KR101106541B1 - Optical Pick-up unit - Google Patents

Optical Pick-up unit Download PDF

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Publication number
KR101106541B1
KR101106541B1 KR1020090110919A KR20090110919A KR101106541B1 KR 101106541 B1 KR101106541 B1 KR 101106541B1 KR 1020090110919 A KR1020090110919 A KR 1020090110919A KR 20090110919 A KR20090110919 A KR 20090110919A KR 101106541 B1 KR101106541 B1 KR 101106541B1
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KR
South Korea
Prior art keywords
plurality
light
dvd
bd
cd
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KR1020090110919A
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Korean (ko)
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KR20110054315A (en
Inventor
강문성
김의열
이용재
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도시바삼성스토리지테크놀러지코리아 주식회사
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Priority to KR1020090110919A priority Critical patent/KR101106541B1/en
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Abstract

An optical pickup apparatus is disclosed. The optical pickup apparatus includes a plurality of light sources emitting different wavelengths, and an optical system for condensing the light emitted from the plurality of light sources, respectively, on the recording surface of the optical recording medium, and for guiding the reflected light from the recording surface to the photodetector. A plurality of objective lenses for respectively condensing light of different wavelengths of the light source to different types of optical recording media, and the paths are respectively changed so that the beam light emitted from the plurality of light sources is directed to the plurality of objective lenses, respectively. It is provided with a plurality of mirrors.

Description

Optical Pick-up Unit

The present invention relates to an optical pickup device, and more particularly, to an optical pickup device having an improved mirror.

With the development of the industry, as the amount of information to be processed and recorded increases, there is a demand for an optical recording medium and an optical recording / reproducing system with higher recording density. In response to these demands, new optical recording / reproducing systems such as Blu-ray disc (BD) systems or HD-DVD systems have been proposed. However, such new systems also need to be compatible with existing systems such as CDs or DVDs. Therefore, in order to make all CD / DVD / HD-DVD / BD compatible, the optical pickup device of the optical recording / reproducing system should be equipped with two objective lens optical systems. For example, the optical lens for the objective lens optical system for CD / DVD / HD-DVD and the separate optical lens for BD object are respectively provided.

One of the obstacles that prevents the miniaturization of the optical pickup device is the material of the mirror that changes the path of the light emitted from the light source toward the objective lens. That is, the conventional mirror is made of glass, and the mirror provided below the objective lens for BD totally reflects the BD wavelength band and causes the DVD / CD wavelength band to be overpowered. However, the glass mirror has a problem that the optical axis height is lowered as the DVD / CD wavelength band is transmitted. The thickness of the mirror increases as the thickness of the mirror increases. Therefore, the thickness of the mirror should be made as thin as possible to minimize the decrease in the optical axis height. In the case of the conventional glass material, when the thickness is changed to less than 1 ton and the shape change such as C cut is not possible, the unit cost rises and mass production is not possible. There is this.

The present invention provides an optical pickup device having a mirror with improved material.

Optical pickup device according to an embodiment of the present invention

A plurality of light sources emitting different wavelengths,

An optical system for condensing the light emitted from the plurality of light sources, respectively, on the recording surface of the optical recording medium, and directing the reflected light from the recording surface to the photodetector,

The optical system

A plurality of objective lenses for respectively condensing light of different wavelengths of the plurality of light sources onto different types of optical recording media;

The paths are respectively changed so that the beam light emitted from the plurality of light sources is directed to the plurality of objective lenses, and includes a plurality of mirrors made of a plastic material.

According to an embodiment of the present invention, the plurality of mirrors further include a reflective layer that reflects light toward the objective lens on a surface facing the plurality of objective lenses, respectively.

According to one embodiment of the present invention, the thickness of the plurality of mirrors is 1t or less.

According to an embodiment of the present invention, the plurality of objective lenses includes an objective lens for a Blu-ray Disc (BD) and an objective lens for a DVD / CD.

The optical pickup device of the present invention can be made thinner by using a mirror made of a plastic material, and can improve moldability, thereby coping with miniaturization.

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

1 is a configuration diagram schematically showing an optical system of an optical pickup apparatus according to an embodiment of the present invention, Figure 2 is a cross-sectional view showing the positional relationship between the mirror and the objective lens according to an embodiment of the present invention.

1 and 2, an optical pickup apparatus 100 according to an embodiment of the present invention, for each optical disk 150 of the DVD / CD and BD (Blu-ray Disc (registered trademark)), respectively Information can be reproduced or recorded by the beam light corresponding to.

The optical pickup apparatus 100 includes a BD light source 111 for emitting light of a wavelength suitable for recording / reproducing BD and a DVD / CD light source 112 for emitting light of a wavelength suitable for recording / reproducing a DVD / CD; BD objective lens 122 for focusing light onto BD for recording / playback of BD, DVD / CD objective lens 123 for focusing light onto DVD / CD for recording / playback of DVD / CD, BD The front light detector 118, the photo detector 127 or the DB objective lens 122 or the DVD / CD objective lens 123 by transmitting or reflecting the light emitted from the light source 111 and the DVD / CD light source 112 A beam splitter 117 for guiding light to the light and a photo detector 127 for receiving the light reflected from the BD or DVD / CD 150 and detecting the information signal and an error signal.

