JP4356004B2 - LASER DRIVE DEVICE, LASER DRIVE METHOD, OPTICAL PICKUP AND OPTICAL DISC DRIVE - Google Patents

Description

The present invention relates to a laser driving device, a laser driving method, an optical pickup, and an optical disc drive for driving a semiconductor laser diode with a high-frequency driving current in which a high-frequency signal is superimposed on the driving current.

  Conventionally, in order to read an information signal from an optical disc, an optical pickup having a semiconductor laser diode as a light source is used. In this optical pickup, a laser driving circuit always emits a light beam with a constant light amount regardless of the temperature characteristics of the semiconductor laser diode, the light amount of which decreases as the operating temperature rises as shown in FIG. The semiconductor laser diode is driven by the semiconductor laser diode, and a part of the light beam emitted from the semiconductor laser diode is received by a photodetection element such as a photodiode, and a direct current (hereinafter, referred to as a direct current) supplied to the semiconductor laser diode based on the detection result This is referred to as drive current) and is feedback controlled (hereinafter referred to as APC (Auto Power Control) drive).

  Furthermore, in the optical pickup having such a configuration, a high-frequency drive current is generated by superimposing a high-frequency signal on the drive current, and the high-frequency light is emitted by supplying the high-frequency drive current to the semiconductor laser diode for driving. There is something like that.

  That is, as shown in FIG. 10, the laser drive circuit 1 of the optical pickup compares a predetermined reference voltage V1 with the average light amount voltage V2, inverts and amplifies the difference with the high gain amplifier 2, and supplies this to the transistor 3. As a result, a drive current I1 that is a collector current for feedback control of the average light quantity is obtained.

  Then, the laser drive circuit 1 has a sine wave with a predetermined amplitude A as shown in FIG. 11A by superimposing a high-frequency signal HS1 with a predetermined amplitude A generated by the oscillator 4 on the drive current I1. A high frequency drive current HI1 is generated, and the high frequency drive current HI1 is supplied to the semiconductor laser diode LD1.

  As a result, as shown in FIG. 12, the semiconductor laser diode LD1 emits a high-frequency light beam that alternately repeats an ON state in which the light amount reaches a peak and an OFF state in which the light amount becomes “0” at regular intervals. Yes.

  Further, the laser drive circuit 1 (FIG. 10) receives a part of the high-frequency light beam emitted from the semiconductor laser diode LD1 by the photodiode PD1, thereby being proportional to the low-band component (that is, the average light amount) of the high-frequency light beam. A direct current is obtained, and this is subjected to current-voltage conversion by the operational amplifier 5 to obtain an average light amount voltage V2.

  Then, the laser drive circuit 1 compares the average light amount voltage V2 and the reference voltage V1 by the subtractor 6 as described above, thereby setting the drive current I1 so that the reference voltage V1 and the average light amount voltage V2 are equal. Feedback control is made.

  In the optical pickup having such a configuration, when the semiconductor laser diode LD1 is turned off at regular intervals, the high-frequency light beam emitted from the semiconductor laser diode LD1 is reflected on the signal recording surface of the optical disk and again the semiconductor. Scoop noise caused by returning to the laser diode LD1 is suppressed.

  By the way, in the optical pickup having such a configuration, the high-frequency drive current HI1 is very easily affected by the operating temperature of the semiconductor laser diode LD1, and as a result, when the operating temperature of the semiconductor laser diode LD1 rises, FIG. As shown, the amplitude A of the high-frequency drive current HI1 increases.

  In this case, the optical pickup can be controlled so that the average light amount of the high-frequency light beam L1 is constant by increasing the drive current I1 by APC driving, but the high-frequency light beam L1 based on the amplitude A of the high-frequency drive current HI1. It is impossible to control up to the high band component (that is, the peak light amount).

  Therefore, in the optical pickup having such a configuration, when the operating temperature of the semiconductor laser diode LD1 rises, the peak light amount of the high-frequency light beam becomes larger than that at normal temperature as shown in FIG. In other words, the optical disk is irradiated with the increased high-frequency light beam, thereby degrading the optical disk and erasing the information signal recorded on the optical disk.

