Method for controlling laser power of an optical pickup unit

Abstract

A method for controlling laser power of an optical pickup unit (OPU) includes: providing a first relationship between the laser power and a driving parameter, wherein the driving parameter is utilized for driving a laser diode (LD) of the OPU, and the first relationship corresponds to a first temperature; utilizing a temperature-related model to convert the first relationship into a second relationship between the laser power and the driving parameter, wherein the second relationship corresponds to a second temperature; and storing the first relationship for being utilized at the first temperature, and storing the second relationship for being utilized at the second temperature.

1 . A method for controlling laser power of an optical pickup unit (OPU), the method comprising:
 providing a first relationship between the laser power and a driving parameter, wherein the driving parameter is utilized for driving a laser diode (LD) of the OPU, and the first relationship corresponds to a first temperature;   utilizing a temperature-related model to convert the first relationship into a second relationship between the laser power and the driving parameter, wherein the second relationship corresponds to a second temperature; and   storing the first relationship for being utilized at the first temperature, and storing the second relationship for being utilized at the second temperature.   
   
   
       2 . The method of  claim 1 , wherein the driving parameter represents an LD driving voltage for controlling an LD driving current of the LD. 
   
   
       3 . The method of  claim 1 , wherein the driving parameter represents an LD driving current of the LD. 
   
   
       4 . The method of  claim 1 , wherein the step of providing the first relationship between the laser power and the driving parameter further comprises:
 applying a target command carrying a specific value to an automatic power calibration (APC) circuit for controlling the laser power; and   when the APC circuit reaches a steady state at the first temperature, measuring the laser power and the driving parameter to derive the first relationship.   
   
   
       5 . The method of  claim 1 , wherein the step of providing the first relationship between the laser power and the driving parameter further comprises:
 applying a target command carrying a first value to an automatic power calibration (APC) circuit for controlling the laser power, and when the APC circuit reaches a steady state at the first temperature, measuring the laser power and the driving parameter to derive a first data point;   applying a target command carrying a second value to the APC circuit, and when the APC circuit reaches a steady state at the first temperature, measuring the laser power and the driving parameter to derive a second data point; and   utilizing the first and second data points to derive the first relationship.   
   
   
       6 . The method of  claim 1 , wherein the temperature-related model corresponds to curves having respective slopes with respect to different temperatures. 
   
   
       7 . The method of  claim 1 , wherein the temperature-related model corresponds to parallel curves with respect to different temperatures. 
   
   
       8 . The method of  claim 1 , further comprising:
 measuring the laser power and the driving parameter at the second temperature to derive information of the temperature-related model.   
   
   
       9 . The method of  claim 8 , wherein the step of measuring the laser power and the driving parameter at the second temperature to derive the information of the temperature-related model further comprises:
 applying a target command carrying a specific value to an automatic power calibration (APC) circuit for controlling the laser power; and   when the APC circuit reaches a steady state at the second temperature, measuring the laser power and the driving parameter to derive the information of the temperature-related model.   
   
   
       10 . The method of  claim 8 , further comprising:
 applying a target command carrying a first value to an automatic power calibration (APC) circuit for controlling the laser power, and when the APC circuit reaches a steady state at the second temperature, measuring the laser power and the driving parameter to derive a first data point;   applying a target command carrying a second value to the APC circuit, and when the APC circuit reaches a steady state at the second temperature, measuring the laser power and the driving parameter to derive a second data point; and   utilizing the first and second data points to derive the information of the temperature-related model.   
   
   
       11 . The method of  claim 1 , wherein the first and second relationships correspond to a first channel; and the method further comprises:
 utilizing the first and second relationships to derive an additional relationship between the laser power and the driving parameter in a second channel.   
   
   
       12 . The method of  claim 11 , wherein the driving parameter represents an LD driving voltage; and the step of utilizing the first and second relationships to derive the additional relationship between the laser power and the driving parameter in the second channel further comprises:
 transforming a first voltage difference into a second voltage difference;   wherein the first voltage difference represents a difference between different voltage values of the LD driving voltage in the first channel at the first and the second temperatures, respectively;   wherein the second voltage difference represents a difference between different voltage values of the LD driving voltage in the second channel at the first and the second temperatures, respectively.   
   
   
       13 . The method of  claim 11 , wherein the driving parameter represents an LD driving current of the LD; and the step of utilizing the first and second relationships to derive the additional relationship between the laser power and the driving parameter in the second channel further comprises:
 transforming a first current difference into a second current difference;   wherein the first current difference represents a difference between different current values of the LD driving current in the first channel at the first and the second temperatures, respectively;   wherein the second current difference represents a difference between different current values of the LD driving current in the second channel at the first and the second temperatures, respectively.   
   
   
       14 . A method for controlling laser power of an optical pickup unit (OPU), the method comprising:
 providing a first relationship between the laser power and a driving parameter, wherein the driving parameter is utilized for driving a laser diode (LD) of the OPU, and the first relationship corresponds to a first temperature;   providing a second relationship between the laser power and the driving parameter, wherein the second relationship corresponds to a second temperature; and   storing the first relationship for being utilized at the first temperature, and storing the second relationship for being utilized at the second temperature.   
   
   
       15 . The method of  claim 14 , wherein the driving parameter represents an LD driving voltage for controlling an LD driving current of the LD. 
   
   
       16 . The method of  claim 14 , wherein the driving parameter represents an LD driving current of the LD. 
   
   
       17 . The method of  claim 14 , wherein the step of providing the first relationship between the laser power and the driving parameter further comprises:
 applying a target command carrying a specific value to an automatic power calibration (APC) circuit for controlling the laser power; and   when the APC circuit reaches a steady state at the first temperature, measuring the laser power and the driving parameter to derive the first relationship.   
   
   
       18 . The method of  claim 14 , wherein the step of providing the first relationship between the laser power and the driving parameter further comprises:
 applying a target command carrying a first value to an automatic power calibration (APC) circuit for controlling the laser power, and when the APC circuit reaches a steady state at the first temperature, measuring the laser power and the driving parameter to derive a first data point;   applying a target command carrying a second value to the APC circuit, and when the APC circuit reaches a steady state at the first temperature, measuring the laser power and the driving parameter to derive a second data point; and   utilizing the first and second data points to derive the first relationship.   
   
   
       19 . The method of  claim 14 , wherein the step of providing the second relationship between the laser power and the driving parameter further comprises:
 applying a target command carrying a specific value to an automatic power calibration (APC) circuit for controlling the laser power; and   when the APC circuit reaches a steady state at the second temperature, measuring the laser power and the driving parameter to derive the second relationship.   
   
   
       20 . The method of  claim 14 , wherein the step of providing the second relationship between the laser power and the driving parameter further comprises:
 applying a target command carrying a first value to an automatic power calibration (APC) circuit for controlling the laser power, and when the APC circuit reaches a steady state at the second temperature, measuring the laser power and the driving parameter to derive a first data point;   applying a target command carrying a second value to the APC circuit, and when the APC circuit reaches a steady state at the second temperature, measuring the laser power and the driving parameter to derive a second data point; and   utilizing the first and second data points to derive the second relationship.