KR100359085B1 - Optical disc pick-up apparatus - Google Patents

Abstract

Disclosed are an optical disc pick-up apparatus that simultaneously detects an optical disc type and an inclination. In the optical disk pick-up apparatus having two light emitting elements and two light receiving elements for detecting the type and inclination of the disc together, a line perpendicular to the disc surface without inclination is referred to as an optical axis. One of the luminous means is used as a light source for detecting the inclination of the disk, with the central axis of divergent light emitting light coinciding with the optical axis, and the other one emitting light with the central axis of the divergent light at an angle with respect to the optical axis. It is disposed so as to be used as a light source for detecting the disc type by detecting the difference in the thickness of the disk substrate.

Description

Optical disc pick-up apparatus

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc pick-up apparatus, and more particularly, to an optical disc pick-up apparatus for detecting the type and tilt of an optical disc.

In general, an optical pick-up device used in an optical memory system is a key component for recording or reproducing information on a disc. There are several types of optical discs with different recording densities and thicknesses. For example, a CD (Compact Disc) disk has a capacity of 650 MBytes and a thickness of 1.2 mm, and a recent DVD (Digital Versatile Disc) disk has a structure in which two sheets having a capacity of 4.7 GByte and a thickness of 0.6 mm are bonded.

On the other hand, the function of detecting and correcting the inclination of the disc is an important factor for improving the playback or recording characteristics. : Tilt Detection Sensor) has been developed. In addition, discs for high-density recording and reproduction such as DVD-RAM use cartridges for stability.

1 illustrates a structure of a general TDS, and includes one light emitting device (LED) and two light receiving devices (PD1, PD2).

2 shows a structure of a general DDD.

3 is an application circuit diagram of TDS and DDD, and includes a light emitting device (LED) and two light receiving devices (PD1, PD2), a 5-pin sensor 310, an RF amplifier 320, 330, and a sum signal detector. 340, the difference signal detection unit 350 is provided.

As shown in FIG. 1, the light emitted from the light emitting device LED is reflected by the disk 110 and incident on the first light receiving device PD1 and the second light receiving device PD2. A difference in the amount of light incident on the first light receiving element PD1 and the second light receiving element PD2 occurs according to the inclination state of the disk 110, and by using the difference signal AB detected by the difference signal detecting unit 350. The disk tilt is detected. In addition, when the difference signal is normalized using the sum signal A + B detected by the sum signal detection unit 340, the disc tilt is detected regardless of the change in intensity with respect to the disc reflectance.

On the other hand, the structure of the DDD as shown in FIG. 2 includes one light emitting device (not shown) and two light receiving devices (not shown) as in the TDS. However, DDD detects the thickness of the disk 210 and detects the disk type by several tens of degrees. The sensor is tilted with respect to the disk 210, and the sensor is inclined with respect to the disk 210, which is a reflective surface. The distance between the sensor and the sensor is different, resulting in a difference in the sum signal (A + B). Therefore, it is possible to detect the disc type using this difference.

In general, however, it is difficult to use DDD and TDS simultaneously when there is a cartridge, such as a drive for DVD-RAM, due to the space limitations of the head window. At the same time, the cost is increased, and the circuit pin count is increased by using DDD and TDS separately.

An object of the present invention is to provide an optical disk pick-up device having two light emitting elements and two light receiving elements to detect a disc type and a disc tilt.

Figure 1 shows the structure of a typical TDS.

2 shows a structure of a general DDD.

3 is an application circuit diagram of TDS and DDD.

4 shows a sensor of an optical disc pick-up device according to the invention.

FIG. 5 is an optical disk pick-up circuit diagram having the sensor of FIG. 4 to detect the disk type and tilt. FIG.

In order to solve the above technical problem, the present invention is an optical pick-up device comprising a device for detecting the type and / or tilt of the disk,

The device,

A first light emitting element for detecting a disk tilt; A second light emitting device for detecting disk type; And a light receiving element that detects light reflected from the disk after being emitted from the first and second light emitting elements,

The first light emitting device is arranged such that the central axis of the divergent light emits light coinciding with the optical axis when a line perpendicular to the disk surface without inclination is called an optical axis.

The second light emitting device is disposed such that the central axis of the divergent light emits light at a predetermined angle with respect to the optical axis,

When the disc is loaded, the second light emitting device is turned off and the first light emitting device is emitted to receive light reflected from the disk to receive the light from the light receiving device to determine the inclination of the disk, and the first light emitting device is turned off and the second light emitting device is turned off. A light pick-up device is characterized in that the light emitting device is emitted and the light reflected from the disk is received by the light receiving device to determine the type of disk.