Therefore, in order to solve such a problem, a high-frequency light beam emitted from a semiconductor laser diode is received by a photo-detecting element such as a photodiode, and the detection signal obtained by the detection signal is passed through a filter. By extracting the low-band detection signal, which is a low-band component, and the high-band detection signal, which is a high-band component, and controlling the amplitude of the high-band detection signal, the peak light amount of the high-frequency light beam is always constant. An optical pickup made has been proposed. (For example, see Patent Document 1)
JP 2002-335041 A

  However, in the optical pickup having such a configuration, a low-band detection signal and a high-band detection signal having different bands are extracted from a single detection signal obtained by the light detection element at a time. It is difficult to increase both the signal detection accuracy and the high-band detection signal detection accuracy at the same time. For example, if the band of the output signal is increased in order to increase the detection accuracy of the high-band detection signal, the output of the detection signal decreases accordingly. As a result, the detection accuracy of the low-band detection signal decreases due to the influence of the offset variation of the amplifier.

  That is, if the peak light amount of the high-frequency light beam is to be reliably controlled, it is difficult to control the average light amount, resulting in difficulty in controlling the light amount.

The present invention has been made in consideration of the above points, and intends to propose a laser driving apparatus, a laser driving method, an optical pickup, and an optical disk drive capable of accurately controlling both the average light amount and the peak light amount. To do.

In the present invention for solving the above problems, by driving the semiconductor laser diode in formed by superimposing a high frequency signal on the drive current high frequency drive current, Available from the semiconductor laser diode to a laser drive equipment that emits a high-frequency light beam Average light quantity control means for detecting the average light quantity of the high-frequency light beam and feedback-controlling the drive current based on the average light quantity, and detecting the peak light quantity of the high-frequency light beam, and based on the peak light quantity, the high-frequency drive current And a first light receiving element for receiving at least a part of the high-frequency light beam, and an average light amount control means. The average light amount of the high frequency light beam is detected from the output current of the first light receiving element, and the peak light amount control means Detecting a peak light quantity of the high frequency optical beam from the output current of the optical element, the second light receiving element, and to so that is set such that many incident light quantity of the high-frequency light beam than the first light receiving element.

  As a result, the average light amount and the peak light amount of the high-frequency light beam emitted from the semiconductor laser diode can be controlled separately, and the average light amount and the peak light amount can be reliably controlled.

  According to the present invention, the average light amount and the peak light amount of the high-frequency light beam emitted from the semiconductor laser diode can be controlled separately to reliably control the average light amount and the peak light amount. Both peak light amounts can be controlled with high accuracy.

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

(1) First Embodiment (1-1) Overall Configuration of Optical Disk Drive In FIG. 1, reference numeral 20 denotes an optical disk drive as a whole, and a control unit 21 having a CPU (Central Processing Unit) configuration performs overall control. The drive control unit 22 controls the optical pickup 23 and the motor 24, and the reproduction processing unit 26 executes a predetermined reproduction process on the reproduction signal SRF read from the optical disc 25. .

  The optical pickup 23 includes, for example, a semiconductor laser diode LD2 that emits a high-frequency light beam L1 having a wavelength of 405 [nm], a photodiode PD2 that receives a part of the high-frequency light beam L1, a photodiode PD3 that receives a reflected light beam L2, A laser drive circuit (not shown) that controls the drive of the semiconductor laser diode LD2 is provided. The semiconductor laser diode LD2 emits a high-frequency light beam L1, and the high-frequency light beam L1 is converted into parallel light by the collimator lens 27. After that, the light is incident on the polarization beam splitter 29 via the optical system 28 including the λ / 2 plate, the grating, and the beam shaping anamorphic prism.

  Here, the high-frequency light beam L1 is a high-frequency light beam L1A directed to the photodiode PD2 via the condenser lens 30 by the polarization beam splitter 29, an optical system 31 and two groups including a spherical aberration correction expander and a λ / 4 plate. A high frequency light beam L1B traveling toward the optical disc 25 through the lens 32 is separated at a predetermined ratio.

