LD) 1 that emits laser light, a photodiode 2 into which a part of light emitted from the semiconductor laser 1 is incident, and an output current of the photodiode 2 as a voltage. 1 is provided as a semiconductor laser output control means for controlling the light emission amount of the semiconductor laser 1. Is provided.
[0031]
The semiconductor laser output control means has a CPU 5 that controls each part. The CPU 5 includes an A / D converter 6 that converts the output of the IV converter 3 into a digital signal, and information reproduction, erasure, or A ROM 7 in which the value of the light emission amount of a predetermined semiconductor laser at the time of recording is stored as a target light emission amount, a RAM 15 that stores a target light emission amount in a data area that can only be reproduced, which is obtained during an operation described later, and a recording medium An information reproducing means 8 for reproducing information recorded on the medium based on a reproduction signal obtained from the reflected light is connected.
[0032]
A D / A converter (abbreviated as DAC) (1) 9 for converting an instruction value corresponding to a semiconductor laser emission amount (read power) output from the CPU 5 into an analog voltage value, and DAC (1 And a V-I converter 11 as a semiconductor laser driving means for converting the output voltage of 9 into a current and supplying it to the semiconductor laser, so that the output current of the V-I converter 11 is input to the adder circuit 13. It has become. Also, a D / A converter (DAC) (2) 10 that converts an instruction value for obtaining a semiconductor laser emission amount (peak power) output from the CPU 5 into an analog voltage value, and a DAC (2) 10 A V-I converter 12 for converting the output voltage into a current is provided, and the output current of the V-I converter 12 is input to the adder circuit 13 via the switch SW3. The switch SW3 is turned on and off in accordance with a modulation signal (recording data pulse) of information to be recorded under the control of the CPU 5.
[0033]
Further, a high frequency oscillation circuit (also referred to as HFM) 14 for generating a high frequency current is provided, and a high frequency current output from the high frequency oscillation circuit 14 is input to the addition circuit 13 serving as a high frequency superimposing means via the switch SW2. Yes. The output terminal of the adder circuit 13 is connected to the semiconductor laser 1 via the switch SW1, and the current superimposed by the adder circuit 13 is supplied to the semiconductor laser 1 as a drive current.
[0034]
The configuration on the recording surface of a partially embossed optical disk as an optical disk used in the optical information reproducing apparatus of this embodiment will be described with reference to FIG.
[0035]
The partially embossed optical disc 51 is provided with a plurality of tracks 52 on the recording surface and divided into a predetermined number of tracks. As shown in FIG. 2 (a), the optical disc 51 is an information reproduction-only track area (referred to as track area A) in which information is recorded in pits and a reproduction-only data area in which only information can be reproduced is formed. And a track area for information recording / reproduction (referred to as track area B) in which a data area for recording / reproduction capable of recording and reproduction of information by a magneto-optical method or the like is formed. In the track area A, in each sector on the track, a header area 53 in which information such as a start mark of the sector, a track number, and a sector number is formed by pits at the time of manufacturing the disk is provided at the head, and a header is provided at the rear. Similar to the area, a read-only data area 54 in which information is recorded in pits and only information can be reproduced is provided. The track area B is provided with a header area 53 in which information is formed by pits at the head part of each sector on the track, as in the track area A, and no pits are formed at the rear part thereof. Thus, a recording / reproducing data area (also referred to as a user data area) 55 capable of recording (rewriting) and reproducing information is provided. Note that the reproduction-only track area A and the recording / reproduction track area B are formed with the same reflectance of the recording surface.
[0036]
As shown in FIG. 2B, the inner peripheral portion 56 on the inner peripheral side from the read-only track region A is a mirror surface portion (mirror) that is a total reflection region for drawing focus servo for performing focus control from the inside. Zone), a tracking pull-in portion 58 in which a plurality of tracks for pulling in tracking servo for tracking control are formed, and a plurality of tracks having the same format as the track area B in which information can be rewritten. A test zone 59 is provided, and a control zone 60 in which information such as the type and format of the disc is recorded by pits is provided.
[0037]
FIG. 3 shows the configuration of the pickup unit including the semiconductor laser 1. The pickup section is configured by a so-called separation optical system pickup having a movable section 21 and a fixed section 22. Opposite to the disk 24 driven to rotate by the spindle motor 23, a movable part 21 is provided so as to be movable in the radial direction of the disk 24. The movable part 21 has a total reflection prism for raising the laser beam toward the disk 24. 25, an objective lens 26 for converging the laser beam on the disk, and a tracking and focusing actuator (not shown) are provided. The fixing unit 22 includes the semiconductor laser 1 and the photodiode 2 described above, a collimator lens 27 that converts the light emitted from the semiconductor laser 1 into a parallel light beam, and a beam splitter that transmits and reflects the light emitted from the semiconductor laser 1 to separate the light beam. 28 is provided.
[0038]
In the pickup section having such a structure, a laser beam is emitted from the semiconductor laser 1 and the beam spot formed by converging the laser beam by the objective lens 26 or the like is moved by the movable section 21 to move the disk 24 (for example, a partially embossed type). Information is recorded and reproduced by irradiating a target track on the optical disc 51).
[0039]
Next, the operation of the semiconductor laser output control means of this embodiment will be described.
[0040]
At the time of information reproduction, the CPU 5 turns on the switch SW1 so that the semiconductor laser 1 can be turned on, and from the ROM 7, a supply current instruction value (a target emission amount value) corresponding to the semiconductor laser emission amount (read power) at the time of information reproduction. ) Is input to the DAC (1) 9, and the output voltage of the DAC (1) 9 is converted into a current by the VI converter 11 and supplied to the semiconductor laser 1 as a drive current. At this time, the switch SW2 is turned on for high frequency superimposition to supply the high frequency current from the high frequency oscillation circuit 14 to the semiconductor laser 1. Then, the light emitted from the semiconductor laser 1 is detected by the photodiode 2, and the emission amount detection value obtained through the IV converter 3 and the A / D converter 6 is input. An error between the actual semiconductor laser light emission amount based on the detected light emission amount and the target light emission amount from the ROM 7 is calculated, and the output value to the DAC (1) 9 is changed so that this error becomes zero. The amount of light emitted from the semiconductor laser 1 is controlled so as to obtain power.
