KR100618842B1 - Optical disc apparatus - Google Patents

Abstract

An object of the present invention is to provide an optical disk apparatus which does not cause a discrimination error in determining the type of optical disk.

Storage means for storing target levels of various signals generated from the return light when the predetermined optical disk is irradiated with laser light, and detection means for irradiating the laser light to the optical disk to detect the level of various signals generated from the return light. And correction means for correcting at least one signal level detected by the detection means to a target level, and optical disk discriminating means for discriminating the type of optical disk based on a level change of each optical disk of the signal corrected by the correction means. There is provided an optical disk apparatus which does not cause a discrimination error in determining the type of optical disk.

Description

Optical disc apparatus

1 is a configuration diagram of an optical disk device according to the present embodiment.

2 is a configuration diagram of a correction circuit according to the present embodiment.

3 is a diagram illustrating a relationship between a command voltage value applied to a laser diode and an output of an all-optical photo detector.

4 is a diagram illustrating S-characteristics of a focus error signal.

5 is a diagram illustrating a relationship between a command voltage value applied to a laser diode and light emission power of the laser diode.

[Description of the code]

One… Optical disc

2… Spindle motor

3... pick up

4… Laser diode

5... All-in-one photo detector

6... Photodiode

7... Feed motor

8… Signal processing IC

9... CPU

10... Memory

11... Driver IC

21... Comparator

22... switch

23... adder

24... amplifier

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc apparatus for recording / reproducing an optical disc, and more particularly, to an optical disc apparatus for determining the type of an optical disc inserted in an optical disc apparatus.

In order to determine the type of a conventional optical disc, a focus error signal (hereinafter referred to as FE) obtained by emitting light at an arbitrary initial LD power (for example, 0.9 mW for a CD system and 0.7 mW for a DVD system) and irradiating the optical disk to start the focus servo, The type of optical disc was determined using the difference by the amplitude of the so-called S-shaped characteristic (refer FIG. 4) as an index.

This is a discriminant method using the difference in reflectance characteristics of light on the surface of each disc for each optical disc. For example, it is known that an amplitude difference of about 6 dB occurs in CD-R and CD-RW. Moreover, in CD and DVD, since the temporal space | interval of S-characteristics of FE differs, the technique which discriminates | reduces this temporal space as an index was also proposed (for example, refer patent document 1).

[Patent Document 1]

Japanese Patent Laid-Open No. 11-191264 (pages 2 to 6, Fig. 4)

In general, since LD power has nonuniformity due to the characteristics of semiconductor lasers, the relationship between the command voltage value and the light emission power is recognized by the process during the manufacture of the optical disk device or the calibration by the device itself. It is necessary to adjust the command voltage value. 5 shows the characteristics of the command voltage value and the luminous power. Calibration of the LD power is performed using this characteristic. Specifically, in order to set an initial light emission power of 0.9 mW for CD, a command voltage is calculated from the characteristic of FIG. 5 (18 mV in this example), and this is set. In addition, there is a method of calibrating LD power using a measuring instrument such as a power meter, and a method of requesting a relationship between the command voltage value and the luminous power, but a measuring instrument is required and an adjustment process is required to perform the measurement. There is a problem in terms of cost.

Therefore, although the command voltage value of the initial light emission power is calculated / set using the command voltage value and the light emission power characteristics as shown in FIG. 5, the output amplitude of the photo detector is changed by the non-uniformity of the sensitivity and the light receiving characteristic of the photo detector. There existed a problem that the nonuniformity of the S-shape amplitude characteristic used at the time of determination of the optical disc type used used was made, and the type of the optical disc was detected incorrectly. In addition, when the type of optical disc is incorrectly detected, it takes a considerable time from the insertion of the optical disc to the optical disc device to start up (lead-in), and in some cases, a fatal defect such as a start error occurs.

Accordingly, an object of the present invention is to provide an optical disk apparatus which has been made in view of the above-described problems and which does not cause a discrimination error in determining the type of an optical disk.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, this invention proposes the following means.