  The high frequency light beam L1A is received by the photodiode PD2, while the high frequency light beam L1B is irradiated onto the signal recording surface 25A of the optical disc 25.

  The high-frequency light beam L1B is reflected by the signal recording surface 25A to become a reflected light beam L2, and enters the polarization beam splitter 29 via the second group lens 32 and the optical system 31.

  The direction of the reflected light beam L2 is bent by the polarization beam splitter 29, and is incident on the photodiode PD3 via the condensing lens 33 and the reflected beam optical system 34 including a hologram and a cylindrical lens.

  As described above, the optical pickup 23 receives the reflected light beam L2 reflected by the signal recording surface 25A of the optical disc 25 by the photodiode PD3, thereby reading the reproduction signal SRF recorded on the signal recording surface 25A. In addition, the photodiode PD2 receives the high frequency light beam L1A which is a part of the high frequency light beam L1.

(1-2) Configuration of Laser Drive Circuit Next, the configuration of the laser drive circuit 40 included in the optical pickup 23 will be described with reference to FIG. The laser driving circuit 40 includes an APC driving circuit 40A and a superimposing amplitude control circuit 40B. The APC driving circuit 40A compares a predetermined average light amount reference voltage V10 and an average light amount voltage V11, and calculates a difference therebetween. Inverted and amplified by the high gain amplifier 41, and supplied to the base of the transistor 42, a drive current I2 comprising a DC collector current for feedback control of the average light quantity is obtained.

  At this time, the superimposed amplitude control circuit 40B compares the predetermined amplitude reference voltage AV1 with the amplitude voltage AV2, amplifies the difference by the high gain amplifier 43, and supplies it to the oscillator 44 for operation to thereby operate the predetermined amplitude A. A high frequency signal HS2 composed of a sine wave is generated.

  Note that the amplitude reference voltage AV1 in this case is superimposed so as to superimpose a high-frequency signal having an amplitude value A optimized to reduce laser noise and reduce the jitter of the reproduction signal SRF as shown in FIG. Is set.

  The APC drive circuit 40A (FIG. 2) generates the high frequency drive current HI2 having the amplitude A by superimposing the high frequency signal HS2 having the amplitude A generated by the superimposed amplitude control circuit 40B on the drive current I2. A drive current HI2 is supplied to the semiconductor laser diode LD2.

  Thus, the APC drive circuit 40A emits the high frequency light beam L1 from the semiconductor laser diode LD2.

  At this time, the APC driving circuit 40A receives the high-frequency light beam L1A, which is a part of the high-frequency light beam L1, by the photodiode PD2 to which the current-voltage conversion resistor R2 is connected in series. In practice, the photodiode PD2 has a predetermined parasitic capacitance, and the output band of the photodiode PD2 is determined by the parasitic capacitance and the resistance value of the current-voltage conversion resistor R2 connected in series to the photodiode PD2.

  Therefore, in the APC driving circuit 40, the current having a resistance value (for example, 1 [kΩ]) set so that the photodiode PD2 outputs a direct current proportional to the low-band component (that is, the average light amount) of the high-frequency light beam L1A. The voltage conversion resistor R2 is connected to the photodiode PD2, thereby outputting a direct current proportional to the average light amount of the high-frequency light beam L1A from the photodiode PD2.

  The APC drive circuit 40A converts the direct current obtained from the photodiode PD2 into a voltage by the current-voltage conversion resistor R2, and amplifies the voltage by the operational amplifier 45, thereby obtaining the average light amount voltage V11.

  Thus, the APC drive circuit 40A performs feedback control of the drive current I2 so that the average light amount of the high-frequency light beam L1A received by the photodiode PD2 is constant.

  The APC drive circuit 40A generates a high frequency drive current HI2 by superimposing the high frequency signal HS2 corresponding to the amplitude reference voltage AV1 on the feedback controlled drive current I2, and supplies this to the semiconductor laser diode LD2.

