Recording/reproducing apparatus including an optical pickup having an objective lens compatible with a plurality of optical disk formats

Abstract

A recording/reproducing apparatus including an optical pickup compatible with a plurality of optical recording media each using light of a different wavelength. The optical pickup includes at least one light source, an objective lens having a function of focusing light emitted from the light source into the optimal light spot on an information recording surface of one of the plurality of the optical recording media, and a light detector to detect light transmitted through the objective lens after being reflected from the information recording surface of the optical recording medium on which the light spot is formed. The objective lens has an inner area, an annular lens area and an outer area such that the annular lens area divides the inner area from the outer area and has a ring shape centered at a vertex. The inner area, the annular lens area and the outer area have aspherical surface shapes.

What is claimed is:  
     
         1 . A recording and/or reproducing apparatus compatible to a plurality of optical recording media having different thicknesses, the recording and/or reproducing device comprising: 
 an optical pickup comprising    a light source to emit light,    an objective lens to focus the light emitted from the light source into a single light spot on an information recording surface of one of the plurality of the optical recording media, and    a light detector to detect light transmitted through the objective lens after being reflected from the information recording surface of the one optical recording medium on which the light spot is focused,    wherein 
 said objective lens has an inner area, an annular lens area and an outer area centered at a vertex, the annular lens area having a ring shape and dividing the inner area from the outer area;  
 the inner area, the annular lens area and the outer area have aspherical surface shapes so as to focus the light transmitted through the inner area and the outer area into the single light spot by which information is read from the information recording surface of the one optical recording medium and to scatter the light transmitted through the annular lens area formed between the inner area and the outer area so that the scattered light is not focused on the information recording surface of the one optical recording medium if the one optical recording medium is a first optical recording medium having a first thickness, and so as to focus the light transmitted through the inner area and the annular lens area into the single light spot by which information is read from the information recording surface of the one optical recording medium and to scatter the light transmitted through the outer lens area so that the scattered light is not focused on the one optical recording medium if the one optical recording medium is a second optical recording medium having a second thickness greater than the first thickness; and  
 a processing unit to process an information signal to control the light emitted from said light source, and to process the detected light from said light source,  
 further comprising at least one additional light source, each of the light source and the at least one additional light source emitting light of different wavelengths.  
   
     
     
         2 . The recording and/or reproducing apparatus according to  claim 1 , further comprising a beam splitter having a beam splitting characteristic with respect to each of the plurality of the beams respectively emitted from the light source and the at least one additional light source.  
     
     
         3 . A recording and/or reproducing apparatus compatible to a plurality of optical recording media having different thicknesses, the recording and/or reproducing device comprising: 
 an optical pickup comprising    a light source to emit light,    an objective lens to focus the light emitted from the light source into a single light spot on an information recording surface of one of the plurality of the optical recording media, and    a light detector to detect light transmitted through the objective lens after being reflected from the information recording surface of the one optical recording medium on which the light spot is focused,    wherein 
 said objective lens has an inner area, an annular lens area and an outer area centered at a vertex, the annular lens area having a ring shape and dividing the inner area from the outer area;  
 the inner area, the annular lens area and the outer area have aspherical surface shapes so as to focus the light transmitted through the inner area and the outer area into the single light spot by which information is read from the information recording surface of the one optical recording medium and to scatter the light transmitted through the annular lens area formed between the inner area and the outer area so that the scattered light is not focused on the information recording surface of the one optical recording medium if the one optical recording medium is a first optical recording medium having a first thickness, and so as to focus the light transmitted through the inner area and the annular lens area into the single light spot by which information is read from the information recording surface of the one optical recording medium and to scatter the light transmitted through the outer lens area so that the scattered light is not focused on the one optical recording medium if the one optical recording medium is a second optical recording medium having a second thickness greater than the first thickness; and  
 a processing unit to process an information signal to control the light emitted from said light source, and to process the detected light from said light source,  
 further comprising at least one additional light source, wherein said first optical recording medium is a digital versatile disk (DVD) and said second optical recording medium is one of a compact disk (CD), a compact disk recordable (CD-R), CD-Rewritable (CD-RW) and a laser disk (LD), when a first one of the light sources emitting the light has a wavelength which is adapted for the digital versatile disk (DVD) and a second one of the light sources has a wavelength which is adapted for the compact disk recordable (CD-R) are used.  
   
