JP2009176332A - Optical disk drive, laser driving circuit, optical pickup, temperature detection circuit, and laser diode package - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify a configuration of a laser driving circuit for an optical disk drive, a laser driving circuit, an optical pickup, a temperature detection circuit, and a laser diode package. <P>SOLUTION: The laser driving circuit 39 connects a laser driver 32 to a cathode of the laser diode 33, a power supply circuit 41 and one end of a thermistor 55 to an anode of the laser diode 33, and grounds the other end of the thermistor 55. Furthermore, the laser driving circuit 39 controls the laser driver 32 by calculating the resistance Rthermo of the thermistor 55 based on a voltage and a current of the power supply provided by the power supply circuit 41 and a control current which should be the laser driving current Iop of a current flowing through the laser diode 33 and adjusting the intensity of illuminating light based on an LD adjacent temperature which is the ambient temperature of the thermistor 55 shown by the resistance Rthermo. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical disk drive, a laser drive circuit, an optical pickup, a temperature detection circuit, and a laser diode package, and is suitable for application to temperature detection of a laser diode.

  Conventionally, a laser diode has been widely used as a light source of laser light in an optical disk drive.

  The temperature of the laser diode changes due to temperature changes due to the environment and heat generation due to laser light emission, but the wavelength and output of the laser light change due to the influence of the heat generation, and the laser diode itself is damaged due to excessive heat generation. There is also a problem.

  For this reason, a temperature detection circuit 1 as shown in FIG. 1 has been proposed (see, for example, Patent Document 1). In this temperature detection circuit 1, a resistor 3 having a predetermined resistance value and a thermistor 4 whose resistance value changes according to temperature are connected in series between the input pin 2 and the ground GND.

  In the temperature detection circuit 1, the voltage supplied from the input pin 2 and divided by the power supply voltage value Vcc is divided between the resistor 3 and the thermistor 4, and the divided voltage by the thermistor monitor voltage value Vmon. Is output from the output pin 6.

  In this temperature detection circuit 1, the value of the thermistor resistance value Rth in the thermistor 4 changes as the resistance value of the thermistor 4 changes according to the ambient temperature. The output thermistor monitor voltage value Vmon also changes.

  The optical disk drive can calculate the resistance value Rth of the thermistor 4 from the relationship between the power supply voltage value Vcc applied to the input pin 2, the thermistor monitor voltage value Vmon, and the resistance value R of the resistor 3. The temperature in the vicinity of the thermistor 4 can be detected from the resistance value Rth.

  For example, as shown in FIG. 2, in the laser drive circuit 9, the thermistor 4 of the temperature detection circuit 1 is disposed in the vicinity of the laser diode 7 in the optical pickup 10, and the laser driver 32 is connected to the cathode of the laser diode 7. Yes.

  A drive circuit 11 disposed outside the optical pickup 10 is provided with a Vmon detector 14 to which the input pin 2 of the temperature detection circuit 1 is connected. Further, the drive side circuit 11 is provided with a laser power supply circuit 13 for supplying a current to the laser diode 7 and connected to the anode of the laser diode 7 and to the output pin 6 of the temperature detection circuit 1. ing.

  When detecting the thermistor monitor voltage Vmon output from the input pin 2, the Vmon detection unit 14 supplies these to the temperature calculation unit 21 </ b> A of the system controller 21. Further, when the laser power supply circuit 13 detects the power supply voltage Vcc applied to the output pin 6, the laser power supply circuit 13 supplies this to the temperature calculation unit 21A.

When the system controller 21 calculates the temperature around the thermistor 4 positioned in the vicinity of the laser diode 7 by the temperature calculation unit 21A, that is, the temperature near the laser diode (hereinafter referred to as the LD vicinity temperature), the temperature near the LD The laser diode 7 is controlled based on the above.
JP 2006-79728 A (FIG. 1)

  However, in the temperature detection circuit 1 configured as described above, it is necessary to connect the output pin 6 to the Vmon detection unit 14 in order to detect the power supply voltage value Vcc and the thermistor monitor voltage value Vmon. I must. In the laser drive circuit 9, it is necessary to separately wire for temperature detection in order to connect the optical pickup 10 and the drive side circuit 11, and there is a problem that the configuration as the laser drive circuit 9 becomes complicated.

  The present invention has been made in consideration of the above points. An optical disc drive having a laser drive circuit with a simple configuration, a laser drive circuit with a simple configuration, an optical pickup capable of simplifying the configuration of the laser drive circuit, and temperature detection Circuits and laser diode packages are to be proposed.

  In order to solve such a problem, in the optical disk drive of the present invention, a laser diode that emits laser light to be irradiated onto the optical disk, a power supply circuit that is connected to the anode of the laser diode and supplies power to the laser diode, A laser driver that is connected to the cathode of the laser diode and controls the intensity of the emitted light when the laser light is emitted, and one end is connected to the anode and the other end is grounded, and is disposed in the vicinity of the laser diode A temperature variable resistance element, a supply current value detection unit that detects a supply current value that is a value of a current supplied to the laser diode and the temperature variable resistance element, and a laser drive current value that is a value of a current flowing through the laser diode A laser current detector to be applied, and an applied voltage value that is a value of a voltage applied to the laser diode. A resistance value calculation unit that calculates the resistance value of the temperature variable resistance element based on the current value and the laser driving current value, and the laser driver is controlled based on the temperature in the vicinity of the temperature variable resistance element corresponding to the resistance value. And a control unit that adjusts the intensity of irradiation light when the optical disk is irradiated with light.

  As a result, the temperature variable resistance element can be connected as a part of the circuit in which the laser diode, the power supply circuit, and the laser driver are connected. Therefore, the wiring for connecting the temperature detection power supply circuit and the temperature variable resistance element The number of wirings for connecting the optical pickup and the drive side circuit can be reduced.