The invention according to claim 1 further includes: memory means for storing target levels of various signals generated from the return light when the predetermined optical disk is irradiated with the laser light, and various signals generated from the return light by irradiating the laser light to the optical disk. Detection means for detecting the level of the optical disc; correction means for correcting at least one signal level detected by the detection means to a target level; and based on a level change of each optical disc of the signal corrected by the correction means. There is proposed an optical disk apparatus having an optical disk discriminating means for discriminating the type.

According to the present invention, at least one signal level of the signals detected by the detection means is corrected to a target level, and the type of the optical disc is determined based on the level of the reference signal and the level change of the signal of the inserted optical disc. do.

The invention according to claim 2 has an adjusting means for adjusting the output power of the laser light with respect to the optical disk device according to claim 1, wherein the correction means adjusts the output power of the laser light by the adjusting means, and the detecting means controls the output power. There is proposed an optical disk apparatus characterized by correcting a detected signal level to a target level.                         

According to the present invention, the correction means adjusts the output power of the laser beam by the adjustment means to correct the signal level detected by the detection means to the target level, for example, based on the FE as well as the RF or tracking error signal (hereinafter TE). The type of the disc can be accurately determined.

The invention according to claim 3 has a signal level varying means for varying a level of a signal detected by said detecting means with respect to the optical disk device according to claim 1, wherein said correcting means uses said signal level varying means for said detecting means. And an optical disk apparatus characterized by varying the level of the signal detected by the step and correcting the signal level detected by the detection means to a target level.

According to the present invention, the same operation as that in the case of adjusting the luminous power by adjusting the level of the detected signal by operating the variable means and correcting it to the target level can be obtained.

The invention according to claim 4 proposes an optical disk apparatus according to claim 1, wherein the correction means operates only when the optical disk discriminating means operates.

According to the present invention, since the correction means is operated only when discriminating the type of the optical disc, it is possible to optimize the light emission power or signal level when discriminating the type of the optical disc and recording and reproducing the optical disc.

Hereinafter, an optical disk apparatus according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 5.

As shown in FIG. 1, the optical disk apparatus according to the embodiment of the present invention includes an optical disk 1, a spindle motor 2, a pickup 3, a laser diode 4, and an all-optical photo detector 5. And a photodiode 6, a feed motor 7, a signal processing IC 8, a CPU (Central Processing Unit) 9, a storage unit 10, and a driver IC 11.

The optical disc 1 is, for example, a CD-R, a CD-RW, a DVD-R, a DVD-RW, or the like as a recording medium capable of recording, reproducing and erasing information by a semiconductor laser. The spindle motor 2 is controlled by the output of the driver IC 11 as a drive device for rotating the optical disc 1 at a constant linear speed or rotational speed. The optical pickup 3 is an optical component such as an objective lens, a polarizing beam splitter, a cylindrical lens driven by a laser light source or a collimator lens, a focus actuator or a tracking actuator of the laser diode 4, and A, B, C, which will be described later, Four divided or two divided photo diodes (PD) 6 for dividing the light into an electric signal or an all-optical photo diode 5 for monitoring the laser output during recording and reproduction are provided.

The laser diode 4 outputs optical power according to the current value controlled and supplied by APC (Auto Power Control), which will be described later. In addition, the wavelength to be used is determined according to the required spot diameter. The all-optical photo detector 5 is an element that receives the emitted light from the laser diode 4, converts it into a current, and outputs it, and is used for detection control of optical power, which is used in a recording operation.

The photodiode 6 is an element that receives the return light reflected by the optical disk 1 from the light emitted from the laser diode 4 and converts the received light amount into an electrical signal corresponding thereto.