  Here, the superimposed amplitude control circuit 40B determines the potential difference between both ends of the current-voltage conversion resistor R3 having a predetermined resistance value (for example, 20 [Ω]) connected in series with the semiconductor laser diode LD2, and the current-voltage conversion resistor R3. A high frequency voltage HV1 proportional to the high frequency drive current HI2 is obtained by detecting and amplifying with the differential amplifier 47 connected to both ends.

  Then, the superimposed amplitude control circuit 40B extracts the high-frequency component of the high-frequency voltage HV1 by passing the high-frequency voltage HV1 through the band-pass filter 48 that selectively extracts only the high-frequency component in the same band as the high-frequency signal HS2, and extracts the high-frequency component. The amplitude of the component is detected by the amplitude detection circuit 49. The amplitude detection circuit 49 outputs an amplitude voltage AV2 proportional to the detected amplitude.

  The superposed amplitude control circuit 40B compares the amplitude voltage AV2 and the amplitude reference voltage AV1 with the subtractor 50, amplifies the difference with the high gain amplifier 43, and supplies the amplified difference to the oscillator 44, thereby responding to the amplitude reference voltage AV1. A high frequency signal HS2 having an amplitude A is generated.

  The APC drive circuit 40A generates a high-frequency drive current HI2 by superimposing a high-frequency signal HS2 whose amplitude A is feedback-controlled on the feedback-controlled drive current I2, and supplies this to the semiconductor laser diode LD2.

  In this way, the superimposed amplitude control circuit 40B takes out the high frequency component of the high frequency drive current HI2, and performs feedback control of the amplitude A of the high frequency signal HS2 generated by the oscillator 44 in accordance with the amplitude of the high frequency component. As a result, the amplitude A of the high-frequency drive current HI2 can always be made constant.

  Thus, as shown in FIG. 4A, the laser drive circuit 40, for example, when the amplitude A of the high-frequency drive current HI2 becomes larger than that at room temperature due to an increase in the operating temperature of the semiconductor laser diode LD2, for example. By performing feedback control of the amplitude A of the high-frequency drive signal HS2 by the superimposed amplitude control circuit 40B, the amplitude A of the high-frequency drive current HI2 can be made the same as that at room temperature as shown in FIG.

  Further, as shown in FIG. 9, even when the temperature rises, the current-light characteristic of the blue-violet LD changes in the direction in which the current threshold increases, but has a characteristic that there is almost no change in the slope. Therefore, in addition to the conventional average light amount control, the peak light amount of the high-frequency light beam L1 emitted from the semiconductor laser diode LD2 can be always constant by simultaneously performing control for making the high-frequency current amplitude constant.

(1-3) Operation and Effect In the above configuration, the optical pickup 23 feedback-controls the drive current I2 according to the average light amount of the high-frequency light beam L1A received by the photodiode PD2 by the APC drive circuit 40A of the laser drive circuit 40. To do.

  Further, the optical pickup 23 detects the amplitude voltage AV2 corresponding to the amplitude A of the high-frequency drive current HI2 generated by the APC drive circuit 40A with the superimposed amplitude control circuit 40B, and superimposes it on the drive current I2 according to the amplitude voltage AV2. The amplitude A of the high frequency signal HS2 is feedback controlled.

  According to the above configuration, the optical pickup 23 can reliably control the average light amount of the high-frequency light beam L1 emitted from the semiconductor laser diode LD2 by the APC drive circuit 40A in the laser drive circuit 40, and can also control the superimposed amplitude control circuit. The peak light quantity of the high-frequency light beam L1 can be reliably controlled by 40B, and thus both the average light quantity control and the peak light quantity control can be performed with high accuracy.

  The optical pickup 23 uses a direct current obtained from the photodiode PD2 to control the average light amount of the high-frequency light beam L1 emitted from the semiconductor laser diode PD2, and uses a high-frequency light to control the peak light amount of the high-frequency light beam L1. By using the high frequency component of the drive current HI2, the average light amount and the peak light amount can be controlled separately.

