WO2005101597A1 - レーザ駆動装置、レーザ駆動ic、光ピックアップ及び情報再生装置 - Google Patents
レーザ駆動装置、レーザ駆動ic、光ピックアップ及び情報再生装置 Download PDFInfo
- Publication number
- WO2005101597A1 WO2005101597A1 PCT/JP2005/006460 JP2005006460W WO2005101597A1 WO 2005101597 A1 WO2005101597 A1 WO 2005101597A1 JP 2005006460 W JP2005006460 W JP 2005006460W WO 2005101597 A1 WO2005101597 A1 WO 2005101597A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- temperature
- voltage controlled
- controlled oscillator
- oscillation amplitude
- laser
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/125—Optical beam sources therefor, e.g. laser control circuitry specially adapted for optical storage devices; Modulators, e.g. means for controlling the size or intensity of optical spots or optical traces
- G11B7/126—Circuits, methods or arrangements for laser control or stabilisation
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
- H01S5/042—Electrical excitation ; Circuits therefor
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
- H01S5/042—Electrical excitation ; Circuits therefor
- H01S5/0427—Electrical excitation ; Circuits therefor for applying modulation to the laser
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/068—Stabilisation of laser output parameters
- H01S5/06804—Stabilisation of laser output parameters by monitoring an external parameter, e.g. temperature
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/068—Stabilisation of laser output parameters
- H01S5/0683—Stabilisation of laser output parameters by monitoring the optical output parameters
Definitions
- Laser drive device laser drive IC , optical pickup and information reproducing device
- the present invention relates to a laser drive device, a laser drive IC, an optical pickup, and an information reproducing device, and in particular, in an optical disk recorder or an optical disk drive for a PC, information is recorded on a phase change recording type optical disk such as a DVD Related to things used to play
- a semiconductor laser light source is used in an optical disc recording / reproducing apparatus to reproduce information from the optical disc.
- the semiconductor laser light source outputs the light intensity necessary for reading out information, when an appropriate drive current is supplied from the laser drive device.
- the laser driving device there is a problem of return light noise in which the light emission intensity fluctuates when the reflected light of the optical disk power returns to the semiconductor laser.
- a laser drive apparatus has been proposed in which a high frequency signal is superimposed on the drive current of the semiconductor laser and the semiconductor laser is oscillated in multiple modes.
- Patent Document 1 Patent No. 2756820
- the conventional configuration has the following problems.
- the higher the temperature the lower the series resistance of the semiconductor laser. Therefore, when high frequency signals are superimposed on a semiconductor laser, the influence of the drop in series resistance is greater than the drop in differential quantum efficiency 7 ?, and the peak level of the light emission intensity may rise. Therefore, the light device If the margin of the reproduction light intensity which does not deteriorate the recording mark is narrowed along with the improvement of the recording density of the image, the peak value of the light emission intensity may deteriorate the information recorded on the optical disc.
- Figure 7 shows an example of the temperature change of series resistance in a red laser.
- the blue laser mainly composed of GaN is considered to be approximately 2 to 4 times as large as the red laser whose series equivalent resistance value is high due to its structure.
- the present invention is intended to solve the above-mentioned conventional problems, and it is an object of the present invention to provide a laser drive device capable of always performing optimum modulation of the light emission intensity even if the load changes due to temperature change.
- a laser drive device superimposes a constant current on a current source for supplying a constant current to a semiconductor laser and a high frequency signal whose oscillation amplitude changes according to temperature. And a voltage controlled oscillator.
- the voltage controlled oscillator preferably has a voltage controlled oscillator and a resistor whose value changes with temperature.
- the resistance has a characteristic that the relative resistance value rises with temperature, and the voltage control oscillator generates a high frequency signal with an oscillation amplitude set in inverse proportion to the relative resistance value. Is preferred.
- the voltage controlled oscillator preferably has a temperature sensor which measures temperature and outputs it as an electrical signal, and a voltage controlled oscillator which generates a high frequency signal whose oscillation amplitude changes according to the measured temperature.
