JP2009043359A - Optical pickup - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pickup which can reduce man-hour for initial adjustment in the manufacturing step thereof to be reduced and does not increase the number of components included in the optical pickup. <P>SOLUTION: A dichroic prism is disclosed which includes at least a first reflection film, a second reflection film and a transparent member. The transparent member causes a light beam passing through the inner part thereof to generate astigmatism having a prescribed direction and a prescribed magnitude. Thereby, the astigmatism in a direction reverse to the direction of astigmatism generated by the other optical members e.g. a rising mirror and an objective lens which constitute the optical pickup is caused to generate to cancel them. Thus, astigmatism generated in the whole optical pickup can be reduced by adjusting the material of the transparent member. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical pickup used in an optical disk device or the like, and more particularly to an optical pickup including a dichroic prism that can correct astigmatism.

  In recent years, optical discs such as compact discs (hereinafter referred to as “CD”) and digital versatile discs (hereinafter referred to as “DVD”) have become widespread and are generally used. As an apparatus for reading and reproducing information recorded on an optical disk, for example, audio information and video information, there is an optical disk reproducing apparatus. Examples of widely known optical disc playback apparatuses include a CD player, a DVD player, a CD-ROM drive connected to a personal computer, and the like.

  The optical disk reproducing apparatus is provided with an optical pickup for reading information by irradiating an optical disk with a light beam. The optical pickup irradiates a light beam onto the information recording surface of the optical disk fixed on the turntable and rotating. Then, the reflected light from the optical disk is received by a light receiving element, for example, a photodiode, provided in the optical pickup. Then, light is converted into an electric signal by the light receiving element, and information recorded on the optical disk is output based on the obtained electric signal.

  However, astigmatism occurs in the light beam when the light beam passes through an optical component that constitutes the optical pickup, such as an objective lens or a rising mirror. In order to reduce this astigmatism, various adjustment operations are performed in the manufacturing stage of the optical pickup.

  In relation to the above, Patent Document 1 discloses an optical pickup that corrects aberration by one liquid crystal optical element and simplifies the electrode pattern and drive control of the liquid crystal optical element. The liquid crystal optical element has a pattern for correcting spherical aberration, a pattern for correcting astigmatism, and a pattern for correcting coma aberration. Each of these patterns is distributed and arranged on a pair of electrodes, respectively. The electrode is divided into a plurality of regions. Then, a plurality of regions divided by the patterns arranged in each are combined to correct aberration. Therefore, optimal correction of each aberration can be realized with one liquid crystal optical element without complicating the electrode pattern of the liquid crystal optical element and its drive control.

  In relation to the above, Patent Document 2 discloses an optical pickup provided with a mirror that can suppress aberrations low without loss of laser light. This optical pickup includes a base having a curved surface, a reflection film formed on the surface of the base, and a substrate and a wavelength selection film provided thereon, and at least one layer formed on the reflection film side. A mirror with a layer is provided. In this mirror, for example, the first wavelength laser light passes through the wavelength selection film and the substrate and is reflected by the reflection film, and the second wavelength laser light is reflected by the wavelength selection film on the outermost surface of the mirror. Thereby, since the intensity | strength of a mirror can be obtained, thickness reduction of the board | substrate on a base | substrate can be achieved.

In relation to the above, Patent Document 3 discloses an optical pickup capable of obtaining the same optical performance as a precise mirror and reducing the time and cost required for manufacturing the mirror. This optical pickup includes a light source that generates light, a mirror that converts an optical path of the light generated by the light source, and an aberration that corrects aberrations generated in the light reflected by the mirror due to non-uniformity of the surface shape of the mirror. And a correction element. The aberration correcting element is arranged on the optical path of the light reflected by the mirror.
JP 2006-120279 A JP 2006-24276 A JP 2006-79815 A

  However, in the optical pickups disclosed in Patent Documents 1 to 3, it is possible to correct aberrations due to surface shake during reproduction of an optical disc. It was necessary to adjust the street. In addition, astigmatism generated during adjustment needs to be corrected using a dedicated member such as an aberration correction element, and there is a problem that the number of members included in the optical pickup increases.

  In view of the above points, an object of the present invention is to provide an optical pickup that can reduce the number of initial adjustment steps in the manufacturing stage of the optical pickup and can be realized without increasing the number of components included in the optical pickup. is there.

  In order to achieve the above object, an optical pickup of the present invention includes a light source that emits a light beam, a dichroic prism that aligns the optical axes of a plurality of light beams by reflecting or transmitting the light beams emitted from the light source, and The dichroic prism includes a first reflective film that reflects a light beam of a predetermined wavelength and transmits a light beam of another wavelength, a second reflective film that reflects the light beam, and A transparent member sandwiched between the first reflective film and the second reflective film, and the first reflective film is attached to the transparent member on the light source side surface of the dichroic prism, The second reflective film can receive incident light transmitted through the first reflective film and the transparent member, and reflects the incident light and transmits the first reflective film, thereby It is characterized by being Chakuse' the transparent member at a position capable of matching the optical axes of the light reflected by the first reflecting film and the light reflected by the second reflecting film.