The feed motor 7 is a mechanism for sending the pickup from the inner circumference to the outer circumference of the optical disc. During the recording / reproducing of the optical disc, the feed motor 7 is started when the offset in the track direction of the objective lens in the pickup becomes a predetermined value or more. DC voltage is supplied to provide fast search. The signal processing IC 8 is divided into a portion for processing an analog signal and a portion for processing a digital signal. The analog signal processor generates RF indicating the sum of the amount of reflected light to each area of the four-split photo detector 6 and generates FE, which is a signal that detects the focal shift of the irradiation laser of the pickup 3 by astigmatism. In addition, TE, which is a signal for detecting the track deviation of the irradiation laser of the pickup 3, is generated by the push-pull method. The focus drive signal FODDR and the tracking drive signal TRDRV are generated based on the generated FE and TE.

The digital signal processing unit inputs an EFM signal generated by RF during reproduction to process data, and includes a PLL circuit (not shown) to control rotation of the spindle motor 2. The CPU 9 controls the entire apparatus based on a control program stored in a ROM (Read Only Memory) or the like. In this embodiment, the calibration of the laser diode 4 is performed by comparing the measured optical power with a reference value. The storage unit 10 is constituted by a rewritable storage device such as an EEPROM and stores a laser output reference value and other setting values. The driver IC 11 inputs the focus drive signal FODV generated by the analog signal processor 4, the tracking drive signal TRDRV, or the spindle control signal generated by the digital signal processor, amplifies it to a desired size, and then focuses it. Supply to actuator, tracking actuator or spindle motor.

As shown in Fig. 2, the correction circuit according to the present embodiment includes a photodiode 6, a signal processing IC 8, a storage unit 10, a comparison unit 21, a switch 22, an adder 23, It consists of an amplifier 24, a laser diode 4, and an all-optical photo detector 5. The comparator 21 compares the level of the RF, FE or TE generated by the signal processing IC 8 with the reference value stored in the memory 10 and supplies the output to the switch 22.

The switch 22 supplies the output from the comparator 21 to the adder 23 at the time of correcting the sensitivity of the photo detector 6 based on the control signal from the CPU 9 and at the time of recording / reproducing of the optical disc 1. Is a switching element for interrupting the signal supply from the comparator 21 to the adder 23. The adder 23 generates an error signal of a signal from the all-optical photodetector 5 and a set reference value stored in the storage unit 10 and supplies it to the amplifier 24 at the time of recording / reproducing of the optical disc 1. When the sensitivity of the photodiode 6 is corrected, the error signal obtained by further calculating the signal supplied from the comparator 22 to the error signal is supplied to the amplifier 24. The amplifier 24 amplifies the supplied error signal to a predetermined level and supplies it to the laser diode 4.

Next, the operation of the present embodiment will be described.

The optical disk apparatus first performs a calibration operation of the all-optical photo detector 5 before the sensitivity correction operation of the photodiode. Specifically, as shown in FIG. 4, the command voltage value V1 (mV) is set from the CPU 9 to the laser diode 4, and a current corresponding thereto is supplied to the laser diode 4. The laser diode 4 emits light of power according to the supplied current value, and the all-optical photo detector 5 receives the emitted light and outputs a current value according to the optical power. The output current value is converted into a voltage by a resistor or the like, and the CPU 9 inputs this voltage value from the A / D input section to obtain digital data corresponding to the voltage value B1 (mV).

Subsequently, the CPU 9 sets a separate command voltage value V2 (mV) for the laser diode 4 and obtains the voltage value B2 (mV) from the all-optical photo detector 5 as described above. The CPU 9 calculates the sensitivity characteristic of the all-optical photo detector 5 by linear approximation from the given command voltage value and the obtained voltage value. Specifically, when the light receiving sensitivity of the all-optical photo detector 5 is 20 (mV / mW), the output power at any point is obtained by dividing the acquired voltage value by 20 (mV / mW), which is the light receiving sensitivity (for example, P1 (mW). ), P2 (mW)).

The command voltage value Vtar (mV) for the laser diode 4 for obtaining the required optical power Preq (mW) can be calculated from the light receiving characteristics of the all-optical photo detector 5 obtained by the calibration operation. have. For example, an arbitrary command voltage value is set to V1 (mV) and V2 (mV), and the optical power obtained from the light receiving characteristics of the all-optical photodetector 5 corresponding thereto is P1 (mW) and P2 (mW). The relationship is established.