  In the optical disk drive of the present invention, a laser diode that emits laser light to be irradiated onto the optical disk, a power supply circuit that is connected to the anode of the laser diode and supplies power to the laser diode, and a cathode of the laser diode A laser driver that controls the intensity of emitted light when laser light is emitted by controlling the laser drive current value, which is a value of the current that flows through the laser diode, to be an arbitrary control current value, and one end The temperature variable resistance element is connected to the anode and the other end is grounded, and a supply current value that is a value of a current supplied to the laser diode and the temperature variable resistance element is detected. Current value detector, applied voltage value that is the value of the voltage applied to the laser diode, supply current And a resistance value calculation unit that calculates the resistance value of the temperature variable resistance element based on the control current value, and a control unit that determines the control current value based on the temperature in the vicinity of the temperature variable resistance element corresponding to the resistance value. I made it.

  As a result, the temperature variable resistance element can be connected as a part of the circuit in which the laser diode, the power supply circuit, and the laser driver are connected. Therefore, the wiring for connecting the temperature detection power supply circuit and the temperature variable resistance element The number of wirings for connecting the optical pickup and the drive side circuit can be reduced.

  Furthermore, in the laser drive circuit of the present invention, a laser diode that emits laser light, a power supply circuit that is connected to the anode of the laser diode and supplies power to the laser diode, and a cathode of the laser diode are connected to the laser diode. A laser driver for controlling the intensity of emitted light when light is emitted; a temperature variable resistance element disposed in the vicinity of the laser diode, having one end connected to the anode and the other end grounded; A supply current value detection unit that detects a supply current value that is a value of a current supplied to the temperature variable resistance element, a laser current detection unit that detects a laser drive current value that is a value of a current flowing through the laser diode, and a laser diode Based on the applied voltage value, supply current value, and laser drive current value, which is the value of the voltage applied to the Intensity of irradiated light when the optical disk is irradiated with the laser light by controlling the laser driver based on the temperature near the temperature variable resistance element corresponding to the resistance value and the resistance value calculation unit for calculating the resistance value of the resistance element And a control unit for adjusting the.

  As a result, the temperature variable resistance element can be connected as a part of the circuit in which the laser diode, the power supply circuit, and the laser driver are connected. Therefore, the wiring for connecting the temperature detection power supply circuit and the temperature variable resistance element The number of wirings for connecting the optical pickup and the drive side circuit can be reduced.

  Further, in the optical pickup for irradiating the optical disk of the present invention with laser light, an anode is connected to a power supply circuit for supplying power, a laser diode for emitting laser light, one end connected to the anode and the other end Is provided with a temperature variable resistance element arranged in the vicinity of the laser diode and a laser driver connected to the cathode of the laser diode and controlling the intensity of the emitted light when the laser light is emitted. .

  As a result, the temperature variable resistance element can be connected as a part of the circuit in which the laser diode, the power supply circuit, and the laser driver are connected. Therefore, the wiring for connecting the temperature detection power supply circuit and the temperature variable resistance element The number of wirings for connecting the optical pickup and the drive side circuit can be reduced.

  Furthermore, in the temperature detection circuit of the present invention, the anode is connected to the power supply circuit that supplies power, the cathode is connected to the laser driver that controls the current, and one end is connected to the anode. The other end is grounded, and a temperature variable resistance element arranged in the vicinity of the laser diode is provided.

  As a result, the temperature variable resistance element can be connected as a part of the circuit in which the laser diode, the power supply circuit, and the laser driver are connected. Therefore, the wiring for connecting the temperature detection power supply circuit and the temperature variable resistance element The number of wirings for connecting the optical pickup and the drive side circuit can be reduced.

  Furthermore, in the laser diode package of the present invention, the anode is connected to the power supply circuit that supplies power, the cathode is connected to the laser driver that controls the current, and one end is connected to the anode. The other end is grounded, and a temperature variable resistance element disposed in the vicinity of the laser diode and a package including the laser diode and the temperature variable resistance element and exposing the anode and the cathode are provided.

  As a result, the temperature variable resistance element can be connected as a part of the circuit in which the laser diode, the power supply circuit, and the laser driver are connected. Therefore, the wiring for connecting the temperature detection power supply circuit and the temperature variable resistance element The number of wirings for connecting the optical pickup and the drive side circuit can be reduced.

  According to the present invention, since the temperature variable resistance element can be connected as a part of the circuit in which the laser diode, the power supply circuit, and the laser driver are connected, the temperature detection power supply circuit and the temperature variable resistance element are connected. The number of wires for connecting the optical pickup and the drive side circuit can be reduced, and thus an optical disc drive having a laser drive circuit with a simple configuration, and the configuration of the laser drive circuit An optical pickup, a temperature detection circuit, and a laser diode package can be realized.

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

(1) Configuration of Optical Disk Drive and Optical Pickup In FIG. 3, in which parts corresponding to those in FIGS. 1 and 2 are assigned the same reference numerals, 20 denotes an optical disk drive as a whole. The optical disk drive 20 is controlled in a centralized manner by a system controller 21 including a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory) (not shown).

  The system controller 21 expands a basic program, a laser drive program, and the like stored in the ROM to the RAM, and reproduces the optical disc 100 based on the BD (Blu-ray Disc, registered trademark) system based on these programs. Processing and recording processing are executed.

  The system controller 21 sends a data read command to the drive control unit 23 together with address information for specifying data to be read from the optical disc 100 during the reproduction process.

  The drive control unit 23 controls the spindle motor 24 in accordance with a data read command from the system controller 21 to rotate the optical disc 100 at a predetermined rotation speed, and the thread motor 25 based on the data read command and address information. Is controlled to move the optical pickup 30 in the radial direction of the optical disc 100.

  The system controller 21 then emits a light beam of, for example, 405 [nm] from the laser diode 33 via the laser driver 32 of the optical pickup 30 to the track corresponding to the address information in the information recording layer of the optical disc 100, The light beam is condensed by the lens 37 and irradiated onto the optical disc 100.

  That is, as shown in FIG. 4, the laser diode 33 of the optical pickup 30 emits a light beam composed of laser light corresponding to each method of the optical disc 100 with a light amount corresponding to the drive current supplied from the laser driver 32, and the beam The light enters the splitter 34.