  According to this, the optical pickup of the present invention includes a light source that emits a light beam, and a dichroic prism that matches the optical axes of the plurality of light beams by reflecting or transmitting the light beams emitted from the light source. Yes. The dichroic prism is configured to include at least a first reflection film, a second reflection film, and a transparent member.

  The first reflective film is formed of a material that reflects a light beam having a predetermined wavelength, such as a DVD light beam, and transmits a light beam having a predetermined wavelength, such as a BD. The second reflective film is formed of a material that reflects all light beams regardless of the wavelength. For this reason, it is possible to reflect the light beam that has passed through the first reflecting film with the second reflecting film, and to transmit the reflected light to the outside of the dichroic prism through the first reflecting film. A transparent member that transmits the light beam is sandwiched between the first reflective film and the second reflective film.

  The first reflective film and the second reflective film are attached to the surface of the transparent member. The first reflective film is attached to the light source side surface of the transparent member that can receive the light beam emitted from the light source. The second reflective film is attached to a place where the light beam transmitted through the first reflective film and the transparent member can be received, for example, on the opposite side of the surface on which the first reflective film is attached when the transparent member is a rectangular parallelepiped. It is touched. Therefore, by adjusting the position of the light source and changing the light beam incident position, it is possible to match the optical axes of the reflected light reflected by both reflection films.

  In order to achieve the above object, in the optical pickup of the present invention, the transparent member is opposite to astigmatism generated in each optical member constituting the optical pickup with respect to the light beam transmitted through the transparent member. It is characterized by being formed of a material that can cancel the astigmatism by generating astigmatism.

  According to this, the transparent member constituting the dichroic prism included in the optical pickup of the present invention generates astigmatism of a predetermined direction and a predetermined size with respect to the light beam transmitted through the inside thereof. As a result, astigmatism that occurs in the opposite direction to astigmatism that occurs in other optical members constituting the optical pickup, such as a raising mirror or an objective lens, is generated and canceled. For this reason, the astigmatism which generate | occur | produces in the whole optical pick-up can be reduced by adjusting the material of a transparent member. It should be noted that the direction in which the material for generating astigmatism in which direction is used can be appropriately changed without departing from the scope of the present invention.

  A liquid crystal element embedded in the transparent member; an optical axis changing means for changing an optical axis of a light beam transmitted through the liquid crystal element by changing a voltage applied to the liquid crystal element; and a light beam by the light receiving element. The light reflected by the first reflecting film is detected by changing the voltage applied by the optical axis changing means on the basis of the light receiving means for detecting and converting to an electric signal, and the electric signal obtained by the light receiving means. A first calculating means for calculating a voltage required to make the axis coincide with the optical axis of the reflected light by the second reflecting film, and a first voltage for applying the voltage calculated by the first calculating means to the optical axis changing means. And an applying means.

  According to this, the dichroic prism included in the optical pickup of the present invention includes an optical axis changing unit (= optical axis changing means) that changes the optical axis of the light beam by applying a voltage to the liquid crystal element embedded in the transparent member. And a light receiving portion (= light receiving means) for converting the light beam into an electrical signal by the light receiving element. The optical axis changing unit can change the optical axis when the light beam transmitted through the first reflective film is transmitted through the liquid crystal element by changing the applied voltage.

  The optical axes of a plurality of light beams, for example, the light beam reflected by the first reflecting film and the light beam reflected by the second reflecting film, are matched based on the electrical signal photoelectrically converted from the light receiving unit. In order to achieve this, a correction amount determination unit (= first calculation means) that calculates a voltage that needs to be applied to the liquid crystal element is provided. The optical axis here represents the optical axis of a light beam emitted from the dichroic prism to another optical member such as a collimator lens.

  The voltage calculated by the correction amount determination unit is applied to the liquid crystal element by the liquid crystal driver (= first application means). As a result, while the voltage is being applied, the light beam reflected by the first reflecting film on the surface of the dichroic prism and the light beam transmitted through the dichroic prism and reflected by the second reflecting film. The axes can be matched.

  In order to achieve the above object, an optical pickup according to the present invention includes a liquid crystal element embedded in the transparent member and an astigmatism of a light beam transmitted through the liquid crystal element by changing a voltage applied to the liquid crystal element. Aberration correction means for correcting aberration, light receiving means for detecting a light beam by a light receiving element and converting it into an electrical signal, and light beam transmitted through the liquid crystal element based on the electrical signal obtained by the light receiving means A second calculating unit that calculates a voltage that needs to be applied to the aberration correcting unit in order to correct the astigmatism, and a second that applies the voltage calculated by the second calculating unit to the aberration correcting unit. And an applying means.

