KR100366408B1 - Apparatus for playing optical disk - Google Patents

Abstract

PURPOSE: An apparatus for playing an optical disk is provided to promptly and accurately discriminate the optical disk by sensing a focus control voltage applied to an actuator when the detected intensity of radiation becomes the maximum value. CONSTITUTION: An actuator(29) receives voltage for controlling an optical focus for changing a position of a focal lens(25). An optical detector(28) detects the intensity of radiation incident from the changed focal lens by the actuator. A voltage detector(31) detects focus control voltage applied to the actuator. An intensity maximum value detector(32) detects the maximum value of the intensity of radiation output from the optical detector. A disk discriminator(33) discriminates a disk according to output voltage of the voltage detector in detecting the maximum intensity of radiation.

Description

The optical disc reproducing apparatus

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk reproducing apparatus, and more particularly, to an optical disk reproducing apparatus for performing a correct control operation by discriminating whether a recording medium is a compact disk or a digital video disk.

As a recording medium and a compact disc (hereinafter referred to as "CD ") that appeared years ago, the disc thickness is 1.2 mm and the total recording capacity is about 650 Mbytes. However, this recording medium has been used in various fields, that is, the image media, the acoustic portion and the computer portion, so that a larger capacity recording medium is required. Therefore, even if the recording medium developed in response to this expectation is a moving image, it is a digital video disc (hereinafter referred to as "DVD ") which is an image recording medium capable of storing data for two hours. In the DVD, the substrate thickness of the disk is 0.6 mm, which is about 1/2 of the CD, and the total storage capacity is about 5 Gbyte (at the time of one-side recording).

However, in using the DVD, existing CDs could not be ignored at all. The reason is that CD has been widely used in the real world. According to this necessity, one optical disc reproducing apparatus is configured to reproduce two optical discs having different substrate thicknesses. In this specification, for convenience of description, CD and DVD will be described as examples of other kinds of optical discs.

FIG. 1 is a block diagram of a conventional optical disc reproducing apparatus. The overall operation of the conventional optical disc reproducing apparatus will now be described in detail with reference to FIG.

Reference numeral 10 shown in the drawing is a pickup device. This pickup apparatus includes a configuration from light emitted from the laser diode 1 to light reflected from the recording medium 6, and reflected light received by the photodetector 8. More specifically, the beams emitted from the optical laser diode 1 are divided into three beams through the diffraction grating 2. Here, dividing the beam into three beams using the diffraction grating 2 is for using the main beam for information reading and for using the sub beams before and after the main beam for tracking control.

The beam divided into three beams in the diffraction grating 2 passes through a collimator lens 4 which is made into a parallel beam via a beamsplitter 3 and then passes through a collimator lens 4 And passes through the object lens 5 which converges.

The beam modulated by the information medium recorded on the information recording surface of the optical disc 6 through the above path is again reflected along the same path up to the objective lens, the collimating lens, and the beam splitter. Then, the path is changed in the beam splitter to be condensed by a sensor lens 7, and the condensed beam is incident on an optical detector 8.

At this time, since three beams are incident on the photodetector, in order to receive the three beams, the light receiving section of the photodetector is further divided into three sections. That is, the light receiving portions A, B, C and D for receiving the main beam are divided into four portions and located at the center, and the light receiving portions E and F for receiving the sub beams above and below the light receiving portion.

As described above, the photodetecting unit configured as the light receiving unit converts an incident optical signal into an electrical signal, and outputs the electrical signal. The output signal is used for information reproduction, tracking, and focusing control. The main beam and the sub- Signal processing is performed.

On the other hand, in order to accurately form a light spot on the two optical discs 6 whose thicknesses are different from each other through the objective lens, it is necessary to adjust the position of the focal point, and the position adjustment is performed by adjusting the distance between the objective lens and the optical disc . At this time, the distance adjustment between the objective lens and the recording medium is performed by driving an actuator 9 mounted on both sides of the objective lens. The voltage applied to the actuator coil at the position where the high frequency is generated in the DVD having the thickness of 0.6 mm is 1.2 mm Is higher than the voltage at the position where the high-frequency signal is generated in the CD having the thickness of. This is because when the recording surface of the DVD having a thickness of 0.6 mm with respect to the reference surface of the objective lens 5 in the recording medium 6 is 1.2 mm in the distance from the objective lens set to the initial position with respect to the recording medium Is closer to the recording surface of the CD.

The actuator voltage is set to an OFFSET voltage value in the servo unit 12 to control the initial focus position according to different discs. This is because the servo unit 12 controls the initial focus position according to the disc By applying an offset voltage. That is, when the actuator 9 is driven under the control of the microcomputer so that the focus of light passing through the objective lens 5 is adjusted to the recording medium 6, While the swing voltage is applied, the photodetector 8 receives the optical signal and outputs a high-frequency signal.