[0041]
At the time of information recording, the CPU 5 reads a supply current instruction value for obtaining a semiconductor laser emission amount (peak power) at the time of information recording from the ROM 7 and inputs it to the DAC (2) 10, and an output voltage of the DAC (2) 10. Is converted into a current by the V-I converter 12 and input to the adder circuit 13 via the switch SW3. At this time, the switch SW3 of the output of the VI converter 12 is turned on / off according to the modulation signal (recording data pulse) of the information to be recorded, and the strength changes to the predetermined peak power and bottom power according to the recording data. The semiconductor laser 1 is caused to emit light.
[0042]
In this embodiment, only the control of the light emission amount of the semiconductor laser during information reproduction will be described in detail.
[0043]
First, as a first stage, a pickup moving operation for initial setting is performed.
[0044]
In the pickup moving operation for the initial setting, the movable part 21 of the pickup unit is moved to a position where the portion irradiated with the beam spot from the pickup unit is outside the user data area of the disk, for example, with a standard disk defined by ISO. If there is, it is moved to a position where there is no innermost track (for example, the focus pull-in portion 57 in the partially embossed optical disc 51).
[0045]
Next, as a second step, an output instruction value (supply current instruction value) to the DAC (1) 9 for information reproduction is obtained.
[0046]
In the second stage, first, the DAC (1) 9 and the DAC (2) 10 are reset to make the output zero, and then the switch SW1 is turned on so that the output current of the VI converter 11 flows to the semiconductor laser 1. The semiconductor laser 1 and the VI converter 11 are connected to each other. Then, the switch SW2 is turned on, and the high-frequency current output from the high-frequency oscillation circuit 14 is supplied to the semiconductor laser 1.
[0047]
Next, the CPU 5 reads the semiconductor laser emission amount (RP) during information reproduction from the ROM 7 and transfers bit data DR corresponding to RP to the read power setting DAC (1) 9. Then, the output voltage of the DAC (1) 9 is converted into a current by the VI converter 11 and supplied to the semiconductor laser 1 as a drive current.
[0048]
The CPU 5 reads the light emission amount detection value (PR1) of the output of the A / D converter 6 and calculates PR1−RP which is an error between the actual light emission amount of the semiconductor laser and the target light emission amount, and if the error is larger than zero. The instruction value of DAC (1) 9 is decreased, and if the error is negative, the instruction value of DAC (1) 9 is increased. When the indicated value of the DAC (1) 9 is increased or decreased, the current supplied to the semiconductor laser 1 is also changed, so that the light emission amount of the semiconductor laser is also increased or decreased.
[0049]
The CPU 5 again reads the output (PR2) of the A / D converter 6 and calculates the error RP -PR2. If the error becomes zero, the output to the DAC (1) 9 increases or decreases the supply current in accordance with the characteristics of the semiconductor laser in order to cause the semiconductor laser 1 to emit light with a predetermined information reproducing power (read power). The setting of the instruction value ends. On the other hand, if the error does not become zero, the increase / decrease of the indicated value to the DAC (1) 9 is repeated until the error converges to zero.
[0050]
After the setting of the output instruction value to the DAC (1) 9 in the second stage is completed, the CPU 5 temporarily stops monitoring the output of the A / D converter 6.
[0051]
Next, as a third stage, the focus servo and tracking servo are pulled in with the semiconductor laser emitting light with a light emission amount for information reproduction.
[0052]
In the third stage, after the setting of the DAC (1) 9 is completed, the CPU 5 controls the actuator in the focus direction (not shown) of the pickup unit to control the beam spot of the irradiation light from the semiconductor laser on the focus pull-in unit 57 of the disk. Auto focus operation is performed to automatically adjust the to the in-focus state, and focus servo is applied.
[0053]
Subsequently, the movable section 21 of the pickup section is moved in the outer circumferential direction of the disk (in the direction of the tracking pull-in section 58) until the tracking error signal can be detected, and tracking servo is applied at the position of the tracking pull-in section 58.
[0054]
Next, as a fourth stage, the type of the loaded disc is recognized.
[0055]
In the fourth stage, the CPU 5 detects the head sector mark of the sector from the reproduction data output from the information reproduction means 8 with the tracking servo applied. After detecting the sector mark, the CPU 5 continues to read the reproduction data of the information reproduction means 8 and recognizes the ID information of the sector currently reproduced from the reproduction data in the header area. If the ID information can be recognized, the CPU 5 can recognize the track currently irradiated with the laser beam.
[0056]
In the case of a disc conforming to the ISO standard or ECMA standard, as shown in FIG. 2B, a track area called a control zone 60 on which information on the disc is recorded is provided on the inner periphery of the disc. . The CPU 5 calculates the number of seeks from the track currently irradiated with the laser beam to the control zone based on the track number recognized by the tracking pull-in unit 58, and moves the pickup to the control zone 60.
[0057]
Then, by reading the information in the control zone 60, it is possible to recognize the type of the disc, such as whether the loaded disc is a partially embossed disc or another disc. Depending on the type of disc recognized, the power for playback of the semiconductor laser is set to an optimal value in the subsequent processing. In the case of a partially embossed disc, the recording / playback data area and playback-only data are set. Different light emission amount control is performed in each of the regions.
[0058]
Here, the subsequent processing will be described only when a partially embossed disk is loaded.
[0059]
Next, as a fifth step, the output instruction value to the DAC (1) 9 is updated so that the optimum light emission amount is obtained in the information rewritable recording / reproducing data area 55.
[0060]
In the fifth stage, the pickup unit is first moved to the test zone 59 on the inner periphery of the disc, and in the second stage, a track in the test zone 59 having no pits in the data area is set in the same way as the user data area where information can be rewritten. The laser beam from the semiconductor laser 1 is emitted according to the output instruction value.
[0061]
Then, the CPU 5 detects the sector mark from the reproduction data output from the information reproduction means 8, and then reads the sector ID information from the reproduction data in the header area.
[0062]
Based on the format of the mounted disk read by the control zone 60 in the fourth stage, the CPU 5 starts the recording / playback data area from the position where the sector mark or ID information is recorded (data area where information is not recorded in pits). Since the time during which the laser beam spot moves to the start point 55 can be calculated, the CPU 5 waits for a predetermined movement time until the irradiation beam moves to the start point of the recording / reproducing data area 55 and then to the A / D converter 6. A sampling timing signal is output, and the light emission amount detection value (PR3) output from the A / D converter 6 is read. When a predetermined time elapses when the irradiation beam reaches the header area of the next sector, monitoring of the output of the A / D converter 6 is stopped for a predetermined time until the irradiation beam moves to the next recording / reproducing data area 55, and the output from the semiconductor laser 1 is stopped. Only when the laser beam irradiates the recording / reproducing data area 55, the emission amount is detected.
