JP2007207353A - Optical pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pickup device having enhanced sensitivity to a signal obtained from a light reception area during position adjustment in the optical pickup device having constitution for performing position adjustment of a light reception element using the signal from the light reception area arranged in the light reception element. <P>SOLUTION: A hologram optical element 4 provided to the optical pickup device is divided into a first area 9 and a second area 10 by a division line (not shown). Five areas of a zeroth order light reception area 14, focus error signal detection areas 16a, 16b, and track error signal detection areas 15a, 15b are arranged side-by-side on the light reception element 7 so that the focus signal detection areas 16a, 16b and the track error signal detection areas 15a, 15b sandwiching the zeroth order light reception area 14 are alternately arranged. The ± first order lights respectively generated by the first area 9 and the second area 10 are divided and separately received by the areas 15a, 15b, 16a, 16b. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical pickup device that enables recording of information and reading of information by irradiating an optical recording medium with a light beam, and in particular, adjusts the position of a light receiving element that receives an optical signal and converts it into an electrical signal. It relates to technology that can be performed accurately.

  In recent years, optical recording media such as compact discs (hereinafter referred to as CDs) and digital versatile discs (hereinafter referred to as DVDs) have become widespread and are generally used. In order to increase the amount of information in the optical recording medium, research on increasing the density of the optical recording medium has been promoted. For example, high-density DVDs such as HD-DVDs and Blu-ray discs (hereinafter referred to as BDs) are used. Optical recording media that have been made into practical use are also being put into practical use.

  When performing recording / reproduction of such an optical recording medium, an optical pickup device is used which can record information or read information by irradiating the optical recording medium with a light beam. A schematic diagram of the configuration of the optical system of the conventional optical pickup apparatus 100 is shown in FIG. The optical pickup device 100 includes a light source 1, a beam splitter 2, a collimator lens 3, a hologram optical element 4, a quarter wavelength plate 5, an objective lens 6, and a light receiving element 7. Hereinafter, details of each optical member provided in the optical pickup device 100 will be described.

  The light source 1 is composed of a semiconductor laser, but the wavelength of the semiconductor laser varies depending on the type of the optical recording medium 8 targeted by the optical pickup device 100. The type of the optical recording medium 8 to be processed is, for example, a semiconductor laser having a wavelength of 780 nm band in the case of CD, a semiconductor laser having a wavelength of 650 nm band in the case of DVD, and a 405 nm band in the case of BD. A semiconductor laser having the following wavelength is used. The light beam emitted from the light source 1 is sent to the beam splitter 2.

  The beam splitter 2 functions as a light separation element that separates an incident light beam. That is, the light beam transmitted from the light source 1 is transmitted through the beam splitter 2 and guided to the optical recording medium 8 side, and the reflected light reflected by the optical recording medium 8 is reflected by the beam splitter 2 and received. Guided to element 7. The light beam that has passed through the beam splitter 2 is sent to the collimating lens 3.

  The collimating lens 3 converts the light beam that has passed through the beam splitter 2 into parallel light. Here, the parallel light means light in which all optical paths of the light beam emitted from the light source 1 are substantially parallel to the optical axis. The light beam converted into parallel light by the collimator lens 3 is sent to the hologram optical element 4.

  The hologram optical element 4 is patterned so as to diffract the passing light beam to generate diffracted light, but this hologram optical element 4 is given polarization and cooperates with the quarter-wave plate 5. Due to the function, the forward light beam guided from the light source 1 to the optical recording medium 8 is not diffracted, and the backward light beam reflected by the optical recording medium 8 is diffracted. The light beam that has passed through the hologram optical element 4 is sent to the quarter-wave plate 5.

  The quarter wavelength plate 5 converts the linearly polarized light beam emitted from the light source 1 into circularly polarized light. The quarter-wave plate 5 also functions as an optical isolator in cooperation with the beam splitter 2. The light beam that has passed through the quarter-wave plate 5 is sent to the objective lens 6.

