JPH07262590A - Optical information reproducing device - Google Patents

Abstract

PURPOSE:To correctly control the emitting light quantity so as to obtain an optimal reproducing power in a data area capable of recording/reproducing information even when a returned light beam from a recording medium to a semiconductor laser exists. CONSTITUTION:The control means for the output of a semiconductor laser of an optical information reproducing device reads the target value of emitting light quantity out of a ROM 7 or a RAM 15 by means of a CPU 5, sends a corresponding instruction value to a DAC(1) 9, supplies a driving current to a semiconductor laser 1 through a V-I converter 11, detects the emitting light quantity of the semiconductor laser 1 by means of a light detecting means 4 and controls the emitting light quantity of the semiconductor laser 1 so that the error between the detected value of the output of an A/D converter 6 and a target emitting light quantity becomes zero. A target emitting light quantity Rp on the area B of a track capable of recording/reproducing is stored in the ROM 7 and a value obtained by measuring the emitting light quantity on a track area A for exclusive reproducing use, while making a supplied current to the semiconductor laser 1 the same value, and being a different value from Rp is stored in the RAM 15 as a target emitting light quantity RP' on the track area A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information reproducing apparatus for reproducing information by irradiating a recording medium with light from a semiconductor laser, and particularly to a recording / reproducing data area in which information can be rewritten and a recording medium. The amount of light emitted from a semiconductor laser in an optical information reproducing apparatus for reproducing information on an optical recording medium in which a reproduction-only data area in which information is rewritten and information cannot be rewritten at the time of manufacture is mixed in one medium Regarding control means.

[0002]

2. Description of the Related Art In an optical information reproducing apparatus for optically reproducing information, for example, an optical disk is used as a recording medium. Information is preliminarily recorded on the optical disk so that only reproduction is possible. Some can do both.

Of the optical discs capable of both recording and reproducing information, the continuous groove type that conforms to the ISO standard is a full rewritable type having a data area in which information can be recorded and reproduced over the entire surface of the disc. There are 1 type of (Fully Rewritable) disc and 2 types of data regions, a data region where information is formed by pits (holes) by molding when the disc is manufactured and only information can be reproduced and a data region where information can be recorded and reproduced. Partial embossed type (Pa
rtially Embossed) disks are commonly used.

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 sector start mark, a track number, and a sector number is formed by pits at the time of manufacturing the disc at the head portion, and then a data area in which data is recorded is provided.
In the case of a partially embossed disc, the data area is a read-only data area in which information is recorded in pits and only information can be reproduced as in the case of the header area, or rewriting and reproduction of information by a magneto-optical method or the like. A recording / reproducing data area (hereinafter also referred to as a user data area) capable of performing the above is provided.

In the case of a magneto-optical disc in the optical disc having such a structure, the Kerr effect is used to reproduce information in the user data area where information can be recorded and reproduced, but the reproduction signal is weak. C / N is not so high.

In order to improve the C / N and reproduce information accurately, it is desired to increase the power of the laser beam applied to the medium at the time of reproduction as much as possible. However, if the power is increased, the recorded information is reproduced for information reproduction. The appropriate range of the irradiation power of the semiconductor laser at the time of reproducing the information in the user data area is very narrow because the heat of the laser irradiated on the laser beam deteriorates.

Semiconductor lasers have large initial variations in their characteristics, and their characteristics change with temperature and time. Therefore, it is necessary to control the amount of light emitted for stable light emission with a predetermined power. As a semiconductor laser emission control circuit, for example, as disclosed in Japanese Patent Laid-Open No. 62-281485, the actual emission of the semiconductor laser is detected so that the error from the target emission becomes zero. Various types have been proposed, such as one that adjusts the drive current of the semiconductor laser and controls the semiconductor laser to emit light stably with a predetermined target power.

By the way, in the case of the optical information reproducing apparatus,
Information is reproduced by irradiating the information recording surface of the disc with laser light and receiving the reflected light from the information recording surface with a photodetector, but it emits light when the reflected light from the disc returns to the semiconductor laser by a certain amount or more. Is known to become unstable and noise in the reproduced signal increases.

In the case of a magneto-optical information recording / reproducing apparatus, since the information mark recorded on the optical disc is detected as the rotation of the polarization plane, in the configuration of the recording / reproducing optical system, the polarization beam splitter and the quarter wavelength are used. It is not possible to use isolator optics that prevent the return light from the disc from returning to the semiconductor laser due to the combination of plates. Therefore, in order to solve the above-mentioned problem caused by the returning light, for example, as disclosed in Japanese Patent Publication No. 59-9086, a means for performing high frequency superposition to reduce the influence of the returning light is used to reproduce semiconductor data at the time of reproducing information. A method of canceling the interference between the emitted light and the returned light by superimposing a high frequency current on the drive current of the laser is adopted.

In recent optical disk information reproducing apparatuses, the pickup apparatus has been made smaller and lighter in order to record and reproduce information at a higher speed, and an objective lens, an actuator capable of moving the objective lens in the vertical direction and in the radial direction of the disk,
Separation optical system separated into a movable part composed of a prism and the like, a semiconductor laser, an optical part composed of a collimator lens and a prism, and a fixed part composed of a photodetector for taking out a signal from return light. A pickup device composed of is adopted. The distance between the semiconductor laser and the reflecting surface of the disk was constant in the case where all the optical components were integrally arranged in the moving part, but in the separation optical system, the moving part is arranged in the radial direction of the disk. The movement causes the distance between the semiconductor laser and the reflecting surface of the disk to change. Therefore, in the device of the separation optical system, it becomes impossible to completely cancel the interference between the return light and the emitted light even if the above-mentioned high frequency superposition is performed,
The amount of light returned to the semiconductor laser varies between the header area where information is recorded in pits and the user data area where information can be recorded and reproduced by a magneto-optical method or the like in a land portion where there is no pit. Therefore, even if the current supplied to the semiconductor laser is controlled to be constant, the amount of light emitted from the semiconductor laser may change.

An example of the IP characteristics (driving current-emitted light quantity characteristic) of the semiconductor laser when the returned light quantity to the semiconductor laser is changed and measured using an apparatus in which the emitted light and the returned light interfere with each other. Is shown in FIG. In the IP characteristics of the semiconductor laser, the slope changes as the amount of returning light changes, and the amount of laser emission light when the laser drive current is kept constant at Ic increases from P1 to P3 as the amount of returning light increases. That is, the emitted light amount of the semiconductor laser may change according to the change of the returned light amount.

The return light from the disk to the semiconductor laser is
In the header area where information is recorded in pits and in the user data area where there is no pit and which can be recorded and reproduced, the header area is smaller than the user data area due to the influence of diffraction, and in the user data area where there is no pit the return light Will increase.

When the amount of light emitted from the semiconductor laser is detected by the light detecting means when the drive current supplied to the semiconductor laser is kept constant and the laser light is applied to the disk of the magneto-optical system under the tracking servo, the semiconductor laser is detected. As shown in FIG. 7, since the amount of emitted light changes as the amount of light returned to the laser changes, as shown in FIG. 8, the amount of emitted light P of the semiconductor laser has more returned light in the header region with less returned light. The phenomenon of lowering than the user data area may be observed.

Therefore, the present applicant has filed Japanese Patent Application No. 5-27559.
In No. 4, when detecting the actual light emission amount of the semiconductor laser in order to control the light emission amount of the semiconductor laser so as to keep the light emission amount of the semiconductor laser at a predetermined value, the detection of the light emission amount of the semiconductor laser that fluctuates depending on the return light amount is performed. Is not performed in the header area recorded with pits, but is controlled in the user data area for information recording / reproduction without pits, and the light emission amount of the semiconductor laser is controlled, so that there is a return light from the recording medium to the semiconductor laser. Even so, an optical information reproducing apparatus has been proposed which can be controlled so that the amount of emitted light is optimum in the user data area where information is rewritten and reproduced.