The BD beam light emitted from the BD light source 111 is indicated by a dashed line, and the DVD / CD beam light emitted from the DVD / CD light source 112 is indicated by a double-dot chain line. The optical axis is shown by the thick solid line.

The BD objective lens 122 is designed to be suitable for the BD beam light emitted from the BD light source 111 (blue light having a wavelength of 405 nm), and focuses the BD beam light on the BD 150. The DVD / CD objective lens 123 uses the DVD beam CD (red light having a wavelength of 660 nm) and the CD beam beam (near infrared light having a wavelength of 785 nm) emitted from the DVD / CD light source 112 to the DVD or CD 150. Condenses on the phase. The BD objective lens 122 and the DVD / CD objective lens 123 are mounted side by side to an actuator (not shown) and are driven in the focus direction and the track direction for error correction.

The beam splitter 117 is a polarization beam splitter that transmits or reflects light according to the polarization component of incident light, and is incident from the BD light source 111 and the DVD / CD light source 112, respectively. The light is incident on the BD objective lens 122 and the DVD / CD objective lens 123, or is incident on the front photodetector 118, and the light reflected from the optical disc BD or DVD / CD 150 is returned. Face toward photodetector 127.

In addition, on the optical path between the beam splitter 117 and the reflection mirror 120, a collimating lens 119 for converting light directed to the objective lens into parallel light is disposed.

The front photo detector 118 receives a part of the light emitted from the BD light source 111 or the DVD / CD light source 112 and outputs a detection signal. The controller (not shown) determines whether the driving current of the light source is appropriate based on the detected detection signal, and transmits a control signal of the light source so that the driving current is appropriate.

A photo diode integrated circuit 127 receives the light reflected from the optical disk 150, converts the light into an electrical signal, and detects a focus error signal, a tracking error signal, a reproduction signal, and other aberration or light signals.

On the optical path between the photodetector 127 and the beam splitter 117, a sensor lens 126 for generating a boiling point on the light reflected from the optical disk 150 is disposed.

Reference numeral 116 denotes a cubic beam splitter that reflects or passes the BD light source 111 or the DVD / CD light source 112 and enters the beam splitter 117. Reference numeral 113 denotes a half wave plate combined with a grating, reference numeral 114 denotes a coupling lens, and reference numeral 115 denotes a twin grating.

Between the beam splitter 117 and the optical path of the BD objective lens 122, a reflection mirror 120 is provided to change the light path through the beam splitter 117 toward the objective lens, and the reflection mirror 120 and the BD are provided. A quarter wave plate 121 and a BD mirror 130 are provided between the optical paths of the objective lens 122. A DVD / CD mirror 140 is provided between the optical path of the BD mirror 130 and the DVD / CD objective lens 123. The BD mirror 130 is installed below the BD objective lens 122 to inject the BD beam light emitted from the BD light source 111 toward the BD objective lens 122 or to receive the beam light reflected from the BD 150. Reflected by the detector 127. The DVD / CD mirror 140 is installed below the DVD / CD objective lens 123 to allow the DVD / CD beam light emitted from the DVD / CD light source 112 to enter the DVD / CD objective lens 123, or The beam light reflected from the DVD / CD 150 is reflected by the photodetector 127.

As shown in FIG. 2, the BD mirror 130 and the DVD / CD mirror 140 are fixed at an interval with respect to the frame 101 of the optical pickup apparatus at predetermined intervals. The BD mirror 130 includes a main body 131 and a reflection layer 132 formed to reflect BD beam light on an upper side of the main body 131 (a surface opposite the BD objective lens 122). The DVD / CD mirror 140 includes a main body 141 and a reflection layer 142 formed to reflect the DVD / CD beam light on the upper side of the main body 141 (the surface opposite the DVD / CD objective lens 123). do. The body 131 of the BD mirror 130 and the body 141 of the DVD / CD mirror 140 may be made of a plastic material.

The manufacture of the BD mirror 130 and the DVD / CD mirror 140 of the present invention with a plastic material is to reduce the thickness of the BD mirror 130 and the DVD / CD mirror 140 so as to make the optical pickup device slim. .

3 is a graph showing the relationship between the thickness change of the BD mirror or DVD / CD mirror of which the material is glass and the height change of the optical axis.

Referring to FIG. 3, when the BD mirror 130 and the DVD / CD mirror 140 are made of glass, the glass corresponds to a change in the optical axis height in proportion to a change in the thickness of the mirror and a thickness of the mirror. Difficult to freely shape while making less than 1t. Therefore, the material of the mirror is changed to plastic that can be freely shaped and can be manufactured to a thickness of 1t or less.