  The objective lens 6 condenses the light beam transmitted through the quarter wavelength plate 5 on the recording surface 8 a of the optical recording medium 8. The objective lens 6 is set to have a different numerical aperture (NA) depending on the type of the optical recording medium 8. For example, NA = 0.50 in the case of CD, NA = 0.65 in the case of DVD, and NA = 0.85 in the case of BD. The The objective lens 6 is mounted on an objective lens actuator (not shown) together with the hologram optical element 4 and the quarter wavelength plate 5. The objective lens actuator controls the position of the objective lens 6 based on the focus error signal and the track error signal.

  The focus error signal is a focusing control signal for controlling the position of the objective lens 6 so that the focal position of the objective lens 6 is always on the recording surface 8a, and the track error signal is a light emitted from the light source 1. This is a tracking control signal for controlling the position of the objective lens 6 so that the beam follows the track formed on the optical recording medium 8.

  The reflected light reflected by the optical recording medium 8 is transmitted through the objective lens 6, then is converted into linearly polarized light orthogonal to the outward light beam by the quarter wavelength plate 5, diffracted by the hologram optical element 4, and collimated lens 3. After passing, the light is reflected by the beam splitter 2 and reaches the light receiving element 7.

  The light receiving element 11 converts the received optical information into an electrical signal and outputs it to, for example, an RF amplifier (not shown). The light receiving element 11 is provided with a plurality of light receiving regions (not shown), and not only a reproduction signal but also a focus error signal and a track error signal are detected.

  In the optical pickup device 100 configured as described above, the reproduction signal, the focus error signal, and the track error signal cannot be accurately detected when the position of the light receiving element 7 is shifted from the correct position. . For this reason, there arises a problem that the quality when the information recorded on the optical recording medium 8 is reproduced using the optical pickup device 100 is deteriorated or the optical pickup device 100 does not operate well in the worst case. . Therefore, there is a need for a technique for accurately and accurately adjusting the mounting position of the light receiving element 7.

  In this regard, for example, Patent Document 1 introduces an adjustment method for easily and accurately adjusting the position of a light receiving element disposed in an optical pickup device in a short time. In the method of adjusting the position of a light receiving element in Patent Document 1, a signal is obtained from a plurality of light receiving areas provided in the light receiving element while performing focus servo, and the position of the light receiving element is adjusted using the obtained signal. It has become.

However, even if the adjustment method introduced in Patent Document 1 is used, when the light receiving element is displaced with respect to the optimum position, the signal value indicating the displacement is small, that is, the signal for the displacement. If the sensitivity is not sufficient, it may actually be determined that the position can be adjusted even though the light receiving element is not arranged at the optimum position. In this case, since the light receiving element is not in an optimal position, if this optical pickup device is used, the quality when reproducing information recorded on the optical recording medium 8 as described above is reduced, or In the worst case, there arises a problem that the optical pickup device 100 does not operate well.
JP 2005-122812 A

  In view of the above points, an object of the present invention is an optical pickup device having a configuration capable of adjusting the position of a light receiving element using a signal from a light receiving area arranged in the attending element, the light receiving area at the time of position adjustment It is an object of the present invention to provide an optical pickup device with improved sensitivity of signals obtained from the above.

  In order to achieve the above object, the present invention provides a light source, a focusing means for focusing a light beam emitted from the light source on a recording surface of an optical recording medium, and a light receiving element that receives reflected light reflected by the recording surface. And a hologram optical element that is disposed between the focusing means and the light receiving element to generate the diffracted light by diffracting the reflected light, and the light receiving element has an RF signal for detecting an RF signal. In the optical pickup device in which a detection area, a focus error signal detection area for detecting a focus error signal, and a track error signal detection area for detecting a track error signal are arranged, the hologram optical element includes: A first dividing line passing through the center of the reflected light beam is divided into two areas, a first area and a second area, and both the first and second areas are divided into the first dividing line. It is divided into two regions by a second dividing line that is orthogonal and passes through the light beam center, the focus error signal is detected by a spot size detection method, and the RF signal detection region is transmitted through the hologram optical element. It is one light receiving area for receiving 0th-order light, and the focus error signal detection area and the track error signal detection area are both composed of two independent light receiving areas and sandwich the RF signal detection area in the middle. And arranged alternately in a direction parallel to the diffraction direction of the diffracted light with respect to the optical axis of the zeroth order light transmitted through the hologram optical element at the light receiving element position, and the first region is the reflected light ± first-order light generated by passing through the first region is received by being distributed to the focus error signal detection region and the track error signal detection region. The second region is different from the ± first-order light generated when the reflected light passes through the second region is received by the ± first-order light from the first region. The focus error signal detection area and the track error signal detection area are formed so as to be received in a distributed manner.