[0015]

Consider a case where the partially embossed type optical disk described above is used in an optical information reproducing apparatus.

FIG. 2 shows a schematic configuration example of each area on the recording surface of the partially embossed type optical disc. The partially embossed optical disc 51 has a plurality of tracks 52 on the recording surface.
Is provided 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 / reproducing data area in which information can be recorded and reproduced by a magneto-optical method or the like. And the formed track area B. 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 in the head portion, and information is recorded in pits in the rear area as in the header area. A 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 portion, as in the track area A, and no pits are formed at the rear portion, and information is recorded. A reproducible recording / reproducing data area (user data area) 55 is provided.

In an apparatus using the partially embossed type optical disc having such a structure, the above-mentioned Japanese Patent Application No. 5-27 is used.
When the light emission amount control in No. 5594 is applied,
In the track area B where recording and reproduction can be performed, the light emission amount of the semiconductor laser is detected only in the user data area without pits, or the data of the light emission quantity which is assumed to be detected in the header area with pits is removed and the user is removed. By calculating the light emission amount in the data area, the light emission amount control for maintaining the light emission amount of the semiconductor laser in the user data area at a predetermined value can be accurately performed. As a result, it is possible to perform accurate and optimal light emission amount control in the user data area that requires highly accurate light emission amount control, and it is possible to prevent data deterioration and erroneous reproduction.

On the other hand, in the track area A which can only be reproduced, pits are continuously formed not only in the header area but also in the reproduction-only data area following the header area, and the light emission amount of the semiconductor laser is controlled for light emission amount control. Since there is no pit-free user data area that is a detection area, the semiconductor laser emission amount detection from the pit-free user data area is possible at least when the laser beam is applied to the track area A dedicated to information reproduction. become unable. For this reason,
In the track area A, the same light emission amount control as in the track area B cannot be performed.

If the drive current value supplied to the semiconductor laser is not updated while the operation of detecting the light emission amount of the semiconductor laser is stopped, the characteristics of the semiconductor laser will change and the drive current will change when the temperature inside the device changes. The amount of emitted light with respect to changes, and it becomes impossible to maintain the output power at a predetermined value. Therefore, the track area A that can only be reproduced
Even when the laser light is being radiated on the semiconductor laser, it is necessary to detect the light emission amount of the semiconductor laser every predetermined time and increase or decrease the supply current to the semiconductor laser so that the error from the target light amount becomes zero.

However, when the semiconductor laser emission amount is detected in the read-only track area A while avoiding only the header area as in the case of the recording / playback track area B, the read-only data area in the track area A is detected. Since the amount of light returning to the semiconductor laser is different from that of the user data area having no pit in the track area B, a light emission amount value different from the light emission amount in the user data area is detected. Therefore, when the light emission amount is detected for controlling the light emission amount of the semiconductor laser, when the light emission amount of the semiconductor laser is detected in the read-only data area where information is formed by pits and the returned light is reduced due to diffraction, Even if 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.

In this case, when the pickup is located in the reproduction-only track area A and the laser light from the semiconductor laser is continuously applied to the tracks in the track area A, the pickup is supplied to the semiconductor laser based on the above judgment. By increasing the amount of current, the amount of light emission is controlled so that the error from the target amount of light emission in the track area A is reduced. However, when the pickup is moved from the track region A to the recording / reproducing track region B after increasing the amount of current supplied to the semiconductor laser as described above, the laser light emitted from the semiconductor laser with the changed drive current amount. Is the optimum amount of light emission in the header area having pits as in the track area A, but the amount of return light is large in the user data area of the land because there is no diffraction due to pits, and the amount of light emission is a predetermined target value. And the beam of high power may deteriorate the information recorded by the user.

Contrary to the case of the above-mentioned disc, in the case of a disc in which the return light is larger in the area with pits than in the user data area without pits, the amount of light emission is detected in the track area A for reproduction only. If it is performed, it is determined that the emission amount is higher than the target emission amount, and the emission amount is controlled so as to reduce the current supplied to the semiconductor laser. However, when the pickup is moved to the recording / reproducing track area B after that, the changed drive current The amount of laser light emitted from the semiconductor laser is lower than a predetermined target emission amount in the user data area, which may deteriorate C / N and make it impossible to read information.

Further, as described above, when the light emission amount is detected in the read-only track area A and the amount of current supplied to the semiconductor laser is adjusted, after the pickup is moved to the recording / playback track area B, It is necessary to perform control to return the changed amount of current supplied to the semiconductor laser to an appropriate value in the user data area of the track area B to correct the amount of light emission, but this requires a predetermined time. However, during the correction period of the power of the semiconductor laser, a rotation waiting state in which a recording operation cannot be performed occurs, so that there is a problem that the transfer rate decreases due to this waiting time and the operation performance of the device deteriorates.

On the other hand, when the light emission amount is detected and the light emission amount is controlled in the reproduction-only track area A, the above-mentioned problems occur. Therefore, when the track of the track area A is irradiated with the laser light, the semiconductor is irradiated. The detection of the laser emission amount is stopped, and the temperature change inside the device is monitored.When the temperature change more than a predetermined value is detected or the predetermined time has passed, the pickup is set to the track area for recording and reproducing. It is conceivable to move to B and detect the light emission amount in the user data area to control the light emission amount of the semiconductor laser. In this case, the semiconductor laser does not have an unsuitable power in the user data area immediately after the pickup is moved from the track area A to the track area B.

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 was originally unnecessary for this operation. Since a predetermined waiting time is additionally required, there is a problem that the transfer rate is lowered and the operation performance of the device is deteriorated.

The present invention has been made in view of these circumstances, and has a recording / reproducing data area in which information can be rewritten and a reproduction-only data area in which information is formed in pits when a recording medium is manufactured and information cannot be rewritten. When using an optical recording medium in which the same is mixed in one medium, the optimum reproduction power in the user data area in which information can be recorded and reproduced even if there is a returning light from the recording medium to the semiconductor laser. It is possible to control the amount of light emission correctly so that the power of the semiconductor laser becomes high and the recorded data is deteriorated, or the power becomes low and information is mistakenly reproduced. It is an object of the present invention to provide an optical information reproducing device capable of preventing the operating performance of the device from deteriorating due to time.

[0027]

In the optical information reproducing apparatus according to the present invention, information such as a start mark of a sector, a track number, and a sector number is recorded in a header area formed by pits when a medium is manufactured and there is no pit and information is recorded. And rewritable track area for recording / reproducing, which is composed of a data area capable of both reproduction and reproduction, and the information of the data area together with the header area is formed of pits at the time of manufacturing the medium and is a reproduction-only information which cannot be rewritten. In a device that reproduces information from an optical recording medium in which a track area is mixed in one medium, the target value of the light emission amount of the semiconductor laser when irradiating the reproduction-only track area is recorded as the recording value. The emission amount of the semiconductor laser is set to a predetermined value by setting it to a value different from the target value of the emission amount of the semiconductor laser when irradiating the reproduction track area. Those having a semiconductor laser output control means for performing light emission amount control to maintain.

[0028]

By the semiconductor laser output control means, the target value of the light emission amount of the semiconductor laser when irradiating the reproduction-only track area where information is formed in the pits at the time of manufacturing the medium and the information cannot be rewritten is recorded and reproduced. By setting to a value different from the target value of the light emission amount of the semiconductor laser when irradiating the track region for, by performing the light emission amount control to maintain the light emission amount of the semiconductor laser at a predetermined value,
Even when there is a return light from the recording medium to the semiconductor laser, the light emission amount is controlled so that the light emission amount is optimum in the data area in the recording / reproducing track area.

