JP2009015929A - Optical disk device and its control method and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk device capable of eliminating inconvenience caused by a thermal influence on a laser diode by eliminating the necessity of adding a new component and accurately measuring the temperature of the laser diode, and its control method and program. <P>SOLUTION: The optical disk device is provided with a laser diode 1, a monitor diode 2 for detecting its light emission amount, a switch for switching electricity to the monitor diode 2 to constant current source 4 and a temperature measuring part 7 for measuring a temperature based on a voltage detected from the monitor diode 2 before the operation of an optical pickup. A laser diode control unit 64 inhibits an operation of the optical pickup when the measured temperature is equal to or higher than a predetermined temperature. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical disc apparatus that reads an optical disc signal with an optical pickup, and more particularly, to an optical disc apparatus with improved thermal influence of a laser diode used in the optical pickup, a control method thereof, and a control program.

  In a disc player that records and reproduces an optical disc such as a CD or DVD, the recording surface is irradiated with laser light through an optical pickup including an objective lens, and the reflected light is converted into an electric signal. Reading the recorded signal.

  A laser diode is used as a light source of laser light in this optical pickup. The laser diode is controlled by APC (Aute Power Control).

  An example of the control structure of the laser diode by such APC is shown in FIG. That is, a part of the laser light output from the front surface or the back surface of the laser diode 1 is received by the monitor diode 2 which is a monitoring photodiode. The laser diode control unit 10 adjusts the light emission amount of the laser diode 1 so that the monitor current from the monitor diode 2 becomes constant. In FIG. 3, reference numerals 4 and 5 denote a constant voltage source and a resistance for light quantity measurement, respectively.

  By the way, there are various types of components that serve as heat sources in the optical disk device, such as an optical pickup and a spindle motor that rotates the disk. In the case of an in-vehicle optical disc apparatus, the vehicle is often in a high temperature state together with the inside of the vehicle due to the vehicle being placed in the sun.

  However, the laser diode in the optical pickup described above has a lower temperature at which operation is guaranteed compared to other components. For this reason, if the temperature exceeds this temperature and the temperature rises, the laser diode is thermally affected, and its operation becomes unstable or becomes inoperable.

  In order to cope with this, there has been proposed an optical disc apparatus that is operated by measuring a temperature of the entire apparatus by disposing a temperature sensor at a position away from the optical pickup (see Patent Document 1). There has also been proposed an optical disc apparatus in which a dedicated temperature sensor is disposed in the vicinity of the optical pickup and the ambient temperature is measured and operated (see Patent Document 2).

Further, a disk device has been proposed that detects the temperature based on the voltage value of the monitor diode provided in the optical pickup and adjusts the light emission amount of the laser diode (see Patent Document 3).
Japanese Patent Laid-Open No. 5-189949 JP-A-5-159308 JP 2001-216672-A

  However, in the case of an optical disk apparatus that measures the temperature of the entire apparatus at a position distant from the optical pickup as in the invention of Patent Document 1, it is not possible to protect the laser diode because the thermal influence on the laser diode cannot be measured faithfully. It was enough. In addition, in the case of an optical disc in which a dedicated temperature sensor is arranged in the vicinity of the optical pickup as in the invention of Patent Document 2, it is necessary to add the dedicated temperature sensor, which is expensive.

  Further, in the invention of Patent Document 3, the temperature is detected by using an existing monitor diode instead of an additional temperature sensor, and the drive current of the laser diode is controlled by the temperature detected by the optical pickup. When there is an abnormal temperature rise, the light emission drive of the laser diode can be stopped. However, as a cause of the high temperature of the optical disk device, there is a possibility that the temperature has already risen from the start of the operation due to the vehicle being placed in the hot sun as described above.

  Under such circumstances, in the case of the invention of Patent Document 3, if the optical disk device is started up in the vehicle at a high temperature and various operations are started, the laser diode starts to emit light at a high temperature. For example, in a general disk device, an operation of automatically reading a TOC (Table of contents) is performed simultaneously with insertion of a disk. After that, even if the light emission of the laser diode is adjusted according to the detected temperature and stopped when abnormal, the laser diode already starts operating at a high temperature. For this reason, if such an operation is repeated, there is a possibility that the operating characteristics and the life will be reduced.

  The present invention has been proposed in order to solve the above-described problems of the prior art, and its purpose is to accurately measure the temperature of the laser diode while eliminating the need for adding new parts, An object of the present invention is to provide an optical disc apparatus, a control method thereof, and a control program capable of eliminating inconvenience due to thermal influence on the diode in advance.