  According to this, the dichroic prism included in the optical pickup of the present invention includes an aberration correction unit (= aberration correction unit) that corrects astigmatism of the light beam by applying a voltage to the liquid crystal element embedded in the transparent member. And a light receiving unit (= light receiving means) for converting the light beam into an electrical signal by the light receiving element. The optical axis changing unit can correct astigmatism of the light beam transmitted through the first reflective film by applying a voltage.

  In addition, a correction amount determination unit (= first) that calculates a voltage that needs to be applied to the liquid crystal element to correct astigmatism generated in the light beam based on the electrical signal photoelectrically converted by the light receiving unit. Two calculation means). The voltage calculated by the correction amount determination unit is applied to the liquid crystal element by the liquid crystal driver (= second applying means). Thereby, astigmatism of the light beam transmitted through the inside of the dichroic prism can be corrected while the voltage is applied.

  In order to achieve the above object, the optical pickup according to the present invention is configured such that the liquid crystal element has the transparent member on the optical axis until the light beam transmitted through the first reflective film reaches the second reflective film. It is characterized by being embedded.

  According to this, in the dichroic prism included in the optical pickup of the present invention, the liquid crystal element is disposed on the optical axis until the light beam transmitted through the first reflective film reaches the second reflective film. Therefore, aberration correction is not performed on the optical axis until the light beam reflected by the second reflective film passes through the first reflective film. For this reason, it is not necessary to embed a liquid crystal element on the entire surface of the transparent member.

  According to the optical pickup of the present invention, the dichroic prism is configured to include at least the first reflection film, the second reflection film, and the transparent member. Therefore, by adjusting the position of the light source and changing the light beam incident position, it is possible to match the optical axes of the reflected light reflected by both reflection films. Since the optical axis can be adjusted easily in this way, the number of adjustment operations during manufacturing of the optical pickup can be reduced. In addition, the installation angle of the dichroic prism and the installation position of the light source can be flexibly changed.

  Further, according to the optical pickup of the present invention, the transparent member constituting the dichroic prism generates astigmatism of a predetermined direction and a predetermined size with respect to the light beam transmitted through the inside thereof, thereby the entire optical pickup. Can be reduced. For this reason, since astigmatism correction members, such as aberration correction elements, can be reduced, costs can be reduced and the size of the optical pickup can be reduced.

  According to the optical pickup of the present invention, the optical axis changing unit that changes the optical axis of the light beam, the light receiving unit that converts the light beam into an electrical signal by the light receiving element, and the correction amount that calculates the voltage applied to the liquid crystal element The optical axis of a plurality of light beams can be made coincident with each other by the determining unit. For this reason, the optical axis of the light beam can be adjusted easily and reliably. Further, since it is not necessary to adjust the optical axis by moving the light source, the position of the light source is not subject to physical restrictions, and thus the degree of freedom in device design is increased. Further, since the liquid crystal element is embedded in the dichroic prism, the size of the dichroic prism does not increase and the size of the apparatus is not affected.

  Further, according to the optical pickup of the present invention, the aberration correction unit that corrects the astigmatism of the light beam by applying a voltage to the liquid crystal element embedded in the transparent member, and the correction amount that calculates the voltage applied to the liquid crystal element A determination unit is provided. The astigmatism of the light beam transmitted through the dichroic prism is corrected by applying the voltage calculated by the correction amount determining unit. For this reason, correction of astigmatism of the light beam can be performed easily and reliably. In addition, since it is not necessary to correct astigmatism using an aberration correction element, it is possible to reduce the number of aberration correction members. Further, since the liquid crystal element is embedded in the dichroic prism, the size of the dichroic prism does not increase and the size of the apparatus is not affected.

  According to the optical pickup of the present invention, the liquid crystal element included in the dichroic prism is disposed on the optical axis until the light beam transmitted through the first reflective film reaches the second reflective film. Thereby, since it is not necessary to embed a liquid crystal element in the whole surface of a transparent member, size reduction of a liquid crystal element and reduction of a member can be aimed at.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, embodiment shown here is an example and this invention is not limited to embodiment shown here.

[Embodiment 1]
<1-1. Internal configuration>
FIG. 1 is a block diagram showing a disc player 100 according to the first embodiment of the present invention. The disc player 100 includes an optical pickup 1, an RF amplifier 31, a DSP (Digital Signal Processor) 32, a reproduction processing circuit 33, an output circuit 34, a system controller 41, a driver 42, a display unit 43, an operation unit 44, a feed motor 51, and A spindle motor 52 is provided.

  The optical pickup 1 irradiates an optical disc 2 (CD, DVD, or BD) with a light beam, and reads various information such as audio information and video information recorded on the optical disc 2. The optical pickup 1 is provided with a CD laser, a DVD laser, and a BD laser. Details of the inside of the optical pickup 1 will be described later.