  The beam splitter 34 transmits most of the incident light beam as it is and enters the collimator lens 35. The collimator lens 35 converts a light beam incident as diverging light into parallel light and enters the rising prism 36.

  The rising prism 36 reflects the incident light beam, changes its direction by 90 [°], and makes the light beam incident on the objective lens 37. The objective lens 37 collects the light beam and irradiates the optical disc 100 with it.

  The objective lens 37 receives a reflected light beam formed by reflecting the light beam by the optical disc 100 and causes the reflected light beam to enter the beam splitter 34 via the rising prism 36 and the collimator lens 35.

  The beam splitter 34 reflects the incident reflected light beam on the polarization plane, changes its direction by 90 [°], and enters the photodetector 39 via the condenser lens 38. The photodetector 39 photoelectrically converts the reflected light beam to generate a light reception signal, and supplies the detection signal to the signal processing unit 26 (FIG. 3).

  The signal processing unit 26, based on the received light signal, a tracking error signal according to the amount of deviation of the irradiation position of the light beam with respect to a desired track and a focus error according to the amount of deviation of the focus of the light beam with respect to the information recording layer of the optical disc 100 A signal is generated and sent to the drive control unit 23 and the system controller 21. A reproduction RF signal is generated based on the received light signal and sent to an external device (not shown).

  The drive control unit 23 generates a tracking drive current and a focus drive current based on the tracking error signal and the focus error signal, and sends them to a lens drive unit (not shown). In response to this, the lens driving unit drives the objective lens 37 in two directions: a tracking direction that is the radial direction of the optical disc and a focus direction that is close to or away from the optical disc, thereby focusing the light beam on the desired optical disc 100. To match the track.

  As described above, the optical disk drive 20 performs information reproduction and recording processing on the optical disk.

  Here, the laser diode 33 changes the intensity of emitted light of the output light beam according to temperature change or deterioration with time even when the same drive current is applied. Therefore, the optical pickup 30 detects the emitted light intensity of the light beam output from the laser diode 33, and adjusts the drive current so that the emitted light intensity becomes a value suitable for reproduction and recording processing.

  That is, the beam splitter 34 (FIG. 4) of the optical pickup 30 separates a part of the light beam from the light beam by reflecting it at a predetermined light quantity ratio by the polarization plane, and collects it by an APC (Auto Power Control) lens 45. The light is detected by the APC photodetector 46, and an APC detection current having a current value corresponding to the light amount is generated and supplied to the laser driver 32.

  The laser driver 32 compares the current value of the APC detection current (hereinafter referred to as the APC detection current value) with the set current value so that the current value of the APC detection current matches the set current value. In addition, the intensity of the light beam emitted from the laser diode 33 (hereinafter referred to as the emitted light intensity) is adjusted by increasing or decreasing the drive current supplied to the laser diode 33.

  That is, the system controller 21 (FIG. 3) determines the set current value based on the reference set current value stored in advance in the ROM during the reproduction process, and supplies this to the laser driver 32 as the laser power control signal SLD.

  The laser driver 32 controls the intensity of the emitted light beam to a predetermined value suitable for reproduction by adjusting the APC detection current so as to be a set current value represented by the laser power control signal SLD. .

  Further, the system controller 21 sends a data write command to the drive control unit 23 together with address information for designating a location for recording data on the information recording layer of the optical disc 100 during the recording process. The drive control unit 23 controls the position of the optical pickup 30 based on the supplied address information.

  Further, the system controller 21 generates a laser power control signal SLD based on write data input from an external device (not shown) and sends it to the laser driver 32.

  The laser driver 32 controls the intensity of the light beam to be emitted to a predetermined value suitable for recording by adjusting the APC detection current to a set current value represented by the laser power control signal SLD. .

  In response to this, the optical pickup 30 focuses the light beam on the track corresponding to the address information in the information recording layer of the optical disc 100, and the light beam adjusted to the intensity suitable for data recording by the control of the laser driver 32. , The write data is recorded on the optical disc 100.

  As described above, the optical pickup 30 monitors the emission light intensity of the light beam actually output by the APC photodetector 46, so that the optical pickup 100 has a set current value for the optical disc 100 during data recording and reproduction processing. A light beam having a corresponding emitted light intensity can be irradiated.

(2) Temperature Detection of Laser Diode According to the Present Invention As described above, the laser diode 33 outputs when the temperature of the laser diode 33 itself changes according to the temperature change due to the surrounding environment or the heat generation of the laser diode 33. It is known to change not only the intensity of the emitted light beam but also the wavelength.

  The optical pickup 30 has a light intensity (hereinafter referred to as an irradiation light intensity) when the optical beam 100 is irradiated with the light beam according to a change in the wavelength of the light beam due to the characteristics of the optical component disposed in the optical pickup 30. Called).

  That is, the optical pickup 30 changes the irradiation light intensity due to the temperature change when the emission light intensity of the light beam emitted from the laser diode 33 is constant.

  In this optical disk drive 20, the thermistor 55 is disposed in the vicinity of the laser diode 33, and the temperature of the thermistor 55 that changes with the ambient temperature is detected as the LD vicinity temperature that represents the temperature in the vicinity of the laser diode 33. The optical disc drive 20 irradiates the optical disc 100 with a light beam having a desired irradiation light intensity by adjusting the emission light intensity of the light beam according to the temperature in the vicinity of the LD.

  As shown in FIG. 5, the optical disc drive 20 has a laser drive circuit 39 for driving the laser diode 33. The laser drive circuit 39 is formed in a state physically separated from the inside of the optical pickup 30 and the drive side circuit 40 outside the optical pickup 30. The optical pickup 30 and the drive side circuit 40 are connected by, for example, an FPC (Flexible Printed Circuit).

  Inside the optical pickup 30, a temperature detection circuit 50 having a laser diode 33 and a thermistor 55 and a laser driver 32 are arranged. In the drive side circuit 40, a power supply circuit 41 that supplies power to the laser diode 33 and a system controller 21 that determines a control current value to flow through the laser diode 33 are arranged.