  In order to achieve the above object, the present invention provides a light source, a focusing means for focusing a light beam emitted from the light source on a recording surface of an optical recording medium, and a light receiving element that receives reflected light reflected by the recording surface. And a hologram optical element that is disposed between the focusing means and the light receiving element to generate diffracted light by diffracting the reflected light, and the light receiving element detects at least a focus error signal. In the optical pickup device in which the focus error signal detection region and the track error signal detection region for detecting the track error signal are arranged, the hologram optical element has at least one first division passing through the center of the reflected light beam. A line is divided into two areas, a first area and a second area, and the focus error signal detection area and the track error signal detection area are both independent. The light receiving regions are arranged alternately in a direction parallel to the diffraction direction of the diffracted light with respect to the optical axis of the zeroth order light transmitted through the hologram optical element at the light receiving element position, The first region is formed such that ± first-order light generated when the reflected light passes through the first region is received by being distributed to the focus error signal detection region and the track error signal detection region. The two regions include the focus error signal detection region and the ± first-order light generated when the reflected light passes through the second region is different from the ± first-order light received from the first region. It is characterized by being formed so as to be received by being distributed to the track error signal detection region.

  According to the present invention, in the optical pickup device configured as described above, the focus error signal is detected by a spot size detection method.

  According to the present invention, in the optical pickup device having the above-described configuration, the light receiving element emits the zero-order light in the center of a column in which the focus error signal detection region and the track error signal detection region are arranged side by side. One zero-order light receiving region for receiving light is arranged.

  According to the present invention, in the optical pickup device configured as described above, each of the first and second regions is divided into two regions by a second dividing line that is orthogonal to the first dividing line and passes through the light beam center. It is characterized by being.

  According to the first configuration of the present invention, it is possible to satisfactorily write information to and read information from the optical recording medium using the optical pickup device. Since the focus error signal area, which is an adjustment area used for adjusting the position of the light receiving element, is arranged at a position as far away as possible in the light receiving element, the sensitivity to the positional deviation in the rotational direction of the light receiving element. The position of the light receiving element can be adjusted with high accuracy. Further, the size of the optical pickup device is not particularly increased as compared with the conventional optical pickup device.

  Further, according to the second configuration of the present invention, since the two focus error signal detection regions or the track error signal detection regions used when adjusting the position of the light receiving element are arranged at separate positions, Sensitivity to the positional deviation of the light receiving element in the rotation direction can be increased, and the position adjustment of the light receiving element can be performed with high accuracy.

  Further, according to the third configuration of the present invention, the optical pickup device having the second configuration can be easily realized.

  According to the fourth configuration of the present invention, in the optical pickup device having the second or third configuration, the 0th-order light receiving area is used as an RF signal detection area. It becomes possible to suppress deterioration in quality at the time of writing information or reading information from an optical recording medium.

  According to the fifth configuration of the present invention, in the optical pickup device having any one of the second to fourth configurations, an objective is written when information is written to or read from the optical recording medium. Even when a lens or the like is displaced, it can be made less susceptible to the influence.

  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. Further, portions that overlap with the conventional optical pickup device 100 shown in FIG. 4 are denoted by the same reference numerals, and the description thereof is omitted unless particularly necessary.

  The arrangement of the optical system in the optical pickup device of this embodiment is the same as that of the conventional optical pickup device 100 shown in FIG. 4, but the conventional problems are solved with respect to the configurations of the hologram optical element 4 and the light receiving element 7. There is a feature to do. Therefore, in the following, first, an embodiment of the hologram optical element 4 and the light receiving element 7 will be described, and then, an operation for solving a conventional problem caused by the embodiment will be described.

  The hologram optical element 4 generates diffracted light from the reflected light reflected by the optical recording medium 8, thereby causing a focus error signal for tracking control and tracking control in relation to a light receiving area (described later) formed on the light receiving element 7. To obtain a track error signal for use. In this embodiment, the hologram optical element 4 and the light receiving region formed in the light receiving element 7 are configured such that the focus error signal is a spot size detection (SSD) method and the track error signal is a collect far field (CFF). ) Method.

