KR100765734B1 - Auto laser diode power controlling apparatus in laser diode driver - Google Patents

Abstract

The present invention relates to an optical recording apparatus, and more particularly, to an automatic laser diode power supply control apparatus for a laser diode driver for optimally controlling a laser diode that determines performance of a recording apparatus. In the laser diode driver, an automatic laser diode power supply control device includes a switching unit for high-speed switching of a plurality of channels corresponding to an optical output level, a first adder for adding a output of the switching unit to generate a predetermined recording waveform, and the first adder. An amplifying unit for amplifying the recording waveform output of the adder at a predetermined ratio, a modulating unit for canceling the optical interference noise generated from the pickup, and a plurality of channels corresponding to the optical output level by inputting a current optical output signal converted into voltage Outputs an optical output signal for recording on a predetermined medium by adding outputs of a compensator, a first amplifier, a modulator, and a compensator to compensate for the reduction of the optical output signal due to the temperature rise of the laser diode according to the signal. It includes a second adder. According to the present invention, two different LDs can be used simultaneously with adding an ALPC function to an existing LD drive. Therefore, the separate ALPC circuit can be reduced or eliminated, and the use of two LDs facilitates the construction of a composite device, and the device can be made smaller, lighter and cheaper.

Description

Auto laser diode power controlling apparatus in laser diode driver

1 is a block diagram showing the configuration of a conventional laser diode power control device.

2 is a diagram showing the light output versus current characteristics of a laser diode.

Figure 3 is a block diagram showing the configuration of an automatic laser diode power control device in the laser diode driver according to the present invention.

4 is a timing diagram illustrating an operation of a control signal according to the apparatus shown in FIG. 3.

The present invention relates to an optical recording apparatus, and more particularly, to an automatic laser diode power supply control apparatus for a laser diode driver for optimally controlling a laser diode that determines performance of a recording apparatus.

The modern society is called the information age or the multimedia age. Therefore, this era requires high-capacity recording media, and optical recording devices such as magnetic optical disc drives (MODDs) and digital versatile disc random access memories (DVD-RAMs) are used. These devices use laser diodes, which are very sensitive to changes in temperature.

1 is a block diagram showing the configuration of a conventional laser diode power control device.

2 is a diagram showing the light output versus current characteristics of a laser diode.

As shown in FIG. 1, a laser diode drive (hereinafter referred to as LD drive) is composed of respective switching units 10, 11, and 12 for high speed switching of a plurality of channels. The output of 12 is added by the adder 13. The added output value is amplified by the amplifier 14 by a predetermined ratio. In order to cancel the optical interference noise generated in the pick-up, the output of the high frequency modulator (HFM) 15 and the amplifier 14 are added by the adder 16 and output as an LD drive signal. The power supplied to the switching units 10, 11, 12 may be either current or voltage. Each switching unit 10, 11, 12 has a control signal for each on / off, and may also have an input terminal to enable / disable the LD drive.

A current corresponding to a power level to be driven is supplied to each channel input terminal, that is, a peak level, a bias level, and a read level. In addition, a signal for controlling each power level is input to each of the control units 10, 11, 12. Thus, the output of each switching section 10, 11, 12 is added in the adding section 13, which has the same waveform as the write pulse. At this time, since it is weak to drive LD directly, the amplification unit 14 amplifies a given amplification ratio (Gain). The amplifying signal and the output signal of the HFM 15 for removing noise from the pickup are added by the adder 16 and output as a signal for driving the LD drive. By this method, the LD can output the light output in the same form as the recording waveform and record it on the media. Here, the HFM 15 is set to the most effective frequency and amplitude, and is mainly used only in the read mode.

2 is a graph showing the light output versus current characteristics of the LD. As shown in FIG. 2, as the LD is turned on and used, the temperature increases, resulting in a decrease in light output on the same current. This causes a problem in the recording apparatus that results in poor recording performance and no recording.

A feature to improve this problem is Auto Laser Diode Power Control (ALPC), which has become an essential technology. However, in the prior art, since the ALPC function cannot be implemented in the LD drive, there is a problem that a separate circuit or IC is required.

In addition, with the request for the development of recording technology and the increase of capacity, the wavelength of LD will be developed to 780nm, 635nm or 650nm and 410nm in the future, and it will be used for the backward compatibility and sharing purposes. In this case, in the prior art, there is a problem in that each circuit and component are used two by two, which has a problem in that the miniaturization, light weight, and low price are realized.

 The technical problem to be achieved by the present invention is to solve the problems of the prior art, automatic laser diode power control in the laser diode driver to enable the use of two different LD at the same time to add the ALPC function to the existing LD drive. To provide a device.