     
     
         4 . A recording and/or reproducing apparatus compatible to a plurality of optical recording media having different thicknesses, the recording and/or reproducing device comprising: 
 an optical pickup comprising    a light source to emit light,    an objective lens to focus the light emitted from the light source into a single light spot on an information recording surface of one of the plurality of the optical recording media, and    a light detector to detect light transmitted through the objective lens after being reflected from the information recording surface of the one optical recording medium on which the light spot is focused,    wherein 
 said objective lens has an inner area, an annular lens area and an outer area centered at a vertex, the annular lens area having a ring shape and dividing the inner area from the outer area;  
 the inner area, the annular lens area and the outer area have aspherical surface shapes so as to focus the light transmitted through the inner area and the outer area into the single light spot by which information is read from the information recording surface of the one optical recording medium and to scatter the light transmitted through the annular lens area formed between the inner area and the outer area so that the scattered light is not focused on the information recording surface of the one optical recording medium if the one optical recording medium is a first optical recording medium having a first thickness, and so as to focus the light transmitted through the inner area and the annular lens area into the single light spot by which information is read from the information recording surface of the one optical recording medium and to scatter the light transmitted through the outer lens area so that the scattered light is not focused on the one optical recording medium if the one optical recording medium is a second optical recording medium having a second thickness greater than the first thickness; and  
 a processing unit to process an information signal to control the light emitted from said light source, and to process the detected light from said light source,  
 wherein the light detector is a single detector used to detect the light from said first and second optical recording media as optical information, when at least two of the plurality of light sources are used and said first and second optical recording media are compatibly reproduced.  
   
     
     
         5 . A recording and/or reproducing apparatus compatible to a plurality of optical recording media having different thicknesses, the recording and/or reproducing device comprising: 
 an optical pickup comprising    a light source to emit light,    an objective lens to focus the light emitted from the light source into a single light spot on an information recording surface of one of the plurality of the optical recording media, and    a light detector to detect light transmitted through the objective lens after being reflected from the information recording surface of the one optical recording medium on which the light spot is focused, 
 wherein  
 said objective lens has an inner area, an annular lens area and an outer area centered at a vertex, the annular lens area having a ring shape and dividing the inner area from the outer area;  
 the inner area, the annular lens area and the outer area have aspherical surface shapes so as to focus the light transmitted through the inner area and the outer area into the single light spot by which information is read from the information recording surface of the one optical recording medium and to scatter the light transmitted through the annular lens area formed between the inner area and the outer area so that the scattered light is not focused on the information recording surface of the one optical recording medium if the one optical recording medium is a first optical recording medium having a first thickness, and so as to focus the light transmitted through the inner area and the annular lens area into the single light spot by which information is read from the information recording surface of the one optical recording medium and to scatter the light transmitted through the outer lens area so that the scattered light is not focused on the one optical recording medium if the one optical recording medium is a second optical recording medium having a second thickness greater than the first thickness; and  
 a processing unit to process an information signal to control the light emitted from said light source, and to process the detected light from said light source,  
 wherein said objective lens has a step difference which is formed in a region where the annular lens area and the outer area contact each other and makes a light path difference between the light transmitted through the inner area of said objective lens and the light transmitted through the annular lens area to have an integer multiple of a wavelength of the light emitted from the light source, during reproduction of information from the second optical recording medium.  
   
     
     
         6 . A recording and or reproducing apparatus compatible with at least two substrates having respectively different thicknesses and information recording surfaces which store information, the recording and/or reproducing device comprising: 
 an objective lens comprising    an inner area, an annular lens area and an outer area centered at a vertex, the annular lens area having a ring shape and dividing the inner area from the outer area,    wherein the inner area, the annular lens area and the outer area have aspherical surface shapes so as to focus light transmitted through the inner area and the outer area into a single light spot by which the information is read from the information recording surface of a first one of the at least two substrates which has a first thickness and to scatter the light transmitted through the annular lens area formed between the inner area and the outer area so that the scattered light is not focused on the information recording surface of the first substrate, when the first substrate is to be used, and so as to focus the light transmitted through the inner area and the annular lens area into the single light spot by which the information is read from the information recording surface of a second one of the at least two substrates which has a second thickness greater than the first thickness and to scatter the light transmitted through the outer lens area so that the scattered light is not focused on the information recording surface of the second substrate, when the second substrate is to be used; and    a processing unit which processes an information signal to control the light transmitted to the objective lens, and to process the light passed through the objective lens,    wherein said objective lens has a step difference which is formed in a region where the annular lens area and the outer area contact each other and the step difference makes a light path difference between the light transmitted through the inner area of said objective lens and the light transmitted through the annular lens area to have an integer multiple of a wavelength of the light emitted from the light source, when the second substrate is to be used.    
     