- the voltage controlled oscillator further comprises a temperature compensation table having information to determine the oscillation amplitude of the voltage controlled oscillator based on the measured temperature.
- the semiconductor laser can always be driven with the optimum emission intensity regardless of the temperature, and the temperature margin in the optical disc reproduction can be expanded. be able to.
- FIG. 1 is a main configuration diagram of a laser drive device according to a first embodiment of the present invention.
- FIG. 2 (a) A diagram showing the relationship between the relative resistance value Ra of the temperature compensation resistor and the temperature (b) A diagram showing the relationship between the oscillation amplitude K and the temperature
- FIG. 4 A main configuration diagram of a laser drive device according to a second embodiment of the present invention
- FIG. 6 Diagram showing oscillation amplitude A, series resistance Rs, laser drive current Id, and laser emission waveform at each temperature
- FIG. 8 A diagram showing an optical pickup equipped with a laser drive device according to the present invention, and an information reproducing device (Embodiment 3).
- FIG. 9 A diagram showing an optical pickup equipped with a laser drive device according to the present invention, and an information reproducing device (Embodiment 4)
- FIG. 1 is a block diagram of a laser drive device or a laser drive IC according to Embodiment 1 of the present invention.
- the semiconductor laser 15 is used as a light source of an optical pickup such as a DVD, and has an equivalent resistance Rs.
- a laser driving device or a laser driving IC is a device for supplying a driving current to a semiconductor laser 15, and includes a current source 11, a temperature compensation resistor 12, a voltage control oscillator 13, and a high pass filter 14. Is equipped.
- the current source 11 outputs a drive current Ir which is supplied to the semiconductor laser 15 so as to obtain a desired light intensity.
- the voltage control oscillator 13 is connected to the temperature compensation resistor 12.
- the voltage controlled oscillator 13 and the temperature compensation resistor 12 constitute a voltage controlled oscillator in which a high frequency signal HF whose oscillation amplitude changes according to the temperature is superimposed on a constant current Ir.
- the temperature compensation resistor 12 has a characteristic that the relative resistance value Ra rises according to the temperature
- the voltage control oscillator 13 has a temperature It oscillates with the oscillation amplitude set in inverse proportion to the relative resistance value Ra of the compensation resistor 12!
- the oscillation frequency of the voltage control oscillator 13 is set to reduce return light noise, and is generally set in the range of 250 to 450 [MHz].
- the voltage control oscillator 13 superimposes the high frequency signal HF on the drive current signal Ir via the high pass filter 14 and superimposes the high frequency signal HF on the drive current signal Ir.
- the current Id is supplied to the semiconductor laser 15. As a result, the semiconductor laser 15 oscillates in a multi mode.
- the feature of the present invention is to make the oscillation amplitude A of the high frequency signal HF superimposed on the drive current Ir outputted from the current source 11 variable according to the temperature. That is, the oscillation amplitude A of the high-frequency signal HF is determined so as to have a monotonically decreasing characteristic with respect to the temperature in inverse proportion to the relative resistance value Ra of the temperature compensation resistor 12, that is, as shown in FIG. .
- the monotonically decreasing function is related by the temperature characteristic (which decreases as the temperature increases) of the equivalent resistance Rs of the semiconductor laser 15 shown in FIG.
- the drive signal Id input to the semiconductor laser 15 is changed according to the temperature change to maintain the light emission waveform of the semiconductor laser 15 equal regardless of the temperature change.
- the temperature T 25 ° C.
- the equivalent series resistance Rs of the semiconductor laser 15 is 5 ⁇ (see FIG. 7).
- FIG. 4 is a block diagram of a laser drive device or a laser drive IC according to a second embodiment of the present invention.
- the semiconductor laser 6 is used as a light source of an optical pickup such as a DVD Have equivalent resistance Rs.
- a laser driving device or a laser driving IC is a device for supplying a driving current Id to the semiconductor laser 6, and includes a current source 1, a temperature sensor 2, a temperature compensation table 3, and a voltage controlled oscillator. 4 and a high pass filter 5 are provided.
