KR20080004691A - Method and apparatus for controling power in optical disc device - Google Patents

Abstract

A method and an apparatus for controlling optical power in an optical disk device are provided to minimize optical power gap and ensure stabilized reproducing and recording by sensing a temperature in an optical pick-up part and changing an FPDO(Front Photo Diode Out) value depending on the sensed temperature. An apparatus for controlling optical power in an optical disk device which forms an APC(Automatic Power Control) loop, the apparatus comprises an optical pick-up part(100), an RF part(102), a memory part(106), and a control part(104). The optical pick-up comprises a PD(Photo Diode,10), an LD(Laser Diode) driving part(12), and a temperature sensor(14). The RF part receives an FPDO value through the PD, and changes a voltage value in the LD driving part. The memory part includes an objective FPDO value table corresponding to the changing temperature data. The control part reads out the objective FPDO value corresponding to the temperature data sensed by the temperature sensor from the memory part and provides it to the RF part, so as to maintain optical power in the optical disk device at a constant level.

Description

Optical power control device and method for optical disk device {METHOD AND APPARATUS FOR CONTROLING POWER IN OPTICAL DISC DEVICE}

1 is a block diagram of an optical power control device of an optical disk device according to an aspect of the present invention;

2 is a flowchart illustrating an optical power control process of an optical disk apparatus according to another aspect of the present invention.

<Explanation of symbols for the main parts of the drawings>

100: optical pickup section 102: RF section

104: control unit 106: ROM

10: PD (Photo Diode) 12: LD (Laser Diode) Driver

14: temperature sensor

The present invention relates to an automatic power control (APC) loop control technique of an optical disk device, and more particularly, to an optical power control device and a method of an optical disk device suitable for minimizing an optical power error against a temperature change.

In general, an optical disk apparatus includes an APC circuit that always maintains a constant power of recording light, and an APC circuit that always maintains a constant power of reproduction light for reproduction. A predetermined recording power voltage or a reproduction power voltage is outputted to the optical pickup so that the power of the predetermined recording light or the power of the reproduction light is kept constant.

A recording and reproducing APC circuit of a general optical disk device outputs an optimum reproducing power voltage or a recording power voltage through a D / A converter provided therein to perform a reproducing or recording operation. The reproduction power voltage or the recording power voltage is appropriately adjusted by feeding back an output signal (FPDO: Front Photo Diode Out) of the internal PD during the reproduction or recording operation.

Accordingly, a reproduction power voltage or a recording power voltage is required for the optical pickup to read and reproduce data on the optical disk or to record data on the optical disk, so that power set-up when power is applied to the optical disk device. The process is performed. By setting the offset, regeneration power voltage, and recording power voltage values of each converter based on the stored offset and voltage values, the reproducing or recording operation is performed by the optimum reproducing power or the optimal recording power. To be done.

On the other hand, LD (Laser Diode) driven by a current has a disadvantage in that the light efficiency decreases as the temperature increases. In order to overcome this problem, the method used in the CD / DVD system is the aforementioned APC algorithm. It is an algorithm that focuses the amount of light emitted from the LD of the pickup onto the disk on one side and monitors the amount of light emitted on the opposite side, increasing the drive current when the amount of light falls, and continuously giving the same power.

In practice, however, it is not easy to maintain perfect optical power because the temperature increases not only the LD efficiency but also the PD efficiency. In other words, the LD that generates the optical power or the PD detector that receives the feedback and controls the feedback is different depending on the temperature (normally, the optical power drops when the temperature rises) to maintain an accurate APC loop. Many difficulties are following.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described prior art situation, and by changing the FPDO target value according to the temperature detected in the pickup, the optical disk device can improve the playback and recording stability by minimizing the optical power error against temperature change. It is an object of the present invention to provide a power control apparatus and method.

According to an aspect of the present invention for achieving the above object, an optical disk device for forming an APC loop, an optical pickup unit having a photodiode, a laser diode driver, a temperature sensor, and the FPDO value through the photodiode An RF unit for changing the voltage value of the laser diode driver, a memory unit in which a target FPDO value corresponding to the changed temperature data is tabled, and a target FPDO corresponding to temperature data measured by the temperature sensor An optical power control apparatus of an optical disk apparatus includes a control unit that reads a value from the memory unit and provides the RF unit to the RF unit to maintain a constant optical power of the optical disk apparatus.

According to another aspect for achieving the object of the present invention, an optical power control method of an optical disk device having a photodiode, a laser diode driver, and an optical pickup unit, each of which is provided with a temperature sensor, the optical power is generated from the optical pickup unit Forming an APC loop such that a target FPDO value of the laser diode driver becomes an initial set voltage, measuring temperature data of the optical pickup unit through the temperature sensor, and measuring the optical pickup unit measured by the temperature sensor And forming an APC loop such that the target FPDO value is changed in accordance with temperature data.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

1 is a schematic block diagram of an optical power control apparatus of an optical disk apparatus according to an aspect of the present invention, and includes an optical pickup unit 100, an RF unit 102, a control unit 104, and a ROM 106. Include.

As shown, the optical pickup unit 100 performs a reproducing or recording operation with a reproducing power or recording power corresponding to a reproducing power voltage or a recording power voltage output from the RF unit 102, which will be described later. By feeding back the output signal (hereinafter referred to as FPDO) of the PD 10 to the RF unit 102, the regenerative power voltage or the write power voltage is adjusted appropriately.

At this time, the optical pickup unit 100 is provided with a temperature sensor 14 according to the present embodiment, and the target FPDO value of the APC loop according to the temperature data detected by the temperature sensor 14 for accurate control of the optical power. Change to maintain optical power. The change of the target FPDO value can be implemented by changing the voltage of the LD driver 12, which is one of the main features of the present invention.