  In order to solve the above-mentioned problems, the invention of claim 1 is directed to an optical disc apparatus having an optical pickup provided with a laser diode, wherein a monitor diode for detecting the light emission amount of the laser diode, and energization to the monitor diode are controlled by temperature. Switching means for switching to measurement, and temperature measurement means for measuring temperature based on a voltage detected from the monitor diode before a predetermined operation of the optical disc apparatus. The inventions of claims 4 and 5 are obtained by capturing the invention of claim 1 from the viewpoint of a method and a computer program.

  In the inventions of claims 1, 4 and 5 as described above, the temperature of the laser diode is obtained by using the existing monitor diode provided in the optical pickup before the predetermined operation of the optical disc apparatus without newly adding a temperature sensor. Therefore, inconvenience due to thermal influence on the laser diode can be eliminated in advance while saving cost.

  According to a second aspect of the present invention, in the optical disc apparatus of the first aspect, a first storage unit that stores a predetermined temperature, and a temperature measured by the temperature measurement unit are stored in the first storage unit. A determination means for determining whether or not the temperature is equal to or higher than a predetermined temperature, and an operation control means for preventing a predetermined operation of the optical disc apparatus from being performed when the determination means determines that the temperature is equal to or higher than a predetermined temperature. To do.

  In the invention of claim 2 as described above, when the laser diode becomes so high that it exceeds a predetermined temperature, the laser diode operates and operates at a high temperature by not performing the predetermined operation of the optical disc apparatus. It is possible to prevent deterioration of characteristics and life.

  According to a third aspect of the present invention, there is provided the optical disk apparatus according to the first or second aspect, wherein the constant current source is used for measurement by the constant current source connected to the monitor diode and the switching means and the temperature measuring means. And a second storage means for storing the relationship between the voltage appearing at both ends of the monitor diode and the temperature by the current applied to the monitor diode.

  In the invention of claim 3 as described above, the temperature of the laser diode can be accurately measured based on the voltage detected from the monitor diode based on the relationship between the voltage stored in the second storage means and the temperature. it can.

  According to the present invention as described above, an optical disc apparatus capable of accurately measuring the temperature of a laser diode and eliminating in advance inconvenience due to a thermal influence on the laser diode without adding new parts. The control method and the control program can be provided.

  One embodiment (this embodiment) to which the present invention is applied will be specifically described with reference to the drawings. In the present embodiment, a laser diode, a monitor diode, and the like are controlled by operating the microcomputer and its peripheral circuits in accordance with a program for realizing the function of each unit described below. Various implementations of hardware and programs can be changed.

  Therefore, in the following description, a virtual circuit block that realizes each function of the present invention is used. In addition, the control method, the program for realizing this by a computer, and the recording medium on which this is recorded are also one aspect of the present invention.

[Constitution]
First, the configuration of the present embodiment will be described. In addition, about the general functional part required for an optical disk apparatus, since all the well-known techniques are applicable, description is abbreviate | omitted. That is, this embodiment is configured by a laser diode 1, a monitor diode 2, a constant voltage source 3, a constant current source 4, a resistor 5, a laser diode control unit 6, a temperature measurement unit 7, a changeover switch 8, and the like.

  The laser diode 1 is a semiconductor laser that outputs laser light when energized. The monitor diode 2 is a photodiode in which the current flowing in the reverse direction from the constant voltage source 3 changes according to the amount of light received by the laser output from the front surface or the back surface of the laser diode 1. The resistor 5 is inserted for current detection for measuring the light quantity.

  The laser diode control unit 6 includes a light emission control unit 61 that performs APC control on the light emission amount of the laser diode 1 based on the current detected from the monitor diode 2, a switching control unit 62 that controls the changeover switch 8, and a temperature measurement unit. 7 based on the temperature measured by the light emitting control unit 61 and the switching control unit 62, and the light emitting control unit 61 and the switching control unit based on the determination result of the determining unit 63. An operation control unit 64 that controls the operation of 62 and a setting storage unit 65 that stores various settings such as determination criteria by the determination unit 63 are included.

  As a determination criterion, for example, it is conceivable to set a predetermined temperature as a threshold value and perform the following operation depending on whether the temperature is equal to or higher than that temperature. First, the light emission control unit 61 does not operate the laser diode 1 until it is determined whether or not the temperature is a predetermined temperature. When it is determined that the temperature is equal to or higher than the predetermined temperature, the light emission control unit 61 does not start the operation of the laser diode 1, and the switching control unit 62 is connected to the changeover switch 8 to the constant voltage source 3 for light quantity measurement. Do not do. When it is determined that the temperature is lower than the predetermined temperature, the light emission control unit 61 causes the laser diode 1 to perform reproduction or recording operation by light emission, and the switching control unit 62 causes the changeover switch 8 to supply a constant voltage source for light quantity measurement. 3 is connected.