- the current source 11 outputs a drive current Ir which is supplied to the semiconductor laser 15 so as to obtain a desired light intensity.
- the temperature sensor 2 measures the temperature and outputs the measured temperature as an electrical signal.
- the temperature compensation table 3 sets the amplitude of the voltage control oscillator 4 according to the temperature measured by the temperature sensor 2.
- the voltage control oscillator 4, the temperature compensation table 3, and the temperature sensor 2 constitute a voltage control oscillation device in which a high frequency signal HF whose oscillation amplitude changes according to temperature is superimposed on a constant current Ir.
- the temperature compensation table 3 holds the correspondence between the temperature and the output current of the voltage control oscillator 4 as data, and as a result, the amplitude of the voltage control oscillator 4 is determined by the temperature compensation table 3.
- the oscillation frequency of the voltage controlled oscillator 4 is set to reduce the return light noise.
- the voltage controlled oscillator 4 superimposes the high frequency signal HF on the drive current signal Ir via the high pass filter 5, and the current Id in which the high frequency signal HF is superimposed on the drive current signal Ir is supplied to the semiconductor laser 6. As a result, the semiconductor laser 6 oscillates in multi mode.
- the laser drive device or the laser drive IC includes the temperature sensor 2 and the temperature compensation table 3 to define the temperature characteristic of the oscillation amplitude of the voltage controlled oscillator 4. Ru.
- the feature of the present invention is to make the oscillation amplitude A of the high frequency signal HF superimposed on the drive current Ir of the semiconductor laser 6 variable according to the temperature. That is, the temperature compensation table 3 determines the oscillation amplitude A of the high frequency signal HF in a monotonically decreasing relationship as shown in FIG. 5 with respect to the temperature measured by the temperature sensor 2.
- the monotonically decreasing function is related by the temperature characteristic (which decreases as the temperature increases) of the equivalent resistance R S of the semiconductor laser 6 as shown in FIG.
- the operation of maintaining the emission waveform of the semiconductor laser 6 equally regardless of the temperature change will be described by changing the drive signal Id input to the semiconductor laser 6 according to the temperature change using FIG. Do.
- Rs 5 ⁇ , equivalent load
- the optical pickup provided with the laser driving device described in the first and second embodiments of the present invention to the information reproducing device, the effect can be exhibited.
- An information reproducing apparatus 110 of FIG. 8 includes an optical pickup 100, a main substrate 111, and a motor 115.
- the optical pickup 100 irradiates the optical disk 119 with a laser beam to convert the information recorded on the optical recording medium into an electric signal and outputs the electric signal.
- the optical pickup 100 includes a laser drive device 101, a semiconductor laser 102, a polarization beam splitter 103, an optical detector 104, an objective lens 105, and a light receiving element 106.
- the semiconductor laser 102 is driven by the laser driving device 101 of the present invention, and light intensity output necessary for reproducing information is made.
- the objective lens 105 condenses the light on the information recording layer of the optical disc 119. Further, the reflected light from the information recording layer is irradiated to the light receiving element 106 by the polarization beam splitter 103, and is converted into an electric signal as a reproduction signal and a servo signal.
- the main substrate 111 includes a controller 112, a laser power control 113, a servo circuit 114, a read channel 116, and an error correction and address decoder unit 117.
- the reproduction signal output from the optical pickup 100 has no waveform equalization by the read channel 116.
- the servo signal output from the optical pickup 100 is input to the controller 112, and the control signal is output to the servo circuit 114.
- the servo circuit 114 drives the actuator 104 based on the control signal to perform focus control and tracking control of the light spot on the optical disc 119.
- An EEP-ROM 118 is mounted on the main board 111 shown in FIG.
- the characteristics of the pickup 100 are stored in the EEP-RO M18.
- the EEP-ROM 118 holds the offset and detection sensitivity of the light receiving element 106 in order to improve the accuracy of laser power control in tracking control and focus control.