  Audio information and video information obtained by the optical pickup 1 are converted into audio and video by the RF amplifier 31 to the output circuit 34 and output from a speaker and a monitor (not shown), respectively. The RF amplifier 31 amplifies an audio signal, a video signal, etc. from the optical pickup 1. The DSP 32 and the reproduction processing circuit 33 perform various information processing (for example, video processing) for reproduction on the signal from the RF amplifier 31. The output circuit 34 performs D / A conversion processing and the like in order to output the signal from the reproduction processing circuit 33 to a speaker and a monitor (not shown).

  The system controller 41 and the driver 42 control the operations of the optical pickup 1 and the driving device (= feed motor 51 and spindle motor 52). The system controller 41 receives information from the operation unit 44 and transmits it to the DSP 32, and transmits information from the DSP 32 to the display unit 43. The driver 42 controls operations of the optical pickup 1 and the driving device based on an instruction from the DSP 32.

  The feed motor 51 is driven by a driver 42 that operates based on an instruction from the DSP 32. As a result, the optical pickup 1 moves in the radial direction of the optical disk 2. The spindle motor 52 drives the optical disc 2 in the rotation direction by the driver 42. The driver 42 performs focus control of the objective lens 17 (FIG. 2) of the pickup device 1 based on an instruction from the DPS 32.

<1-2. About optical pickup configuration>
FIG. 2 is a schematic view showing an optical system of the optical pickup 1 according to the first embodiment of the present invention. The optical pickup 1 is a device that can read information recorded on the recording surface of the optical disc 2 by irradiating the optical disc 2 such as a CD with a light beam and receiving reflected light. The type and number of optical discs 2 that can be read with the optical pickup 1 are not limited to the type and number shown in the present embodiment, and various changes can be made without departing from the scope of the present invention.

  The optical pickup 1 includes a first light source 11a (= light source), a second light source 11b (= light source), a dichroic prism 12, a collimator lens 13, a beam splitter 14, a rising mirror 15, and a liquid crystal element 16. An objective lens 17, a detection lens 18, a photodetector 19 (= light receiving means), and an actuator 21. Below, the detail of each optical member which comprises the optical pick-up 1 is demonstrated.

  The first light source 11a is a semiconductor laser capable of emitting a 650 nm band light beam corresponding to a DVD and a 780 nm band light beam corresponding to a CD. The second light source 11b is a semiconductor laser capable of emitting a 405 nm band light beam corresponding to BD. In this embodiment, a two-wavelength integrated semiconductor laser having two light emitting points capable of emitting light beams of two types of wavelengths is used as the first light source 11a. However, the present invention is not limited to this. For example, a semiconductor laser that emits only a light beam having a single wavelength may be used.

  The dichroic prism 12 reflects the light beam emitted from the first light source 11a by the first reflecting film 12a (FIG. 3) on the surface thereof. The light beam emitted from the second light source 11b is transmitted through the first reflective film 12a on the surface and reflected by the second reflective film 12c (FIG. 3) inside the light beam. Then, the optical axes of the light beams emitted from the first light source 11a and the second light source 11b are aligned on the same axis. The light beam reflected by the dichroic prism 12 is sent to the collimating lens 13. Details of the dichroic prism 12 will be described later.

  The collimating lens 13 converts the light beam that has passed through the dichroic prism 12 into parallel light. Here, the parallel light means light in which all optical paths of the light beams emitted from the first light source 11a and the second light source 11b are substantially parallel to the optical axis. The light beam converted into parallel light by the collimator lens 13 is sent to the beam splitter 14.

  The beam splitter 14 functions as a light separation element that separates an incident light beam, transmits the light beam transmitted from the collimating lens 13, guides it to the optical disk 2 side, and reflects the reflected light reflected by the optical disk 2. Is reflected and guided to the photodetector 19 side. The light beam that has passed through the beam splitter 14 is sent to the rising mirror 15.

  The raising mirror 15 reflects the light beam transmitted through the beam splitter 14 and guides it to the optical disc 2. The rising mirror 15 is inclined by 45 ° with respect to the optical axis of the light beam from the beam splitter 14, and the optical axis of the light beam reflected by the rising mirror 15 is the same as the recording surface of the optical disc 2. It is almost orthogonal. The light beam reflected by the rising mirror 15 is sent to the liquid crystal element 16.

  The liquid crystal element 16 controls the change in the refractive index by applying a voltage to a liquid crystal (neither of which is shown) sandwiched between transparent electrodes, utilizing the property that the liquid crystal molecules change the orientation direction thereof, and the liquid crystal element 16 This element enables control of the phase of the light beam that passes through the element 6. By disposing the liquid crystal element 16, it is possible to correct spherical aberration caused by a difference in the thickness of the protective layer that protects the recording surface of the optical disc 2. The light beam that has passed through the liquid crystal element 16 is sent to the objective lens 17.