  The temperature measurement unit 7 includes a determination unit 71 that determines the temperature of the laser diode 1 based on the current detected from the monitor diode 2, and a setting storage unit 72 that stores various settings such as a temperature determination criterion. Yes. The determination by the determination unit 71 utilizes the property that the voltage Vd at both ends changes according to the temperature T when the monitor diode 2 applies a current in the forward direction from the constant current source 4.

  As a determination criterion, for example, the voltage Vd for a certain temperature T is different for each monitor diode 2, so the voltage is measured in advance for a plurality of reference temperatures, and the relationship between the temperature T and the forward voltage Vd is stored. In this case, it is necessary to calibrate the temperature characteristics of the monitor diode 2 when the device is manufactured.

  The changeover switch 8 is means for switching the energization of the monitor diode 2 to either the constant voltage source 3 side or the constant current source 4 side according to an instruction from the change control unit 62. When the optical disk is not played back or recorded, the changeover switch 8 is on the constant current source 4 side, or on the constant current source 4 side when the optical disk apparatus is started or before the playback and recording operations. It is set to switch.

[Action]
The operation of the present embodiment as described above will be described with reference to the flowchart of FIG. First, when an operation input for reproducing or recording is given after the optical disk device is activated (step 201), a constant current in the forward direction is applied to the monitor diode 2 by the constant current source 4 (step 202). As a result, the voltage across the monitor diode 2 is detected (step 203). The determination unit 71 of the temperature measurement unit 7 determines the temperature of the laser diode 1 based on the detected voltage and the setting of the setting storage unit 72 (step 204).

  The determination unit 63 in the laser diode control unit 6 determines whether or not the temperature of the laser diode 1 determined by the determination unit 71 is equal to or higher than a set temperature (step 205). Then, according to the determination result, the operation control unit 64 controls the operations of the light emission control unit 61 and the switching control unit 62. That is, when it is determined that the temperature of the laser diode 1 is not equal to or higher than the set temperature, the switching control unit 62 switches the changeover switch 8 to the constant voltage source 3 side (step 206).

  Then, the light emission control unit 61 causes the optical pickup to reproduce or record by the light emission of the laser diode 1 (step 207). At this time, a reverse voltage is applied to the monitor diode 2 by the constant voltage source 3, and the light emission control unit 61 adjusts the light emission amount of the laser diode 1 based on the detected current value. When there is an operation input for stopping the reproduction or recording operation (step 208), the operation of the optical pickup is stopped (step 209).

  On the other hand, when it is determined that the temperature of the laser diode 1 has become equal to or higher than the set temperature, the operation control unit 64 does not cause the switching control unit 62 to switch the changeover switch 8 and causes the light emission control unit 61 to switch the laser diode 1 on. The reproduction or recording operation of the optical pickup by light emission is not performed (step 210). The above processing is performed until the apparatus is stopped by turning off the power (step 211, step 201 and subsequent steps).

[effect]
According to the present embodiment as described above, the temperature of the laser diode 1 is measured using the existing monitor diode 2 provided in the optical pickup before the operation of the optical pickup without newly adding a temperature sensor. It is possible to start operation only at a reasonable temperature while saving costs and avoiding inconvenience due to thermal influence on the laser diode 1.

  The voltage detection from the monitor diode 2 for temperature measurement is separated from the control of the laser diode 1 during reproduction or recording operation by the changeover switch 8. For this reason, if the temperature is already high before the operation of the optical disk apparatus starts, the laser diode 1 does not operate at all including the reading operation of the TOC even if the operation of the optical disk apparatus is started. It can be surely prevented that the lifetime is reduced.

  In particular, in the case of an on-vehicle optical disk device, there is a means for lowering the temperature in the vehicle by operating a cooling or ventilating when it is used during traveling. It is unlikely that it will be necessary to stop it. However, since there is no means for lowering the temperature of a vehicle parked under a hot sun, there is a high possibility that the temperature has risen abnormally. In such a case, the laser diode 1 of this embodiment is not used. It is effective to adopt a configuration that does not allow the operation itself.

  Furthermore, since the temperature can be determined based on the relationship between the voltage of the monitor diode 2 and the temperature of the laser diode 1 stored in advance in the setting storage unit 65, control based on accurate temperature measurement is possible.

[Other Embodiments]
The present invention is not limited to the above embodiment. For example, the set temperature value serving as the threshold value is not limited to a specific value. For example, the optimum value may be set in consideration of the guaranteed operating temperature of the laser diode, the use environment of the optical disk device, the frequency of occurrence of operation stoppage, and the like. Even if it is determined that the temperature is lower than a certain temperature after setting the low temperature, it is possible to set the operation not to be performed.