[0029]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 relate to a first embodiment of the present invention, FIG. 1 is a block diagram showing a 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 the present embodiment. FIG. 3 is an explanatory diagram showing a schematic configuration of each area on a recording surface in an embossed optical disc, FIG. 3 is a configuration explanatory diagram showing a configuration of a pickup section, and FIG. 4 is an operation description showing a light emission amount detection state when performing a track jump operation. Figure, Figure 5
FIG. 6 is an operation explanatory diagram showing the light emission amount of the semiconductor laser in a track area B capable of recording and reproducing and a track area A capable of only reproducing.

The optical information reproducing apparatus according to the present embodiment has a semiconductor laser (also referred to as LD) 1 for emitting a laser beam, a photodiode 2 on which a part of light emitted from the semiconductor laser 1 is incident, and an output of the photodiode 2. The pickup section is provided with a photodetecting means 4 having an IV converter 3 for converting a current into a voltage, and a structure as shown in FIG. 1 is provided as semiconductor laser output control means for controlling the amount of light emitted from the semiconductor laser 1. Circuit is provided.

The semiconductor laser output control means has a CPU 5 for controlling each part, and the CPU 5 has an A / D converter 6 for converting the output of the IV converter 3 into a digital signal and reproduction of information. , A ROM 7 in which a value of a predetermined light emission amount of a semiconductor laser at the time of erasing or recording is stored as a target light emission amount, and an RA for storing a target light emission amount in a data area which can be reproduced only and which is required during an operation described later.
Information reproducing means 8 for reproducing the information recorded on the medium based on M15 and the reproduced signal obtained from the reflected light from the recording medium.
And are connected.

Then, a D / A converter (D) for converting an instruction value, which is output from the CPU 5 and corresponds to a semiconductor laser emission amount (read power) at the time of reproducing information, into an analog voltage value.
(Abbreviated as AC) (1) 9 and a VI converter 11 as a semiconductor laser driving means for converting the output voltage of the DAC (1) 9 into a current and supplying the current to the semiconductor laser.
The output current of the converter 11 is input to the adder circuit 13. Further, a D / A converter (D which converts an instruction value output from the CPU 5 for obtaining a semiconductor laser emission amount (peak power) at the time of recording information into an analog voltage value
AC) (2) 10 and a VI converter 12 for converting the output voltage of the DAC (2) 10 into a current are provided, and the output current of the VI converter 12 is added through the switch SW3 to the addition circuit 13
It is designed to be input into. Switch SW3 is CP
It is adapted to be turned on and off according to a modulation signal (recording data pulse) of information to be recorded under the control of U5.

Further, a high-frequency oscillator circuit (also referred to as HFM) 14 for generating a high-frequency current is provided, and the high-frequency current output from the high-frequency oscillator circuit 14 is input to the adder circuit 13 serving as a high-frequency superimposing means via the switch SW2. It has become. The output terminal of the adder circuit 13 is connected to the semiconductor laser 1 via the switch SW1.
The superposed current is supplied to the semiconductor laser 1 as a drive current.

The structure on the recording surface of a partially embossed type optical disc as an optical disc used in the optical information reproducing apparatus of the present embodiment will be described with reference to FIG.

The partially embossed optical disk 51 has a plurality of tracks 52 provided on the recording surface and is divided into a predetermined number of tracks. The optical disc 51 is shown in FIG.
As shown in FIG. 2, a track area dedicated to information reproduction (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 information is recorded by a magneto-optical method or the like. A track area for recording / reproducing information (referred to as a track area B) in which a data area for recording / reproducing capable of reproduction is formed. In the track area A, in each sector on the track, a header area 53 in which information such as a sector start mark, a track number, and a sector number is formed in pits at the time of manufacturing the disc is provided at a head portion, and a header area 53 is provided at a rear portion thereof. Similar to the area, a read-only data area 54 is provided in which information is recorded in pits and only information can be reproduced. 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 portion as in the track area A, and no pits are formed at the rear portion thereof by a magneto-optical method or the like. A recording / reproducing data area (also referred to as a user data area) 55 capable of recording (rewriting) and reproducing information is provided. The reproduction-only track area A and the recording / reproduction track area B are formed so that the recording surfaces have the same reflectance.

As shown in FIG. 2B, the inner peripheral portion 56 on the inner peripheral side of the reproduction-only track area A is a mirror surface which is a total reflection area for drawing in a focus servo for focus control from the inside. And a tracking pull-in portion 58 formed with a plurality of tracks for pulling in tracking servo for performing tracking control, and a format similar to the rewritable track area B of information. A test zone 59 having a plurality of tracks and a control zone 60 in which information such as disc type and format is recorded by pits are provided.

FIG. 3 shows the structure of the pickup unit including the semiconductor laser 1. The pickup section is composed of a so-called separation optical system pickup having a movable section 21 and a fixed section 22. A movable portion 21 is provided so as to be movable in the radial direction of the disk 24 so as to face the disk 24 which is rotationally driven by the spindle motor 23, and the movable portion 21 raises the laser beam toward the disk 24. 25, an objective lens 26 for converging the laser light on the disk, and an actuator (not shown) for tracking and focusing are provided. The fixed portion 22 includes the semiconductor laser 1 and the photodiode 2, the collimator lens 27 that makes the emitted light of the semiconductor laser 1 into a parallel light flux, and the beam splitter that transmits and reflects the emitted light of the semiconductor laser 1 to separate the light flux. 28 is provided.

In the pickup section having such a structure, the 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 portion). Information is recorded and reproduced by irradiating a target track on the embossed type optical disc 51).

Next, the operation of the semiconductor laser output control means of this embodiment will be described.

When reproducing information, the CPU 5 uses the switch S
W1 is turned on so that the semiconductor laser 1 can be turned on,
Supply current instruction value (value of target light emission amount) corresponding to semiconductor laser light emission amount (read power) at the time of reproducing information from the ROM 7.
Is read and 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. Further, at this time, the switch SW2 is turned on for high frequency superimposition to turn on the high frequency oscillator
A high frequency current from 4 is supplied to the semiconductor laser 1. Then, the light emitted from the semiconductor laser 1 is detected by the photodiode 2, and the light emission amount detection value obtained through the IV converter 3 and the A / D converter 6 is input, and the CPU 5 outputs from the A / D converter 6. The difference between the actual emission amount of the semiconductor laser and the target emission amount from the ROM 7 is calculated according to the emission amount detection value of, and the output value to the DAC (1) 9 is changed so that this error becomes zero. Semiconductor laser 1 for power
Control the amount of light emitted.

At the time of information recording, the CPU 5 further reads the supply current instruction value for obtaining the semiconductor laser emission amount (peak power) at the time of information recording from the ROM 7 and DAC.
(2) Input to 10 and output voltage of DAC (2) 10 to VI
It is converted into a current by the converter 12 and input to the adding circuit 13 via the switch SW3. At this time, the switch SW3 of the output of the VI converter 12 is turned on and off according to the modulation signal (recording data pulse) of the information to be recorded, and the strength changes to a predetermined peak power and bottom power according to the recording data. The semiconductor laser 1 is caused to emit light so that

In this embodiment, only the control of the light emission amount of the semiconductor laser at the time of reproducing information will be described in detail.

First, as a first step, a pickup moving operation for initial setting is performed.

In the moving operation of the pickup for the initial setting, the movable portion 21 of the pickup portion is defined by ISO, for example, at a position where the portion irradiated with the beam spot from the pickup portion is outside the user data area of the disc. If the disc is a standard disc, the disc is moved to the innermost track-free position (for example, the focus pull-in portion 57 in the partially embossed optical disc 51).

Next, as a second step, DA for information reproduction is used.
The output instruction value (supply current instruction value) to C (1) 9 is obtained.