  The objective lens 17 focuses the light beam transmitted through the liquid crystal element 16 on the recording surface of the optical disc 2. The objective lens 17 can be moved, for example, in the vertical and horizontal directions in FIG. 2 by an actuator 21 to be described later, and its position is controlled based on the focus servo signal and the tracking servo signal.

  In the present embodiment, the liquid crystal element 16 is also mounted on the actuator 21 so that it can move together with the objective lens 17. However, the liquid crystal element 16 does not necessarily need to be mounted on the actuator 21, and the configuration can be changed according to the configuration of the optical system.

  The reflected light reflected by the optical disk 2 passes through the objective lens 17 and the liquid crystal element 16 in this order, is reflected by the rising mirror 15, is further reflected by the beam splitter 14, and is reflected on the photodetector 19 by the detection lens 18. The light is condensed to a light receiving element provided in the.

  The photodetector 19 converts optical information received using a light receiving element such as a photodiode into an electrical signal, and outputs the electrical signal to, for example, an RF amplifier (not shown). This electric signal is used as a reproduction signal for data recorded on the recording surface, and further as a servo signal for performing focus control and tracking control.

  The actuator 21 moves the objective lens 17 in the radial direction of the optical disc 2 in accordance with the lens drive signal generated and output by the driver 42. The actuator 21 is not limited thereto, but here the actuator 21 can drive the objective lens 17 with Lorentz force by passing a drive current through a coil (not shown) in a magnetic field formed by a permanent magnet (not shown). It may be.

  In the present invention, the actuator 21 performs a tracking operation for moving the objective lens 17 in a direction along the recording surface of the optical disc 2, but in addition to this, the optical axis of the laser light emitted from the objective lens 17 oscillates. As described above, a tilting operation for tilting the objective lens 17 and a focusing operation for moving the objective lens 17 so as to approach and separate from the optical disc 2 can be performed as necessary.

<1-3. About the structure of the dichroic prism>
FIG. 3 is a schematic view showing the configuration of the dichroic prism 12 according to the first embodiment of the present invention. 6 and 7 are schematic views showing the configuration of a conventional pickup 9 and dichroic prism 90. FIG. First, a conventional configuration will be described.

  FIG. 6 is a schematic view showing an optical system of an optical pickup 9 existing conventionally. 2 differs from the configuration of the optical pickup 1 in FIG. 2 in that the dichroic prism 90 is used instead of the dichroic prism 12 as a member for aligning the optical axes of the light beams emitted from the first light source 11a and the second light source 11b on the same axis. Is used.

  As shown in FIG. 7, the dichroic prism 90 includes a reflective film 91 therein. The reflective film 91 has a property of transmitting a light beam having a specific wavelength and reflecting the light beam when irradiated with a light beam having a different wavelength. In the example of FIG. 7, a light beam emitted from the first light source 11a, for example, a 650 nm band light beam corresponding to a DVD is reflected upward in the drawing. Further, the light beam emitted from the second light source 11b, for example, the light beam in the 405 nm band corresponding to BD is transmitted. As a result, the optical axes of the light beams having different wavelengths incident from different directions can be aligned in the upward direction in the figure.

  Since the dichroic prism 90 having the above-described structure is used, the position at which the first light source 11 a and the second light source 11 b are disposed in the pickup 9 is different from that of the pickup 1. As shown in FIG. 2, the two light sources in the pickup 1 are arranged so that their light beam emission angles are parallel to each other. However, the pickup 9 is arranged so that the light beam emission angles are perpendicular to each other.

  As described above, since the pickup 9 and the pickup 1 have the same configuration except for the difference in the arrangement of the light sources and the configuration of the dichroic prism, the description thereof is omitted here.

  Next, the configuration of the dichroic prism 12 according to the first embodiment of the present invention will be described with reference to FIG. The dichroic prism 12 includes a first reflecting film 12a on the surface irradiated with the light beam from the first light source 11a and the second light source 11b. The first reflective film 12a is made of the same material as the reflective film 91 included in the dichroic prism 90, and has a property of reflecting a light beam with a specific wavelength and transmitting a light beam with another wavelength. In the example of FIG. 3, the light beam emitted from the first light source 11a is reflected, and the light beam emitted from the second light source 11b is transmitted.

  The dichroic prism 12 includes a glass thick plate 12b (= transparent member) as a transparent member constituting the main body. The glass thick plate 12b has a property of transmitting a light beam, but astigmatism occurs in the transmitting light beam. The direction and magnitude of astigmatism change depending on the material of the glass thick plate 12b. For this reason, it is possible to adjust the direction and magnitude of astigmatism by changing the material of the glass thick plate 12b. As a result, an astigmatism difference in the opposite direction to the astigmatism generated in the optical member other than the dichroic prism, for example, the rising mirror 15 and the objective lens 17 is generated, thereby canceling out the aberrations as a result. Can be corrected.

