JPH01220144A - Optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To facilitate a light source control at the time of recording or erasing by adding a prescribed signal at the time of recording or erasing to a control signal in the previous recording time. CONSTITUTION:At the time of reproducing, a switch 4 is closed, and a switch 7 is closed to the side of a voltage 8, so as to control an electric current source 3 by way of passing through a hold circuit 15 as it is. For an erasing operation, an additive electric current in the erasing time is passed through a switch 13 from an electric current source 12 via a control part 14 to be added to an electric current in the reproducing time. Then, an automatic control is carried out with an erasing laser power by a voltage 10, and on completion of the erasing, this mode is changed back to the reproducing state. Then, for a recording operation, the electric current source 12 is set for an additive electric current in the recording time, and the recording is performed by operating the switch 13 according to a modulation signal MOD. At this time, the circuit 15 is under the hold state by a signal B. Since this operation is repeated by each sector from the reproducing state, even at the time of recording, the quantity of light can easily be controlled based on an automatic control with a reproducing laser power.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to an optical information recording and reproducing device that records, reproduces, and/or erases information on a recording medium by irradiating the recording medium with light from a light source. Regarding. In particular, the present invention relates to a device for controlling the output power of a laser in an optical information recording/reproducing device.

[Prior Art] Laser light amount control devices such as those described above are used in various technical fields, but in particular, they are used to irradiate light onto a recording medium, record information,
It is often used in optical information recording and reproducing devices that perform reproduction and/or erasing.

Conventionally, a laser light source is usually used as a light source for this optical recording/reproducing apparatus because the beam spot can be narrowed down to an extremely small size. Devices using such laser light sources detect the laser output power during playback, recording, and erasing, compare it with each target value, and control the current that drives the laser. Ta.

A block diagram of an example of this laser light amount control device is shown in Fig. 5. In the figure, 1 is a laser, 2 is a monitoring optical sensor that detects a part of the laser light, and 3 is a sensor that generates a driving current for the laser. 4 is a switch that is turned ON and OFF according to the modulation signal during recording, and is turned OFF during playback and erasing.
I'm doing N. 5 is an amplifier that converts the output of sensor 2 into voltage; 6 is a differential amplifier that compares the target value with the output of the monitor light sensor; 7 is a switch that switches the target value by recording, reproducing, or erasing; 8, 9.10 are recorded and played back respectively.

a voltage generating section 11 that generates voltages of three target values for erasing;
is the power supply. In such a device, for example, during reproduction, the reference voltage is set to the reproduction voltage 9 by the switch 7, and is input to one side of the amplifier 5. In this state,
The light intensity of the laser 1 is received by a sensor 2, converted into a voltage by an amplifier 5, and then the difference from the reference voltage is taken by an amplifier 6, and the output controls a current source 3 that generates a driving current for the laser. Laser power during reproduction is maintained at a desired value.

[Problems to be Solved by the Invention] However, with the configuration shown in FIG. 5, it is difficult to accurately detect the amount of monitor light during recording when continuous light is not irradiated, such as during playback and erasing. There was a drawback. As a countermeasure in this case, since the laser beam is modulated by recorded information during recording, it is possible to detect this peak value or to average it and detect a light amount proportional to the peak light amount. However, in order to achieve this, it is necessary to use a circuit that responds to one high frequency of recorded information and accurately detects its peak value, or to use a laser beam that responds to one high frequency of recorded information and accurately detects its peak value, or so that the value is proportional to the peak light amount when averaged. However, this has disadvantages such as requiring expensive circuitry or limiting the number of modulation methods.

[Means for Solving the Problems] In view of the above-mentioned problems of the prior art, an object of the present invention is to provide an optical information recording/reproducing device using a light source such as a laser, which requires complicated circuitry during recording and erasing. Recorded without using
An object of the present invention is to provide an optical information recording and reproducing device that can control the amount of laser light in each state of reproduction and erasing.

The above purpose is to detect the irradiated light from the light source.

Optical information that has a control loop means that increases or decreases the irradiation light from a light source compared to a reference light amount, and records, reproduces, and/or erases information on a recording medium by irradiating the recording medium with light from the light source. In a recording/reproducing device, when recording or erasing, a predetermined signal for recording or erasing is added to the control signal that generates the amount of light irradiated during the previous reproduction, so that the light source at the time of recording or erasing is controlled. This is achieved by an optical information recording/reproducing apparatus (first invention) characterized by having means for setting the amount of irradiation light.