Next, how information reproduction is performed by controlling a main beam and a sub beam in a single reproducing apparatus in which signals recorded on two different optical discs are performed will be described.

First, the microcomputer 15 controls the servo unit 12 to apply an offset voltage corresponding to a specific disk to the actuator 9. [ The actuator 9 sets the initial position of the objective lens 5 by this offset voltage. Then, the microcomputer 15 controls the servo unit 12 to apply the driving voltage of the actuator 9 according to the specific disk. By this drive voltage, the actuator starts to swing, and the beam, which is modulated by the signal recorded on the recording medium 6 by this swinging operation and reflected, is reflected along the same optical path up to the beam splits 3.

The main beam and the sub beam incident on the optical detector 7 are input to the reproduction signal processing unit 11 and signal processing is performed by changing the optical path in the beam splitter 3. The reproduction signal processing section 11 performs high frequency reproduction with the total light amount of the main beam, that is, the sum value of A + B + C + D, and outputs it to the digital signal processing section 13 and the disc discrimination section 14. The digital signal processing unit 13 decodes and error-corrects an input signal and outputs digital information.

A signal corresponding to the main beam reproduced by the reproduction signal processing unit 11 as a high frequency signal is input to the disc discrimination unit 14. [ The disk discrimination unit 14 compares the input high frequency signal with a reference signal. At this time, when the recording medium and the actuator drive voltage are equal to each other, that is, when the recording medium is CD and the actuator bulb voltage and the drive voltage according to CD are applied, the high frequency signal inputted to the disc discrimination unit Is applied as a larger signal. However, when a voltage corresponding to the CD is applied to the actuator due to the initial focal adjustment voltage applied to the actuator and the drive voltage for swinging the actuator when the recording medium is a DVD, the signal recorded on the disk can not be read, The high frequency signal inputted to the signal processing unit 14 is applied as a signal smaller than the reference signal to discriminate the disc type.

If it is determined by the disc discriminator 14 that the current recording medium matches the current recording medium, the microcomputer 15 performs overall control of the system so that the control process corresponding to the determined recording medium is performed. However, if the signal determined by the disk discrimination unit 14 does not coincide with the current recording medium, the microcomputer 15 returns to the initial operation state again to perform proper operation from the initial focus adjustment of the actuator, Thereby performing a control operation coinciding with the medium.

(A + C) - (B + D), the information of the main beam applied by the photodetector 11 is written to the recording medium And the high-frequency signal of the sub-beam is calculated by using (EF) as a control signal for tracking control. Of course, the above calculation process is also performed in the reproduction signal processing unit. The two control signals are applied to the servo unit so that tracking and pacing are controlled by the signals.

As described above, in the conventional system, the CD mode is arbitrarily selected at the time of discriminating the recording medium, and the information recorded on the recording medium is read by adjusting the focus of the light beam and applying the driving voltage of the actuator according to the selection. However, if the selected mode is incorrect, the system can not read the signal on the disc, and the system switches to DVD mode to play the disc.

Therefore, the conventional optical disc reproducing apparatus has a problem that it takes a long time by judging the disc with the high frequency signal to be reproduced.

It is therefore an object of the present invention to provide an optical disc reproducing apparatus for detecting a driving voltage of an actuator by discriminating a disc, judging a recording medium according to the detected voltage, and performing a correct control operation.

FIG. 1 is a block diagram of a conventional optical disc reproducing apparatus. FIG.

FIG. 2 is a configuration diagram of an optical disc reproducing apparatus according to the present invention; FIG.

FIG. 3 is a detailed circuit diagram of a disc discrimination circuit according to the present invention; FIG.

FIG. 4 is a diagram showing the operation state of the reproducing apparatus in the disk discriminating mode according to the present invention. FIG.

Description of the Related Art [0002]

21: laser diode 22: diffraction grating

23: beam splitter 24: collimating lens

25: objective lens 26: recording medium

27: sensor lens 28: photo detector

29: actuator 31: drive voltage detecting section

31a, 32a: sample and hold circuit 32: light amount maximum value detection section

32b: comparison unit 33: disk discrimination unit

34: Microcomputer 35: Playback signal processor

36: Digital signal processing unit 37: Servo unit

According to an aspect of the present invention, there is provided an apparatus for reproducing an optical disc, comprising: an actuator for changing a position of a focus lens by receiving a voltage for adjusting a focus; A voltage detector for detecting a focal point adjustment voltage applied to the actuator; A light amount maximum value detecting unit for detecting a maximum value of light amount outputted from the light detecting unit; And a disc discrimination unit for discriminating the disc according to the output voltage of the voltage detection unit when the light amount of the maximum value is detected by the maximum light amount detection unit.