  In this laser drive circuit 39, a power supply circuit 41 is connected to the anode of the laser diode 33 via the input pin 51. The power supply circuit 41 always sets the power supply voltage value Vcc so that the value of the voltage applied to the temperature detection circuit 50 (hereinafter referred to as the power supply voltage value) Vcc becomes a predetermined voltage value (for example, 8V). Monitor and feedback control. Further, the power supply circuit 41 constantly monitors a current value (hereinafter referred to as a power supply current value) Icc supplied to the temperature detection circuit 50 in order to prevent overcurrent, for example.

  In the laser drive circuit 39, the laser driver 32 is connected to the cathode of the laser diode 33 via the output pin 56. The laser driver 32 draws and adjusts the current flowing through the laser diode 33 so that the laser drive current value Iop becomes the control current value represented by the laser power control signal SLD supplied from the system controller 21.

  Here, it is known that, in a general laser diode that emits blue laser light, high-speed response can be improved by controlling so as to draw current. In the laser drive circuit 39, the laser driver 32 is connected to the cathode of the laser diode 33 so that the high-speed response can be enhanced by utilizing the characteristics of the laser diode 33.

  Further, the laser drive circuit 39 has a temperature detection circuit 50 that detects a change in the resistance value of the thermistor 55 disposed in the vicinity of the laser diode 33.

  In the temperature detection circuit 50, a laser diode 33 is connected between the input pin 51 and the output pin 56, and an anode is connected to the input pin 51 and a cathode is connected to the output pin side. The laser diode 33 is disposed in a metallic laser diode (hereinafter abbreviated as LD) package 53, and the LD package 53 is connected to the housing of the optical pickup 30 as a case ground CGND.

  In the temperature detection circuit 50, a thermistor 55 is connected in parallel with the laser diode 33. One end of the thermistor 55 is connected to the anode of the laser diode 33, and the other end of the thermistor 55 is connected to the ground GND. .

  The output pin 56 is connected to the ground GND via the laser driver 32 installed in the optical pickup 30. The input pin 51 is connected to the ground GND via a power supply circuit 41 installed in the drive side circuit 40. Since the ground GND is connected to the case ground CGND in the optical disk drive 20, both are common.

  That is, in the temperature detection circuit 50, the thermistor 55 can be provided as a part of the circuit connecting the laser diode 33, the power supply circuit 41, and the laser driver 32 by connecting the thermistor 55 in parallel to the laser diode 33. .

  In the laser drive circuit 39, when power having the power supply voltage value Vcc and the power supply current value Icc is supplied from the power supply circuit 41, current is supplied to the temperature detection circuit 50 through the input pin 51. The power supply current value Icc supplied to the temperature detection circuit 50 is branched, supplied to the laser driver 32 through the laser diode 33 as the laser drive current value Iop, and supplied to the thermistor 55 as the current Ithermo.

  The laser driver 32 draws a current so that the control current value represented by the laser power control signal SLD supplied from the system controller 21 is obtained. At this time, the laser driver 32 detects a drive current value (hereinafter referred to as a laser drive current value) Iop that actually flows through the laser diode 33 by the Iop detection unit 32A, and the laser drive current value Iop is detected by the system controller 21. To send.

  The power supply circuit 41 detects the power supply voltage value Vcc and the power supply current value Icc of the power supply supplied to the temperature detection circuit 50 by the Vcc / Icc detection unit 41A, and sends them to the system controller 21.

  Here, the thermistor 55 has a characteristic that its resistance value (hereinafter referred to as the thermistor resistance value) Rthermo changes according to the temperature. Therefore, if the current thermistor resistance value Rthermo of the thermistor 55 can be recognized, the laser driving circuit 39 specifies the LD vicinity temperature from the relationship between the characteristic of the thermistor resistance value Rthermo with respect to the temperature and the recognized thermistor resistance value Rthermo. be able to.

  In this temperature detection circuit 50, since the laser diode 33 and the thermistor 55 are connected in parallel, the laser drive current value Iop, the power supply current value Icc, and the value of the current flowing through the thermistor 55 (hereinafter referred to as the thermistor current value). The sum of Ithermo is equal. Therefore, the thermistor current value Ithermo flowing through the thermistor 55 can be calculated by subtracting the laser drive current value Iop from the power supply current value Icc according to the equation (1).

  Further, according to Ohm's law, the thermistor resistance value Rthermo of the thermistor 55 can be calculated according to the equation (2) by dividing the power supply voltage value Vcc, which is the value of the voltage applied to the thermistor 55, by the thermistor current value Ithermo. .

  Substituting equation (1) into equation (2) yields equation (3).

  Therefore, when the power supply voltage value Vcc and the power supply current value Icc are supplied from the power supply circuit 41 and the laser drive current value Iop is supplied from the laser driver 32, the temperature calculation unit 21A of the system controller 21 follows the equation (3). The thermistor resistance value Rthermo of the thermistor 55 is calculated.

  The temperature calculation unit 21A stores a table indicating the relationship between the thermistor resistance value Rthermo and the temperature of the thermistor 55 in a ROM (not shown). The temperature calculation unit 21A selects the temperature corresponding to the thermistor resistance value Rthermo as the current LD vicinity temperature.

  Then, the emitted light intensity setting unit 21B of the system controller 21 performs a reference setting that represents an APC detection current value (that is, a set current value) to be detected by the APC photodetector 26 when the temperature near the LD is a predetermined reference temperature. Calculate the current value. This reference set current value represents the emitted light intensity of the light beam that should be emitted by the laser diode 33 when the temperature near the LD is the reference temperature.

  The emitted light intensity setting unit 21B stores a table in which the temperature near the LD and the temperature coefficient are associated with each other in the ROM. The system controller 21 multiplies the reference set current value by an arbitrary temperature coefficient corresponding to the LD vicinity temperature, so that the set current to be set in the laser driver 32 when the laser diode 33 is near the LD vicinity temperature. Generate a value. This set current value represents the emitted light intensity of the light beam that should be emitted by the laser diode 33 in accordance with the temperature in the vicinity of the LD.