Automatic laser diode power supply control apparatus for a laser diode driver for solving the technical problem to be achieved by the present invention is a optical recording device using a laser diode, a switching unit for high-speed switching each of a plurality of channels corresponding to the light output level ; A first adder which adds an output of the switching unit to generate a predetermined recording waveform; An amplifier for amplifying the recording waveform output of the first adder at a predetermined ratio; A modulator to cancel the optical interference noise generated in the pickup; A compensator for compensating for the reduction of the light output signal due to the temperature rise of the laser diode according to a plurality of channel signals corresponding to the light output level as the input of the current light output signal converted into voltage; And a second adder for adding an output of the first amplifier, modulator, and compensator to output an optical output signal for recording on a predetermined medium.

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

Figure 3 is a block diagram showing the configuration of an automatic laser diode power control device in the laser diode driver according to the present invention.

The apparatus shown in FIG. 3 includes the first to third switching units 30, 31 and 32, and the first to third switching units 30, for fast switching a plurality of channels (peak level, bias level, read level). A first adder 33 for adding the outputs of 31 and 32, a first amplifying unit 34 for amplifying the output of the first adder 33 at a constant ratio, and an HFM for canceling optical interference noise generated in the pickup. (35), a second adder 37 that adds the outputs of the ALPC 36, the first amplifier 34, the HFM 35, and the ALPC 36 to compensate for the reduction in light output due to the rise of the LD temperature. ) And a fourth switching unit 40 for selectively switching the first LD or the second LD by the LD selection signal.

In the present invention, the ALPC 36 converts an optical output signal into a current in a monitor photo diode and amplifies the current at a predetermined ratio. A comparator 36-2 for comparing the amplified signal and the bias level reference value, an up / down counter 36-3 which is operated according to a comparison result of the comparator 36-2 to determine the increase or decrease of the current; And a digital analog converter (DAC) 36-4 for converting the output of the up / down counter 36-3 to analog.

4 is a timing diagram illustrating an operation of a control signal according to the apparatus shown in FIG. 3.

Next, the present invention will be described in detail with reference to FIGS. 3 and 4.

The current or voltage corresponding to the light output level to be used is input to each channel, that is, a pit current of the first switching unit 30, a bias current of the second switching unit 31, It is input to the read current terminal of the third switching unit 32. 4 shows waveforms of power supplied to each channel (peak, bias, lead terminal). At this time, current or voltage is continuously supplied during system operation, and each on / off control is controlled by each channel control signal (peak control, bias control, lead control terminal).

The outputs of the first to third switching units 30, 31, and 32 switched by the respective channel control signals may be added by the first adder 33 to generate a desired recording waveform. Since the LD is weak to drive, it is amplified by the first amplifier 34 by giving a constant amplification ratio (Gain).

The amplified recording waveform is supplied to the LD to give an optical output. However, as the LD characteristic of FIG. 2 increases, the optical output decreases. In order to compensate for this, the ALPC 36 operates, and the current optical output is converted into a current in the Monitor-PD and input to the ALPC 36. The Monitor-PD signal is converted from current to voltage and amplified to a suitable channel level for comparison in the second amplifier 36-2. The comparator 36-2 compares the amplified Monitor-PD signal and the bias (erase) level reference value to operate the up / down counter 36-3. At this time, the peak level value can be used as a reference value. The output value of the up / down counter 36-3 is converted to analog by the DAC 36-4 and output.

The output of the DAC 36-4 is added to the recording waveform amplified by the first amplifier 34 and the output of the HFM 35 and the second adder 37 to be used as an input of the fourth switching unit 40. .

The comparator 36-2 compares the amplified Monitor-PD signal and the bias (ease) level reference value, and compares the amplified Monitor-PD signal (current optical output signal) with a reference level of the bias (ease) level. Smaller values increase the up / down counter 36-3. The output of the DAC 36-4 is increased by the output of the up / down counter 36-3 to increase the current input to the LD. On the contrary, when the comparison result of the comparison unit 36-2, the amplified Monitor-PD signal (current light output signal) is greater than the reference bias (ease) level to reduce the up / down counter 36-3. . The output of the DAC 36-4 is reduced by the output of the up / down counter 36-3, thereby reducing the current input to the LD. At this time, it is effective to be low enough not to be affected by precision ripple for each bit.

On the other hand, in the read mode, as shown in FIG. 3, an analog path using the output of the comparator 36-2 as the output of the ALPC 36 may be provided in parallel and may be selectively used. It is effective to select the lead mode in consideration of the performance of the system.

