Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of Korean Patent Application No. 2005-44659, filed on May 26, 2005, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   An aspect of the present invention relates to an optical recording and/or reproducing apparatus to record and playback data of an optical disc, and, more particularly, to an interface device of an optical recording and/or reproducing apparatus wherein the configuration of an interface circuit between a pickup that reads and writes information from/on an optical disc and a radio frequency (RF) integrated circuit (IC) for signal processing is simplified. 
   2. Description of the Related Art 
   With advances in video and audio media technologies, a recording medium in which high quality video and audio data may be recorded and stored for a lengthy period of time, for example an optical disc like a digital versatile disc (DVD), has been developed and made commercially available. Along with this medium, an optical recording and/or reproducing apparatus which may record and/or reproduce video and audio data on the optical disc, for example, a DVD player, has also been developed and made commercially available. 
   This optical recording and/or reproducing apparatus reproduces video and/or audio data recorded on the optical disc and outputs the reproduced data via a screen and/or a speaker. The optical recording and/or reproducing apparatus has various advantages over a conventional video and/or audio reproducing apparatus in terms of higher-quality video and/or audio signal reproduction due to a higher signal-to-noise ratio, a lower noise level due to regularities in reproduction and modulation, minimal signal distortion, ghost-free reproduction, and a random access capability. Thus, the optical recording and/or reproducing apparatus has been in a trend towards rapid advances and widespread use. 
   Various types of optical recording and/or reproducing apparatuses, such as a compact disc player (CDP), a laser disc player (LDP), a compact disc graphic player (CDGP), and a video compact disc player (VCDP), have been developed and used extensively. Recently, DVDs have been developed using moving picture compression techniques such as moving picture experts group 2 (MPEG2), moving picture experts group 4 (MPEG4), and Digital Video EXpress (DivX). A blu-ray disc (BD) and a high definition-DVD (HD-DVD) have also been developed using a blue laser technology. Along with these, DVD players have been developed to record and playback corresponding discs. 
   As shown in  FIG. 1 , such an optical recording and/or reproducing apparatus uses a laser diode (LD) which generates a laser signal to read and write information from/on a disc  12 , a BD, HD-DVD, DVD, or CD. The LD has input/output characteristics which vary relatively very sensitively with the operating temperature thereof. 
   That is, the LD requires a different input (typically expressed in an electric current value) depending upon the operating temperature thereof to output a laser signal of a constant power level irrespective of the operating temperature thereof. Thus, there is a need for an Auto laser diode Power Control (APC) technique to optimally control the LD. This APC technique determines the performance of the optical recording and/or reproducing apparatus. 
   An APC unit  22  using such an APC technique is provided to feed a variation in the output of the LD back to the LD to keep the output of the LD constant. Generally, the APC unit  22  is provided in a radio frequency (RF) integrated circuit (IC)  20  together with an RF signal processor  24 . The RF IC  20  is placed on a main printed circuit board (PCB)  30 . 
   On the other hand, an LD driver  14  is provided in a pickup  10  to drive the LD. Thus, the pickup  10  and the main PCB  30  are interconnected via connectors  40  to constitute an interface circuit between the LD driver  14  and the RF IC  20 . 
   As a result, the RF IC  20  has to receive a monitor signal corresponding to an output variation of a monitor photo diode (MPD) attached to the LD through the connectors  40 . The LD driver  14  also has to receive a control signal from the RF IC  20  through the connectors  40 . 
   For this reason, where the optical recording and/or reproducing apparatus of  FIG. 1  is a universal optical recording and/or reproducing apparatus that is capable of recording and playing back all kinds of discs  12  including a BD, HD-DVD, DVD, and CD, a plurality of LD drivers  14  must be separately provided corresponding respectively to a plurality of LDs configured for recording/playback of the respective discs  12 , and have separate outputs corresponding respectively to the LDs. This increases the number of input/output pins of the pickup  10  and RF IC  20  on the main PCB  30 , thus making the layout of the PCB and the structures of the connectors  40  complicated, resulting in degradation in signal quality. 