On the upper side of the BD mirror 130 and the DVD / CD mirror 140, the BD objective lens 122 and the DVD / CD objective lens 123 are fixed to the objective lens holder 102, respectively. Accordingly, the BD mirror 130 reflects the BD beam light toward the BD objective lens 122 and passes the DVD / CD beam light toward the DVD / CD mirror 140. The DVD / CD mirror 140 reflects the beam of DVD / CD beams that have passed through the BD mirror 130 toward the DVD / CD objective lens 123.

 Figure 4 is a graph showing the results of simulating the optical musk of the mirror made of a conventional glass material, Figure 5 is a graph showing the results of simulating the optical specifications of the BD mirror made of a plastic material according to an embodiment of the present application to be. The thickness of the mirror was 0.7t, and the experiment was performed with the incident angle of the beam of light at 45 ° ± 6 °. Here, Rp represents the reflectance of the p-wave, and Rs represents the reflectance of the s-wave.

Referring to FIGS. 4 and 5, the reflectances of the two graphs of 405 nm, the wavelength of the BD beam, 660 nm, the wavelength of the DVD beam, and 785 nm, the wavelength of the CD beam, are almost the same. It can be seen that they are identical.

Therefore, even if the BD mirror 130 and the DVD / CD mirror 140 are made of plastic and the thickness is less than 1t, the optical musk can be made thin without making any difference from the glass material. It can be seen that. As a result, the thickness can be reduced while maintaining the optical specifications of the BD mirror 130 and the DVD / CD mirror 140, which can be applied to slim the optical pickup device.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true scope of protection of the present invention should be defined only by the appended claims.

1 is a configuration diagram schematically showing an optical system of an optical pickup apparatus according to an embodiment of the present invention.

2 is a cross-sectional view showing the positional relationship between the mirror and the objective lens according to an embodiment of the present invention.

3 is a graph showing the relationship between the thickness change and optical axis height change of a BD mirror or DVD / CD mirror whose material is glass.

Figure 4 is a graph showing the results of simulating the optical musk of a mirror made of a conventional glass material.

Figure 5 is a graph showing the results of simulating the optical specifications of the BD mirror made of a plastic material according to an embodiment of the present application.

<Description of the symbols for the main parts of the drawings>

111 ... BD light source 112 ... DVD / CD light source

116 Cubic Beam Splitter

120 ... reflective mirror 122 ... BD objective

123 ... DVD / CD objective 126 ... Sensor lens

127 ... photodetector 130 ... BD mirror

140 ... DVD / CD objective 150 ... Optical disc (BD or DVD / CD)

Claims (4)

  1. A plurality of light sources emitting different wavelengths,
    An optical system for condensing the light emitted from the plurality of light sources, respectively, on the recording surface of the optical recording medium, and directing the reflected light from the recording surface to the photodetector,
    The optical system
    A plurality of objective lenses for respectively condensing light of different wavelengths of the plurality of light sources onto different types of optical recording media;
    And a plurality of mirrors, each of which is made of plastic and whose thickness is 1t or less, by changing paths of the beams respectively emitted from the plurality of light sources toward the plurality of objective lenses.
  2. The method of claim 1,
    The plurality of mirrors
    And a reflective layer reflecting light toward the objective lens on a surface facing each of the plurality of objective lenses.
  3. The method of claim 1,
    And a thickness of the plurality of mirrors is 0.7t or less.
  4. The method of claim 1,
    The plurality of objective lenses comprises an objective lens for a Blu-ray Disc (BD) and an objective lens for a DVD / CD.
KR1020090110919A 2009-11-17 2009-11-17 Optical Pick-up unit KR101106541B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
KR1020090110919A KR101106541B1 (en) 2009-11-17 2009-11-17 Optical Pick-up unit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
KR1020090110919A KR101106541B1 (en) 2009-11-17 2009-11-17 Optical Pick-up unit

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KR20110054315A KR20110054315A (en) 2011-05-25
KR101106541B1 true KR101106541B1 (en) 2012-01-20

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR920005398Y1 (en) * 1989-12-30 1992-08-08 김희수 Optical pick-up unit
KR940001451A (en) * 1992-06-27 1994-01-11 김광호 fid polysilicon having a bottom gate tft
KR100230529B1 (en) 1990-11-05 1999-11-15 가나이 쓰도무 Optical disk apparatus and optical head
KR20060003176A (en) * 2004-07-05 2006-01-10 삼성전자주식회사 Optical pickup and optical recording and/or reproducing apparatus employing it

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR920005398Y1 (en) * 1989-12-30 1992-08-08 김희수 Optical pick-up unit
KR100230529B1 (en) 1990-11-05 1999-11-15 가나이 쓰도무 Optical disk apparatus and optical head
KR940001451A (en) * 1992-06-27 1994-01-11 김광호 fid polysilicon having a bottom gate tft
KR20060003176A (en) * 2004-07-05 2006-01-10 삼성전자주식회사 Optical pickup and optical recording and/or reproducing apparatus employing it

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