The RF unit 102 includes a recording and reproducing APC circuit, and outputs a reproducing power voltage or a recording power voltage through a digital-analog converter (not shown) provided therein.

The controller 104 sets the offset, the reproduction power voltage, and the write power voltage of the RF unit 102 based on the values stored in the ROM 106 to be described later when the power is applied to the optical disk device. . In particular, the control unit 104 controls the RF unit 102 to maintain the optical power by changing the target FPDO value according to the temperature data applied from the temperature sensor 14 according to the present embodiment. The detailed control operation of the control unit 104 will be described in more detail with reference to FIG. 2.

The ROM 106 stores the offset and regeneration power voltages of the recording and reproducing APC circuits, and the recording power voltages for optimal reproduction power and recording power output. Further, in the ROM 106, a target FPDO value corresponding to the temperature data to be changed is tabulated according to the present embodiment, and a predetermined target FPDO value is read out by the control unit 104 and provided to the RF unit 102. do.

Hereinafter, the optical power control process of the optical disk apparatus according to another aspect of the present invention together with the above-described configuration will be described in detail with reference to the flowchart of FIG. 2.

First, in step S200, the controller 104 generates optical power to the optical pickup unit 100, and proceeds to step S202.

In step S202, the controller 104 forms an APC loop such that the FPDO value becomes the first set voltage. More specifically, the LD drive unit 12 is controlled so that the target FDPO value becomes 2.457V, for example. This process is an APC operation that is initially performed when the optical power of the optical disk device is generated, and the temperature in the optical pickup unit 100 at this time is usually measured at 20 ° C.

Thereafter, the controller 104 proceeds to step S204 to measure temperature data from the temperature sensor 14 according to the present embodiment.

After the temperature measurement, the control unit 104 proceeds to step S206 to determine whether the measurement temperature is the first set temperature, for example, 30 ° C.

If it is determined in step S206 that the measured temperature data of the temperature sensor 14 is the first set temperature, the control unit 104 proceeds to step S208 to form an APC loop such that the FPDO value becomes the second set voltage. . More specifically, the LD driver 12 is controlled so that the target FPDO value is changed to, for example, 2.456V.

Similarly, if the measured temperature data of the temperature sensor 14 is the second set temperature, for example 40 ° C., the LD driver 12 is controlled so that the target FPDO value is changed to the third set voltage, for example, 2.455V.

That is, the present embodiment changes the FPDO value so that the optical power output always maintains the same value, for example, 1.2 mW, even if the temperature of the optical pickup unit 100 changes from 20 ° C. to 40 ° C., for example. It features.

If a target FPDO value corresponding to such temperature data is expressed in a table, it may be illustrated as shown in Table 1 below.

TABLE 1

Temperature FPDO Input current Measurement power 20 ℃ 2.457 V 0.639 1.2 mW 30 ℃ 2.456 V 0.796 1.2 mW 40 ℃ 2.455 V 0.868 1.2 mW

As shown in Table 1, by applying an algorithm that decreases the target FPDO value by 0.001V each time the temperature rises by 10 ° C, the target FPDO value is changed when the temperature of the optical pickup portion is changed from 20 ° C to 40 ° C. Reduce from 2.457V to 2.455V so that the optical power is always the same at 1.2mW.

If the FPDO value is not changed even though the temperature is changed as in the related art, it can be seen through experiments that the final optical power is measured at 1.14 mW.

However, in the present invention, it was found that the optical power is always kept constant by flexibly applying the FPDO value according to the temperature change.

As mentioned above, although this invention was demonstrated concretely based on the Example, this invention is not limited to such an Example, Of course, various deformation | transformation are possible for it within the technical idea and the scope of a claim mentioned later.

According to the present invention, by measuring the temperature of the optical pickup unit of the optical disk device and by changing the FPDO value according to the measured temperature to maintain a constant optical power at all times regardless of the temperature change, thereby minimizing the optical power error of the optical disk device Play and record stability can be maximized.

Claims (7)

An optical disk device forming an APC loop, An optical pickup unit including a photodiode, a laser diode driver, and a temperature sensor, An FPDO value is input through the photodiode, and the RF unit changes a voltage value of the laser diode driver; A memory section in which a target FPDO value corresponding to the temperature data to be changed is tabulated; A control unit that maintains a constant optical power of the optical disk device by reading a target FPDO value corresponding to the temperature data measured by the temperature sensor from the memory unit and providing it to the RF unit. Optical power control device of the optical disk device comprising a. The method of claim 1, And a target FPDO value tabled in the memory unit is an FPDO value of a preset decrease change unit corresponding to temperature data of a preset rise change unit. The method of claim 2, The preset upward change unit is 10 ° C., and the preset decrease change unit is 0.001V. An optical power control method of an optical disk device having a photodiode, a laser diode driver, and an optical pickup unit, each of which is provided with a temperature sensor, Forming an APC loop such that a target FPDO value of the laser diode driver becomes an initial set voltage when optical power is generated from the optical pickup unit; Measuring temperature data of the optical pickup unit through the temperature sensor; Forming an APC loop such that the target FPDO value is changed according to temperature data of the optical pickup unit measured by the temperature sensor; Optical power control method of an optical disk device comprising a. The method of claim 4, wherein And the target FPDO value is an FPDO value of a preset decrease change unit corresponding to temperature data of a preset rise change unit. The method of claim 5, The preset rising change unit is 10 ° C., and the preset decreasing change unit is 0.001V. The method of claim 4, wherein And the optical disk device always outputs a constant optical power even if the temperature data changes.

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