In the second stage, first, DAC (1) 9, DAC
(2) After resetting 10 to set the output to zero, the switch SW1 is turned on to pass the output current of the VI converter 11 to the semiconductor laser 1 and the semiconductor laser 1 and the VI converter 1.
Connect between 1 and 1. 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.

Next, the CPU 5 reads the semiconductor laser emission amount (RP) at the time of reproducing information from the ROM 7, and transfers the 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.

The CPU 5 reads the light emission amount detection value (PR1) of the output of the A / D converter 6, calculates PR1-RP which is the error between the actual light emission amount of the semiconductor laser and the target light emission amount, and the error is zero. If it is larger, 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 instruction value of the DAC (1) 9 is increased / 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 / decreased.

Then, the CPU 5 reads the output (PR2) of the A / D converter 6 again and calculates the error RP-PR2.
Here, if the error becomes zero, the output to the DAC (1) 9 that increases or decreases the supply current according to 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 indicated value is completed. on the other hand,
If the error does not become zero, increase / decrease of the instruction value to the DAC (1) 9 is repeated until the error converges to zero.

After the setting of the output instruction value to the DAC (1) 9 in the second stage is completed, the CPU 5 causes the A / D converter 6 to operate.
Pause output monitoring.

Next, as a third step, the focus servo and the tracking servo are pulled in while the semiconductor laser is made to emit light with the light emission amount for information reproduction.

In the third stage, first, after the setting of the DAC (1) 9 is completed, the CPU 5 controls the focus direction actuator (not shown) of the pickup unit to irradiate light from the semiconductor laser on the focus pull-in unit 57 of the disk. The auto focus operation is performed to automatically adjust the beam spot of to the focused state, and the focus servo is activated.

Subsequently, the movable portion 21 of the pickup portion is moved in the outer peripheral direction of the disc (direction of the tracking pull-in portion 58) until the track error signal can be detected,
Tracking servo is applied at the position of the tracking pull-in portion 58.

Next, as the fourth step, the type of the loaded disc is recognized.

In the fourth stage, with the tracking servo applied, the CPU 5 detects the sector mark at the head of the sector from the reproduced data output from the information reproducing means 8. Then, after detecting the sector mark, the CPU 5 causes the information reproducing means 8 to operate.
Of the reproduced data in the header area is continuously read, and the ID information of the currently reproduced sector is recognized from the reproduced data in the header area.
When the ID information can be recognized, the CPU 5 can recognize the track currently being irradiated with the laser beam.

In the case of a disc conforming to the ISO standard or the ECMA standard, as shown in FIG. 2B, a track area in which information of the disc is recorded, called a control zone 60, is provided in the inner peripheral portion of the disc. Has been. CP
U5 calculates the number of seeks from the track currently being irradiated with laser light 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.

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 disc type recognized, the power for semiconductor laser playback etc. is set to an optimum value in the subsequent processing.For partially embossed discs, the recording / playback data area and playback-only data are set. Different light emission amount control is performed in each of the regions.

Here, the subsequent processing will be described only when the partially embossed type disk is mounted.

Next, as a fifth step, the output instruction value to the DAC (1) 9 is updated so that the optimal light emission amount is obtained in the rewritable recording / reproducing data area 55.

In the fifth stage, first, the pickup section is moved to the test zone 59 in the inner peripheral portion of the disc, and the second zone is set on the track of the test zone 59 where there is no pit in the data area like the user data area in which information can be rewritten. Laser light from the semiconductor laser 1 is emitted according to the output instruction value set at the stage.

Then, the CPU 5 detects the sector mark from the reproduced data output from the information reproducing means 8, and subsequently reads the sector ID information from the reproduced data in the header area.

Based on the format of the mounted disc read by the control zone 60 in the fourth stage, the CPU 5 starts the recording / reproducing data area (information is not recorded in pits) from the position where the sector mark or ID information is recorded. Since the time required for the beam spot of the laser beam to move to the start point of the (data area) 55 can be calculated, the CPU 5
Waits for a predetermined moving time until the irradiation beam moves to the start point of the recording / reproducing data area 55, and then outputs a sampling timing signal to the A / D converter 6 to detect the light emission amount detection value ( Read PR3). When the irradiation beam reaches the header area of the next sector for a predetermined time, the monitor 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. The light emission amount is detected only when the laser beam irradiates the recording / reproducing data area 55.

In the case of a disk having tracks formed in a spiral shape, a track jump operation is necessary to keep the irradiation beam on a specific track. Here, the operation when performing the track jump operation will be described with reference to FIG.

As shown in FIG. 4, when the track jump operation for moving the beam spot to the adjacent track is performed, the beam spot is located in the groove formed between the tracks during the movement of the pickup section. At T1, the emission amount detection value (PR3) of the output of the A / D converter 6, which is the detection value of the emitted light amount of the semiconductor laser 1, becomes low due to the influence of diffraction in the groove. That is, at the time of a track jump, the amount of returned light is different from that when the irradiation beam is in a data area where information can be recorded and reproduced due to the influence of diffraction caused by the groove when the irradiation beam crosses the groove. The amount of laser emission cannot be detected.

In this embodiment, as described above, the sampling timing signal is output to the A / D converter 6 to detect the amount of light emitted from the semiconductor laser 1 while the beam spot is located in the data area. When the sampling period of the A / D converter and the timing of the track jump overlap, the CPU 5 stops the output of the sampling signal to the A / D converter 6 during the period of the track jump, and the track jump ends. After reading the ID information of the next sector, the sampling timing signal is output in the next data area to detect the emission amount detection value (P
Be sure to read R3).

Thus, the A / D is used during the track jump.
By stopping the sampling of the converter 6,
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 tracks, the amount of return light changes from that in the on-track to the data area where information can be recorded / reproduced, and the amount of light emitted from the semiconductor laser is equal to the value in the data area. It is possible to prevent a problem that different values are detected, and it is possible to accurately detect the light emission amount of the semiconductor laser.

After reading the light emission amount detection value (PR3) of the output of the A / D converter 6 as described above, the CPU 5 sets the ROM
The target light emission amount (RP) of the semiconductor laser at the time of reproducing information corresponding to the mounted disc is read from the data table in 7 and PR3 and RP are compared, and if there is an error, the light emission amount of the semiconductor laser becomes the target light emission amount. In this way, the instruction value to the DAC (1) 9 is increased or decreased.

As described above, the monitor of the output of the A / D converter 6 for detecting the light emission amount of the semiconductor laser is performed by setting the period based on the format of the disk. A / only in area 55
The output of the D converter 6 can be monitored, and the amount of light emitted from the semiconductor laser can be detected by avoiding the header area having pits.

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 thereof is calculated. You may perform the process which makes it the light emission amount of a semiconductor laser. By performing such processing, it is possible to eliminate the influence of disturbance such as scratches on the disk and noise, and it is possible to more accurately control the light emission amount of the semiconductor laser.

When the error between the semiconductor laser light emission amount detection value 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 causes the A / D converter. Stop monitoring the output of 6 again.

Thereafter, in order to prevent the characteristics of the semiconductor laser from changing due to a change in ambient temperature and the like from causing an error between the light emission amount of the semiconductor laser and the target light emission amount, a host computer of an optical information reproducing device (not shown) is used. Until the instruction to record or reproduce the information comes from the CPU 5, the CPU 5 repeats the operation of updating the output instruction value to the DAC (1) 9 in the fifth step described above at a predetermined time interval.

As described above, the initial operation for setting the light emission amount of the semiconductor laser in the initial state is completed.

Next, as the sixth step, the operation relating to the light emission amount control when receiving the information reproducing instruction output from the host computer will be described.