It also has a control loop means that detects the laser irradiation light and increases or decreases the laser drive current by comparing it with a reference light amount, and is an optical information recording/reproducing device that records, reproduces, and/or erases information on a recording medium using the laser beam. The apparatus includes means for causing a predetermined additional current to flow through the laser driving means at a predetermined time.

Detects the laser irradiation light and compares it with the reference light intensity.

A first current control signal that increases or decreases the laser drive current, a second current control signal that controls the current added to the laser drive current by the first current control signal, and a second current control signal that controls the laser drive current. Also by an optical information recording/reproducing device (second invention) having an on/off signal that controls whether or not to flow additional current to the laser, and a first current control stop signal that stops changing the first current control signal. achieved.

[Function] According to the first invention, by adding a predetermined signal to the control signal that generates the reference irradiation light amount during reproduction, it is possible to perform the APC operation during recording or erasing even if the APC operation is not performed during recording or erasing. The amount of light irradiated by the light source can be set, and the above problems can be solved.

Further, according to the second invention, by combining two types of control currents, it is possible to control the amount of laser light for recording, reproducing, and erasing without using a complicated circuit. In particular, control during recording can be simplified.

[Example] Hereinafter, the optical information recording/reproducing apparatus of the present invention will be described in detail based on the drawings. In the following description, an optical information recording/reproducing apparatus using a laser as a light source will be exemplified.

FIG. 1 is a block diagram of a laser light amount control device of an optical information recording/reproducing apparatus according to the present invention. Also, Figure 2 (
(a) and (b) are timing diagrams for explaining the operations, respectively.

In the 881 diagram, 1 is a laser, 2 is a monitoring optical sensor that detects a part of the emitted light of the laser, 3 is a current source that generates a driving current for the laser, and 4 is whether or not the current of current source 3 flows to laser l. 5 is an amplifier that converts the output of sensor 2 into voltage; 6 is a differential amplifier that compares the target value with the output of the monitor light sensor; 7 is a switch that switches the reference voltage for reproduction or erasure; 8; Reference numeral 10 represents a voltage generating section that generates recording and erasing voltages, respectively, and 11 represents a power source. Further, 12 is a current source that generates additional current.

3 is a switch for selecting whether or not to flow additional current to the laser 1; 14 is a control unit composed of a microcomputer and a DA converter; Erase selection signal RD
(Read), WR (Write), E
Switch 7, switch 1 according to R (Erase)
3. It controls the switch 4, the current value of the current source 12, and the hold circuit 15. In the figure, A is a signal from the differential amplifier 6, which detects the laser irradiation light, compares it with a reference light amount, and increases or decreases the laser drive current.
is the current control signal. B is a signal output from the control unit 14 to the hold circuit 15, and is a first current control stop signal that stops the change in the first current control signal. C is a signal output from the control unit 14 to the current source 12, and is a second current control signal that controls the current added to the first current control signal. D is a signal output from the control unit 14 to the switch 13, and is an on/off signal that controls whether or not to flow the additional current controlled by the second current control signal to the laser.

Next, the operation of the first embodiment of the present invention will be explained with reference to FIG. 5(A).

Here, we will consider a case where two consecutive sectors, the first and second, are erased, then recorded, and finally reproduced. First, the reproduction laser power is focused on the disc, and tracking is performed at a certain location on the disc.

At this time, the switch 4 is closed, the switch 13 is open, the switch 7 is closed to the reproduction voltage 8, and the hold circuit 15 does not hold the output of the differential amplifier 6. a A current source is controlled, and APC (A
auto+*atic Power Control) is operating.

Next, the laser beam is moved to the target sector, and immediately after confirming the address of the target first sector, a selection signal ER is inputted to set the erase laser power to the information recording area of the first sector. According to the ER signal, the control unit 14 sets the current source 12 to the additional current for erasing, and switches the switch 1.
When 3 is closed, the switch 7 is also closed to erase voltage 10. Now, the APC operation is performed using the erase laser power. The erase laser power is A until the information recording area of the first sector is finished and the address of the primary second sector is read.
Continue PC operation. Once the address of the second sector is confirmed, the APC operation is continued for the information recording area of the second sector with the erase laser power, and when the erasure of the second sector is completed, the selection signal changes from ER to RD. Transferred to APC operation with regenerative laser power. If the address of the second sector cannot be confirmed, the selection signal changes from ER to RD immediately, the APC operation starts with the reproduction laser power, the beam moves to the second sector again, and address confirmation continues. .