- the threshold current of the laser, the slope efficiency, the amplitude setting value of high frequency superposition, the frequency setting value and the like are held.
- the contents stored in the temperature compensation table 3 of the second embodiment are also stored in the EEP-ROM 118. In this case, the EEP-ROM 118 functions as the temperature compensation table 3
- the following method may be considered.
- the characteristic value of the pickup 100 is measured and stored in the EEP-ROM.
- a characteristic value is previously described as a bar code on the pickup 100, and after combining the pickup 100 and the drive, the bar code is read and the characteristic value of the pickup 100 is stored in the EEP-ROM 118. Do. In this case, it is possible to absorb the element variation of the temperature characteristic of the high frequency superposition amplitude.
- the EEP-ROM 120 is mounted on the pickup 100, and the characteristic value of the pickup 100 is held in the EEP-ROM 120.
- This structure has the advantage of shortening the manufacturing process of the optical disc apparatus. Furthermore, since the E EP-ROM 120 on the pickup 100 has the function of the temperature compensation table 3, it is possible to absorb the element variation of the temperature characteristic of the high frequency superposition amplitude.
- the laser driving device has high light intensity characteristics without depending on temperature, and is useful as a DVD recording / reproducing device or the like.
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- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Optical Head (AREA)
- Semiconductor Lasers (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2004120128A JP2007234624A (ja) | 2004-04-15 | 2004-04-15 | レーザ駆動装置 |
JP2004-120128 | 2004-04-15 |
Publications (1)
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WO2005101597A1 true WO2005101597A1 (ja) | 2005-10-27 |
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Application Number | Title | Priority Date | Filing Date |
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PCT/JP2005/006460 WO2005101597A1 (ja) | 2004-04-15 | 2005-04-01 | レーザ駆動装置、レーザ駆動ic、光ピックアップ及び情報再生装置 |
Country Status (2)
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JP (1) | JP2007234624A (ja) |
WO (1) | WO2005101597A1 (ja) |
Families Citing this family (1)
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JP2010146673A (ja) * | 2008-12-22 | 2010-07-01 | Hitachi Ltd | 光情報再生方法 |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0575192A (ja) * | 1991-09-11 | 1993-03-26 | Ricoh Co Ltd | 半導体レ−ザ駆動回路 |
JP2001167439A (ja) * | 1999-12-03 | 2001-06-22 | Matsushita Electric Ind Co Ltd | 光ディスク記録再生装置および撮像装置 |
JP2002111120A (ja) * | 2000-09-28 | 2002-04-12 | Toshiba Electronic Engineering Corp | 光送信モジュール |
JP2002335041A (ja) * | 2001-05-07 | 2002-11-22 | Sony Corp | レーザ駆動装置及びレーザ駆動方法 |
JP2003308624A (ja) * | 2002-04-12 | 2003-10-31 | Matsushita Electric Ind Co Ltd | 光ディスク装置 |
-
2004
- 2004-04-15 JP JP2004120128A patent/JP2007234624A/ja active Pending
-
2005
- 2005-04-01 WO PCT/JP2005/006460 patent/WO2005101597A1/ja active Application Filing
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0575192A (ja) * | 1991-09-11 | 1993-03-26 | Ricoh Co Ltd | 半導体レ−ザ駆動回路 |
JP2001167439A (ja) * | 1999-12-03 | 2001-06-22 | Matsushita Electric Ind Co Ltd | 光ディスク記録再生装置および撮像装置 |
JP2002111120A (ja) * | 2000-09-28 | 2002-04-12 | Toshiba Electronic Engineering Corp | 光送信モジュール |
JP2002335041A (ja) * | 2001-05-07 | 2002-11-22 | Sony Corp | レーザ駆動装置及びレーザ駆動方法 |
JP2003308624A (ja) * | 2002-04-12 | 2003-10-31 | Matsushita Electric Ind Co Ltd | 光ディスク装置 |
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JP2007234624A (ja) | 2007-09-13 |
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