  A second reflective film 12c is bonded to the surface opposite to the first reflective film 12a bonded to the glass thick plate 12b. The second reflective film 12c has a property of reflecting all types of light beams. The second reflecting film 12c reflects the light beam of the second light source 11b that has passed through the first reflecting film 12a and the glass thick plate 12b. As a result, the light beam is reflected upward in the drawing, passes through the glass thick plate 12b and the first reflective film 12a, and is emitted to the outside of the dichroic prism 12.

  According to the above configuration, regardless of the arrangement angle of the dichroic prism 12, the arrangement position of the first light source 11a, and the emission angle of the light beam emitted from the first light source 11a, the arrangement position of the second light source 11b, By changing the emission angle of the light beam emitted from the second light source 11b, the optical axes of the light beams emitted from both light sources can be easily aligned on the same optical axis. Therefore, it is possible to easily and efficiently perform the optical axis adjustment work at the time of manufacturing the pickup 1.

  The above adjustment operation is performed at the time of assembling the pickup using a test apparatus such as a test light receiving element and a correction amount calculator (not shown) such as a test camera. As a result, for example, rough adjustment of the entire pickup apparatus can be performed by the dichroic prism 12 as a pre-stage for correcting fine aberrations caused by, for example, surface vibration of the optical disc 2.

[Embodiment 2]
<2-1. Internal configuration>
Since the contents are the same as those of the disc player 100 (FIG. 1) of the first embodiment, the description thereof is omitted.

<2-2. About optical pickup configuration>
Since the contents are the same as those of the optical pickup 1 (FIG. 2) of the first embodiment, the description thereof is omitted.

<2-3. About the structure of the dichroic prism>
FIG. 4 is a schematic diagram showing the configuration of the dichroic prism 12 according to the second embodiment of the present invention. The dichroic prism 12 of this embodiment includes an optical axis changing element 12d (= liquid crystal element) in addition to the first reflecting film 12a to the second reflecting film 12c provided in the dichroic prism of the first embodiment. A light receiving element 61 (= light receiving means) and a correction amount determining unit 62 (= first calculating means) are connected to the optical axis changing element 12d.

  The optical axis changing element 12d is for shifting the optical axis of the light beam in an arbitrary direction when the light beam emitted from the second light source 11b passes through the dichroic prism 12. As a specific member, for example, a liquid crystal element for correcting aberration is used. When a voltage is applied to the optical axis changing element 12d by a liquid crystal driver (= first applying means) (not shown), the trajectory of the light beam is changed in proportion to the applied voltage. Thereby, the optical axis of the light beam passing through the inside of the dichroic prism 12 when passing through the second reflective film 12c can be shifted.

  As described above, the optical axis changing element 12d can correct the optical axis by adjusting the applied voltage. Therefore, the optical axes of the light beam emitted from the first light source 11a and the light beam emitted from the second light source 11b can be matched. The optical axis of the light beam emitted from the first light source 11a is fixed in advance.

  The light receiving element 61 receives the light beam emitted from the first light source 11a and reflected by the first reflecting film 12a, and the light beam emitted from the second light source 11b and passed through the dichroic prism 12, and each light beam is received. This is for measuring the deviation of the optical axis.

  The light receiving element 61 converts optical information received using a light receiving element such as a photodiode into an electrical signal. The converted electrical signal is output to the correction amount determination unit 62 as a measurement result of the light beam. The light receiving element 61 is not a device inside the optical pickup but a member of an external test device (not shown).

  Accordingly, the installation location of the light receiving element 61 is not particularly limited, but it is desirable to receive light immediately after the light beam is emitted from the dichroic prism 12, that is, before being applied to the collimating lens 13 shown in FIG. . The light receiving element 61 is a separate member from the light detector 19 that converts light information into an electrical signal by the light receiving element.

  The correction amount determination unit 62 calculates the correction amount of the optical axis necessary for matching the optical axes of the two light beams based on the measurement result of the light beam given from the light receiving element 61, and calculates the calculated correction amount. Based on the above, the voltage applied to the optical axis changing element 12d is calculated. The correction amount determination unit may be realized by using an arithmetic device such as an LSI chip, or may be realized by executing a specific program on a CPU provided in a personal computer or the like.

  Specifically, the correction amount determination unit 62 receives the electrical signal photoelectrically converted by the light receiving element 61, and calculates the deviation of the optical axes of the two light beams from the electrical signal. Then, in what direction and how much the optical axis of the light beam emitted from the second light source 11b is moved, the optical axes of the two light beams coincide with each other. Based on the calculated value, the magnitude of the voltage applied to the optical axis changing element 12d is determined, and the determined voltage is applied using a liquid crystal driver.