The optical disc reproducing apparatus according to the present invention uses a different focal adjustment voltage applied to the actuator for adjusting the distance between the recording surface for recording information on CD and DVD and the objective lens, The driving voltage of the actuator is detected. By detecting the recording medium by the detection voltage and performing the system control, it is possible to accurately determine the recording medium while shortening the disc discrimination time.

Hereinafter, an optical disc reproducing apparatus according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a block diagram of an optical disc reproducing apparatus according to an embodiment of the present invention.

First, the configuration will be described. The pickup device 30 includes a light emitting diode 21 for emitting light, a diffraction grating 22 for dividing the beams emitted from the light emitting diode 21 into three beams, a beam splitter 23, a collimator lens 24 which is made into a parallel beam, and an object lens 25 which condenses the beam on the recording medium 26.

The beam arriving at the recording medium 26 through the optical path according to the above configuration is modulated by the information medium recorded on the information recording surface and then reflected along the same path from the objective lens to the collimator lens to the beam splitter. The path is changed in the beam splitter to be converged by a sensor lens 27, and the condensed beam is incident on an optical detector 28.

At this time, since three beams are incident on the photodetector 28, in order to receive the three beams, the light receiving unit of the photodetector is also divided into three. That is, the light receiving portions A, B, C and D for receiving the main beam are divided into four portions and located at the center, and the light receiving portions E and F for receiving the sub beams above and below the light receiving portion.

The photodetector 28 configured as the light receiving unit converts the incident optical signal into an electrical signal and outputs the electrical signal. The output signal is input to the reproduction signal processing unit 35 and used for information reproduction, tracking, and focusing Soon, the main beam and the sub beam are appropriately controlled to perform signal processing.

That is, the reproduction signal processing section 11 performs high frequency reproduction with the total light amount of the main beam, that is, the sum value of A + B + C + D, and outputs it to the digital signal processing section 13. The digital signal processing unit 13 decodes and error-corrects an input signal and outputs digital information. The high frequency signal of the main beam applied by the photodetector 11 is calculated as (A + C) - (B + D) to determine whether the spot (spct) And the high-frequency signal of the sub-beam is calculated by using EF as a control signal for tracking control. Of course, the above-described calculation process is performed in the reproduction signal processing unit 35 as well. The two control signals are applied to the servo unit 37 and the voltage applied to the actuator 29 is adjusted by the signal to control the tracking and focusing.

Meanwhile, the optical signal applied to the photodetector 28 during the initial focusing operation of the pick-up device 30 is a non-signal optical signal in which information recorded on the information recording surface is not displayed. The amount of light detected is output to the light amount detection unit 32. [ The light amount detecting unit 32 outputs a control signal to the disc discriminating unit 33 when the amount of light to be input reaches a maximum. A detection section 31 for detecting the drive voltage of the actuator 29 is constituted, and the output of the detection section is inputted to the disk discrimination section 33. The disc discriminating unit 33 judges the current recording medium with the driving voltage of the actuator 29 when the control signal is applied by the light amount detecting unit 32 and applies the disc discriminating signal to the microcomputer 34 .

Hereinafter, how the discrimination of the recording medium in the reproducing apparatus of the present invention constituted as described above is performed will be described in detail.

The light passing through the objective lens needs to adjust the position of the focal point in order to form a light spot on the two recording media 26 having different thicknesses of the substrate, Adjustment is made by adjusting the distance between the objective lens and the optical disk. At this time, the distance between the objective lens and the recording medium is adjusted by driving the actuator 29 mounted on both sides of the objective lens. The voltage applied to the actuator coil at the position where the high frequency is generated in the DVD having the thickness of 0.6 mm is 1.2 mm thick because the voltage applied to the actuator 29 for driving the actuator is high and the voltage is high when the amount of movement of the actuator is large. Is higher than the voltage applied at the position where the high-frequency signal is generated in the CD having the high-frequency signal. This is because the recording surface of the DVD having a thickness of 0.6 mm with the side surface of the objective lens 25 as the reference surface in the recording medium 26 has a thickness of 1.2 mm from the objective lens set to the initial position with respect to the recording medium Is closer to the recording surface of the CD.

As described above, the focal adjustment voltage applied to the actuator 29 according to the CD or DVD according to the recording medium is lower than the reference voltage when the CD is compared with the reference voltage for separating the two recording media. The actuator voltage becomes higher than the reference voltage. Therefore, the present invention uses this feature to make judgment of the disc.

FIG. 4 is a system operation state diagram in the disc discrimination mode according to the present invention.