[0063]
In the case of a disc in which tracks are formed in a spiral shape, a track jump operation is necessary to maintain the irradiation beam on a specific track. Here, the operation when the track jump operation is performed will be described with reference to FIG.
[0064]
As shown in FIG. 4, when performing a track jump operation for moving a beam spot to an adjacent track, a period T1 during which the beam spot is located in a groove formed between the tracks during movement of the pickup unit is: Due to the influence of diffraction in the groove, the light emission amount detection value (PR3) of the output of the A / D converter 6 which is the detection value of the emitted light quantity of the semiconductor laser 1 becomes low. That is, at the time of track jump, the amount of return light is different from when the irradiation beam is in a data area where information can be recorded / reproduced due to the effect of diffraction caused by the groove when the irradiation beam crosses the groove. The amount of laser emission cannot be detected.
[0065]
In the present embodiment, as described above, a sampling timing signal is output to the A / D converter 6 during a period in which the beam spot is located in the data area, and the amount of light emitted from the semiconductor laser 1 is detected. If the sampling period overlaps with the track jump timing, the CPU 5 stops outputting the sampling signal to the A / D converter 6 during the track jump period, and the next one after the end of the track jump. The sector ID information is read and a sampling timing signal is output in the next data area to read the light emission amount detection value (PR3).
[0066]
Thus, by stopping the sampling of the A / D converter 6 at the time of track jump, when the irradiation beam crosses the groove formed between the tracks, the light emission amount of the semiconductor laser is not detected. As a result, when the irradiation beam crosses the groove between the tracks, the amount of light that is returned to the data area where information can be recorded / reproduced is on track, and the light emission amount of the semiconductor laser is the value in the data area. The problem of detecting different values can be prevented, and the amount of light emitted from the semiconductor laser can be accurately detected.
[0067]
After reading the light emission amount detection value (PR3) of the output of the A / D converter 6 as described above, the CPU 5 reads from the data table in the ROM 7 the target light emission amount (RP) of the semiconductor laser at the time of information reproduction according to the mounted disk. ) And PR3 and RP are compared. If there is an error, the instruction value to the DAC (1) 9 is increased or decreased so that the light emission amount of the semiconductor laser becomes the target light emission amount.
[0068]
As described above, the monitor of the output of the A / D converter 6 for detecting the light emission amount of the semiconductor laser sets the period based on the format of the disc, so that only the recording / reproduction data area 55 is displayed. Thus, the output of the A / D converter 6 can be monitored, and the emission amount of the semiconductor laser can be detected without failing to avoid the header area with pits.
[0069]
The sampling of the A / D converter 6 and the reading of the output of the A / D converter 6 by the CPU 5 are performed a plurality of times while the irradiation beam from the semiconductor laser is in the data area, and the average is calculated to calculate the average of the semiconductor laser. You may perform the process which makes it light-emission quantity. By performing such processing, it is possible to remove the influence of disturbances such as scratches and noise on the disk, and it is possible to more accurately control the light emission amount of the semiconductor laser.
[0070]
When the error between the detected light emission amount of the semiconductor laser and the target light emission amount in the recording / reproducing data area 55 becomes zero and the update of the output instruction value to the DAC (1) 9 is completed, the CPU 5 outputs the output of the A / D converter 6. Stop monitoring again.
[0071]
Thereafter, in order to prevent an error between the light emission amount of the semiconductor laser and the target light emission amount due to a change in the characteristics of the semiconductor laser due to a change in the ambient temperature or the like, the information from the host computer of the optical information reproducing apparatus (not shown) Until an instruction for recording or reproduction is received, the CPU 5 repeats the operation of updating the output instruction value to the DAC (1) 9 in the fifth stage described above at predetermined time intervals.
[0072]
Thus, the initial operation for setting the light emission amount of the semiconductor laser in the initial state is completed.
[0073]
Next, as a sixth stage, an operation related to the light emission amount control when receiving an information reproduction instruction output from the host computer will be described.
[0074]
When an information reproduction instruction is issued from the host computer and the CPU 5 receives this reproduction instruction, if a certain target track of the sector in which the information to be reproduced is recorded is different from the track currently being tracked, the CPU 5 Detection of the light emission amount of the semiconductor laser avoiding the header area performed at predetermined time intervals in the stage and the updating operation of the instruction value to the DAC (1) 9 are stopped, and the output instruction value to the DAC (1) 9 is changed. While being held, the pickup unit is moved to a predetermined target track.
[0075]
At the end of the fifth stage, the irradiation beam from the semiconductor laser is in the test zone 59. Therefore, at the beginning of the sixth stage, the irradiation beam from the semiconductor laser is positioned on the track of the test zone 59 having the recording / reproducing data area. It shall be.
[0076]
In the present embodiment, different light emission amount control is performed during the reproduction operation depending on whether the track currently being tracked and the destination track are areas having a recording / reproduction data area or a reproduction-only data area.
[0077]
[1] First, when the track currently being tracked is in the track area B having the recording / playback data area (user data area) 55 or in the test zone 59 and the destination track is also the track area B. The operation will be described.
[0078]
In this case, after the movement of the pickup unit is completed and on-tracking is performed, the CPU 5 outputs the A / D converter 6 which is performed in the data area (the user data area 55 or the test zone data area) without the pit and avoiding the header area. The detection of the light emission amount of the semiconductor laser by the monitor and the update operation of the instruction value to the DAC (1) 9 are restarted, and at the same timing as the light emission amount detection in the track of the test zone 59 performed in the fifth stage of the initial operation. The output of the A / D converter 6 is sampled, and the output instruction value to the DAC (1) 9 is updated so that the error from the target light emission amount converges to zero. Then, the updating operation of the output instruction value to the DAC (1) 9 is repeated at a predetermined time interval.
[0079]
[2] Next, the track currently being tracked is in the track area B having the recording / playback data area (user data area) 55 or in the test zone 59, and the destination track has the playback-only data area 54 The operation in the area A will be described.