  After the application of the voltage, the correction amount determination unit 62 further measures the light beam using the light receiving element 61, and determines whether or not the optical axes of the two light beams match. If they do not match, the correction amount is calculated and the voltage is applied again. Then, the value of the voltage used when the optical axes coincide is recorded in a recording device such as a memory (not shown) as a definite value.

  The light receiving element 61 and the correction amount determining unit 62 are members used only at the time of initial adjustment of the pickup 1, and thus are removed from the dichroic prism 12 after the above definite value is obtained. Thereafter, by using a liquid crystal driver that constantly applies a certain amount of voltage, the optical axes of both light beams can be made to coincide with each other.

  According to said structure, at the time of the initial adjustment of the pick-up 1, it is not necessary to match | combine both optical axes by adjusting the installation position of the 2nd light source 11b. For this reason, the optical axis changing operation can be performed easily and reliably. Further, for example, even if it is difficult to change the optical axis by position adjustment because the installation position of the second light source 11b is physically restricted, the optical axis can be changed. For this reason, the apparatus design of the pickup 1 can be flexibly performed.

[Embodiment 3]
<3-1. Internal configuration>
Since the contents are the same as those of the disc player 100 (FIG. 1) of the first embodiment, the description thereof is omitted.

<3-2. About optical pickup configuration>
Since the contents are the same as those of the optical pickup 1 (FIG. 2) of the first embodiment, the description thereof is omitted.

<3-3. About the structure of the dichroic prism>
FIG. 5 is a schematic diagram showing the configuration of the dichroic prism 12 according to the second embodiment of the present invention. The dichroic prism 12 of this embodiment includes an aberration correction element 12e in addition to the first reflecting film 12a to the second reflecting film 12c included in the dichroic prism of the first embodiment. In addition, a light receiving element 61 and a correction amount determining unit 62 are connected to the aberration correction element 12e. The light receiving element 61 and the correction amount determining unit 62 are not members inside the optical pickup, but are members of an external test device (not shown) as in the second embodiment.

  The aberration correction element 12e is for correcting astigmatism generated when the light beam emitted from the second light source 11b passes through the dichroic prism 12. As a specific member, for example, a liquid crystal element for correcting astigmatism is used. The aberration correction element 12e shapes a light beam according to the applied voltage when a voltage is applied by a liquid crystal driver (not shown).

  The light receiving element 61 receives a light beam and measures astigmatism generated in the light beam. The light receiving element 61 converts optical information received using a light receiving element such as a photodiode into an electrical signal. The converted electrical signal is output to the correction amount determination unit 62 as an astigmatism measurement result. The light receiving element 61 is not a device inside the optical pickup but a member of an external test device (not shown).

  Accordingly, the installation location of the light receiving element 61 is not particularly limited, but immediately before the light beam is applied to the information recording surface of the optical disc 2 or the light beam reflected from the optical disc 2 enters the photodetector 19. It is desirable to receive light immediately before. Accordingly, it is possible to perform correction in consideration of not only astigmatism generated from the dichroic prism 12 but also astigmatism generated by other optical members such as the rising mirror 15 and the objective lens 17. The light receiving element 61 is a separate member from the light detector 19 that converts light information into an electrical signal by the light receiving element.

  The correction amount determination unit 62 calculates the correction amount of astigmatism to be corrected based on the measurement result of the light beam given from the light receiving element 61, and corrects the astigmatism based on the calculated correction amount. Do. Specifically, the correction amount determination unit 62 receives the electrical signal photoelectrically converted by the light receiving element 61, and calculates astigmatism generated in the light beam from the electrical signal. Then, it is calculated how the astigmatism can be eliminated by shaping the light beam emitted from the second light source 11b. Based on the calculated value, the magnitude of the voltage applied to the optical axis changing element 12d is determined.

  A voltage is applied using a liquid crystal driver. After the voltage is applied, the correction amount determination unit 62 further measures the light beam using the light receiving element 61, and determines whether astigmatism has been reduced. If not, the correction amount is calculated and the voltage is applied again. Then, the voltage when the amount of astigmatism generated becomes the lowest is recorded as a definite value in a recording device such as a memory (not shown).

  Since the light receiving element 61 and the correction amount determining unit 62 are members used only at the time of initial adjustment of the pickup 1 as in the second embodiment, the light receiving element 61 and the correction amount determining unit 62 are detached from the dichroic prism 12 after the above definite values are obtained. It is. Thereafter, astigmatism can be continually corrected using a liquid crystal driver that constantly applies a certain amount of voltage.

  According to the above configuration, astigmatism generated by each optical member during initial adjustment of the pickup 1 can be reduced. For this reason, the initial adjustment at the time of manufacture of the pickup 1 can be performed efficiently and reliably.