   Moreover, because a multiplexer (MUX)  26  is provided in the RF IC  20  to multiplex input/output signals of the pickup  10  and RF IC  20 , the number of pins of the connectors  40  from the pickup  10  to the RF IC  20  on the main PCB  30  increases, which leads to an obstacle that prevents smallness, lightness, and cost effectiveness of the optical recording and/or reproducing apparatus. 
   SUMMARY OF THE INVENTION 
   Therefore, an aspect of the invention provides an interface device for an optical recording and/or reproducing apparatus, wherein a multiplexer is provided in a pickup to multiplex input/output signals of the pickup and an RF IC so that the number of pins of connectors from the pickup to the RF IC is reduced, leading to simplification of PCB layout and preservation of signal quality. 
   Another aspect of the invention provides an interface device for an optical recording and/or reproducing apparatus which may reduce the size and cost of the optical recording and/or reproducing apparatus by decreasing the number of input/output pins of an RF IC. 
   In accordance with an aspect of the invention, there is provided an interface device for an optical recording and/or reproducing apparatus comprising: a pickup to drive a plurality of laser diodes generating laser signals to record and/or reproduce information on a plurality of discs, respectively, and to receive the laser signals reflected from the discs and output photodiode (PD) signals corresponding respectively to the received laser signals; an integrated circuit to control outputs of the laser diodes, and to process the PD signals from the pickup; and a multiplexer, disposed in the pickup, to select a PD signal corresponding to a particular one of the discs from among the PD signals from the pickup and interface the selected particular PD signal to the integrated circuit. 
   According to an embodiment of the invention, the discs may be of different types and the laser diodes may correspond to the discs, respectively. The laser diodes may generate the laser signals depending upon types of the discs, respectively, and the laser signals may correspond to the discs, respectively. 
   According to another embodiment of the invention, the multiplexer includes a plurality of multiplexing channels which are selectively operated to multiplex output signals of monitor photodiodes (MPDs) attached to the respective laser diodes for the discs to output an output signal of an MPD (MPD signal) corresponding to the particular disc. 
   The integrated circuit may be a radio frequency (RF) integrated circuit (IC) which converts the particular PD signal among the PD signals from the pickup into a servo control signal and an RF signal necessary to the particular disc and performs a servo control operation and RF data processing operation for the particular disc respectively, according to the converted servo control signal and RF signal. 
   The particular disc may be any one of a Blu-ray disc (BD), digital versatile disc (DVD), high definition-DVD (HD-DVD), and/or a compact disc (CD). 
   The RF IC may be provided on a main printed circuit board (PCB) and connected to the pickup through connectors. 
   A microcomputer may be mounted on the main PCB. The microcomputer may output a switch control signal to the pickup and RF IC to select a desired one of types of the discs corresponding to the particular disc. 
   In accordance with another aspect of the invention, there is provided an interface device for an optical recording and/or reproducing apparatus comprising: a pickup to record and/or reproduce information on a plurality of discs; a radio frequency (RF) integrated circuit (IC) to perform an RF signal processing operation on the information on the discs; and a multiplexer to select an output signal from the pickup and interface the selected signal to the RF IC. 
   The multiplexer may be provided in the pickup. 
   Additional and/or other aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
       FIG. 1  is a block diagram showing the circuit configuration of an interface device for a conventional optical recording and/or reproducing apparatus; 
       FIG. 2  is a block diagram showing the circuit configuration of an interface device for an optical recording and/or reproducing apparatus according to an embodiment of the present invention; and 
       FIG. 3  is a block diagram showing the circuit configuration of an interface device for an optical recording and/or reproducing apparatus according to another embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE EMBODIMENTS 
   Reference will now be made in detail to the present embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures. 
     FIG. 2  is a block diagram showing the circuit configuration of an interface device for an optical recording and/or reproducing apparatus according to an embodiment of the present invention. As shown in  FIG. 2 , the interface device for the optical recording and/or reproducing apparatus mainly includes a pickup  100  and a main PCB  200 . The pickup  100  and the main PCB  200  are connected to each other via a cable  400  through connectors  300 . 