When an instruction to reproduce information is issued from the host computer and the CPU 5 receives this reproduction instruction, if the target track having the sector in which the information to be reproduced is recorded is different from the track currently being tracked, the CPU 5 executes the above-mentioned operation. And the DAC of the semiconductor laser emission amount avoiding the header area, which is performed at a predetermined time interval in the fifth step of
(1) Stop the operation of updating the indicated value to 9 and set DAC (1)
The pickup section is moved to a predetermined target track while the output instruction value to 9 is held.

Since the irradiation beam from the semiconductor laser is in the test zone 59 at the end of the fifth step,
At the beginning of the step, the irradiation beam from the semiconductor laser is assumed to be located on the track of the test zone 59 having the recording / reproducing data area.

In this embodiment, depending on whether the track currently being tracked and the track to which the track is moved are areas having a recording / reproducing data area or a reproduction-only data area, different emission control is performed during the reproducing operation. I do.

[1] First, the track currently being tracked is in the track area B having the recording / reproducing data area (user data area) 55 or in the test zone 59, and the destination track is similarly the track area B. The operation in a case will be described.

In this case, after the pickup unit has been moved and on-tracked, the CPU 5 performs the A / D converter in the data area (the user data area 55 or the data area of the test zone) having no pit while avoiding the header area. The detection of the light emission amount of the semiconductor laser by the monitor of the output of 6 and the operation of updating the instruction value to the DAC (1) 9 are restarted, and the same 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 at the timing of, 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, at a predetermined time interval, the DAC
(1) The operation of updating the output instruction value to 9 is repeated.

[2] Next, the track currently being tracked is in the track area B having the recording / reproducing data area (user data area) 55 or in the test zone 59, and the destination track is the reproduction-only data area 54. The operation in the case of the track area A having “A” will be described.

In this case, after the movement of the pickup section is completed and the track is on-track, the CPU 5 detects the sector mark from the reproduced data output from the information reproducing means 8, and then the sector ID from the reproduced data in the header area. Read the information.
In the case of a disc conforming to the ISO standard or the ECMA standard, a pit-free area called an offset detection field is provided between the header area and the data area. C
The PU 5 generates a light beam while maintaining the output of the DAC (1) 9 set at the end of the fifth step, and the irradiation beam passes through the offset detection field and moves to the start point of the read-only data area 54. After waiting for a predetermined moving time, a sampling timing signal is output to the A / D converter 6 and the light emission amount detection value (PR4) of the output of the A / D converter 6 is read.

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 thereof is calculated. You may perform the process which makes it the light emission amount of a semiconductor laser. By performing such processing, it is possible to remove the influence of disturbance such as scratches on the disk and noise, and it is possible to more accurately detect the light emission amount of the semiconductor laser.

Subsequently, the CPU 5 determines the above-mentioned A / A which is the light emission amount detection value in the reproduction-only data area 54 having a pit.
The output value (PR4) of the D converter 6 is stored in the RAM 15 as the target light emission amount (RP ') in the track area A dedicated to information reproduction.
Memorize as.

After that, the CPU 5 does not use RP read from the ROM 7 in the fifth step as the target light emission amount of the light emission amount control when the irradiation beam from the semiconductor laser is irradiating the track of the reproduction-only track area A. ,
The RP 'obtained by the above measurement is used.

In the track area A, the return light is returned to the user data area 5 of the track area B due to the influence of diffraction in the pits.
Since the amount of light emission is smaller than that of No. 5, even if the semiconductor laser is emitted under the same conditions of the drive current and the track is irradiated, if the light emission amount is detected in the reproduction-only data area 54, the detection value of the light emission amount becomes small due to the difference in the returning light. Become. In this embodiment, R is set in the user data area 55 of the recording / reproducing track area B.
A current having the same value as the drive current for obtaining the target light emission amount RP stored in the OM7 is supplied to the semiconductor laser, and the light emission amount in the reproduction-only data area 54 at this time is set as the target light emission amount RP ', and the reproduction-only track area is set. The light emission amount of the semiconductor laser in A is controlled.

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 in the data area while avoiding the header area, and the DAC ( 1) The operation of updating the instruction value to 9 is restarted, the output of the A / D converter 6 is sampled 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, and the target light emission is performed. The output instruction value to the DAC (1) 9 is updated so that the error with the quantity (RP ') converges to zero. And
The operation of updating the output instruction value to the DAC (1) 9 is repeated at predetermined time intervals.

FIG. 5 shows a user data area 5 without pits.
A recordable and reproducible track area B having a number 5 (see (a)) and a reproducible track area A having a read-only data area 54 in which information is formed by pits ((b))
(Refer to FIG. 3) shows the light emission amount detection value in each track.

Regarding the header area in which information is formed by pits, the track area A and the track area B are the same, and the returned light is less than the user data area 55 due to the diffraction by the pits, and the light emission amount detection in the user data area 55 is detected. The amount of laser emission light becomes smaller than the value (PR3). Since the pit length of the first sector mark in the header area is 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 a smaller laser emission light amount. Further, since there is no pit in the offset detection field, a large amount of return light is generated, and the amount of laser emission light is increased.

The detection value (PR4) of the light emission amount in the reproduction-only data area 54 is the same as in the header area when the returned light is less than that in the user data area 55 due to diffraction by the pits and the supply current to the semiconductor laser is the same. Further, the laser emission light quantity becomes smaller than the light emission quantity detection value (PR3) in the user data area 55. In the reproduction-only data area 54, the target light emission amount is changed from RP to RP 'as described above according to the change in the laser emission light amount due to the difference in the return light amount, and the light emission amount detection value (the output of the A / D converter 6 is detected. PR4) and target luminescence amount (RP ')
And the output instruction value to the DAC (1) 9 is updated so that the error becomes zero, thereby controlling the light emission amount.

When such a light emission amount control is performed, the temperature inside the device changes and the characteristics of the semiconductor laser change within a short time such that the pickup unit is moved from the track region B or the test zone to the track region A. Therefore, the supply current to the semiconductor laser is the same as the value in the track area B before moving the pickup portion or the track in the test zone.

As described above, the recording / reproducing of information from the track area A is performed again by changing and controlling the target light emission amount so as not to change the current supplied to the semiconductor laser depending on the influence of the returning light due to the presence or absence of the pits. Even when the pickup unit is moved to a possible track area B, the optimum light emission amount of the semiconductor laser can be maintained in the recording / reproducing data area, and it is not necessary to perform control for adjusting the light emission amount again.

Further, 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 that of the read-only data area, and the return light quantity which is influenced by diffraction is short. The sector mark part at the beginning of the header area, which is different from the read-only data area, and the pit-free offset detection field between the header area and the data area are avoided so that the semiconductor memory is better than the recording medium. Even if there is light returning to the laser,
It is possible to correctly measure the light emission amount of the semiconductor laser during irradiation of the track area A dedicated to information reproduction, and to set the correct target light emission amount.

If track area B to track area A
When information is reproduced continuously for a long time in the track area A after the pickup section is moved, the temperature inside the device may change and the characteristics of the semiconductor laser may change.

Even in this case, the CPU 5 monitors the output of the A / D converter 6 in the data area while avoiding the header area at a predetermined time interval to detect the emission amount of the semiconductor laser and to give the instruction value to the DAC (1) 9. Since the update operation of the target light emission amount (R
The emission amount of the semiconductor laser is controlled so that the error from P ') becomes zero.

As described above, the target light emission amount is made different in the track area A so that the drive current of the semiconductor laser is not changed, and the light emission amount of the semiconductor laser is adjusted so that the optimum light emission amount is obtained in the recording / reproducing data area. When the control is performed, an error may occur between the optimum light emission amount in the header area where the information is formed by pits or the reproduction-only data area, but the information reproduction in the area where the information is formed by pits Unlike a rewritable user data area that uses the Kerr effect to reproduce a weak signal, a signal is reproduced by increasing or decreasing the amount of return light, so that reproduction with good C / N can be performed even if the amount of light emission decreases. Even if the light emission amount increases, the information pits are not deteriorated, so the reading margin is large, and the irradiation amount of the laser light slightly changes in the header area and the read-only data area. There is no problem.