(2) Second Embodiment (2-1) Overall Configuration of Optical Disk Drive In FIG. 5, in which the same reference numerals are assigned to the corresponding parts to FIG. 1, the optical disk drive 60 is the light in the first embodiment. Instead of the pickup 23, an optical pickup 61 is provided.

  The optical pickup 61 has a two-divided photodiode PD4 composed of two photodiodes PD4A and PD4B instead of the photodiode PD2 in the first embodiment, and the photodiodes PD4A and PD4B are high-frequency light beams. L1A is received at a predetermined ratio (for example, a ratio of 1: 3).

(2-2) Configuration of Laser Drive Circuit Next, the configuration of the laser drive circuit 70 included in the optical pickup 61 will be described with reference to FIG. The laser drive circuit 70 includes an APC drive circuit 70A and a superimposed amplitude control circuit 70B. The APC drive circuit 70A compares a predetermined average light amount reference voltage V10 and an average light amount voltage V11, and calculates a difference between them. Inverted and amplified by the high gain amplifier 41, and supplied to the base of the transistor 42, a drive current I2 comprising a DC collector current for feedback control of the average light quantity is obtained.

  At this time, the superimposed amplitude control circuit 70B compares the predetermined amplitude reference voltage AV1 with the amplitude voltage AV2, amplifies the difference by the high gain amplifier 43, and supplies it to the oscillator 44 for operation to thereby operate the predetermined amplitude A. A high frequency signal HS2 composed of a sine wave is generated.

  Note that the amplitude A in this case is also set to an optimized amplitude value so as to reduce the laser noise and reduce the jitter of the reproduction signal SRF as shown in FIG.

  Then, the APC drive circuit 70A generates the high frequency drive current HI2 having the amplitude A by superimposing the high frequency signal HS2 having the amplitude A generated by the superimposed amplitude control circuit 70B on the drive current I2, and the high frequency drive current HI2 is generated. This is supplied to the semiconductor laser diode LD2.

  Thus, the APC drive circuit 70A emits the high frequency light beam L1 from the semiconductor laser diode LD2.

  At this time, the APC drive circuit 70A receives the high-frequency light beam L1A, which is a part of the high-frequency light beam L1, by the photodiode PD4A. Here, the photodiode PD4A has a resistance value (for example, 1 [kΩ]) set so that the photodiode PD4A outputs a direct current proportional to the low-band component (that is, the average light amount) of the high-frequency light beam L1A. The voltage conversion resistor R2 is connected in series, so that the photodiode PD4A outputs a direct current proportional to the average light amount of the received high-frequency light beam L1A.

  Then, the APC drive circuit 70A converts the direct current obtained from the photodiode PD4A into a voltage by the current-voltage conversion resistor R2, and amplifies it by the operational amplifier 45, thereby obtaining the average light amount voltage V11.

  Further, the APC driving circuit 70A compares the average light amount voltage V11 and the average light amount reference voltage V10 with the subtractor 46, and inverts and amplifies the difference with the high gain amplifier 41 to supply the average to the base of the transistor 42. A drive current I2 corresponding to the light quantity reference voltage V10 is obtained.

  Thus, the APC drive circuit 40A performs feedback control of the drive current I2 in accordance with the average light amount of the high-frequency light beam L1A received by the photodiode PD4A.

  On the other hand, the superimposed amplitude control circuit 70B receives the high-frequency light beam L1A with the photodiode PD4B. Here, the photodiode PD4B has a resistance voltage (for example, 20 [Ω]) that is set so that the photodiode PD4B outputs an alternating current proportional to the high-frequency component (that is, the peak light amount) of the high-frequency light beam L1A. The conversion resistor R10 is connected in series, so that the photodiode PD4B outputs an alternating current proportional to the peak light amount of the received high-frequency light beam L1A.

  Then, the superimposed amplitude control circuit 70B converts the alternating current obtained from the photodiode PD4B into a voltage by the current-voltage conversion resistor R10, and amplifies it by the operational amplifier 71 to obtain the peak light amount voltage V20.