[0080]
In this case, after the movement of the pickup unit is completed and on-tracking is performed, the CPU 5 detects the sector mark from the reproduction data output from the information reproduction means 8, and then reads the sector ID information from the reproduction data in the header area. . In the case of a disc conforming to the ISO standard or ECMA standard, an area without a pit called an offset detection field is provided between the header area and the data area. The CPU 5 generates a light beam while maintaining the output of the DAC (1) 9 set at the end of the fifth stage, and the irradiation beam passes through the offset detection field and moves to the start point of the reproduction-only data area 54. A sampling timing signal is output to the A / D converter 6 after waiting for a predetermined movement time until the light emission amount detection value (PR4) output from the A / D converter 6 is read.
[0081]
The sampling of the A / D converter 6 and the reading of the output of the A / D converter 6 by the CPU 5 are performed a plurality of times while the irradiation beam from the semiconductor laser is in the data area, and the average is calculated to calculate the average of the semiconductor laser. You may perform the process which makes it light-emission quantity. By performing such processing, it is possible to remove the influence of disturbances such as scratches and noise on the disk, and more accurately detect the light emission amount of the semiconductor laser.
[0082]
Subsequently, the CPU 5 stores the output value (PR4) of the A / D converter 6 that is the light emission amount detection value in the reproduction-only data area 54 with pits in the RAM 15 in the target light emission amount (RP) in the track area A dedicated to information reproduction. Remember as').
[0083]
Thereafter, the CPU 5 does not use the RP read from the ROM 7 in the fifth step as the target light emission amount for the light emission amount control when the irradiation beam from the semiconductor laser irradiates the track in the reproduction-only track area A. RP ′ obtained by the above is used.
[0084]
In the track area A, the return light is less than the user data area 55 in the track area B due to the influence of diffraction at the pits. When the light emission amount is detected in the data area 54, the light emission amount detection value is reduced due to the difference in the return light. In this embodiment, in the user data area 55 of the recording / reproducing track area B, a current having the same value as the driving current for obtaining the target light emission amount RP stored in the ROM 7 is supplied to the semiconductor laser. The amount of light emitted from the region 54 is set as the target amount of light emitted RP ', and the amount of light emitted from the semiconductor laser in the track area A for reproduction is controlled.
[0085]
When the target light emission amount (RP ') is stored in the RAM 15, the CPU 5 detects the light emission amount of the semiconductor laser by monitoring the output of the A / D converter 6 performed in the data area while avoiding the header area, and DAC (1) 9 The update operation of the instruction value is resumed, the output of the A / D converter 6 is sampled at the same timing as the detection of the light emission amount in the track of the test zone 59 performed in the fifth stage of the initial operation, and the target light emission amount (RP) The output instruction value to the DAC (1) 9 is updated so that the error from ') converges to zero. Then, the updating operation of the output instruction value to the DAC (1) 9 is repeated at a predetermined time interval.
[0086]
FIG. 5 shows a track area B (see (a)) capable of recording / reproduction having a user data area 55 without pits, and a track area capable of reproduction only having a reproduction-only data area 54 in which information is formed by pits. A light emission amount detection value in each track of A (see (b)) is shown.
[0087]
The header area in which the information is formed of pits is the same in the track area A and the track area B, and the return light is less than the user data area 55 due to diffraction by the pits, and the emission amount detection value (PR3 in the user data area 55). ), The amount of light emitted from the laser becomes smaller. Since the head sector mark in the header area has a pit length longer than that of the read-only data area, the sector mark has a smaller amount of return light due to the influence of diffraction, and the amount of light emitted from the laser becomes smaller. Further, since there are no pits in the offset detection field, there is a large amount of return light and the amount of light emitted from the laser is increased.
[0088]
The light emission amount detection value (PR4) in the read-only data area 54 is the user data when the return light is less than the user data area 55 due to diffraction by the pits as in the header area, and the current supplied to the semiconductor laser is the same. The amount of light emitted from the laser is smaller than the detected light amount (PR3) in the region 55. In the reproduction-only data area 54, the target light emission amount is changed from RP to RP 'in accordance with the change in the laser emission light amount due to the difference in the return light amount, and the light emission amount detection value (( PR4) is compared with the target light emission amount (RP '), and the light emission amount control is performed by updating the output instruction value to the DAC (1) 9 so that the error becomes zero.
[0089]
When such light emission amount control is performed, the temperature inside the apparatus changes and the characteristics of the semiconductor laser change in a short time enough to move the pickup unit from the track area B or the test zone to the track area A. Therefore, the supply current to the semiconductor laser is not different from the values in the track area B and the test zone track before moving the pickup section.
[0090]
As described above, a track on which information can be recorded / reproduced again from the track area A by controlling the target light emission amount so as not to change the supply current to the semiconductor laser due to the influence of the return light due to the presence or absence of pits. Even when the pickup unit is moved to the region B, the optimum light emission amount of the semiconductor laser can be maintained in the recording / reproducing data region, and it is not necessary to perform control for adjusting the light emission amount again.
[0091]
In the measurement of the light emission amount of the semiconductor laser for setting the target light emission amount in the track area A, the pit length is longer than the pit in the reproduction-only data area, and the return light amount influenced by the influence of diffraction is only for reproduction of the short pit. Since the sector mark part at the head of the header area, which is different from the data area, and the offset detection field without pits between the header area and the data area are avoided, the recording medium is connected to the semiconductor laser. Even if there is return light, the light emission amount of the semiconductor laser that is irradiating the track area A dedicated to information reproduction can be measured correctly, and the correct target light emission amount can be set.
[0092]
If the information is continuously reproduced for a long time in the track area A after moving the pickup section from the track area B to the track area A, the temperature inside the apparatus changes, and the characteristics of the semiconductor laser are changed. It can change.
[0093]
Even in this case, the CPU 5 detects the light emission amount of the semiconductor laser by monitoring the output of the A / D converter 6 in the data area while avoiding the header area at predetermined time intervals, and the update operation of the instruction value to the DAC (1) 9 Therefore, the light emission amount of the semiconductor laser is controlled so that the error from the target light emission amount (RP ′) corrected for the difference in the return light amount becomes zero.
[0094]
As described above, the target light emission amount is varied in the track area A so that the drive current of the semiconductor laser does not change, and the light emission amount control of the semiconductor laser is performed so that the optimum light emission amount is obtained in the recording / reproducing data area. In the header area where information is formed by pits and the read-only data area, there may be an error between the optimum light emission amount, but information reproduction in areas where information is formed by pits is a car effect. Unlike a rewritable user data area that performs weak signal reproduction using a signal, the signal is reproduced by increasing or decreasing the return light, so that reproduction with good C / N can be performed even if the light emission amount decreases, and the light emission amount The information pits will not be degraded even if the laser beam increases, so the reading margin is large, and there is no problem even if the laser beam dose changes slightly in the header area or the read-only data area.