[3] Next, the operation when the currently tracked track is in the track area A and the destination track is the track area B will be described.

In this case, as in the case of the movement from the track area B, the CPU 5 detects the light emission amount of the semiconductor laser and DA at a predetermined time interval while avoiding the header area.
The operation of updating the indicated value to C (1) 9 is stopped, and the DAC
(1) The pickup unit is moved to a predetermined target track while the output instruction value to 9 is held.

Subsequently, after the movement of the pickup section is completed and the track is on-track, the CPU 5 calculates the target light emission amount from RP 'obtained by measuring in the track area A, and the semiconductor for reproducing predetermined information stored in the ROM 7 is obtained. Return to the laser emission amount (read power) RP, and detect the 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 and update the instruction value to the DAC (1) 9. And the output of the A / D converter 6 is sampled 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 so that the error from the target light emission amount converges to zero. To DAC (1)
The output instruction value to 9 is updated. Then, the operation of updating the output instruction value to the DAC (1) 9 is repeated at predetermined time intervals.

[4] Next, the operation when the currently tracked track is in the track area A and the destination track is similarly in the track area A will be described.

In this case, after the movement of the pickup section is completed and the track is on-track, the CPU 5 outputs the output of the A / D converter 6 avoiding the header area which was being performed at a predetermined time interval in the track area A before the movement. The detection of the light emission amount of the semiconductor laser by the monitor and the operation of updating the instruction value to the DAC (1) 9 are restarted.

At this time, the emission amount of the semiconductor laser by the output of the A / D converter 6 is sampled and the DAC is
(1) When updating the instruction value to 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 moving the pickup unit from the track area B to the track area A.

However, since the dispersion of the reflectivity in the radial direction of the disk is not zero, the amount of light returned from the disk to the semiconductor laser changes in the radial direction, and the light emission amount of the semiconductor laser changes. An error may occur in the radial direction in the target light emission amount RP 'for correcting the influence of light. In the case of a disc conforming to the ECMA standard in which a plurality of track areas A may coexist in the radial direction of the disc on a band-by-band basis, and the bands before and after the movement of the pickup unit are not close to each other, the pickup A / D as performed when moving from the recording / reproducing track area B to the reproduction-only track area A after the movement of the parts is completed and the track is on-track.
It is also possible to detect the light emission amount of the output of the converter 6 and reset the target light emission amount in which the influence of the return light is corrected.
In addition, the target emission amount may be reset without fail when moving to a track of a different band. As a result, it is possible to control the light emission amount with higher accuracy.

As described above, according to the present embodiment, there are two types of data areas, that is, a data area in which information is formed in pits by molding at the time of manufacturing a disc and only information can be reproduced, and a data area in which information can be recorded and reproduced. Even in the case of using a partially embossed type disk in which the data area of 1 is mixed in one disk, the optimum reproduction power in the user data area in which information can be rewritten even if there is light returning from the recording medium to the semiconductor laser. Thus, it is possible to correctly control the light emission amount, and it is possible to prevent the recorded data from being deteriorated by increasing the power of the semiconductor laser, and the information from being erroneously reproduced by decreasing the power.

Further, even if the pickup section is moved from the track area A capable of only reproducing information to the track area B capable of both recording and reproducing, the supply current to the semiconductor laser is controlled so as not to change. Therefore, it is not necessary to readjust the current supplied to the semiconductor laser immediately after moving the pickup unit between different data areas, and a waiting time for this readjustment does not occur. It is possible to prevent the operating performance of the device from being deteriorated.

Further, the target value of the amount of light emission in the data area where only the information can be reproduced is supplied with the same value as the current supplied to the semiconductor laser when the amount of light emission is controlled in the data area where the recording and reproduction are possible. The target power of the semiconductor laser in the data area dedicated to information reproduction is set by setting the amount of light emission detected by Therefore, it is possible to set an appropriate target light emission amount of the semiconductor laser corresponding to the mounted disc, and it is possible to perform a correct light emission amount control according to the medium.

FIG. 6 is a block diagram showing the structure of the output control means of the semiconductor laser in the optical information reproducing apparatus according to the second embodiment of the present invention.

In the first embodiment, the output of the light detecting means 4 is used as the output control means of the semiconductor laser, and the A / D converter 6 is used.
The amount of light emitted from the semiconductor laser converted into a digital value by
The CPU 5 digitally compares and calculates the target light emission amount data stored in the OM 7 or the digital value which is the target light emission amount obtained in the actual measurement and stored in the RAM 15 to calculate the supply current amount to the semiconductor laser 1. Although the configuration using the setting method is shown, in the second embodiment, the output of the photodetector corresponding to the light emission amount of the semiconductor laser and the target light emission amount by the variable voltage power source configured by the D / A converter or the like are used. It is an example of the configuration of the output control means of the semiconductor laser using the method of analogically comparing the corresponding voltage output with a comparator to set the amount of current supplied to the semiconductor laser.

The semiconductor laser output control means of this embodiment comprises a circuit as shown in FIG.
On the output side of the light detecting means 4 for detecting a part of the emitted light of
A comparator (1) 31 for comparing the output of the light detecting means 4 and the output of the variable voltage power supply 33, and a comparator for comparing the output of the light detecting means 4 with a predetermined reference voltage 34.
(2) 32 is provided.

A CPU 35 for controlling each part is provided, a ROM 42 in which the value of the target light emission amount of the semiconductor laser at the time of reproducing information and the like, and a target light emission in a data area which can be reproduced only, which is required during operation, are stored. The RAM 43 for storing the amount and the like and the information reproducing means 8 for reproducing the information recorded on the medium based on the reproduction signal obtained from the reflected light from the recording medium are connected.

The CPU 35 is connected to the variable voltage power source 33, and the output of the variable voltage power source 33 is stored in the ROM 42.
Alternatively, a setting signal for setting to a voltage value corresponding to a predetermined target light emission amount stored in the RAM 43 is sent out.

The output terminals of the comparators (1) 31 and (2) 32 are connected to the up / down counters (1) 36 and (2) 3 respectively.
7 are connected to each comparator (1) 31, (2) 3
Each up / down counter based on 2 outputs
(1) 36 and (2) 37 are adapted to count the clock signals from the clock signal generator 38. The output value of the up-down counter (1) 36 corresponds to the semiconductor laser emission amount (read power) at the time of reproducing information, and the output value of the up-down counter (2) 37 is the semiconductor laser emission amount at the time of information recording (peak The power is added to the read power to obtain the value.

The output of the comparator (1) 31 is CP
The signal is also input to U35, and the enable signal for permitting counting is sent from the CPU 35 to the up / down counter (1) 36.

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 semiconductor laser emission amount at the time of information reproduction is It is adapted to be converted into an analog voltage value by the D / A converter (1) 39. The output terminal of the up / down counter (2) 37 has a D / A
Converter (2) 40 is connected and is an up / down counter that is an added value for obtaining the peak power at the time of recording information.
(2) The output value of 37 is converted into an analog voltage value by the D / A converter (2) 40.

The D / A converters (1) 39, (2) 40 are V
Is connected to a drive circuit 41 composed of a −I converter, and the drive circuit 41 allows the D / A converters (1) 39, (2) 4
Each output voltage of 0 is converted into a current, and a driving current of the semiconductor laser at the time of reproducing information and a driving current to be added to obtain the peak power at the time of recording information are generated.