  Here, in the optical pickup 30, the irradiation light intensity changes according to the temperature near the LD due to the change in the wavelength of the light beam according to the change in the temperature near the LD and the characteristics of the optical components in the optical pickup 30. This temperature coefficient is set so as to correct the irradiation light intensity when the optical disk 100 is irradiated with a light beam that increases or decreases according to a change in the temperature near the LD.

  Then, the emitted light intensity setting unit 21 </ b> B generates a laser power control signal SLD representing the set current value and supplies this to the laser driver 32.

  The laser driver 32 draws a current so that the APC detection current value becomes a set current value represented by the laser power control signal SLD, thereby causing the laser diode 33 to emit a light beam having an appropriate emitted light intensity according to the set current value. The light can be emitted.

  As a result, the system controller 21 can control the laser diode 33 so as to emit a light beam having an appropriate emitted light intensity based on the current temperature near the LD. As a result, the system controller 21 can adjust the irradiation light intensity of the light beam irradiated to the optical disc 100 to a desired light intensity regardless of the change in the temperature near the LD.

  Thus, in the laser drive circuit 39, the power supply circuit 41 is connected to the anode of the laser diode 33 and the laser driver 32 is connected to the cathode, and then the thermistor 55 is connected in parallel to the laser diode 33. Thereby, in the laser drive circuit 39, the thermistor 55 can be provided as a part of the circuit for connecting the laser diode 33, so that the wiring for connecting the optical pickup 30 and the drive side circuit 40 can be reduced. .

(3) Operation and Effect In the above configuration, the laser drive circuit 39 of the optical disc drive 20 is connected to the laser diode 33 that emits a light beam of laser light and the anode of the laser diode 33, and A power supply circuit 41 that supplies power and a laser driver 32 that is connected to the cathode of the laser diode 33 and controls the intensity of irradiation light when the light beam is emitted.

  Further, the laser drive circuit 39 is connected in parallel to the laser diode 33, one end is connected to the anode and the other end is grounded, and the thermistor which is a temperature variable resistance element disposed in the vicinity of the laser diode 33. 55.

  Accordingly, since the thermistor 55 can be provided as part of the circuit having the laser diode 33 in the laser driving circuit 39, the conventional laser driving circuit in which the temperature detection circuit 1 having the thermistor 4 (FIG. 1) is arranged independently. Compared to 9, the number of wires for connecting the optical pickup 30 and the drive side circuit 40 can be reduced.

  Further, since the laser drive circuit 39 only needs to extend the wiring slightly from the anode of the laser diode 33 and connect the thermistor 55, the thermistor 55 can be easily disposed in the vicinity of the laser diode 33.

  As a result, the laser drive circuit 39 is placed in the vicinity of the laser diode 7 in the vicinity of the laser diode 7 for convenience of wiring space as in the case of the conventional laser drive circuit 9x in which an independent wiring needs to be routed to the thermistor 4 as shown in FIG. It is difficult to cause a situation that cannot be placed.

  Further, the laser drive circuit 39 detects the power supply current detected by the Vcc / Icc detection unit 41A as a supply current value detection unit that detects the power supply current value Icc supplied to the laser diode 33 and the thermistor 55 (that is, the temperature detection circuit 50). The resistance value Rthermo of the thermistor 55 is calculated based on the value Icc, the power supply voltage value Vcc, and the laser drive current Iop that is the value of the current flowing through the laser diode 33.

  Then, the laser drive circuit 39 selects the temperature near the thermistor 55 from the resistance value Rthermo by selecting the temperature corresponding to the resistance value Rthermo from the resistance value Rthermo in the table stored in the ROM in advance. Identify. Further, the laser drive circuit 39 multiplies the reference set current value to be set in the laser driver 32 at a predetermined reference temperature by a temperature coefficient corresponding to the LD vicinity temperature, thereby obtaining the LD vicinity temperature corresponding to the resistance value Rthermo. Based on this, the laser driver 32 was controlled to adjust the irradiation light intensity.

  As a result, the laser drive circuit 39 can calculate the resistance value Rthermo by simple calculation according to the equation (3), and can determine an appropriate control current value based on the LD vicinity temperature corresponding to the resistance value Rthermo.

  Incidentally, in general, a constant voltage power supply circuit is provided with a circuit for detecting a power supply current value Icc to be supplied because the current value is likely to fluctuate due to environmental influences such as temperature. In the laser drive circuit 39, a low voltage (8V) electric circuit having the Vcc / Icc detection unit 41A is used as the power supply circuit 41, and the power supply current value Icc detected by the power supply circuit 41 is supplied to the temperature calculation unit 21A. did.

  As a result, the laser drive circuit 39 can detect the power supply current value Icc by the Vcc / Icc detection unit 41A that the power supply circuit 41 originally has, so there is no need to provide a separate element for detecting the power supply current value Icc of the power supply. Compared with the conventional laser drive circuit 9 having the Vmon detector 14, the configuration can be simplified.

  That is, the laser drive circuit 39 shares the Iop detection unit 32A that is originally provided to perform feedback control so that the laser drive current value Iop matches the control current value, so that the number of parts of the laser drive circuit 39 is reduced. can do.

  The laser drive circuit 39 detects a laser drive current value Iop that is adjusted based on the set current value, and supplies the laser drive current value Iop to the temperature calculation unit 21A. In the laser drive circuit 39, the temperature calculation unit 21A calculates the resistance value Rthermo of the thermistor 55 using the laser drive current value Iop, and thereby based on the power supply voltage value Vcc, the power supply current value Icc, and the laser drive current value Iop. The resistance value Rthermo of the thermistor 55 is calculated.

  As a result, the laser drive circuit 39 can calculate the resistance value Rthermo from the laser drive current value Iop that actually flows through the laser diode 33, and therefore predicts the laser drive current value from the set current value and calculates the resistance value Rthermo. Compared to the case, the resistance value Rthermo can be calculated with high accuracy.