[0095]
[3] Next, the operation when the track currently being tracked is in the track area A and the destination track is the track area B will be described.
[0096]
In this case, as in the case of movement from the track area B, the CPU 5 detects the light emission amount of the semiconductor laser avoiding the header area performed at predetermined time intervals and updates the instruction value to the DAC (1) 9. The operation is stopped, and the pickup unit is moved to a predetermined target track while the output instruction value to the DAC (1) 9 is held.
[0097]
Subsequently, after the movement of the pickup unit is completed and on-tracking is performed, the CPU 5 calculates the target light emission amount from the RP ′ obtained by measurement in the track area A, and the semiconductor laser light emission amount at the time of reproducing predetermined information stored in the ROM 7. Return to (read power) RP, restart the detection of the amount of light emitted from the semiconductor laser by monitoring the output of the A / D converter 6 in the data area while avoiding the header area, and update the instruction value to the DAC (1) 9 The output of the A / D converter 6 is sampled at the same timing as the detection of the light emission amount in the track of the test zone 59 performed in the fifth stage of the initial operation, and the DAC ( 1) Update the output instruction value to 9. Then, the updating operation of the output instruction value to the DAC (1) 9 is repeated at a predetermined time interval.
[0098]
[4] Next, the operation when the track currently being tracked is in the track area A and the destination track is also the track area A will be described.
[0099]
In this case, after the movement of the pickup unit is completed and on-tracking is performed, the CPU 5 performs a semiconductor by monitoring the output of the A / D converter 6 avoiding the header area performed at a predetermined time interval in the track area A before the movement. The detection of the light emission amount of the laser and the update operation of the instruction value to the DAC (1) 9 are resumed.
[0100]
At this time, when sampling the light emission amount of the semiconductor laser by the output of the A / D converter 6 and updating the instruction value to the DAC (1) 9, there are pits in the data area both before and after the movement of the pickup unit. Since the conditions are basically the same, the target light emission amount to be compared with the detected value is kept as RP ′ obtained by measuring immediately after the pickup unit is moved from the track area B to the track area A.
[0101]
However, since the variation in the reflectivity in the radial direction of the disk is not zero, the amount of return light from the disk to the semiconductor laser changes in the radial direction and the amount of light emitted from the semiconductor laser changes. In some cases, an error may occur in the radial direction in the target light emission amount RP ′ for correcting. In the case of a disc conforming to the ECMA standard in which a plurality of track areas A may be mixed in the radial direction of the disc in band units, when the bands with tracks before and after moving the pickup section are not close to each other, the pickup After the movement of the part is completed and on-tracking is performed, the light emission amount of the output of the A / D converter 6 as detected when moving from the recording / reproducing track area B to the reproducing-only track area A is detected, You may make it reset the target light emission amount which correct | amended the influence of the return light. Further, when moving to a track of a different band, the target light emission amount may be reset. This makes it possible to control the light emission amount with higher accuracy.
[0102]
As described above, according to the present embodiment, two types of data areas, that is, a data area in which information is formed by pits by molding at the time of manufacturing the disk and only information can be reproduced and a data area in which information can be recorded and reproduced. Even when using partially embossed discs mixed in one disc, the correct reproduction power is obtained in the user data area where information can be rewritten even if there is return light from the recording medium to the semiconductor laser. The amount of emitted light can be controlled, and it is possible to prevent the recorded data from being deteriorated by increasing the power of the semiconductor laser, or from reproducing information erroneously by reducing the power.
[0103]
Further, even if the pickup unit is moved from the track area A where only information can be reproduced to the track area B where both recording and reproduction are possible, the supply current to the semiconductor laser is controlled so as not to change. There is no need to readjust the supply current to the semiconductor laser immediately after moving the pickup between data areas, and there is no waiting time for this readjustment. It is possible to prevent the operating performance of the camera from being degraded.
[0104]
Furthermore, the target value of light emission in the data area where only information can be reproduced can be detected by supplying the same current as the current supplied to the semiconductor laser when the light intensity is controlled in the data area where recording and reproduction is possible. By setting based on the amount of emitted light, the target power of the semiconductor laser can be set in the data area dedicated to information reproduction, including differences in reflectivity for each mounted disc and variations in pit shaping. Therefore, it is possible to set the target light emission amount of the appropriate semiconductor laser corresponding to the mounted disk, and to perform the correct light emission amount control according to the medium.
[0105]
FIG. 6 is a block diagram showing the configuration of the output control means of the semiconductor laser in the optical information reproducing apparatus according to the second embodiment of the present invention.
[0106]
In the first embodiment, as the output control means of the semiconductor laser, the light emission amount of the semiconductor laser obtained by converting the output of the light detection means 4 into a digital value by the A / D converter 6 and the target light emission amount data stored in the ROM 7 or Although the digital value which is the target light emission amount obtained by actual measurement and stored in the RAM 15 is digitally compared and calculated by the CPU 5, the configuration using the method of setting the supply current amount to the semiconductor laser 1 is shown. In the second embodiment, the output of the light detection means corresponding to the light emission amount of the semiconductor laser and the voltage output corresponding to the target light emission amount by the variable voltage power source constituted by a D / A converter or the like are analogized by a comparator. 2 is a configuration example of output control means of a semiconductor laser using a method of setting the amount of current supplied to the semiconductor laser as compared with FIG.
[0107]
The semiconductor laser output control means of this embodiment is composed of a circuit as shown in FIG. 6, and the light detection means 4 is provided on the output side of the light detection means 4 for detecting a part of the emitted light of the semiconductor laser 1. And a comparator (1) 31 for comparing the output of the variable voltage power supply 33 and a comparator (2) 32 for comparing the output of the light detection means 4 with a predetermined reference voltage 34.
[0108]
Then, a CPU 35 for controlling each part is provided, and the ROM 42 in which the value of the target light emission amount of the semiconductor laser at the time of information reproduction or the like is stored, and the target light emission amount in the data area where only reproduction required at the time of operation can be obtained. A RAM 43 to be stored is connected to information reproducing means 8 for reproducing information recorded on the medium based on a reproduction signal obtained from reflected light from the recording medium.