After erasing the two sectors, the beam is moved to the first sector again. During this time, APC is performed using the regenerative laser power.
It's working.

Once the address of the first sector has been confirmed, the 1 selection signal changes from RD to WR, and a laser modulation signal is input at MOD. When the input to WR changes, a recording current is set to the current source 12, and the switch 13 is opened and closed according to the MOD signal.

Further, the hold circuit 15 enters a hold state. This is the state of record. Note that the switch 7 at this time is also on the reproduction voltage 8 side.

When the recording of the first sector is completed, the input signal changes from WR to RD, and the APC operation is started using the reproduction laser power. When the address of the second sector is confirmed by the reproduction laser power, the input signal changes from RD to WR again, and recording is performed in the information recording area of the second sector. When the second sector is completed, the input signal changes from WR to RD, and the 0th order beam, which becomes the regeneration APC, is moved to the first sector again and the signal is regenerated. At this time, the laser is switched to the regeneration Ar
c operation remains.

During playback and erasing, the monitor light is referred to and fed back as in the conventional example, and the power is controlled by APC operation.

Next, a method of controlling power during recording without performing an APC operation will be explained with reference to FIG.

Figure 3 shows the relationship between the laser drive current (horizontal axis) and optical output (vertical axis).If the temperature changes from T to Tz, the characteristics of the laser change as shown in the figure. Move in parallel. APC for playback just before recording! ! Because I'm working on T.I.
The laser is driven by IR+ when it is I, and by IR2 when it is Tz. During recording, this current is held and a recording current is added on top of it. This additional current is Iwt when it is TI and Iwz when it is Tz, but as the characteristic line moves in parallel due to temperature changes, Iw+=Iw2
bawl. Therefore, by simply maintaining the reproduction APC current and adding a constant recording current to it, the optical power for recording can also be made constant. If the recording state continues for a long time and the temperature changes, it is not possible to compensate for this, but here, the part that confirms the address of the recording sector is APC operation for playback, so long-term recording This state does not continue, but is intermittently in a reproducing state, and the APC operation for reproducing at that time is taken as a reference, so there are few errors.

Next, the operation of the second embodiment will be explained with reference to FIG. 5(b).

In this case as well, consider the case where two consecutive sectors, the first and second, are erased, then recorded, and finally reproduced. First, the reproduction laser power is focused on the disk and tracking is performed at a certain location on the disk. At this time.

The switch 4 is closed, the switch 13 is open, and the switch 7 is closed toward the regeneration voltage 8.The hold circuit 15 does not hold, and the output of the differential amplifier 6 directly controls the current source 3 to control the regeneration laser power. APC(Automa)
tic Power Control) Next, move the laser beam to the target sector, and immediately after confirming the address of the target first sector, turn the erase laser power on the information recording area of the first sector. A selection signal ER is input. According to the ER signal, the control unit 14
sets the current source 12 to the additional current for erasing, closes the switch 13, and simultaneously puts the hold circuit 15 in a hold state. This is the erased state. When the information recording area of the first sector is completed, the selection signal becomes RD, and APC operation is performed at the reproduction power. If the address of the second sector is confirmed in this state, the input signal changes from HD to ER in the information recording area of the second sector. Here, too, the data is in an erased state.

When the erasure of the second sector is completed, the selection signal changes from ER to RD, and the APC operation is started using the reproduction laser power. If the address of the second sector cannot be confirmed, the selection signal immediately changes from ER to HD, moves to APC operation with reproduction laser power, moves the beam to the second sector again, and continues to confirm the address. . After erasing the two sectors, the beam is moved to the first sector again. During this time, APC operation is performed using the reproduction laser power. Once the address of the first sector has been confirmed, the selection signal changes from HD to WR, and a laser modulation signal is input at MOD. When the input changes to WR, current source 1
A recording current is set to 2, and the switch 13 is opened and closed according to the MOD signal. Further, the hold circuit 15 enters a hold state. This is the state of record. When the recording of the M1 sector is completed, the input signal changes from WR to HD, and the APC operation is started using the reproduction laser power. When the address of the second sector is confirmed by the reproduction laser power, the input signal changes from RD to WR again: recording is performed in the information recording area of sector 52. When the recording of the second sector is completed, the input signal changes from WR to RD, and the 0th order beam, which becomes the reproduction APC, is moved to the first sector again to reproduce the signal. At this time, the laser Regeneration A
It remains a PC.