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 to be added to obtain the peak power at the time of information recording is passed through the switch SW3. Are input to the adder circuit 13. In addition, the high frequency current output from the high frequency oscillation circuit 14 is switched to the addition circuit 13 by the switch SW.
It is designed to be input via 2. Adder circuit 13
The output terminal of is connected to the semiconductor laser 1 via the switch SW1, and the current superposed by the adder circuit 13 is supplied to the semiconductor laser 1 as a drive current.

The other parts are constructed in the same way as in the first embodiment, and their explanations are omitted.

In the second embodiment, similarly to the first embodiment, the switches SW1, SW2 and SW3 are turned on and off under the control of the CPU 35 at the time of reproducing information and at the time of recording information, and the semiconductor laser 1 is emitted at a predetermined light emission amount. The light emission amount of the semiconductor laser 1 is detected, and the light emission amount is controlled so that the error from the target light emission amount becomes zero.

Also in the present embodiment, only the control of the light emission amount of the semiconductor laser at the time of reproducing information when the partially embossed type disc is used will be described.

As in the first embodiment, in a test zone having a pit-free data area similar to the user data area in which information can be recorded and reproduced as the initial operation, the optimum light emission amount for the user data area is obtained. The light emission amount is controlled.

The CPU 35 turns on the enable signal of the up-down counter (1) 36 when detecting the light emission amount of the semiconductor laser 1 and updating the input value to the D / A converter (1) 39. Allow counting.

At this time, the comparator (1) 31 is set to a voltage value corresponding to the detected light emission amount of the semiconductor laser 1 output from the light detection means 4 and a predetermined target light emission amount (RP) during information reproduction. Output of variable voltage power supply 33 (V1
), And if there is an error between the voltage value corresponding to the laser emission amount detected by the light detecting means 4 and the variable voltage power supply output (V1), the output of the comparator (1) 31 is turned on. Becomes 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 changes.

When the output of the up-down counter (1) 36 changes, the output of the D / A converter (1) 39 and the output of the drive circuit 41 corresponding to the output change of the up-down counter (1) 36, the semiconductor laser. Since the current supplied to the semiconductor laser 1 changes, the light emission amount of the semiconductor laser 1 changes.

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 detecting means 4 and the variable voltage power supply output (V1) becomes zero, and the comparator (1) 31 Output is turned off. This allows
The output of the up / down counter (1) 36 is in a hold state, and the light emission amount adjustment of the semiconductor laser 1 is completed.

In such an analog system configuration, the enable signal of the up / down counter (1) 36 of FIG. 6 is changed to the A / D converter 6 of FIG. 1 shown in the first embodiment.
The same effect as in the case of the digital system described above can be obtained by performing the on / off control while avoiding the header area at a predetermined time interval similar to the sampling timing of, and a user data area and a test zone where information can be recorded and reproduced. It is possible to perform the correct light emission amount control so that the light emission amount is optimum in the data area.

That is, when adjusting the emission power of the semiconductor laser in the user data area where information can be rewritten,
When the enable signal terminal of the up / down counter (1) 36 is turned on by the CPU 35 while avoiding the header area, the output voltage from the light detecting means 4 and the voltage corresponding to the predetermined target light emission amount RP in the user data area read from the ROM 42. If there is a difference from the variable voltage power supply output (V1) set to the value, the output of the up / down counter (1) 36 changes until the difference becomes zero, and the up / down counter (1) 36 The output current of the D / A converter (1) 39 and the output current of the drive circuit 41 to the semiconductor laser are changed according to the change of the output of the semiconductor laser 1, and the emission amount of the semiconductor laser 1 is adjusted to the target emission amount. Adjusted.

Then, the difference between the output voltage from the light detecting 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 of the up / down counter (1) 36. When the change is stopped, the CPU 35 outputs the output value (D1) of the up / down counter (1) 36 at this time.
) Is stored in the RAM 43.

Thereafter, the CPU 35 sets the enable signal terminal of the up / down counter (1) 36 in order to prevent the characteristics of the semiconductor laser from changing and the light emission amount of the semiconductor laser from changing due to changes in temperature inside the device. The up / down counter (1) 36 when it is turned on while avoiding the header area, 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 turns off. The output value (D1) is read and rewritten with the value previously stored in the RAM 43, and the operation is repeated at predetermined time intervals.

When the pickup section is moved from the recording / reproducing track area B or the test zone to the information reproducing-only track area A in response to the information reproducing instruction,
Before the movement, the CPU 35 turns off the enable signal terminal of the up / down counter (1) 36, and holds the output of the variable voltage power supply 33 corresponding to the target light emission amount at the rewritable user data area value (V1). The pickup unit is moved to a predetermined target truck.

After the movement of the pickup section is completed and the track area A is on-tracked, the CPU 35 turns on the enable signal of the up / down counter (1) 36 while avoiding the header area.
(1) Up / down counter stored in RAM 43 in the user data area in which the output value of 36 and information can be rewritten (1) 3
The output value (D1) of No. 6 is compared, and the output of the variable voltage power supply 33 is changed so that the difference becomes zero. Where C
The output value of the up / down counter (1) 36 of the PU 35 is R
Output voltage (V2) of the variable voltage power supply 33 when it becomes equal to the value D1 in the user data area stored in the AM43
Is a reference value corresponding to the target light emission amount (Rp ') in the track area A dedicated to information reproduction, and the instruction value to the variable voltage power supply 33 for outputting V2 is stored in the RAM 43.

Thereafter, the CPU 35 uses Rp 'as the target light emission amount when the irradiation beam from the semiconductor laser is irradiating the track of the reproduction-only track area A in which information is formed by pits, and uses the target light emission stored in the RAM 43. Amount R
Variable voltage power supply 3 set to the voltage value corresponding to the indicated value of p '
The output (V2) of No. 3 and the output of the light detecting means 4 are compared by the comparator (1) 31, and the light emission amount is controlled so that the difference becomes zero as in the case of the user data area.

As described above, the target light emission amount is changed and controlled in the track area A dedicated to the information reproduction so as not to change the current supplied to the semiconductor laser depending on the influence of the returned light due to the presence or absence of the pits. The same effect as in the case of the method can be obtained, and the semiconductor laser can be controlled to emit light with the drive current that provides the optimum light emission amount in the user data area where information can be recorded and reproduced.

When the pickup section is moved from the track area A dedicated to information reproduction to the track area B for recording and reproduction, the CPU 35 turns off the enable signal terminal of the up / down counter (1) 36 to turn the up / down counter on.
(1) After moving the pickup unit to a predetermined target track with the output of 36 held, the output instruction value to the variable voltage power supply 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 voltage of the variable voltage power source 33 is set to V1 by returning the read target value of the predetermined target light emission amount Rp. Then, the enable signal of the up / down counter (1) 36 is controlled so as to avoid the header area, and the output voltage from the light detecting means 4 and the output voltage V1 of the variable voltage power supply 33 are compared by the comparator (1) 31. The light emission amount of the semiconductor laser is controlled.

By performing such a light emission amount control, the same effect as that obtained when the light emission amount is controlled by the above-mentioned digital arithmetic processing is obtained, and the information is recorded again from the track area A dedicated to the information reproduction. Even when the pickup unit is moved to the reproducible track area B, the optimum light emission amount of the semiconductor laser can be maintained in the user data area in which information can be rewritten, and there is no need to perform the control for adjusting the light emission amount again. , It is possible to prevent the recorded data from being deteriorated due to the high power of the semiconductor laser and to prevent the information from being mistakenly reproduced due to the low power. It can be prevented from lowering.