  Further, in the laser drive circuit 39, the laser driver 32 has an Iop detection unit 32A that is a laser current value detection unit, and the laser drive current value Iop is increased or decreased so that the APC detection current value becomes the set current value. While controlling the current, the laser drive current value Iop is detected and supplied to the temperature calculation unit. In the laser drive circuit 39, the resistance value Rthermo of the thermistor 55 is calculated from the power supply voltage value Vcc, the power supply current value Icc, and the laser drive current value Iop by a temperature calculation unit 21A as a resistance value calculation unit.

  As a result, the laser drive circuit 39 can detect the laser drive current value Iop by the Iop detection unit 32A that the laser driver 32 originally has to adjust the laser drive current value Iop, so there is no need to provide a laser current value detection unit. The configuration can be simplified.

  In the laser drive circuit 39, the power supply voltage value Vcc is detected by the Vcc / Icc detection unit 41A and supplied to the temperature calculation unit 21A, whereby the resistance value Rthermo is calculated from the power supply voltage value Vcc actually applied to the thermistor 55. Therefore, the resistance value Rthermo can be calculated with high accuracy.

  Further, in the laser drive circuit 39, the set current value is determined based on the temperature in the vicinity of the LD by the system controller 21 as the control unit, and the set current value is supplied to the laser driver 32 as the laser power control signal SLD.

  As a result, the laser drive circuit 39 can control the laser drive current value Iop so that the APC detection current value becomes an appropriate set current value in accordance with the temperature in the vicinity of the LD, so that the emitted light intensity of the light beam emitted from the laser diode 33 is increased. Can be adjusted to an appropriate intensity of emitted light substantially matching the temperature of the laser diode 33. As a result, the laser drive circuit 39 can stabilize the irradiation light intensity of the light beam when irradiating the optical disc 100 to a desired intensity regardless of the temperature near the LD.

  In the laser drive circuit 39, the laser diode 33 emits a blue laser beam as a light beam. As a result, the laser drive circuit 39 can connect the laser driver 32 to the cathode to improve its high-speed response, and can detect the laser drive current Iop on the cathode side to calculate the resistance value Rthermo.

  Furthermore, since the laser diode 33 requires a higher voltage than a red laser diode that emits red laser light (5V is connected as a power supply circuit), a power supply circuit 41 of 8V is connected. In the drive side circuit 40, most of the circuits are operated by a 5V power supply circuit, so that the power supply circuit 41 is usually used exclusively for the laser diode 33. For this reason, in the laser drive circuit 39, since the thermistor 55 is provided as the temperature detection circuit 50, it is not necessary to eliminate the element connected to the power supply circuit 41 so far. There is no need to prepare a power supply circuit.

  According to the above configuration, the laser drive circuit 39 of the optical disc drive 20 connects the laser driver 32 to the cathode of the laser diode 33, connects one end of the power supply circuit 41 and the thermistor 55 to the anode of the laser diode 33, and The other end of the thermistor 55 is grounded. Further, the laser drive circuit 39 calculates the resistance value Rthermo of the thermistor 55 based on the voltage and current of the power supplied from the power supply circuit 41 and the laser drive current value Iop which is the current flowing in the laser diode 33, and the resistance value Rthermo. The emitted light intensity is determined on the basis of the LD vicinity temperature, which is the ambient temperature of the thermistor 55 expressed by As a result, the laser drive circuit 39 can connect the thermistor 55 as a part of a circuit in which the laser diode 33, the power supply circuit 41, and the laser driver 32 are connected, so that the temperature detection power supply circuit 14 and the thermistor 4 are connected. Wiring for connecting can be omitted, the number of wiring for connecting the optical pickup 30 and the drive side circuit 40 can be reduced, and thus an optical disc drive having a laser driving circuit with a simple configuration, simple It is possible to realize a laser drive circuit having a configuration, and an optical pickup, a temperature detection circuit, and a laser diode package that can simplify the configuration of the laser drive circuit.

(4) Other Embodiments In the above-described embodiment, the case where the other end of the thermistor 55 is connected to the ground GND has been described. However, the present invention is not limited to this, and for example, FIG. As shown in A), it may be connected to the case ground CGND via the package 53. Even in this case, the same effects as those of the above-described embodiment can be obtained.

  In the above-described embodiment, the thermistor 55 is disposed in the vicinity of the laser diode package 53 so that the thermistor 55 is disposed in the vicinity of the laser diode 33. For example, as shown in FIG. 7B, the thermistor 55 may be arranged inside the laser diode package 53. In this case, although not shown, the laser diode package 53 covers the laser diode 33 and the thermistor 55 and exposes the anode and cathode from the laser diode package 53. As a result, the thermistor 55 can be arranged closer to the laser diode 33, so that a temperature closer to the laser diode 33 can be specified as the LD vicinity temperature.

  Furthermore, in the above-described embodiment, the optical pickup 30 has the APC circuit (the condensing lens 45 and the APC photodetector 46), and the laser driver 32 sets the APC detection current value to the set current value. Although the case where the laser driving current value Iop is controlled has been described, the present invention is not limited to this. For example, the optical pickup 30 does not have an APC circuit, and the laser driver 32 controls the laser driving current value Iop. While controlling so that it may become an electric current value, the emitted light mirror O setting part 21B may be made to set a control electric current value.

  Further, it is not always necessary to detect the laser drive current value Iop actually flowing through the laser diode 33. By using the control current value determined by the system controller 21 as the laser drive current value Iop as it is, the thermistor according to the equation (3) is used. The resistance value Rthermo can be calculated. Even in this case, the same effects as those of the above-described embodiment can be obtained.

  Furthermore, in the above-described embodiment, the case where the emitted light intensity is adjusted so as to have a constant irradiation light intensity has been described. However, the present invention is not limited to this, for example, according to the change in the wavelength of the light beam. The emitted light intensity may be adjusted to change the irradiation light intensity.