  FIG. 1 is a diagram for explaining the configuration of the hologram optical element 4 of the present embodiment, in which a diffraction pattern is formed among two surfaces substantially orthogonal to the optical axis of the light beam incident on the hologram optical element 4. It is the schematic diagram which showed typically the structure of one surface. As shown in FIG. 1, the hologram optical element 4 is divided into two regions, a first region 9 and a second region 10, by a first dividing line 18 a passing through the light beam center 17 of the light beam incident on the hologram optical element 4. It is divided. The first region 9 and the second region are further divided into regions 9a and 9b and regions 10a and 10b by a second dividing line 18b orthogonal to the first dividing line 18a and passing through the light beam center 17, respectively. It is divided.

  The first region 9 and the second region 10 have different diffraction patterns to be formed, and how the reflected light reflected by the optical recording medium 8 is diffracted when passing through these regions 9 and 10. Is different. On the other hand, the regions 9a and 9b and the regions 10a and 10b separated by the second dividing line 18b that further divides the first region 9 and the second region 10 are diffracted in the same manner. The second dividing line 18b performs only the function of dividing the light beam spot when the diffracted light diffracted in the first region 9 and the second region 10 is received by the light receiving element 7.

  In the present embodiment, the first region 9 and the second region 10 are divided by the second dividing line 18b. However, the present invention is not limited to this, and the second dividing line 18b is not divided. It doesn't matter. However, when the first region 9 and the second region 10 are divided by the second dividing line 18b, for example, the positional deviation between the objective lens 6 (see FIG. 4) and the light receiving element 7 when the optical pickup device is operated. A configuration in which the first region 9 and the second region 10 are divided by the second dividing line 18b is preferable because the influence of the spot deviation on the light receiving region of the reflected light from the optical recording medium 8 generated in step S1 can be suppressed.

  FIG. 2 is a diagram schematically showing a correspondence relationship between the 0th-order light 11 and the ± first-order lights 12a, 12b, 13a, 13b and the light receiving element 7 generated through the hologram optical element 4, and FIG. FIG. 2 (a) is a diagram showing a position on the light receiving surface 7a of the light receiving element 7 where the 0th order light 11 and the ± first order light 12a, 12b, 13a, 13b from the hologram optical element 4 reach. Corresponding to FIG. 2A, the light receiving regions 14, 15a, 15b, 16a, 16b formed on the light receiving surface 7 where the 0th order light 11 and the ± first order lights 12a, 12b, 13a, 13b reach. It is the top view which showed.

  As shown in FIG. 2 (b), five light receiving regions 14, 15 a, 15 b, 16 a, 16 b are provided on the light receiving surface 7 a of the light receiving element 7. ± .first order light 12 a, 12 b with respect to the optical axis 19 of the zero order light 11. , 13a and 13b are arranged side by side in a direction parallel to the diffraction direction (left-right direction in the figure). The reflected light reflected by the optical recording medium 8 passes through the hologram optical element 4 and is distributed and received by the five light receiving regions 14, 15 a, 15 b, 16 a, and 16 b formed in the light receiving element 7. The

  Of the reflected light, the 0th-order light 11 that passes through the hologram optical element 4 without being diffracted is received by the 0th-order light-receiving area 14 disposed in the middle of the five light-receiving areas 14, 15a, 15b, 16a, and 16b. Is done. The optical information received by the zero-order light receiving area 14 is converted into an RF signal and used for reproducing information recorded on the optical recording medium 8. For this reason, the 0th-order light receiving region 14 serves as an RF signal detection region.

  The reflected light passing through the first region 9 is diffracted to generate + 1st order light 12a and −1st order light 12b. The + 1st order light 12a is focused before the light receiving surface 7a (between the hologram optical element 4 and the light receiving surface 7a in FIG. 2A), and the −1st order light 12b is ahead of the light receiving surface 7a (FIG. 2). In (a), focusing is performed on the lower side of the light receiving element 7). The + 1st order light 12a is received by the light receiving region 16b, and the −1st order light 12b is received by the light receiving region 15a.