   The pickup  100  is a device to read and write information from/on discs  110 , each of which may be a BD, HD-DVD, DVD, and/or CD or another format. The pickup  100  includes laser diode driver units (hereinafter referred to as LD units)  112  to drive laser diodes (LDs) for the respective discs  110 , respectively, photo diode (PD) units (hereinafter referred to as PD units)  114  to receive laser signals reflected from the associated discs  110 , respectively, and an MUX IC  120  including a plurality of MUX channels Ch 1  to Ch 9 , each of which selects an output signal from a PD unit (PD signal) corresponding to an associated one of the discs  100  from among output signals from the PD units  114  (PD signals) corresponding respectively to the discs  100 . 
   Each of the MUX channels Ch 1  to Ch 9  in the MUX IC  120  is also adapted to multiplex output signals from monitor photo diodes (hereinafter referred to as MPDs) attached to the respective LDs for the discs  110  to select an output signal from an MPD (MPD signal) corresponding to the associated disc from among the output signals from the MPDs (MPD signals). 
   The main PCB  200  includes an RF IC  210  for RF signal processing, and a microcomputer  220  which outputs a switch control signal BD/HD-DVD/DVD/CD to the pickup  100  and the RF IC  210  to select a desired one of the types of the discs  110 . 
   The RF IC  210  includes an Auto laser diode Power Control unit (hereinafter referred to as an APC unit)  230  which optimally controls outputs of the LDs for all the types of discs  110  including at least one of a BD, HD-DVD, DVD, and/or CD. The RF IC  210  also includes an RF signal processor  240  which converts a PD signal from the MUX IC  120  into a servo control signal and an RF signal necessary to a particular disc  110  corresponding to the PD signal and performs a servo control operation and an RF data processing operation for the particular disc, respectively, according to the converted servo control signal and RF signal. The RF IC  210  further includes a demultiplexer (DEMUX)  250  which receives an MPD signal corresponding to the particular disc  110  from the MUX IC  120 , selects one of a plurality of output terminals thereof corresponding to the particular disc  110  in response to the switch control signal BD/HD-DVD/DVD/CD from the microcomputer  220 , and outputs the MPD signal to a corresponding APC of the APC unit  230  through the selected output terminal. 
   The APC unit  230  optimally controls outputs (amounts of light) of the respective LDs for the discs  110 , each of which is at least one of a BD, HD-DVD, DVD, and/or CD. That is, the APC unit  230  keeps the outputs of the LDs constant by feeding variations in the outputs of the LDs back thereto, respectively. To this end, the APC unit  230  includes at least one of a BD APC, HD APC, DVD APC, and CD APC. 
   The RF signal processor  240  includes an RF controller  242  to generate the RF signal for the RF data processing operation, and a servo controller  244  to generate the servo control signal for the servo control operation. 
     FIG. 3  is a block diagram showing the circuit configuration of an interface device for an optical recording and/or reproducing apparatus according to another embodiment of the present invention. Some parts in  FIG. 3  are the same as those in  FIG. 2 . Therefore, the same elements are denoted by the same reference numerals and names, and a repeated description thereof will be omitted. 
   As shown in  FIG. 3 , the main PCB  200  includes the RF IC  210 , the microcomputer  220 , and a DEMUX  260 . It is noted that the DEMUX  260  is provided on the main PCB  200  rather than in the RF IC  210  in a different manner from that of the DEMUX  250  in  FIG. 2 . 
   The DEMUX  260  receives the MPD signal of the particular disc  110  from the MUX IC  120 , selects one of a plurality of output terminals thereof for selection of the particular disc  110 , and outputs the MPD signal to a corresponding APC of the APC unit  230 . The DEMUX  260  also receives the outputs of the respective PD units  114  for the discs  110 , selects the PD signal corresponding to the particular disc  110 , and outputs the PD signal to a MUX  270  provided in the RF IC  210 . 
   In addition, the RF IC  210  includes the MUX  270  which selects the PD signal of the particular disc  110  among the PD signals outputted from the DEMUX  260  in a different manner from the DEMUX  250  in  FIG. 2 . This PD signal selected by the MUX  270  is inputted to the RF signal processor  240  and is used for the servo control operation and the RF data processing operation of the particular disc  110 . 