  Further, in the above-described embodiment, the case where the power supply voltage value Vcc and the power supply current value Icc are detected has been described. However, the present invention is not limited to this, and for example, the power supply circuit 41 has a constant power supply voltage value Vcc. When power is supplied in a fixed manner, the power supply voltage value Vcc is known, so that only the power supply current value Icc needs to be detected. The power supply circuit 41 does not necessarily need to detect the power supply voltage value Vcc and the power supply current value Icc. For example, as shown in FIG. 8, a Vcc / Icc detector 93 is provided in the optical pickup 91, and the Vcc / Icc detector The power supply voltage value Vcc and the power supply current value Icc detected by 93 may be supplied to the system controller 21 provided in the drive side circuit 92. Even in this case, the same effects as those of the above-described embodiment can be obtained. Although not shown, it is also possible to provide the outgoing light intensity setting unit 21B in the microcomputer 114. In this case, the wiring connecting the system controller 21 and the optical pickup 111 can be only the line connecting the power supply circuit 41 and the temperature detection circuit 50, and the number of wirings can be further reduced.

  Further, in the above-described embodiment, the case where the power supply circuit 41 supplies power only to the temperature detection circuit 50 has been described. However, the present invention is not limited to this, for example, in parallel with the laser diode 33. In other words, when the temperature detection circuit 50 and the element are branched and connected to the power supply circuit 41, a Vcc / Icc detection unit is provided after the branch, and the temperature detection circuit 50 after the branch is provided. On the other hand, by detecting the value of the current supplied as Iop and the voltage as Vcc, the thermistor resistance value Rthermo can be calculated in the same manner as in the above-described embodiment according to the equation (3).

  Further, in the embodiment described above, the resistance value Rthermo of the thermistor 55 is calculated, the LD vicinity temperature is specified from the resistance value Rthermo, and the reference setting current value is multiplied by an arbitrary temperature coefficient corresponding to the LD vicinity temperature. However, the present invention is not limited to this. For example, when the resistance value Rthermo and an arbitrary temperature coefficient are stored in association with each other, the resistance value is determined. The set current value may be determined by selecting an arbitrary temperature coefficient corresponding to the LD vicinity temperature from the value Rthermo and multiplying this by the reference set current value. A table in which the resistance value Rthermo and the set current value are associated with each other may be stored in advance, and the corresponding set current value may be selected. Even in this case, the same effects as those of the above-described embodiment can be obtained.

  Further, in the above-described embodiment, the case where the temperature in the vicinity of the LD is calculated by the temperature calculation unit 21A included in the system controller 21 has been described. However, the present invention is not limited thereto, and for example, as illustrated in FIG. By providing a microcomputer (hereinafter abbreviated as a microcomputer) 114 having a Vcc / Icc detector 93 and a temperature calculator 114A in the optical pickup 111, it is possible to calculate the LD vicinity temperature in the optical pickup 114. In this case, the microcomputer 114 can obtain the same effect as the above-described embodiment by supplying the calculated LD vicinity temperature to the system controller 21 in the drive side circuit 112.

  Further, in the above-described embodiment, the case where the laser diode 54 emits laser light having a wavelength of 405 [nm] has been described. However, the present invention is not limited to this, and laser light having various other wavelengths is also described. You may make it radiate | emit.

  Furthermore, in the above-described embodiment, the temperature calculation unit 114A has a table in which the thermistor resistance value Rthermo and the temperature are associated with each other, and the temperature selected from the thermistor resistance value Rthermo is set as the LD vicinity temperature. Although the case has been described, the present invention is not limited to this. For example, the temperature calculated by multiplying the thermistor resistance value Rthermo by a predetermined coefficient may be set as the LD vicinity temperature.

  Furthermore, in the above-described embodiment, the case where the thermistor 55 is used has been described. However, the present invention is not limited to this, and if the element having a characteristic that the resistance value changes according to temperature is used, the above-described implementation is performed. The same effect as that of the embodiment can be obtained.

  Furthermore, in the above-described embodiment, the laser diode 33 as the laser diode, the power supply circuit 41 as the power supply circuit, the laser driver 32 as the laser driver, and the Vcc / Iop detection unit 41A as the supply current value detection unit When the optical disk drive 20 as the optical disk drive is configured by the Iop detection part 32A as the laser current detection part, the temperature calculation part 21A as the resistance value calculation part, and the emitted light intensity setting part 21B as the control part Although the present invention is not limited to this, the laser diode, the power supply circuit, the laser driver, the supply current value detection unit, the laser current detection unit, the resistance value calculation unit, and the control are not limited thereto. The optical disk drive of the present invention may be configured by the unit.

  Furthermore, in the above-described embodiment, the laser diode 33 as the laser diode, the power supply circuit 41 as the power supply circuit, the laser driver 32 as the laser driver, and the Vcc / Iop detection unit 41A as the supply current value detection unit The case where the optical disk drive 20 as the optical disk drive is configured by the temperature calculation unit 21A as the resistance value calculation unit and the emitted light intensity setting unit 21B as the control unit has been described, but the present invention is not limited thereto. Alternatively, the optical disk drive of the present invention may be configured by a laser diode having various other configurations, a power supply circuit, a laser driver, a supply current value detection unit, a resistance value calculation unit, and a control unit.

  The present invention can be widely applied to various optical disk drives.

It is a basic diagram which shows the conventional temperature detection circuit. It is a basic diagram with which it uses for description of the detection (1) of conventional LD vicinity temperature. 1 is a schematic diagram showing an overall configuration of an optical disc drive. It is a basic diagram which shows the structure of an optical pick-up. It is a basic diagram with which it uses for description of detection of LD near temperature by one embodiment of this invention. It is a basic diagram with which it uses for description of the detection (1) of conventional LD vicinity temperature. It is a basic diagram which shows the temperature detection circuit by other embodiment. It is a basic diagram with which it uses for description of detection (1) of LD vicinity temperature by other embodiment. It is a basic diagram with which it uses for description of detection (2) of LD vicinity temperature by other embodiment.

Explanation of symbols

  1, 50, 60, 65... Temperature detection circuit, 2, 51... Input pin, 4, 55... Thermistor, 6, 56... Output pin, 7, 33. 91, 111... Optical pickup, 11, 11x, 40, 92, 112... Drive side circuit, 21... System controller, 21 A... Temperature calculation unit, 32 ... Laser driver, 32 A. …… Power circuit, 41A, 93 …… Vcc / Icc detector, 53 …… LD package, 26 …… Signal processor, 23 …… Drive controller, 36 …… Objective lens, 100 …… Optical disk, GND …… Ground electrode, CGND: Case ground.