Since the operation of the pickup apparatus 30 is the same as that of the conventional art in the operation of the present system, the process until the emitted light beam is received is omitted, and according to the control operation of the microcomputer 34, Describe the process by which the discrimination is made.

The microcomputer 34 applies an offset voltage to the actuator 29 through the servo unit 37 in the disk discrimination mode (step 101). At this time, the actuator 29 moves up and down according to the applied offset voltage to adjust the focus. (Step 102) In this operation, an optical signal is detected through the photodetector 28. At this time, the detected optical signal is an optical signal detected according to the initial focusing adjustment operation of the actuator, and the signal corresponding to the recorded information is not loaded. The light amount In to be applied is detected by the light amount detection unit 32 with a constant period and the offset voltage Vn applied to the actuator 29 is continuously detected through the drive voltage detection unit 31 And is output to the disc discrimination unit 33. (Step 103)

Then, the light amount detected by the light amount detecting unit 32 is continuously compared with the previously detected light amount, thereby detecting when the presently inputted light amount becomes the maximum (Step 104)

That is, the microcomputer 34 continuously adjusts the offset voltage of the actuator 29 through the servo unit 37 until the maximum amount of light is detected by the light amount detecting unit 32, and the offset voltage Vn is also continuously And detection is performed. The offset voltage applied to the actuator 29 refers to a voltage for adjusting the focus.

When the output of the light amount detecting unit 32 reaches a maximum value while the operation is being performed as described above, the light amount detecting unit 32 outputs a control signal to the disc discriminating unit 33. At this time, the disc discriminator 33 compares the reference voltage ref with the offset voltage Vn output from the driving voltage detector 31. In this case, if the compared voltage is greater than the reference voltage, The disc discrimination unit judges the recording medium as a DVD (step 106), and judges the recording medium as a CD when the pre-comparison voltage is lower than the reference voltage (step 107)

When the disc is discriminated through the above process, the microcomputer 34 performs control according to the discriminated disc, and the system normally starts to reproduce the signal.

That is, the main beam and the sub beam incident on the photodetector 28 are input to the reproduction signal processing unit 35, and signal processing is performed. The reproduction signal processing section 35 performs high frequency reproduction with the total light amount of the main beam, that is, the sum value of A + B + C + D, and outputs it to the digital signal processing section 36. The digital signal processor 36 decodes and error-corrects an input signal and outputs digital information.

The high-frequency signal of the main beam applied by the photodetector 28 is calculated as (A + C) - (B + D), and used as a control signal indicating whether the pick- And the high-frequency signal of the sub-beam is computed by using EF as a control signal for tracking control. Of course, the above-described calculation process is performed in the reproduction signal processing unit 35 as well. The two control signals are applied to the servo unit 37 and the voltage applied to the actuator 29 is adjusted by the signal to control the tracking and focusing.

FIG. 3 is an embodiment of the disc discrimination circuit according to the present invention. That is, a sample-and-hold circuit 32a for sampling and outputting the amount of light detected by the photodetector 28 at regular intervals, and a sample-and-hold circuit 32b for continuously inputting the output of the sample- And a sample-and-hold circuit 31 for sampling and outputting an actuator driving voltage. The output of the sample-and-hold circuit 31 for sampling the drive voltage of the actuator is input to the disc discriminator 33 and the control signal output at the maximum intensity of the light by the comparator 32b is also supplied to the disc discriminator 33 .

That is, when the amount of light to be applied by the photodetector 28 is compared with the maximum value by the comparator 32b, the disc discriminating unit 33 compares the actuator driving voltage and the reference voltage ref. The disc is judged by being higher or lower than the voltage.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, (High-density Disc).

As described above, the disc discrimination circuit of the optical disc reproducing apparatus according to the present invention detects the focus adjustment voltage applied to the actuator when the amount of light detected by the optical detector reaches a maximum before the operation of the actuator for reading the signal , It is advantageous in that the system can be prevented from malfunctioning because it is possible to determine the disk quickly and accurately according to the disk discrimination.

Claims (2)

An actuator for varying a position of the focusing lens by receiving a voltage for adjusting a focus, A photodetector for detecting an amount of light incident from a position of the focal lens, which is varied by the actuator, A voltage detector for detecting a focal point adjustment voltage applied to the actuator; A light amount maximum value detecting unit for detecting a maximum value of light amount outputted from the light detecting unit; And a disc discrimination unit for discriminating a disc according to an output voltage of the voltage detection unit when the light amount of the maximum value is detected by the maximum light amount detection unit. 2. The optical disc reproducing apparatus according to claim 1, further comprising a servo unit for variably controlling the driving of the actuator according to a disc type discrimination result which is an output signal of the disc discriminating unit.