  In addition, regarding whether the temperature is high or low, it is free to include a predetermined temperature serving as a threshold (above or below) or not (greater or less). Therefore, “above” or “below” in the claims is merely an expedient expression and includes a determination that does not include a threshold value. The various settings may be set as defaults, but may be input / changed to desired settings by the user using the input means.

  In addition, it is free to restrict which functions of the optical disk apparatus are restricted under a temperature at which the laser diode is not desired to operate (for example, when the temperature exceeds a predetermined temperature). Some functions, for example, the operation of a mechanism for moving the optical pickup may be restricted, or the operation of a mechanism for inserting a disk (such as a tray drive mechanism or a loading mechanism) may be restricted. It is also free to limit the operation of a drive source such as an actuator or a motor, or limit the transmission of power from the drive source to various mechanisms. Further, the activation of the entire optical disk device may be restricted in conjunction with the power switch of the optical disk device. In other words, the “predetermined operation of the optical disc apparatus” in the claims includes all operations including the above-described example so that the optical disc apparatus does not function.

  In addition, when the temperature is less than the temperature at which the laser diode is not to be operated (for example, a predetermined temperature or higher), the notification means (for example, display on a display device provided in the optical disk device or blinking of a lamp) indicates that fact. A configuration for notifying the user is also possible. Thereby, the user can know the reason why the optical disk apparatus cannot be used, and can take measures to lower the temperature by air conditioning, ventilation, or the like. Further, under such a temperature, before the optical pickup is operated, it is possible to operate the cooling means (fan or the like) provided in the optical disk device to forcibly cool it and to enable the operation when the temperature is lowered. .

  The hardware configuration for control can be realized in various ways, for example, by a so-called chip that realizes each function exemplified above and its peripheral circuit, or by a system LSI or ASIC that integrates a plurality of functions. And is not limited to a specific embodiment. Furthermore, the disc that is the subject of the present invention is not limited to various CDs and DVDs (regardless of standard), and can be applied to all types of optical recording media. It may be a reproduction-only one or a recordable / reproducible one.

1 is a functional block diagram showing an embodiment of an optical disc device of the present invention. It is a flowchart which shows the process sequence in embodiment of FIG. It is a functional block diagram which shows an example of the control structure of the conventional laser diode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laser diode 2 ... Monitor diode 3 ... Constant voltage source 4 ... Constant current source 5 ... Resistance 6, 10 ... Laser diode control part 7 ... Temperature measurement part 8 ... Change-over switch 61 ... Light emission control part 62 ... Switching control part 63, 71: Determination unit 64 ... Operation control unit 65, 72 ... Setting storage unit

Claims (5)

In an optical disc apparatus having an optical pickup provided with a laser diode,
A monitor diode for detecting the light emission amount of the laser diode;
Switching means for switching energization to the monitor diode for temperature measurement;
Temperature measuring means for measuring a temperature based on a voltage detected from the monitor diode before a predetermined operation of the optical disc device;
An optical disc apparatus comprising: First storage means for storing a predetermined temperature;
Determining means for determining whether the temperature measured by the temperature measuring means is equal to or higher than a predetermined temperature stored in the first storage means;
An operation control unit that does not perform a predetermined operation of the optical disc device when the determination unit determines that the temperature is equal to or higher than a predetermined temperature;
The optical disk apparatus according to claim 1, further comprising: A constant current source connected to the monitor diode and the switching means;
Second storage means for storing a relationship between a voltage and a temperature appearing at both ends of the monitor diode by a current applied to the constant current source for use in measurement by the temperature measurement means;
The optical disk apparatus according to claim 1, wherein the optical disk apparatus includes: In an optical disc device control method for controlling an optical disc device provided with an optical pickup provided with a laser diode and a monitor diode for detecting a light emission amount of the laser diode by a computer or an electronic circuit,
The computer or electronic circuit is
Switch the energization to the monitor diode for temperature measurement,
A method of controlling an optical disk apparatus, comprising: measuring a temperature based on a voltage detected from the monitor diode before a predetermined operation of the optical disk apparatus. In a control program for controlling an optical disk device provided with an optical pickup provided with a laser diode and a monitor diode for detecting the light emission amount of the laser diode by a computer,
The program is stored in the computer.
Switch the energization to the monitor diode for temperature measurement,
A control program for an optical disc apparatus, comprising: measuring a temperature based on a voltage detected from the monitor diode before a predetermined operation of the optical disc apparatus.

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