[0109]
The CPU 35 is connected to a variable voltage power source 33 and sends a setting signal for setting the output of the variable voltage power source 33 to a voltage value corresponding to a predetermined target light emission amount stored in the ROM 42 or RAM 43. It has become.
[0110]
Up / down counters (1) 36 and (2) 37 are connected to the output terminals of the comparators (1) 31 and (2) 32, respectively. Based on the outputs of the comparators (1) 31 and (2) 32, respectively. Each up / down counter (1) 36, (2) 37 counts the clock signal from the clock signal generator 38. The output value of the up / down counter (1) 36 is a value corresponding to the semiconductor laser emission amount (read power) during information reproduction, and the output value of the up / down counter (2) 37 is the semiconductor laser emission amount (peak) during information recording. Each value is added to the read power to obtain (power).
[0111]
The output of the comparator (1) 31 is also input to the CPU 35, and an enable signal for permitting counting is sent from the CPU 35 to the up / down counter (1) 36.
[0112]
A D / A converter (1) 39 is connected to the output terminal of the up / down counter (1) 36, and the output value of the up / down counter (1) 36 corresponding to the amount of light emitted from the semiconductor laser during information reproduction is D / A. A converter (1) 39 converts the voltage into an analog voltage value. Further, a D / A converter (2) 40 is connected to an output terminal of the up / down counter (2) 37, and an output value of the up / down counter (2) 37 which is an addition value for obtaining peak power at the time of information recording. Is converted into an analog voltage value by the D / A converter (2) 40.
[0113]
The D / A converters (1) 39 and (2) 40 are connected to a drive circuit 41 composed of a VI converter, and the drive circuit 41 outputs the output voltages of the D / A converters (1) 39 and (2) 40. Are converted into currents, and a driving current of the semiconductor laser at the time of information reproduction and a driving current to be added to obtain a peak power at the time of information recording are generated.
[0114]
Of the two outputs of the drive circuit 41, the drive current of the semiconductor laser at the time of information reproduction is directly input to the adder circuit 13, and the drive current added to obtain the peak power at the time of information recording is added via the switch SW3. 13 is input. The high frequency current output from the high frequency oscillation circuit 14 is input to the adding circuit 13 via the switch SW2. The output terminal of the adder circuit 13 is connected to the semiconductor laser 1 via the switch SW1, and the current superimposed by the adder circuit 13 is supplied to the semiconductor laser 1 as a drive current.
[0115]
Other parts are configured in the same manner as in the first embodiment, and a description thereof is omitted.
[0116]
In the second embodiment, as in the first embodiment, the switches SW1, SW2, and SW3 are turned on and off under the control of the CPU 35 during information reproduction and information recording, respectively, and the semiconductor laser 1 emits light with a predetermined light emission amount. The light emission amount of the semiconductor laser 1 is detected and the light emission amount control is performed so that the error from the target light emission amount becomes zero.
[0117]
Also in this embodiment, only the control of the light emission amount of the semiconductor laser at the time of information reproduction when a partially embossed disk is used will be described.
[0118]
As in the first embodiment, the light emission amount is set so that the optimum light emission amount is obtained in the user data area in the test zone having the data area without pits similar to the user data area where information can be recorded and reproduced as the initial operation. Take control.
[0119]
When detecting the light emission amount of the semiconductor laser 1 and updating the input value to the D / A converter (1) 39, the CPU 35 turns on the enable signal of the up / down counter (1) 36 and permits the count. To do.
[0120]
At this time, the comparator (1) 31 is a variable voltage set to a light emission amount detection value of the semiconductor laser 1 output from the light detection means 4 and a voltage value corresponding to a predetermined target light emission amount (RP) during information reproduction. The output (V1) of the power supply 33 is compared, and if there is an error between the voltage value corresponding to the laser emission amount detected by the light detection means 4 and the variable voltage power supply output (V1), the comparator (1 ) Output 31 is turned on. When the output of the comparator (1) 31 is turned on, the clock signal is counted by the up / down counter (1) 36 and the output of the up / down counter (1) 36 is changed.
[0121]
When the output of the up / down counter (1) 36 changes, the output of the D / A converter (1) 39 according to the output change of the up / down counter (1) 36 and the output of the drive circuit 41 to the semiconductor laser 1 Since the supply current changes, the light emission amount of the semiconductor laser 1 changes.
[0122]
When the light emission amount of the semiconductor laser becomes equal to the target light emission amount (RP), the difference between the output voltage from the light detection means 4 and the variable voltage power supply output (V1) becomes zero, and the output of the comparator (1) 31 is Turn off. As a result, the output of the up / down counter (1) 36 is in the hold state, and the light emission amount adjustment of the semiconductor laser 1 is completed.
[0123]
In such an analog system configuration, the enable signal of the up / down counter (1) 36 in FIG. 6 is sent at predetermined time intervals similarly to the sampling timing of the A / D converter 6 in FIG. 1 shown in the first embodiment. By performing on / off control while avoiding the header area, the same effect as in the case of the digital system described above can be obtained, and an optimum light emission amount can be obtained in the user data area and the test zone data area where information can be recorded and reproduced. Thus, it becomes possible to perform correct light emission amount control.
[0124]
That is, when adjusting the emission power of the semiconductor laser in the user data area where information can be rewritten, the CPU 35 turns on the enable signal terminal of the up / down counter (1) 36 while avoiding the header area. And the variable voltage power output (V1) set to a voltage value corresponding to a predetermined target light emission amount RP in the user data area read from the ROM 42, the difference is zero. The output of the up / down counter (1) 36 is changed until the output of the D / A converter (1) 39 and the output of the drive circuit 41 are changed according to the change of the output of the up / down counter (1) 36. The supply current to the laser changes, and the light emission amount of the semiconductor laser 1 is readjusted to become the target light emission amount.
[0125]
Then, the difference between the output voltage from the light detection means 4 and the variable voltage power supply output (V1) becomes zero, the output of the comparator (1) 31 is turned off, and the output change of the up / down counter (1) 36 is stopped. Then, the CPU 35 stores the output value (D1) of the up / down counter (1) 36 at this time in the RAM 43.