During reproduction, as in the conventional example, monitor light is referred to and fed back, and power is controlled by APC operation. Power control during recording is the same as the explanation in FIG. 3.

Next, power control during erasing will be explained with reference to FIG.

FIG. 4 shows the relationship between the laser drive current and the optical output. When the temperature changes from T3 to T4, the characteristics shift in parallel as shown in the figure due to the characteristics of the laser. Since the APC operation is performed for reproduction immediately before recording, the laser is driven by IR3 at T3 and by IRJ at T4. During recording, this current is held and a recording current is added on top of it.

This additional current is IF5 when T3. At T4, IF5 is obtained, but due to a change in temperature, the characteristic line moves in parallel, so IE3=IE4. Therefore, M of the regenerated APC
Is it possible to keep the current flowing and eliminate a certain amount of this? By simply adding ll1t, the optical power for erasing becomes constant.

If the erase state continues for a long time and the temperature changes.

Although it is not possible to correct this, here, since the APC operation for reproduction is performed in the part where the sector address is confirmed, the erased state does not continue for a long time.

The present invention is not limited to the above-mentioned embodiments, and various modifications and applications are possible.

For example, in the above embodiment, two current sources were used to control the amount of S, but it is also possible to prepare two types of signals for controlling one current source.

In addition, the circuit configuration that adds a predetermined signal for recording or erasing to the control signal that produces the irradiation light intensity for the immediately preceding reproduction during recording or erasing is also applicable to the configuration of the light source light intensity control circuit of the recording and reproducing equipment. It is clear that the configuration can be changed accordingly and is not limited to the configuration shown in FIG.

[Effects of the Invention] As explained above, according to the optical information recording and reproducing bag of the present invention, the output of the control loop means during reproduction is held and a constant signal (current, etc.) is applied thereto. By this,
Even during recording and erasing, the amount of light from the light source can be efficiently controlled in response to temperature changes without performing the APC operation. This facilitates power control especially during recording, where APC operation is difficult.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a laser light amount control device for an optical information recording/reproducing apparatus according to the present invention. FIG. 2(A) is a timing diagram for explaining the first embodiment of the present invention, and FIG. 2(B) is a timing diagram for explaining the second embodiment. FIG. 3 is a diagram of laser characteristics for explaining the first embodiment. FIG. 4 is a diagram of laser characteristics for explaining the second embodiment. FIG. 5 is a block diagram of a conventional light amount control circuit. 1: Laser 2: Monitor optical sensor 3: Current source 4: Switch 5: Amplifier 6: Differential amplifier 7: Reference power supply changeover switch 8.10: Voltage generator 11: TL source 12: Additional current source 13: Addition Current source switch 14: Control circuit 15: Hold circuit Agent Patent attorney Seki Yamashita Box 1 Figure @ 3 Figure

Claims (4)

[Claims] (1) It has a control loop means that detects the irradiated light from the light source and increases or decreases the irradiated light from the light source compared to a reference light amount, and records information on the recording medium by irradiating the recording medium with the light from the light source. In an optical information recording and reproducing device that performs reproduction and/or erasing, when recording or erasing, a predetermined signal for recording or erasing is added to the control signal that produces the amount of irradiation light during the previous reproduction. 1. An optical information recording/reproducing apparatus comprising means for setting the amount of light irradiated by a light source during recording or erasing. (2) Optical information recording that has a control loop means that detects laser irradiation light and increases or decreases the laser drive current by comparing it with a reference light amount, and records, reproduces, and/or erases information on a recording medium using laser light. The reproduction device includes means for flowing a predetermined additional current to the laser drive means at a predetermined time, detects the laser irradiation light, compares it with a reference light amount, and increases or decreases the laser drive current with a first current control signal; a second current control signal for controlling the current added to the laser drive current according to the current control signal; an on-off signal for controlling whether or not to flow the additional current controlled by the second current control signal to the laser; an optical information recording/reproducing device having a first current control stop signal for stopping a change in the first current control signal. (3) In the device according to claim 2, ▲mathematical formula,
Optical information recording and reproducing device that contains chemical formulas, tables, etc.▼. (4) In the device according to claim 2, ▲mathematical formula,
Optical information recording and reproducing device that contains chemical formulas, tables, etc.▼.