     
         7 . A recording and/or reproducing apparatus device in an optical device and compatible with disks having different thicknesses, the recording and/or reproducing apparatus comprising: 
 an optical pickup device comprising    a light source,    an objective lens, facing one of the disks which is placed in the optical device, having a light passing region divided into inner, annular lens and outer regions respectively corresponding to a near axis area, an intermediate axis area and a far axis area of incident light, wherein curvatures of the central and periphery regions are optimized for the one disk if the one disk has a first thickness and a curvature of the annular region is optimized for the one disk if the one disk has a second thickness greater than the first thickness,    a photo detector for detecting light reflected from the one disk, and    a separation unit to separate the incident light transmitted from said light source from the reflected light reflected by the one disk; and    a processing unit to process an information signal to control the incident light generated by said light source to process the detected light from said light detector, 
 wherein a surface of the annular lens area forms a step difference with a surface of one of the inner and outer areas,  
 wherein the surface of the annular lens area forms the step difference with the surface of the outer area, wherein the step difference is a value such that a light path difference between the light passing through the inner area and the light passing through the annular lens area is an integer multiple of a wavelength of the light emitted from the light source.  
   
     
     
         8 . A recording and/or reproducing apparatus device in an optical device and compatible with disks having different thicknesses, the recording and/or reproducing apparatus comprising: 
 an optical pickup device comprising    a light source,    an objective lens, facing one of the disks which is placed in the optical device, having a light passing region divided into inner, annular lens and outer regions respectively corresponding to a near axis area, an intermediate axis area and a far axis area of incident light, wherein curvatures of the central and periphery regions are optimized for the one disk if the one disk has a first thickness and a curvature of the annular region is optimized for the one disk if the one disk has a second thickness greater than the first thickness,    a photo detector for detecting light reflected from the one disk, and    a separation unit to separate the incident light transmitted from said light source from the reflected light reflected by the one disk; and    a processing unit to process an information signal to control the incident light generated by said light source to process the detected light from said light detector,    further comprising: 
 a unit on which the light source and the photo detector are formed adjacent to each other;  
 the separation unit being a holographic beam splitter; and  
 a collimating lens to collimate the light passing through the holographic beam splitter from the light source and to transmit the reflected light from the one disk toward the holographic beam splitter;  
 wherein the holographic beam splitter directs the reflected light toward the photo detector.  
   
     
     
         9 . The recording and/or reproducing apparatus as claimed in  claim 8 , further comprising a quarter wave plate disposed between the holographic beam splitter and the collimating lens.  
     
     
         10 . The recording and/or reproducing apparatus as claimed in  claim 8 , wherein the holographic beam splitter is a polarizing hologram.  
     
     
         11 . A recording and/or reproducing apparatus device in an optical device and compatible with disks having different thicknesses, the recording and/or reproducing apparatus comprising: 
 an optical pickup device comprising    a light source,    an objective lens, facing one of the disks which is placed in the optical device, having a light passing region divided into inner, annular lens and outer regions respectively corresponding to a near axis area, an intermediate axis area and a far axis area of incident light, wherein curvatures of the central and periphery regions are optimized for the one disk if the one disk has a first thickness and a curvature of the annular region is optimized for the one disk if the one disk has a second thickness greater than the first thickness,    a photo detector for detecting light reflected from the one disk, and    a separation unit to separate the incident light transmitted from said light source from the reflected light reflected by the one disk; and    a processing unit to process an information signal to control the incident light generated by said light source to process the detected light from said light detector,    wherein a surface of the annular lens area forms a step difference with a surface of one of the inner and outer areas,    further comprising: 
 a unit on which the light source and the photo detector are formed adjacent to each other;  
 the separation unit being a holographic beam splitter; and  
 a collimating lens to collimate the light passing through the holographic beam splitter from the light source and to transmit the reflected light from the one disk toward the holographic beam splitter;  
 wherein the holographic beam splitter directs the reflected light toward the photo detector.  
   