  The superimposed amplitude control circuit 70B extracts the high frequency component of the peak light amount voltage V20 by passing the peak light amount voltage V20 through the bandpass filter 48 that selectively extracts only the high frequency component in the same band as the high frequency signal HS2, The amplitude of the high frequency component is detected by the amplitude detection circuit 49. The amplitude detection circuit 49 outputs an amplitude voltage AV2 proportional to the detected amplitude.

  Further, the superimposed amplitude control circuit 70B compares the amplitude voltage AV2 and the amplitude reference voltage AV1 with the subtractor 50, amplifies the difference with the high gain amplifier 43, and supplies it to the oscillator 44, thereby obtaining the amplitude reference voltage AV1. A high frequency signal HS2 having a corresponding amplitude A is generated.

  In this way, the superimposed amplitude control circuit 70B extracts the high-band component of the high-frequency light beam L1A received by the photodiode PD4B, and feedback controls the amplitude A of the high-frequency signal HS2 generated by the oscillator 44 according to the amplitude of the high-band component. As a result, the amplitude A of the high-frequency drive current HI2 can always be kept constant.

  The APC drive circuit 70A generates a high frequency drive current HI2 by superimposing the high frequency signal HS2 whose amplitude A is feedback controlled on the feedback controlled drive current I2, and supplies this to the semiconductor laser diode LD2.

  Thus, in the laser driving circuit 70, as shown in FIG. 4A, for example, the operating temperature of the semiconductor laser diode LD2 is increased, so that the amplitude A of the high-frequency driving current HI2 becomes larger than the amplitude A at normal temperature. In this case, the amplitude A of the high-frequency signal HS2 is feedback-controlled by the superimposed amplitude control circuit 70B, so that the amplitude A of the high-frequency drive current HI2 becomes the same as the amplitude A at normal temperature as shown in FIG. Therefore, the peak light quantity of the high-frequency light beam L1 emitted from the semiconductor laser diode LD2 can always be kept constant.

(2-3) Operation and Effect In the above configuration, the optical pickup 61 feedback-controls the drive current I2 according to the average light amount of the high-frequency light beam L1A received by the photodiode PD4A by the APC drive circuit 70A of the laser drive circuit 70. To do.

  Further, the optical pickup 61 obtains an alternating current proportional to the peak light amount of the high-frequency light beam L1A by the photodiode PD4B of the superimposed amplitude control circuit 70B, and applies the amplitude voltage AV2 corresponding to the amplitude of the high-frequency component of the alternating current to the superimposed amplitude control circuit. The amplitude A of the high-frequency signal HS2 detected at 70B and superimposed on the drive current I2 according to the amplitude voltage AV2 is feedback-controlled.

  According to the above configuration, the optical pickup 61 can reliably control the average light amount of the high-frequency light beam L1 emitted from the semiconductor laser diode LD2 by the APC drive circuit 70A in the laser drive circuit 70, and can also control the superimposed amplitude control circuit. The peak light amount of the high-frequency light beam L1 can be reliably controlled by 70B, and thus both the average light amount control and the peak light amount control can be performed with high accuracy.

  The optical pickup 61 uses a direct current obtained from the photodiode PD4A to control the average light amount of the high-frequency light beam L1 emitted from the semiconductor laser diode PD2, and uses a photocurrent to control the peak light amount of the high-frequency light beam L1. By using the alternating current obtained from the diode PD4B, the average light amount and the peak light amount can be controlled separately.

  Furthermore, the optical pickup 61 is incident on the control of the peak light amount that requires a larger amount of light than the control of the average light amount by making the incident light amount of the high-frequency light beam L1A larger on the photodiode PD4B than on the photodiode PD4A. By assigning a large amount of light, the amount of light of the high-frequency light beam L1 emitted from the semiconductor laser diode LD2 can be controlled more reliably.