[0126]
Thereafter, in order to prevent the semiconductor laser characteristics from changing due to temperature changes in the apparatus and the like, the CPU 35 sets the enable signal terminal of the up / down counter (1) 36 in the header area. The output value of the up / down counter (1) 36 when it is turned on and the difference between the output voltage from the light detection means and the variable voltage power supply output (V1) becomes zero and the output of the comparator (1) 31 is turned off. The operation of reading (D1) and rewriting the value previously stored in the RAM 43 is repeated at a predetermined time interval.
[0127]
When the pickup unit is moved from the recording / reproducing track area B or the test zone to the information reproducing-dedicated track area A in response to the information reproducing instruction, the CPU 35 enables the enable signal of the up / down counter (1) 36 before the movement. The pickup unit is moved to a predetermined target track while the terminal is turned off and the output of the variable voltage power supply 33 corresponding to the target light emission amount is held at the value (V1) in the rewritable user data area.
[0128]
After the movement of the pickup section is completed and the track area A is on-tracked, the CPU 35 avoids the header area and turns on the enable signal of the up / down counter (1) 36. At this time, the up / down counter (1) 36 The output value is compared with the output value (D1) of the up / down counter (1) 36 stored in the RAM 43 in the rewritable user data area, and the output of the variable voltage power supply 33 is changed so that the difference becomes zero. Let Here, the CPU 35 uses the output voltage (V2) of the variable voltage power supply 33 when the output value of the up / down counter (1) 36 becomes equal to the value D1 in the user data area stored in the RAM 43 as a track dedicated for information reproduction. A reference value corresponding to the target light emission amount (Rp ′) in the region A is used, and an instruction value to the variable voltage power source 33 for outputting V 2 is stored in the RAM 43.
[0129]
Thereafter, the CPU 35 uses Rp ′ as the target light emission amount when the irradiation beam from the semiconductor laser irradiates the track in the reproduction-only track area A in which information is formed by pits, and uses the target light emission amount Rp ′ stored in the RAM 43. The comparator (1) 31 compares the output (V2) of the variable voltage power supply 33 set to a voltage value corresponding to the indicated value with the comparator (1) 31, and the difference is zero in the user data area. The amount of light emission is controlled in the same manner as in.
[0130]
In the case of the digital system described above, the target light emission amount is controlled and changed in the track area A dedicated to information reproduction so as not to change the current supplied to the semiconductor laser due to the influence of the return light due to the presence or absence of pits. Thus, the semiconductor laser can be controlled to emit light with a driving current that provides an optimum light emission amount in a user data area where information can be recorded and reproduced.
[0131]
When the pickup unit is moved from the track area A dedicated for information reproduction to the track area B for recording / reproduction, the CPU 35 turns off the enable signal terminal of the up / down counter (1) 36 and turns on the up / down counter (1) 36. After moving the pickup unit to a predetermined target track while maintaining the output, the output instruction value to the variable voltage power source 33 is read from the ROM 42 again from the instruction value of the target light emission amount Rp ′ stored in the RAM 43. The output value of the variable voltage power supply 33 is set to V1 by returning to the instruction value of the target light emission amount Rp. Then, the enable signal of the up / down counter (1) 36 is controlled so as to avoid the header region, and the output voltage V1 of the variable voltage power source 33 and the output voltage from the light detection means 4 are compared by the comparator (1) 31. The amount of light emitted from the semiconductor laser is controlled.
[0132]
By performing such light emission amount control, the same effect as when the light emission amount is controlled by the above-described digital arithmetic processing is obtained, and information can be recorded and reproduced again from the track area A dedicated to information reproduction. Even when the pickup unit is moved to a proper track area B, the optimum light emission amount of the semiconductor laser can be maintained in the user data area where information can be rewritten, and there is no need to perform control for adjusting the light emission amount again. Can prevent the recorded data from degrading and the recorded data from being deteriorated, or the power from becoming low and information from being played back accidentally. In addition, there is a waiting time during operation, which reduces the operating performance of the device. Can be prevented.
[0133]
[Appendix]
(1) Information rewriting consisting of a header area in which information such as a start mark of a sector, a track number, and a sector number is formed by pits when a medium is manufactured and a data area in which information can be recorded and reproduced without pits An optical recording medium in which a recordable / reproducible track area and a read-only track area in which information in the data area as well as the header area is formed by pits when the medium is manufactured cannot be rewritten are mixed in one medium In an optical information reproducing apparatus for reproducing information,
The target value of the emission amount of the semiconductor laser when irradiating the reproduction-only track area is set to a value different from the target value of the emission amount of the semiconductor laser when irradiating the recording / reproduction track area. An optical information reproducing apparatus comprising semiconductor laser output control means for performing light emission amount control for keeping the light emission amount of the semiconductor laser at a predetermined value.
[0134]
(2) Information rewriting in which information such as a start mark of a sector, a track number, and a sector number is composed of a header area formed by pits when a medium is manufactured and a data area where there is no pit and information can be recorded and reproduced. An optical recording medium in which a recordable / reproducible track area and a read-only track area in which information in the data area as well as the header area is formed by pits when the medium is manufactured cannot be rewritten are mixed in one medium In an optical information reproducing apparatus for reproducing information,
Detection of the amount of light emitted from a semiconductor laser, which is a light source for irradiating the recording medium with laser light, is stopped during the period in which the header area is irradiated with laser light, and information in the header area is reproduced. In a data area where there is no pit in the track area for recording / reproduction after a predetermined time or in a data area where information in the reproduction-only track area is formed by pits, the emission amount of the semiconductor laser is detected,
The target value of the emission amount of the semiconductor laser when irradiating the reproduction-only track area is set to a value different from the target value of the emission amount of the semiconductor laser when irradiating the recording / reproduction track area. An optical information reproducing apparatus comprising semiconductor laser output control means for performing light emission amount control for keeping the light emission amount of the semiconductor laser at a predetermined value.
[0135]
(3) The semiconductor laser output control means sets the target value of the light emission amount of the semiconductor laser when irradiating the reproduction-dedicated track area to a value obtained by correcting the influence of the return light due to the presence or absence of pits. The optical output according to appendix (1), wherein the light emission amount control is performed so that the drive current supplied to the semiconductor laser in the dedicated track area is maintained at the same value as that in the data area having no pits in the recording / reproducing track area. Formula information playback device.