     
     
         12 . A recording and/or reproducing apparatus which reads information from an optical recording medium, the recording and/or reproducing device comprising: 
 an optical pickup comprising    a first light source to emit a first light,    a second light source to emit a second light, wherein only one of the first and second light sources emits the first and second lights, respectively, at a given time,    an objective lens to receive the one of the first and second lights emitted from the corresponding one of the first and second light sources, and to focus the one of the first and second lights emitted toward the optical recording medium and pass light reflected from the optical recording medium, and    a photo detector to receive the light reflected from the optical recording medium and passed through the objective lens, to reproduce the information; and    a processing unit to process information signals to control the first and second lights emitted from said first and second light sources, and to process the received light from said photo detector, for the reproduction of the information.    
     
     
         13 . The recording and/or reproducing apparatus device as claimed in  claim 12 , wherein the first light source emits the first light if the optical recording medium has a first thickness and the second light source emits the second light if the optical recording medium has a second thickness greater than the first thickness.  
     
     
         14 . The recording and/or reproducing apparatus device as claimed in  claim 12 , wherein the first light has a first frequency and the second light has a second frequency different from the first frequency.  
     
     
         15 . The recording and/or reproducing apparatus device as claimed in  claim 13 , wherein the first light has a first frequency and the second light has a second frequency different from the first frequency.  
     
     
         16 . The recording and/or reproducing apparatus device as claimed in  claim 12 , wherein the objective lens is a single lens.  
     
     
         17 . The recording and/or reproducing apparatus device as claimed in  claim 12 , wherein the objective lens includes a light passing region divided into inner, annular lens and outer regions, wherein curvatures of the central and periphery regions are optimized for the optical recording medium if the optical recording medium has a first thickness and a curvature of the annular region is optimized for the optical recording medium if the optical recording medium has a second thickness greater than the first thickness.  
     
     
         18 . The recording and/or reproducing apparatus device as claimed in  claim 12 , wherein the objective lens includes a light passing region divided into inner, annular lens and outer regions, wherein curvatures of the central and periphery regions are optimized for the optical recording medium if the optical recording medium has the first thickness and a curvature of the annular region is optimized for the optical recording medium if the optical recording medium has the second thickness.  
     
     
         19 . The recording and/or reproducing apparatus as claimed in  claim 17 , wherein a surface of the annular lens area forms a step difference with a surface of one of the inner and outer areas.  
     
     
         20 . The recording and/or reproducing apparatus as claimed in  claim 18 , wherein a surface of the annular lens area forms a step difference with a surface of one of the inner and outer areas.  
     
     
         21 . The recording and/or reproducing apparatus as claimed in  claim 12 , further comprising: 
 a first beam splitter to transmit the first light from the first light source and to reflect the second light from the second light source;    a second beam splitter to transmit the first light transmitted through the first beam splitter and the second light reflected by the first beam splitter; and    a collimating lens to collimate the first light and reflected second light transmitted through the second beam splitter, and transmit the collimated light to the objective lens;    wherein the second beam splitter reflects the first and second lights reflected from the optical recording medium.    
     
     
         22 . The recording and/or reproducing apparatus as claimed in  claim 19 , further comprising: 
 a first beam splitter to transmit the first light from the first light source and to reflect the second light from the second light source;    a second beam splitter to transmit the first light transmitted through the first beam splitter and the second light reflected by the first beam splitter; and    a collimating lens to collimate the first light and reflected second light transmitted through the second beam splitter, and transmit the collimated light to the objective lens;    wherein the second beam splitter reflects the first and second lights reflected from the optical recording medium.    
     