(3) Other Embodiments In the first embodiment described above, the differential amplifier 47 detects the potential difference across the current-voltage conversion resistor R3 connected in series with the semiconductor laser diode LD2 in FIG. As described above, the case where the high frequency voltage HV1 proportional to the high frequency drive current HI2 is obtained and the amplitude A of the high frequency drive current HI2 is feedback-controlled using the high frequency voltage HV1 is described. However, the present invention is not limited to this. For example, an L-shaped antenna 80 is provided in the vicinity of the semiconductor laser diode LD2 so as to be parallel to the wiring pattern of the semiconductor laser diode LD2, as shown in FIG. The high frequency leakage radio wave generated when the high frequency drive current HI2 is supplied to the semiconductor laser diode LD2 Further, the amplitude of the leaked radio wave may be detected via the band-pass filter 48 and the amplitude detection circuit 49, and the amplitude A of the high-frequency drive current HI2 may be feedback controlled according to the amplitude.

  In addition, since such high-frequency leakage radio waves easily propagate to other circuits, for example, if a wiring pattern of the photodiode PD2 is provided in the vicinity of the semiconductor laser diode LD2, it can be obtained from the photodiode PD2. The high frequency component of the leaked radio wave is superimposed on the direct current that is generated. Accordingly, as shown in FIG. 8 in which the same reference numerals are assigned to the parts corresponding to those in FIG. 2, the high frequency superimposed voltage obtained from the photodiode PD2 is converted into current voltage and amplified by the operational amplifier 90 to obtain the high frequency superimposed voltage. The high frequency component of the high frequency superimposed voltage may be amplified by the operational amplifier 91 and used for feedback control of the amplitude A of the high frequency drive current HI2, and the low band component of the high frequency superimposed voltage may be used for feedback control of the drive current I2. .

  Further, in the first and second embodiments described above, the case where the peak light amount of the high-frequency light beam L1 is always constant has been described. However, the present invention is not limited to this, and reproduction recorded on an optical disc is performed. You may make it change the peak light quantity of the high frequency light beam L1 with the case where the signal SRF is read, and the case where an information signal is recorded on the said optical disk. However, even in this case, the peak light amount is not changed during reading or recording.

  Furthermore, in the first and second embodiments described above, the laser drive circuits 40 and 70 are configured by the APC drive circuits 40A and 70A as the average light amount control means and the superimposed amplitude control circuits 40B and 70B as the peak light amount control means. Although the case of doing so has been described, the present invention is not limited to this, and the laser drive circuit may be configured by other various average light quantity control means and peak light quantity control means.

  The present invention can be applied to an optical disc recording / reproducing machine that uses a rewritable optical disc such as Blu-ray Disk (registered trademark) as a medium.

1 is a schematic diagram illustrating an overall configuration of an optical disc drive according to a first embodiment. It is a basic diagram which shows the structure of the laser drive circuit in 1st Embodiment. It is a basic diagram which shows the relationship between the amplitude of a high frequency signal, laser noise, and jitter. It is a basic diagram which shows the temperature change (at the time of amplitude control) of a high frequency drive current. It is a basic diagram which shows the whole structure of the optical disk drive in 2nd Embodiment. It is a basic diagram which shows the structure of the laser drive circuit in 2nd Embodiment. It is a basic diagram which shows the structure (1) of the laser drive circuit in other embodiment. It is a basic diagram which shows the structure (2) of the laser drive circuit in other embodiment. It is a basic diagram which shows the electric current-light quantity change by the temperature characteristic of a semiconductor laser diode. It is a basic diagram which shows the structure of the conventional laser drive circuit. It is a basic diagram which shows the temperature change of a high frequency drive current. It is a basic diagram which shows the light quantity change of a high frequency light beam. It is a basic diagram which shows the light quantity change (at the time of high temperature) of a high frequency light beam.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 40, 70 ... Laser drive circuit 20, 60 ... Optical disk drive, 23, 61 ... Optical pick-up, 40A, 70A ... APC drive circuit, 40B, 70B ... Superimposition amplitude control circuit, HI1, HI2 ... ... High-frequency drive current, HS1, HS2 ... High-frequency signal, I1, I2 ... Drive current, L1 ... High-frequency light beam, LD1, LD2 ... Semiconductor laser diode, PD1, PD2, PD3, PD4A, PD4B ... Photodiode , PD4... Two-divided photodiode, R2, R3, R10... Current-voltage conversion resistor.