The fourth switching unit 40 switches the output of the second adder 37 input by the switch selection signal Sel-LD to the first LD 38 or the second LD 39, for example, CD. You can choose the series 780nm LD or the DVD series 650nm LD. In this way, when LD is selected, current is supplied to the selected LD to emit light after driving LD.

In the present invention, the input channel is an example of peak level, bias (ease) level, read level, but at least three channels are required for the CD series, and five channels for the DVD series (DVD-RAM). need.

On the other hand, the HFM 35 for removing noise from the pickup can also select a frequency and amplitude suitable for each LD. In the future, two LDs can be used for circuit sharing even if a blue LD having a wavelength of 410 nm is commercially available. At this time, the HFM 35 is mainly used in the lead mode.

The present invention is not limited to the above-described embodiments and can be modified by those skilled in the art within the spirit of the invention.

As described above, according to the present invention, two different LDs can be used simultaneously with adding an ALPC function to an existing LD drive. Therefore, the separate ALPC circuit can be reduced or eliminated, and the use of two LDs facilitates the construction of a composite device, and the device can be made smaller, lighter and cheaper.

Claims (8)

In the optical recording device using a laser diode, A switching unit for high-speed switching each of a plurality of channels corresponding to the light output level; A first adder which adds an output of the switching unit to generate a predetermined recording waveform; An amplifier for amplifying the recording waveform output of the first adder at a predetermined ratio; A modulator to cancel the optical interference noise generated in the pickup; A compensator for compensating for the reduction of the light output signal due to the temperature rise of the laser diode according to a plurality of channel signals corresponding to the light output level as the input of the current light output signal converted into voltage; And And a second adder configured to add an output of the first amplifier, the modulator, and the compensator to output an optical output signal for recording on a predetermined medium. The method of claim 1, wherein the compensation unit An amplifier for amplifying the current optical output signal converted into the voltage at a predetermined ratio; A comparison unit for comparing reference values of the optical output signal of the amplifier and a plurality of channel signals corresponding to the optical output level; A counting unit for counting a current for compensating the optical output signal according to a comparison result of the comparing unit; And And a digital-to-analog converter for converting the output of the counter to analog and outputting the analog to the second adder. The method of claim 2, wherein the comparison unit When the optical output signal of the amplifier is smaller than the reference value of the plurality of channel signals corresponding to the optical output level, the reference outputs a signal for increasing the counting operation of the counter, and the optical output signal of the amplifier is a reference. And a signal for reducing the counting operation of the counting unit when the reference value of the plurality of channel signals corresponding to the light output level is greater than the reference value of the plurality of channel signals. 3. The device of claim 2, wherein the device is in lead mode. Automatic laser diode power supply control device in the laser diode driver, characterized in that operated in a simple analog path for outputting the comparison value of the comparison unit to the second adder. A plurality of laser diodes for recording an optical output signal in a predetermined medium; A switching unit for high-speed switching each of a plurality of channels corresponding to the light output level; A first adder which adds an output of the switching unit to generate a predetermined recording waveform; An amplifier for amplifying the recording waveform output of the first adder at a predetermined ratio; A modulator to cancel the optical interference noise generated in the pickup; A compensator for compensating for the reduction of the light output signal due to the temperature rise of the laser diode according to a plurality of channel signals corresponding to the light output level as the input of the current light output signal converted into voltage; A second adder for adding an output of the first amplifier, modulator, and compensator to output an optical output signal for recording on the media; And And a laser diode selection means for selectively switching the light output signal of the second adder to the plurality of laser diodes by a selection signal. The method of claim 5, wherein the compensation unit An amplifier for amplifying the current optical output signal converted into the voltage at a predetermined ratio; A comparison unit for comparing reference values of the optical output signal of the amplifier and a plurality of channel signals corresponding to the optical output level; A counting unit for counting a current for compensating the optical output signal according to a comparison result of the comparing unit; And And a digital-to-analog converter for converting the output of the counter to analog and outputting the analog to the second adder. The method of claim 6, wherein the comparison unit When the optical output signal of the amplifier is smaller than the reference value of the plurality of channel signals corresponding to the optical output level, the reference outputs a signal for increasing the counting operation of the counter, and the optical output signal of the amplifier is a reference. And a signal for reducing the counting operation of the counting unit when the reference value of the plurality of channel signals corresponding to the light output level is greater than the reference value of the plurality of channel signals. 7. The device of claim 6, wherein the device is in lead mode. Automatic laser diode power supply control device in the laser diode driver, characterized in that operated in a simple analog path for outputting the comparison value of the comparison unit to the second adder.

Images