   A description will hereinafter be given of the operation of the interface device for the optical recording and/or reproducing apparatus with the above-stated configuration according to the present invention. 
   An aspect of the present invention aims to simplify the configuration of the interface circuit between the pickup  100  to read and write disc information and the RF IC  210  for RF signal processing in a universal optical recording and/or reproducing apparatus which is capable of reading and writing information from/on all kinds of optical discs including at least one of a BD, HD-DVD, DVD, and CD. The operation of this interface configuration will hereinafter be described with reference to  FIG. 2 . 
   First, the user opens a disc tray, inserts a disc  110  of at least one of a BD, HD-DVD, DVD, or CD type into the disc tray, and closes the disc tray. Then, the microcomputer  220  loads the inserted disc  110 , identifies the type thereof, and drives an LD corresponding to the inserted disc  110  of the identified type. 
   As the LD is driven, a corresponding PD unit  114  receives a laser signal reflected from the inserted disc  110  and generates a PD signal corresponding to at least one of a BD, HD-DVD, DVD, or CD, depending upon the determination of the type of the inserted disc  110 . 
   The MUX IC  120  provided in the pickup  100  selects the PD signal of the inserted disc  110  from among respective outputs of the BD, HD-DVD, DVD, and CD PD units  114  in response to a switch control signal from the microcomputer  220 . The PD signal selected by the MUX IC  120  is outputted through the connectors  300  to the RF IC  210  placed in the main PCB  200 . 
   Accordingly, reduction of a number of pins of the connectors  300  from the pickup  100  to the main PCB  200  is possible by placing the MUX IC  120 , which selects input/output signals of the pickup  100  and RF IC  210 , in the pickup  100 . 
   Also a reduction of a size of the RF IC  210  for RF signal processing is possible by reducing the number of input/output pins thereof. In addition, a simplification of an assembly between the pickup  100  and the main PCB  200  is possible. 
   Afterwards, an MPD signal inputted from the pickup  100  to the RF IC  210  is switched through the DEMUX  250  according to the type of the inserted disc  110 , and fed to a corresponding APC of the APC unit  230 , which then performs an APC operation to control the amount of output light from the LD corresponding to the inserted disc  110 . 
   In the APC operation, if the amount of the output light of the LD, set to a predetermined value, is altered with a change in voltage or temperature of the LD, the APC unit  230  in the RF IC  210  detects a variation in output current of the associated MPD of the pickup  100  to maintain an amount of the output light of the LD. 
   The PD signal, inputted to the RF IC  210  from the pickup  100 , is converted by the RF signal processor  240  in the RF IC  210  into a servo control signal and an RF signal necessary to be used in accordance with the determined type of the inserted disc  110 , and is then used for a servo control operation and an RF data processing operation for the inserted disc  100 . 
   The second embodiment of  FIG. 3  has the same configuration as that of the first embodiment of  FIG. 2 , except that the DEMUX  260  is placed on the main PCB  200  not in the RF IC  210  and the MUX  270  is disposed between the DEMUX  260  and the RF signal processor  240 . This arrangement may be changed by the designer. 
   With the configuration of  FIG. 3  in which the MUX IC  120 , which selects input/output signals of the pickup  100  and the RF IC  210 , is placed within the pickup  100 , a reduction of a number of pins of the connectors  300  from the pickup  100  to the main PCB  200  is also possible. 
   As is apparent from the above description, the present invention provides an interface device for an optical recording and/or reproducing apparatus, wherein a multiplexer MUX is provided in a pickup and adapted to multiplex input/output signals of the pickup and an RF IC. Thus, the number of pins of connectors from the pickup to the RF IC may be reduced so as to lead to advantages in that PCB layout is relatively simplified and signal quality is relatively preserved. 
   In addition, the interface device according to the present invention has another advantage of reducing the size and cost of the optical recording and/or reproducing apparatus by decreasing the number of input/output pins of the RF IC. 
   Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.

Technology Category: 3