In order to solve the above technical problem, the present invention is an optical pick-up device for detecting the type and tilt of the disk,

A first light emitting element arranged to emit light whose central axis of divergent light corresponds to the optical axis, a second light emitting element arranged so that the central axis emits light at an angle with respect to the optical axis, and the first and second light emitting elements A light receiving element for receiving light emitted from any one of the light reflected from the disk;

When the disc is loaded, the disc type is detected by the difference or sum of the signals emitted from the second light emitting element and incident on the light receiving element, and then the disc tilt is increased by the difference or sum of the signals emitted from the first light emitting element and incident on the light receiving element. A signal detector for detecting;

And a switching unit for switching a power supply for emitting light of the first light emitting device and the second light emitting device to the disk when the disk is loaded.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

4 shows a sensor of the optical disk pick-up apparatus according to the present invention, and is composed of two light emitting elements LED1 and LED2 and two light receiving elements PD1 and PD2 in one sensor.

As shown in FIG. 4, when a line perpendicular to the surface of the disk 410 having no inclination is defined as the optical axis 420, one of the two light emitting devices LED1 and LED2 is the central axis of the divergent light. It is arranged to emit light in correspondence with the optical axis 420 to be used as a light source for detecting the tilt of the disk. Therefore, the light emitted from the light emitting element LED1 and reflected from the disk 410 are incident on the two light receiving elements PD1 and PD2, and the incident light signal is respectively summed signal A + B or difference signal. Disc tilt is determined using (AB).

In addition, the other light emitting device LED2 is disposed so that the central axis of the divergent light emits light at an angle with respect to the optical axis 420 adjacent to the light emitting device LED1 to recognize the difference in the thickness of the disk 410 substrate. It is used as a light source to detect the kind. At this time, the center axis of the divergent light is disposed so as to satisfy the condition of 10 ° ≤θ≤45 ° when the angle with respect to the optical axis 420 is? If the angle is smaller than this condition, it is difficult to recognize the disc thickness difference. If the angle is larger than this condition, the amount of light detected by the light receiving elements PD1 and PD2 is reduced, resulting in a decrease in output signal characteristics. Therefore, the light emitted from the light emitting element LED2 and reflected from the disk are incident to the two light receiving elements PD1 and PD2, and the incident light signal is respectively summed signal A + B or difference signal AB. Determine the disk type using.

FIG. 5 is an optical disk pick-up circuit diagram including a disk type and an inclination in which the sensor of FIG. 4 is detected, and includes a first switch SW1 and a second switch SW2 for controlling a power supply (+ 5V). The light emitting elements LED1 and LED2 and the two light receiving elements PD1 and PD2 include a six-pin sensor unit 510, an RF amplifier 520 and 530, a sum signal detector 540, and a difference signal detector 550. It is provided.

As shown in FIG. 5, when there is no disk in the drive, the first switch SW1 and the second switch SW2 for switching the power supply (+ 5V) are turned off to turn off the two light emitting devices LED1 and LED2. When the disk is loaded in the drive and the disk is loaded, the switch S / W2 for detecting the disk type is turned on. Subsequently, the disk type detection light emitting element LED2 is supplied with power (+ 5V) by the switch S / W2 to emit light to the disk. The emitted light reflects off the disk and enters the two light receiving elements PD1 and PD2. At this time, the amount of light incident on the two light receiving elements PD1 and PD2 is input to the RF amplifiers 520 and 530 each consisting of a resistor R1 and a capacitor C1 and an amplifier IC1 to detect the reflectance of the light reflected from the disk. The signals A and B output from the RF amplifiers 520 and 530 are input to the sum signal detector 540 or the difference signal detector 540 which is composed of the resistors R4 and R5 and the amplifier IC1. Therefore, the sum signal detector 540 or the difference signal detector 540 adds or subtracts the optical signals of the two light receiving elements PD1 and PD2 amplified from the RF amplifiers 520 and 530, respectively, to sum the signal A + B or the difference signal. (AB) is detected. This sum signal A + B or difference signal A-B eventually becomes the disk reflectance. Therefore, the disc type is determined using the sum signal A + B or the difference signal A-B, which electrically detects the amount of light reflected differently from the disc according to the disc thickness. For example, CDs and DVDs have different disk thicknesses, and thus have different disk reflectances. In this case, even if the thickness of the disk is the same, the reflectance of the disk varies depending on the type of disk according to the purpose of the disk. For example, the CD series has the same board thickness of 1.2mm, but the CD-ROM which is dedicated to playback and the CD-R, which is a write once read many (WORM) method, have a high reflectance of about 80% and can be repeatedly recorded. -RW has a low reflectance of about 20%. In addition, the DVD series has the same disk substrate thickness as 0.6mm, but the DVD-ROM monolayer structure has a high reflectance of about 80%, and the repeatable CD-RW and DVD-RAM have a low reflectance of about 20%, The write once read many (WORM) CD-R and DVD-ROM two-layer structure has a medium reflectance of about 50%. Knowing the type and reflectance of the disc allows you to immediately determine the light source used for the disc and set the appropriate gain for the reflectivity of the disc.