Claims (4)

In a laser driving device that emits a high-frequency light beam from a semiconductor laser diode by driving the semiconductor laser diode with a high-frequency driving current formed by superimposing a high-frequency signal on the driving current,
An average light amount control means for detecting an average light amount of the high-frequency light beam and feedback-controlling the drive current based on the average light amount;
A peak light amount control unit that detects a peak light amount of the high-frequency light beam and feedback-controls the amplitude of the high-frequency drive current independently of the control of the average light amount control unit based on the peak light amount ;
First and second light receiving elements for receiving at least part of the high frequency light beam;
With
The average light amount control means is
Detecting an average light amount of the high-frequency light beam from an output current of the first light receiving element;
The peak light amount control means is
Detecting the peak light amount of the high-frequency light beam from the output current of the second light receiving element;
The second light receiving element is:
It is set so that the amount of incident light of the high-frequency light beam is larger than that of the first light receiving element.
Les over The drive unit. In a laser driving method for emitting a high-frequency light beam from a semiconductor laser diode by driving the semiconductor laser diode with a high-frequency driving current formed by superimposing a high-frequency signal on the driving current,
An average light amount control step of detecting an average light amount of the high-frequency light beam and feedback-controlling the drive current based on the average light amount;
A peak light amount control step for detecting a peak light amount of the high-frequency light beam, and feedback-controlling the amplitude of the high-frequency drive current independently of the control of the average light amount control step based on the peak light amount ,
In the average light amount control step,
Detecting an average light amount of the high-frequency light beam from an output current of a first light receiving element that receives at least a part of the high-frequency light beam;
In the peak light intensity control step,
The high-frequency light beam is received from the output current of the second light-receiving element that receives at least a part of the high-frequency light beam and is set so that the amount of incident light of the high-frequency light beam is larger than that of the first light-receiving element. Detect peak light intensity
Les over The driving method. In an optical pickup having a laser driving device that emits a high-frequency light beam from the semiconductor laser diode by driving the semiconductor laser diode with a high-frequency driving current formed by superimposing a high-frequency signal on the driving current,
An average light amount control means for detecting an average light amount of the high-frequency light beam and feedback-controlling the drive current based on the average light amount;
A peak light amount control unit that detects a peak light amount of the high-frequency light beam and feedback-controls the amplitude of the high-frequency drive current independently of the control of the average light amount control unit based on the peak light amount;
First and second light receiving elements for receiving at least part of the high frequency light beam;
With
The average light amount control means is
Detecting an average light amount of the high-frequency light beam from an output current of the first light receiving element;
The peak light amount control means is
Detecting the peak light amount of the high-frequency light beam from the output current of the second light receiving element;
The second light receiving element is:
It is set so that the amount of incident light of the high-frequency light beam is larger than that of the first light receiving element.
Optical pickup. In an optical disc drive having an optical pickup that emits a high-frequency light beam from the semiconductor laser diode by driving the semiconductor laser diode with a high-frequency drive current formed by superimposing a high-frequency signal on the drive current,
An average light amount control means for detecting an average light amount of the high-frequency light beam and feedback-controlling the drive current based on the average light amount;
A peak light amount control unit that detects a peak light amount of the high-frequency light beam and feedback-controls the amplitude of the high-frequency drive current independently of the control of the average light amount control unit based on the peak light amount;
First and second light receiving elements for receiving at least part of the high frequency light beam;
With
The average light amount control means is
Detecting an average light amount of the high-frequency light beam from an output current of the first light receiving element;
The peak light amount control means is
Detecting the peak light amount of the high-frequency light beam from the output current of the second light receiving element;
The second light receiving element is:
It is set so that the amount of incident light of the high-frequency light beam is larger than that of the first light receiving element.
Optical disk drive.

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