[Equation 1]

Vtar = ((V2-V1) / (P2-P1)) * Preq

     + ((V1 * P2)-(V2 * P1)) / (P2-P1)

The values of V1, V2, P1, and P2 are stored in the storage unit 10 connected to the CPU 9 and stored in the above formula 1 and the storage unit 10 after the calibration operation of the all-optical photo detector 5. Any optical output power can be output accurately based on the value.

Next, after the calibration operation of the all-optical photo detector 5, the sensitivity of the photodiode 6 is corrected using a specific disk. Specifically, light is emitted at the initial optical power calculated in the calibration operation of the all-optical photo detector, and the servo operation is started. At this time, the output signal of the photodiode 6 is input to the signal processing IC 8 and the calculated signal is output to the comparator 21.

The signal input to the comparator 21 is acquired by the A / D converter of the comparator 21 as its amplitude value as a digital signal.

The amplitude value acquired by the comparator 21 is compared with a predetermined reference value so that the optical output power, that is, the command voltage value to the laser diode 4, is controlled so that the obtained amplitude value coincides with the reference value. ) Thereafter, the disk is determined by performing initial light emission on the stored value and using the S-shape characteristic of the FE. Further, after the type determination of the optical disc is finished, the switch 22 is opened and subsequent read-in processing and recording / reproducing operation of the optical disc are executed by the optical output power based on the measured value.

Furthermore, in the above, the example of correcting the sensitivity of the photodiode 6 by adjusting the optical output power has been described, but the level of FE, for example, is obtained in the comparator 21 without adjusting the optical output power, and this is referred to as the reference level. In comparison with the above, the disk may be discriminated by adjusting the level of the FE to match the reference value by operating with a level changing means (for example, a gain adjusting circuit) provided in the signal processing IC 8.

Specifically, the signal processing IC 8 generates the level of FE by the output from the photodiode 6 and inputs it to the comparator. The signal input to the comparator 21 is converted into a digital signal by an A / D converter in the comparator 21, and this value is compared with a reference value. The comparison result is output to the signal processing IC 8 as gain information, and the signal processing IC 8 controls the desired gain adjusting circuit based on the gain information input. Furthermore, the target signal is not limited to FE and may be RF or TE. By such a configuration, the same operation as in the case of controlling the laser output power can be obtained. Furthermore, this operation is executed only when the type of the optical disc is determined, and after the type determination of the optical disc is finished, the operation returns to the appropriate gain setting.

Embodiments of the present invention have been described above with reference to the drawings, but specific configurations are not limited to these embodiments, and design changes and the like within the scope of the present invention are included. For example, in the present embodiment, the optical disc is not particularly illustrated, but the optical disc used may be a CD, a CD-R, a CD-RW, a DVD, a DVD-R, a DVD-RW, or another type of optical disc.

As described above, according to the present invention, even when a light receiving sensitivity of the photodiode detecting the return light occurs, the non-uniformity can be corrected by a simple method to provide an optical disk device which does not generate an error when determining the type of the optical disk. There is.

Claims (4)

Storage means for storing target levels of various signals generated from the return light when the laser beam is irradiated to a predetermined optical disc; Detection means for irradiating laser light to the optical disc to detect the level of various signals generated from the return light; Correction means for correcting at least one signal level detected by the detection means to a target level; And optical disc discriminating means for discriminating the type of optical disc based on the level change of each optical disc executed by the signal corrected by said correcting means. 2. The apparatus according to claim 1, further comprising adjustment means for adjusting the output power of the laser beam, And the correction means adjusts the output power of the laser light by the adjustment means to correct the signal level detected by the detection means to a target level. 2. The apparatus according to claim 1, further comprising signal level varying means for varying a level of a signal detected by said detecting means, And the correction means changes the level of the signal detected by the detection means using the signal level varying means and corrects the signal level detected by the detection means to a target level. An optical disc apparatus according to claim 1, wherein said correcting means operates only when said optical disc discriminating means is operated.

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