Subsequently, when the type of the disc is determined, the disc discriminating light emitting element LED2 is turned off, and the inclination detection light emitting element LED1 of the disc is turned on by the switch S / W1 and the light emitted is reflected from the disc to receive two light. Incident to the elements PD1 and PD2. The optical signals detected from the two light receiving elements PD1 and PD2 are converted into voltages through RF amplifiers 520 and 530 consisting of a resistor R1, a capacitor C1, and an amplifier IC1, respectively. The signals A and B output from the signals 520 and 530 are outputted from the difference signal AB or the sum signal through the difference signal detector 550 or the sum signal detector 540 formed of the resistors R4 and R5 and the amplifier IC1. A + B) is detected. The inclination of the disc is detected using the difference signal A-B or the sum signal A + B.

The present invention is not limited to the above-described embodiment, and of course, modifications may be made by those skilled in the art within the spirit of the present invention. That is, it is applicable to all pick-up apparatuses for playing back optical discs.

As described above, according to the present invention, even when there is a space limitation of the head window of the cartridge structure such as a DVD-RAM drive, disc type determination and disc inclination can be detected in real time by a switching operation. It is possible to determine the type of disc, which greatly reduces the time required for initializing the drive when the disc is loaded, and greatly reduces the probability of focus and track servo malfunctions. It is possible to maintain optimal recording or reproducing characteristics.Because the number of circuit pins increases only 1 pin from 5 pins to 6 pins because DDD and TDS are used together, when using DDD (4 pins) and TDS (5 pins) separately The number of pins is reduced.

Claims (4)

An optical pick-up device comprising a device for detecting the type and / or tilt of a disc, The device, A first light emitting element for detecting a disk tilt; A second light emitting device for detecting disk type; And a first and second light receiving element for detecting light reflected from the disk after being emitted from any one of the first and second light emitting elements, The first light emitting device is arranged such that the central axis of the divergent light emits light coinciding with the optical axis when a line perpendicular to the disk surface without inclination is called an optical axis. The second light emitting device is disposed such that the central axis of the divergent light emits light at a predetermined angle with respect to the optical axis, When the disc is loaded, the second light emitting device is turned off, the first light emitting device is emitted, and the light reflected from the disk is received by the first and second light receiving devices to detect a sum signal for disc inclination determination, and then 1. The optical pick-up apparatus of claim 1, wherein the first light emitting device is turned off and the second light emitting device is emitted, and the light reflected from the disk is received by the first and second light receiving devices to detect a disc type discrimination signal. . The optical pick-up device according to claim 1, wherein the central axis of divergent light of the light source for detecting the type of the disc is 10 ° ≤θ≤45 ° when the angle with respect to the optical axis is θ. An optical pick-up apparatus for detecting the type and / or tilt of a disc, A first light emitting element for disc tilt detection arranged to emit light whose central axis of divergent light corresponds to an optical axis, a second light emitting element for disc type detection arranged to emit light with a central axis angled to the optical axis; A light receiving element for receiving the light reflected from the disk emitted from any one of the first and second light emitting elements; A signal detector for detecting a difference or sum of a signal emitted from the second light emitting element and incident to the light receiving element when the disc is loaded, and detecting a difference or sum of a signal emitted from the first light emitting element and incident to the light receiving element; And a switching unit for switching a power supply to selectively apply power to the first light emitting device and the second light emitting device when the disk is loaded. The disc type is determined by the difference or sum of the signals emitted from the second light emitting element and incident on the light receiving element by the signal detector, and the disc is tilted by the difference or sum of the signals emitted from the first light emitting element and incident on the light receiving element. The optical pick-up device, characterized in that is determined. 4. The optical disc pick-up apparatus of claim 3, wherein the sum signal incident from the light receiving element determines a disc reflectance.