  The reflected light passing through the second region 10 is diffracted to generate + 1st order light 13a and −1st order light 13b. The + 1st order light 13a is focused before the light receiving surface 7a, and the −1st order light 13b is focused before the light receiving surface 7a. The + 1st order light 13a is received by the light receiving region 15b, and the −1st order light 13b is received by the light receiving region 16a.

The light receiving region 16b that receives the + 1st order light 12a generated in the first region 9 and the light receiving region 16a that receives the −1st order light 13b generated in the second region 10 detect a focus error signal obtained by the SSD method. It is a focus error signal detection area. Correspondingly, the focus error signal detection areas 16a and 16b are divided into divided areas C, D, E, and F and divided areas I, J, and K, respectively. In each of the divided areas C, D, E, F, I, J, and K, when the electrical signals obtained from the optical information are SC, SD, SE, SF, SI, SJ, and SK, respectively, the focus error signal ( FES) is obtained by the following equation.
FES = (SC + SD + SJ + SF) − (SI + SE + SK)

On the other hand, the light receiving region 15a that receives the −1st order light 12b generated in the first region 9 and the light receiving region 15b that receives the + 1st order light 13a generated in the second region 10 detect the track error signal obtained by the CFF method. The track error signal detection areas 15a and 15b are divided into divided areas A, B and G and divided areas H and L, respectively. In each divided area A, B, G, H, and L, when the electrical signals obtained from the optical information are SA, SB, SG, SH, and SL, the track error signal (TES) is calculated by the following equation. can get.
TES = (SA + SB + SG)-(SH + SL)

  In the present embodiment, the zero-order light receiving region 14 is arranged to obtain an RF signal, but this is not necessarily limited to this configuration. That is, for example, without adding the 0th-order light receiving region 14, addition of signals obtained in the respective divided regions (C, D, E, F, I, J, K) of the focus error signal regions 16a, 16b (SC + SD + SE + SF + SI + SJ + SK) A configuration for obtaining an RF signal may be used. However, when an RF signal is obtained by adding signals obtained from a large number of divided areas, there is a possibility that the RF signal may be deteriorated due to an increase in noise or the like. A configuration in which the region 14 is arranged is preferable.

  As described above, on the light receiving surface 7a of the light receiving element 7, the five light receiving regions 14, 15a, 15b, 16a, 16b are ± first order lights 12a, 12b, 13a, 13b with respect to the optical axis 19 of the zero order light 11. The light receiving regions 14, 15a, 15b, 16a, and 16b are arranged in the order from the left to the right in FIG. 2B. An error signal detection area 15a, a focus error signal detection area 16a, a zero-order light receiving area 14, a track error signal detection area 15b, and a focus error signal detection area 16b are formed.

  Then, the five light receiving regions 14, 15a, 15b, 16a, 16b arranged in the light receiving element 7 are sandwiched between the zero-order light receiving region 14 in this way, and the focus error signal detecting regions 16a, 16b and the track error are arranged. By arranging the signal detection areas 15a and 15b so as to be alternately arranged, it is possible to accurately adjust the position of the light receiving element 7 when the optical pickup device is assembled. Hereinafter, this point will be described.

  In the adjustment of the position of the light receiving element 7 during the assembly of the optical pickup device, the adjustment in the X direction shown in FIG. 2B is performed by adjusting the spot position of the light beam in each of the light receiving regions 14, 15a, 15b, 16a, and 16b. It is sufficient that the adjustment is made so that it does not protrude outside, and the adjustment accuracy in the X direction is not so strict. However, if there is a deviation between the Y direction and the θ direction (rotation direction) shown in FIG. 2B, the focus error signal and the track error signal cannot be obtained accurately, and information recording is performed using the optical pickup device. The quality of playback decreases. For this reason, adjustment in the Y direction and adjustment in the rotation direction are important.