[Additional Notes] (1) A header area in which information such as a sector start mark, a track number, and a sector number is formed by pits at the time of manufacturing a medium, and a data area where there is no pit and both recording and reproduction of information are possible. A rewritable recording / reproducing track area composed of the above and a reproduction-only track area in which information in the data area as well as the header area is formed by pits at the time of manufacturing the medium and cannot be rewritten is formed on one medium. In an optical information reproducing apparatus for reproducing information from a mixed optical recording medium, a target value of the light emission amount of a semiconductor laser when irradiating the reproduction-only track area is set to the recording / reproducing track area. The emission amount of the semiconductor laser is controlled to a predetermined value by setting it to a value different from the target value of the emission amount of the semiconductor laser during irradiation. Optical information reproducing apparatus having a semiconductor laser output control means.

(2) Information such as a sector start mark, track number and sector number is composed of a header area formed by pits at the time of manufacturing the medium and a data area without pits and capable of both recording and reproducing of information. An optical disc in which a rewritable information recording / reproducing track region and a reproduction-only track region in which information in the data region as well as the header region is formed by pits at the time of manufacturing the medium and the information cannot be rewritten are mixed in one medium. In an optical information reproducing apparatus for reproducing information from a recording medium, the amount of light emitted from a semiconductor laser, which is a light source for irradiating the recording medium with laser light, is detected, and the header region is irradiated with laser light. During a certain period of time, the information area of the header area is reproduced, and after a predetermined time, a data area having no pits in the recording / reproducing track area or The target value of the light emission amount of the semiconductor laser when irradiating the read-only track area is detected while detecting the light-emission amount of the semiconductor laser in the data area in which the information in the read-only track area is formed by pits. A semiconductor laser that controls the amount of light emitted from the semiconductor laser so that the amount of light emitted from the semiconductor laser is set to a value different from the target value of the amount of light emitted when irradiating the track area for recording and reproduction. An optical information reproducing device having an output control means.

(3) The semiconductor laser output control means sets the target value of the light emission amount of the semiconductor laser when irradiating the reproduction-only track area to a value in which the influence of returning light due to the presence or absence of pits is corrected. , Note that the light emission amount is controlled so that the drive current supplied to the semiconductor laser in the read-only track area is maintained at the same value as the value in the data area having no pits in the record-playback track area. The described optical information reproducing device.

In this structure, the light emission amount is controlled 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 pit-free data area in the recording / playback track area. As a result, when the optical head moves between the read-only track area and the read / write track area, the current supplied to the semiconductor laser does not change due to the effect of the return light due to the presence or absence of pits, and the recording medium Even if there is light returning to the semiconductor laser, the light emission amount is controlled so that the optimum reproduction power is obtained in the data area where information can be recorded and reproduced.

(4) The semiconductor laser output control means sets the target value of the light emission amount of the semiconductor laser when irradiating the reproduction-only track area from the track area for recording and reproduction by the optical head to the reproduction-only track area. After the laser beam is moved to the semiconductor laser before the optical head starts moving, the amount of light emitted from the semiconductor laser is detected while the driving current having the same value as the driving current supplied to the semiconductor laser is supplied to the semiconductor laser. The optical information reproducing device as described in appendix (1), wherein the effect of is detected and a value is set based on the detection result.

In this structure, a drive current having the same value as the current supplied to the semiconductor laser in the recording / reproducing track area is supplied to the semiconductor laser in the reproducing-only track area to detect the emission amount of the semiconductor laser at this time. By setting a target value for the amount of light emission that corrects the effect of the return light depending on the presence or absence of pits, even if the reflectance is different for each mounted medium or there is variation in pit formation, the track area is exclusively for playback. The target value of the light emission amount of the semiconductor laser in can be accurately set.

(5) 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 at the beginning of the header area. A predetermined time has elapsed since the information in the header area of the read-only track area was reproduced as in the data area, avoiding the sector mark section provided and the offset detection field provided between the header area and the data area. The optical information reproducing device as described in appendix (4), characterized in that the light emission amount is detected later.

In this structure, the light emission amount detection for setting the light emission amount target value of the semiconductor laser when irradiating the reproduction-only track region is performed, and the pit length is provided at the head of the header region and the pit length is the reproduction-only track region. Offset that is longer than the pits in the inner data area and has a return light amount that is influenced by diffraction and is different from the data area of the short pits, and the pit-less offset provided between the header area and the data area Do away with the detection field. As a result, even if there is light returning from the recording medium to the semiconductor laser, it is possible to correctly measure the light emission amount of the semiconductor laser during irradiation of the data area in the reproduction-only track area, and to set the correct target light emission amount. It will be possible.

[0141]

As described above, according to the present invention, the recording / reproducing data area in which the information can be rewritten and the reproduction-only data area in which the information cannot be rewritten because the information is formed in the pits when the recording medium is manufactured. When using optical recording media that are mixed in one medium, the optimum reproduction power is set in the user data area where information can be recorded and reproduced even if there is returning light from the recording media to the semiconductor laser. Correct light emission control is possible, and it is possible to prevent the recorded data from being deteriorated due to the high power of the semiconductor laser, and to prevent the information from being mistakenly reproduced due to the low power. There is an effect that it is possible to prevent the occurrence of a decrease in the operating performance of the device.

[Brief description of drawings]

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.

FIG. 2 is an explanatory diagram showing a schematic configuration of each area on a recording surface of a partially embossed optical disc used in the apparatus of the present embodiment.

FIG. 3 is a configuration explanatory view showing a configuration of a pickup section.

FIG. 4 is an operation explanatory view showing a light emission amount detection state when performing a track jump operation.

FIG. 5 is an operation explanatory diagram showing a light emission amount of a semiconductor laser in a track area B capable of recording and reproducing and a track area A capable of only reproducing.

FIG. 6 is a block diagram showing the configuration of output control means of a semiconductor laser in an optical information reproducing apparatus according to a second embodiment of the present invention.

FIG. 7 is a characteristic diagram showing the IP characteristics of the semiconductor laser when the amount of light returning to the semiconductor laser is changed by using a device in which emitted light and return light interfere with each other.

FIG. 8 is a characteristic explanatory view showing an example of changes in the emitted light amount of a semiconductor laser in a read-only header area where information in the disc is formed by pits and a user data area where recording and reproduction are possible without pits.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Semiconductor laser 4 ... Photodetection means 5 ... CPU 6 ... A / D converter 7 ... ROM 8 ... Information reproducing means 9, 10 ... D / A converter 11, 12 ... VI converter 15 ... RAM 51 ... Partial embossing -Shaped optical disk 53 ... Header area 54 ... Reproduction-only data area 55 ... Recording / reproduction data area (user data area)

Claims (3)

[Claims] 1. 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 at the time of manufacturing a medium, and a data area without pits in which information can be recorded and reproduced. An optical system in which an information rewritable recording / reproducing 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 when the medium is manufactured and information cannot be rewritten are mixed in one medium. In an optical information reproducing apparatus that reproduces information from a recording medium, a target value of the emission amount of a semiconductor laser when irradiating the track area dedicated to reproduction is used when irradiating the track area for recording and reproduction. A semiconductor laser that controls the amount of light emitted from the semiconductor laser so as to keep the amount of light emitted from the semiconductor laser at a predetermined value by setting the amount of light emitted from the semiconductor laser different from the target value. Optical information reproducing apparatus characterized by comprising a force control means. 2. The 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 The target value of the light emission amount of the semiconductor laser when irradiating the track area of is driven to the semiconductor laser after the optical head is moved from the recording / reproducing track area to the read-only track area and before the movement of the optical head is started. 2. The optical information reproducing apparatus according to claim 1, wherein the amount of light emitted from the semiconductor laser is detected while a drive current having the same value as the current is supplied to the semiconductor laser, and the value is set based on the detection result. . 3. 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 in the header area of the reproducing-only track area. The optical information reproducing apparatus according to claim 2, wherein the reproduction is performed after a predetermined time has elapsed after reproducing the information.