[Other embodiments]
The present invention has been described with reference to the preferred embodiments and examples. However, the present invention is not necessarily limited to the above embodiments and examples, and various modifications may be made within the scope of the technical idea. Can be implemented.

Therefore, the present invention can also be applied to the following embodiments.
(A) In the present embodiment, the disk player 100 is described as an example of the optical disk apparatus provided with the pickup 1. However, the optical disk apparatus other than this may use the pickup 1 and the dichroic prism 12 of the present invention. For example, it may be used in a car navigation system, a TV / DVD combined machine, a personal computer, an optical disk recorder, or the like.

  (B) In this embodiment, the glass thick plate 12b is used as the transparent member constituting the dichroic prism 12, but a form using a transparent member of a material other than this may be used. In addition, the material for forming the first reflective film 12a and the second reflective film 12c can be appropriately changed without departing from the scope of the present invention.

  (C) The liquid crystal driver is described as an example of a member that constantly applies a voltage to the liquid crystal element after the correction voltage is calculated, but the voltage is applied using other members such as a power supply circuit or an LSI chip. It may be a form to do.

  (D) In this embodiment, correction of astigmatism by the aberration correction element 12e is performed immediately after the light beam has transmitted through the first reflection film. The form which arrange | positions the aberration correction element 12e so that it may correct | amend until it permeate | transmits one reflective film may be sufficient.

These are the block diagrams which show the optical disk reproducing | regenerating apparatus based on one Embodiment of this invention. These are the block diagrams which show the optical system of the optical pick-up which concerns on one Embodiment of this invention. These are the block diagrams which show the structure of the dichroic prism which concerns on 1st embodiment of this invention. These are block diagrams which show the structure of the dichroic prism which concerns on 2nd embodiment of this invention. These are block diagrams which show the structure of the dichroic prism which concerns on 3rd embodiment of this invention. These are the block diagrams which show the conventional optical disk reproducing | regenerating apparatus. These are the block diagrams which show the optical system of the conventional optical pick-up.

Explanation of symbols

1 Optical pickup 2 Optical disc 11a First light source (light source)
11b Second light source (light source)
12 dichroic prism 12a first reflective film 12b glass plate (transparent member)
12c Second reflective film 12d Optical axis changing element (optical axis changing means)
12e Aberration correction element (aberration correction means)
61 Light receiving element (light receiving means)
62 Correction amount determination unit (first calculation means, second calculation means)

Claims (5)

A light source that emits a light beam;
A dichroic prism that matches the optical axes of a plurality of light beams by reflecting or transmitting a light beam emitted from a light source;
In an optical pickup equipped with
The dichroic prism reflects a light beam of a predetermined wavelength and transmits a light beam of another wavelength, a second reflection film that reflects a light beam, the first reflection film, and the second reflection film. A transparent member sandwiched between reflective films,
The first reflective film is attached to the transparent member on the light source side surface of the dichroic prism;
The second reflective film is capable of receiving incident light that has passed through the first reflective film and the transparent member, and reflects the incident light and transmits the first reflective film, whereby the second reflective film Being attached to the transparent member at a position where the optical axis of the light reflected by the film and the light reflected by the first reflective film can coincide with each other;
Features an optical pickup. The transparent member cancels the astigmatism by generating astigmatism that is opposite to the astigmatism generated in each optical member constituting the optical pickup with respect to the light beam transmitted through the transparent member. The optical pickup according to claim 1, wherein the optical pickup is made of a possible material. A liquid crystal element embedded in the transparent member;
An optical axis changing means for changing an optical axis of a light beam transmitted through the liquid crystal element by changing a voltage applied to the liquid crystal element;
A light receiving means for detecting a light beam by a light receiving element and converting it into an electrical signal;
Based on the electric signal obtained by the light receiving means, the voltage applied by the optical axis changing means is changed to change the optical axis of the reflected light by the first reflecting film and the light of the reflected light by the second reflecting film. First calculating means for calculating a voltage necessary for matching the axis;
First application means for applying the voltage calculated by the first calculation means to the optical axis changing means;
The optical pickup according to claim 1, further comprising: A liquid crystal element embedded in the transparent member;
An aberration correction unit that corrects astigmatism of a light beam transmitted through the liquid crystal element by changing a voltage applied to the liquid crystal element;
A light receiving means for detecting a light beam by a light receiving element and converting it into an electrical signal;
A second voltage for calculating the voltage required to be applied to the aberration correction means to correct astigmatism generated in the light beam transmitted through the liquid crystal element based on the electrical signal obtained by the light receiving means. A calculation means;
Second application means for applying the voltage calculated by the second calculation means to the aberration correction means;
The optical pickup according to claim 1, further comprising: The liquid crystal element is embedded in the transparent member on the optical axis until the light beam transmitted through the first reflective film reaches the second reflective film;
The optical pickup according to claim 4.

Images