[0136]
In this configuration, by controlling the amount of light emission so that the drive current supplied to the semiconductor laser in the read-only track area is kept at the same value as the value in the data area without pits in the recording / playback track area, When the optical head moves between the read-only track area and the recording / playback track area, the supply current to the semiconductor laser does not change due to the influence of the return light due to the presence or absence of pits, and the semiconductor laser from the recording medium does not change. The amount of light emission is controlled so that the optimum reproduction power is obtained in a data area where information can be recorded / reproduced even when there is a return light.
[0137]
(4) The semiconductor laser output control unit moves the optical head from the recording / reproducing track area to the reproducing-only track area for the target value of the emission amount of the semiconductor laser when irradiating the reproducing-only track area. After that, by detecting the light emission amount of the semiconductor laser in the state where the drive current of the same value as that supplied to the semiconductor laser is supplied to the semiconductor laser before the movement of the optical head starts, the influence of the return light due to the presence or absence of pits is detected. The optical information reproducing apparatus according to appendix (1), which detects and sets a value based on the detection result.
[0138]
In this configuration, a drive current having the same value as the supply current to the semiconductor laser in the recording / reproducing track area is supplied to the semiconductor laser in the reproduction-dedicated track area, and the light emission amount of the semiconductor laser at this time is detected, By setting a target value for the amount of light emission that compensates for the influence of return light due to the presence or absence of a semiconductor laser, even in the case where the reflectance varies depending on the mounted medium or the pit formation varies, the semiconductor laser in the track area dedicated to playback The target value of the light emission amount can be set accurately.
[0139]
(5) The semiconductor laser output control means is provided at the head of the header area for detecting the light emission amount of the semiconductor laser after the optical head is moved from the recording / reproducing track area to the reproducing-only track area. The amount of light emission after a predetermined time has elapsed since the information in the header area of the read-only track area is reproduced so that it is performed in the data area while avoiding the offset detection field provided between the sector mark portion, the header area, and the data area. The optical information reproducing apparatus according to appendix (4), wherein detection is performed.
[0140]
In this configuration, the light emission amount detection for setting the light emission amount target value of the semiconductor laser when irradiating the reproduction-only track area is performed, and the data in the track area where the pit length is provided at the beginning of the header area A sector mark portion that is longer than the pit of the area and has a return light amount that is influenced by the influence of diffraction, which is different from the data area of the short pit, and an offset detection field without a pit provided between the header area and the data area; To avoid. As a result, even if there is return light from the recording medium to the semiconductor laser, the light emission amount of the semiconductor laser that is irradiating the data area in the read-only track area can be measured correctly, and the correct target light emission amount can be set. It becomes possible.
[0141]
【The invention's effect】
As described above, according to the present invention, a recording / playback data area in which information can be rewritten and a read-only data area in which information is formed in pits and cannot be rewritten when the recording medium is manufactured are contained in one medium. When mixed optical recording media are used, the correct light emission amount control is performed so that the optimum reproduction power is obtained in the user data area where information can be recorded and reproduced even if there is return light from the recording medium to the semiconductor laser. It is possible to prevent the recorded data from deteriorating due to the high power of the semiconductor laser, or from reproducing the information by mistake due to the low power. There is an effect that it is possible to prevent the operating performance from being lowered.
[Brief description of the drawings]
FIGS. 1 to 5 relate to a first embodiment of the present invention, and FIG. 1 is a block diagram showing a configuration of output control means of a semiconductor laser in an optical information reproducing apparatus.
FIG. 2 is an explanatory diagram showing a schematic configuration of each area on a recording surface in a partially embossed optical disk used in the apparatus of the present embodiment.
FIG. 3 is an explanatory diagram illustrating a configuration of a pickup unit.
FIG. 4 is an operation explanatory diagram illustrating a light emission amount detection state when performing a track jump operation.
FIG. 5 is an operation explanatory view showing the light emission amount of the semiconductor laser in a track area B where recording and reproduction are possible and a track area A where reproduction is possible
FIG. 6 is a block diagram showing the configuration of the output control means of the semiconductor laser in the optical information reproducing apparatus according to the second embodiment of the present invention.
FIG. 7 is a characteristic diagram showing the I-P characteristics of a semiconductor laser when the amount of light returning to the semiconductor laser is changed using an apparatus in which outgoing light and return light interfere with each other.
FIG. 8 is a characteristic explanatory diagram showing an example of a change in the amount of light emitted from a semiconductor laser in a read-only header area in which information in a disc is formed by pits and a user data area in which recording and reproduction is possible without pits
[Explanation of symbols]
1. Semiconductor laser
4 ... light detection means
5 ... CPU
6 ... A / D converter
7 ... ROM
8. Information reproduction means
9, 10 ... D / A converter
11,12 ... V-I converter
15 ... RAM
51. Partially embossed optical disk
53 ... Header area
54: Reproduction-only data area
55 ... Recording / reproduction data area (user data area)

Claims (2)

Information rewritable recording in which information such as sector start mark, track number, sector number, etc. is composed of a header area formed by pits when the medium is manufactured and a data area without pits and capable of recording and reproducing information For an optical recording medium in which a reproduction track area and a reproduction-only track area in which information in the data area as well as the header area is formed by pits during production of the medium and information cannot be rewritten are mixed in one medium In an optical information reproducing apparatus for reproducing information,
The target value of the light emission amount of the semiconductor laser at the time of information reproduction is set on condition that a high frequency superimposed current is supplied to the semiconductor laser before the focus servo operation at the time of initial setting, and when the track area for recording / reproduction is irradiated. the semiconductor laser of the light emission amount of the target value so as to set the test area, Bei example a semiconductor laser output control means for performing light emission amount control for maintaining the light emission amount of the semiconductor laser at a predetermined value,
The semiconductor laser output control means sets a target value of the light emission amount of the semiconductor laser when irradiating the recording / reproducing track area to a predetermined value corresponding to the mounted medium, and irradiates the reproduction-only track area. The target value of the light emission amount of the semiconductor laser is set to the same value as the drive current supplied to the semiconductor laser before the optical head starts moving after the optical head is moved from the recording / reproducing track area to the reproducing-only track area. An optical information reproducing apparatus, wherein a light emission amount of a semiconductor laser is detected in a state where a drive current is supplied to the semiconductor laser, and a value is set based on the detection result. The semiconductor laser output control means detects the light emission amount of the semiconductor laser after the optical head is moved from the recording / reproducing track area to the reproducing-only track area, and reproduces information in the header area of the reproducing-only track area. The optical information reproducing apparatus according to claim 1, wherein the optical information reproducing apparatus is performed after a predetermined time.

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