Claims (16)

A laser diode that emits laser light to be irradiated onto the optical disc;
A power supply circuit connected to the anode of the laser diode and supplying power to the laser diode;
A laser driver connected to the cathode of the laser diode and controlling the intensity of the emitted light when the laser light is emitted;
One end is connected to the anode and the other end is grounded, and the temperature variable resistance element disposed in the vicinity of the laser diode;
A supply current value detection unit that detects a supply current value that is a value of a current supplied to the laser diode and the temperature variable resistance element;
A laser current detector for detecting a laser drive current value which is a value of a current flowing through the laser diode;
A resistance value calculation unit that calculates a resistance value of the temperature variable resistance element based on an applied voltage value that is a value of a voltage applied to the laser diode, the supply current value, and the laser drive current value;
A controller that controls the laser driver based on the temperature in the vicinity of the temperature variable resistance element corresponding to the resistance value, and adjusts the intensity of irradiation light when the laser light is irradiated onto the optical disc. An optical disc drive characterized by that. An outgoing light intensity detector for detecting the outgoing light intensity,
The control unit
The laser driver is controlled so that the emitted light intensity detected by the emitted light intensity detection unit becomes an arbitrary set light intensity corresponding to a temperature in the vicinity of the temperature variable resistance element. Optical disk drive. The optical disk drive according to claim 1, further comprising: a resistance value detecting unit that detects the applied voltage value and supplies the detected applied voltage value to the resistance value calculating unit. The current detector is
The optical disk drive according to claim 2, wherein the optical disk drive is a power supply current detection unit provided in the power supply circuit for detecting a current supplied by the power supply circuit. The voltage detector is
5. The optical disk drive according to claim 4, wherein the optical disk drive is a power supply voltage detector provided in the power supply circuit for detecting a voltage applied by the power supply circuit. The power circuit is
Adjust the voltage value applied to the laser diode to a constant value,
The resistance value calculation unit
The optical disc drive according to claim 1, wherein the resistance value of the temperature variable resistance element is calculated by using the constant value as the applied voltage value. The control unit
The temperature coefficient corresponding to the temperature in the vicinity of the temperature variable resistance element with respect to the reference set light intensity that indicates the intensity of the emitted light to be set at the reference temperature by specifying the temperature in the vicinity of the temperature variable resistance element from the resistance value The optical disk drive according to claim 2, wherein a value obtained by multiplying is determined as the set light intensity. The control unit
The optical disk drive according to claim 3, wherein a temperature corresponding to the resistance value is selected as a temperature in the vicinity of the temperature variable resistance element from a table in which the resistance value and temperature stored in advance are associated with each other. The control unit
The optical disk drive according to claim 3, wherein the temperature in the vicinity of the temperature variable resistance element is calculated by multiplying the resistance value by a predetermined coefficient. The control unit
The optical disc drive according to claim 2, wherein a light intensity corresponding to the resistance value is selected from a prestored table, and the selected light intensity is determined as the set light intensity. The laser driver
Control the laser drive current value to be an arbitrary control current value,
The control unit
The optical disk drive according to claim 1, wherein the control current value is determined. A laser diode that emits laser light to be irradiated onto the optical disc;
A power supply circuit connected to the anode of the laser diode and supplying power to the laser diode;
By controlling the laser drive current value, which is connected to the cathode of the laser diode and flowing through the laser diode, to an arbitrary control current value, the intensity of the emitted light when the laser light is emitted is controlled. A laser driver to control,
One end is connected to the anode and the other end is grounded, and the temperature variable resistance element disposed in the vicinity of the laser diode;
A current value detection unit that detects a supply current value that is a value of a current supplied to the laser diode and the temperature variable resistance element;
A resistance value calculation unit that calculates a resistance value of the temperature variable resistance element based on an applied voltage value that is a value of a voltage applied to the laser diode, the supply current value, and the control current value;
An optical disc drive comprising: a control unit that determines the control current value based on a temperature in the vicinity of the temperature variable resistance element corresponding to the resistance value. A laser diode that emits laser light;
A power supply circuit connected to the anode of the laser diode and supplying power to the laser diode;
A laser driver connected to the cathode of the laser diode and controlling the intensity of the emitted light when the laser light is emitted;
One end is connected to the anode and the other end is grounded, and the temperature variable resistance element disposed in the vicinity of the laser diode;
A supply current value detection unit that detects a supply current value that is a value of a current supplied to the laser diode and the temperature variable resistance element;
A laser current detector for detecting a laser drive current value which is a value of a current flowing through the laser diode;
A resistance value calculation unit that calculates a resistance value of the temperature variable resistance element based on an applied voltage value that is a value of a voltage applied to the laser diode, the supply current value, and the laser drive current value;
A controller that controls the laser driver based on the temperature in the vicinity of the temperature variable resistance element corresponding to the resistance value, and adjusts the intensity of irradiation light when the laser light is irradiated onto the optical disc. A laser driving circuit. In an optical pickup that irradiates an optical disk with laser light,
A laser diode having an anode connected to a power supply circuit for supplying power and emitting the laser beam;
One end is connected to the anode and the other end is grounded, and the temperature variable resistance element disposed in the vicinity of the laser diode;
An optical pickup comprising: a laser driver connected to a cathode of the laser diode and controlling intensity of emitted light when the laser light is emitted. A laser diode having an anode connected to a power supply circuit that supplies power and a cathode connected to a laser driver that controls current;
A temperature detection circuit comprising: a temperature variable resistance element disposed at one end of the laser diode and having one end connected to the anode and the other end grounded. A laser diode having an anode connected to a power supply circuit that supplies power and a cathode connected to a laser driver that controls current;
One end is connected to the anode and the other end is grounded, and the temperature variable resistance element disposed in the vicinity of the laser diode;
A laser diode package comprising: a package containing the laser diode and the temperature variable resistance element and exposing the anode and the cathode.

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