     
         23 . The recording and/or reproducing apparatus as claimed in  claim 12 , further comprising: 
 a first beam splitter to reflect the first light from the first light source;    a second beam splitter to transmit the first light reflected by the first beam splitter and reflect the second light reflected by the first beam splitter; and    a collimating lens to collimate the first light and reflected second light transmitted through the second beam splitter, and transmit the collimated light toward the objective lens;    wherein the first and second beam splitters transmit the first and second lights reflected from the optical recording medium to the photo detector.    
     
     
         24 . The recording and/or reproducing apparatus as claimed in  claim 19 , further comprising: 
 a first beam splitter to reflect the first light from the first light source;    a second beam splitter to transmit the first light reflected by the first beam splitter and reflect the second light reflected by the first beam splitter; and    a collimating lens to collimate the first light and reflected second light transmitted through the second beam splitter, and transmit the collimated light toward the objective lens;    wherein the first and second beam splitters transmit the first and second lights reflected from the optical recording medium.    
     
     
         25 . A recording and/or reproducing apparatus which reads information from an optical recording medium, the recording and/or reproducing apparatus comprising: 
 an optical pickup device comprising    a first light source to emit a first light,    a second light source to emit a second light, wherein only one of the first and second light sources emits the first and second lights, respectively, at a given time,    an objective lens to receive the one of the first and second lights emitted from the corresponding one of the first and second light sources, and to focus the one of the first and second lights emitted toward the optical recording medium and pass light reflected from the optical recording medium,    a first photo detector to receive the first light reflected from the optical recording medium and passed through the objective lens, to reproduce the information, and    a second photo detector to receive the second light reflected from the optical recording medium and passed through the objective lens, to reproduce the information; and    a processing unit to process information signals to control the first and second lights emitted from said first and second light sources, and to process the received first and second lights from said first and second detectors.    
     
     
         26 . The recording and/or reproducing apparatus device as claimed in  claim 25 , wherein the first light source emits the first light if the optical recording medium has a first thickness and the second light source emits the second light if the optical recording medium has a second thickness greater than the first thickness.  
     
     
         27 . The recording and/or reproducing apparatus device as claimed in  claim 26 , wherein the first light has a first frequency and the second light has a second frequency different from the first frequency.  
     
     
         28 . The recording and/or reproducing apparatus device as claimed in  claim 25 , wherein the objective lens includes a light passing region divided into inner, annular lens and outer regions, wherein curvatures of the central and periphery regions are optimized for the optical recording medium if the optical recording medium has a first thickness and a curvature of the annular region is optimized for the optical recording medium if the optical recording medium has a second thickness greater than the first thickness.  
     
     
         29 . The recording and/or reproducing apparatus as claimed in  claim 28 , wherein a surface of the annular lens area forms a step difference with a surface of one of the inner and outer areas.  
     
     
         30 . The recording and/or reproducing apparatus as claimed in  claim 19 , further comprising: 
 a beam splitter to transmit the first light from the first light source and to reflect the second light from the second light source; and    a collimating lens to collimate the first light transmitted through the beam splitter and the second light reflected by the second beam splitter, and transmit the collimated light to the objective lens;    wherein the beam splitter transmits the first light reflected from the optical recording medium to the first photo detector and reflects the second light reflected from the optical recording medium to the second photo detector.    
     
     
         31 . A recording and/or reproducing apparatus compatible with different types of optical memory media, the recording and/or reproducing apparatus comprising: 
 an objective lens having a plurality of portions having different optical characteristics, wherein one of said plurality of lens portions focuses said light onto one of said optical memory media independent of the type of said one optical memory medium;    wherein said plurality of lens portions include    a first portion to focus a light emitted from a light source onto said one optical memory medium independent of a thickness of said one optical memory medium,    a second portion to focus said light emitted from the light source onto said one optical memory medium if said optical memory medium has a first predetermined thickness,    a third portion to focus said light emitted from said light source onto said one optical memory medium if said optical memory medium has a second predetermined thickness which is different from said first predetermined thickness, and    a surface of the second portion forms a step difference with a surface of one of the first and third portions; and    a processing unit to process an information signal to control the light emitted from the light source, and to process the light passed through said objective lens,    wherein the surface of the second portion forms the step difference with the surface of the third portion, wherein the step difference is a value such that a light path difference between the light passing through the first portion and the light passing through the second portion is an integer multiple of a wavelength of the light emitted from the light source.