In the optical pickup device of the present embodiment, the adjustment in the Y direction and the adjustment in the rotation direction are performed using the focus error signal detection areas 16a and 16b. That is, one of the focus error signal detection areas 16a and 16b is used as a Y direction adjustment area for adjusting the Y direction, and the other is used as a rotation direction adjustment area for adjusting the rotation direction. Here, the focus error signal detection region 16a is described as a Y direction adjustment region, and the focus error signal detection region 16b is described as a rotation direction adjustment region. In this case, the position adjustment of the light receiving element 7 is completed if the following expression is established for the Y direction adjustment signal obtained from the Y direction adjustment area and the rotation direction adjustment signal obtained from the rotation direction adjustment area.
Y direction adjustment signal = SC + SD−SF = 0
Rotation direction adjustment signal = SI−SK = 0

  It is also possible to adjust the Y direction and the rotation direction using the track error signal detection areas 15a and 15b instead of the focus error signal detection areas 16a and 16b. However, in the case of the present embodiment, since the hologram optical element 4 is divided by the second dividing line 18b (see FIG. 1), for example, it reaches the track error signal detection regions 15a and 15b. The beam spot to be split is in a divided state (a semicircle is divided into two by a line parallel to the X direction), and the presence of a gap between the beam spots caused by this splitting makes the adjustment in the Y direction impossible. Therefore, it is preferable to adjust the Y direction and the rotation direction using the focus error signal detection regions 16a and 16b.

  When adjusting the Y direction and the rotation direction, the Y direction adjustment signal is usually set to 0 or near 0 by moving the Y direction, and then the rotation direction is moved to set the rotation direction adjustment signal in the rotation direction to 0 or near 0. The position of the light receiving element 7 is adjusted so that both the Y direction adjustment signal and the rotation direction adjustment signal are finally zero.

  FIG. 3 is a diagram illustrating a state where the position of the light receiving element 7 is shifted by θ1 in the rotation direction. As can be seen from FIG. 3, the larger the distance N between the Y-direction adjustment area (light-receiving area 16a) and the rotation-direction adjustment area (light-receiving area 16b), the greater Δd against rotational deviation (from the optimum position of the light-receiving area 16b in the Y direction). The value of the deviation amount) increases, and the value of the rotation direction adjustment signal for the rotation deviation also increases. That is, the greater the distance N between the Y direction adjustment area and the rotation direction adjustment area, the higher the sensitivity of the rotation direction adjustment signal with respect to the rotation direction deviation.

  In this regard, in the optical pickup device of the present embodiment, the light receiving regions 14 and 15b are arranged between the Y direction adjustment region and the rotation direction adjustment region, and the space between both is large. Therefore, the rotation direction of the light receiving element 7 can be adjusted with the sensitivity of the rotation direction adjustment signal being increased, and the light receiving element 7 can be adjusted with high accuracy. The optical pickup device of the present embodiment increases the sensitivity of the adjustment signal by devising the arrangement of the light receiving areas necessary for performing servo control such as focus control and tracking control, and thus increases the number of parts. In addition, an increase in the size of the apparatus is also suppressed.

  Note that the arrangement order of the zero-order light receiving area 14, the focus error signal detection areas 16a and 16b, and the track error signal detection areas 15a and 15b is not limited to the configuration of the present embodiment, Changes can be made without departing from the purpose. That is, if the zero-order light receiving region 14 is arranged in the middle and the focus error signal region and the track error signal detection region are alternately arranged, the order of the focus error signal detection region and the track error signal detection region does not matter. Absent. As described above, the focus error signal area and the track error signal detection area may be alternately arranged without arranging the zero-order light receiving area.

In this embodiment, the focus error signal is obtained by the SSD method and the track error signal is obtained by the CFF method. However, the configuration can be changed without departing from the object of the present invention. That is, for example, a configuration using a phase difference method or a push-pull method may be used as a method for obtaining a track error signal. Note that in the case of the push-pull method, the track error signal (TES) is obtained by the same calculation as in the case of the CFF method. An error signal (TES) is obtained.
TES = (SA + SB + SH)-(SG + SL)

  In addition, the arrangement of the optical system of the optical pickup device is not limited to the configuration of the optical pickup device 100 (see FIG. 4) having a conventional configuration, and various changes can be made according to the object of the present invention. That is, for example, the light source may be configured to emit a light beam having two or more wavelengths, and the wavelength plate 5 is not necessarily provided, and the wavelength plate 5 may not be provided. In this case, it is not necessary for the hologram optical element 4 to have polarization. Furthermore, the position at which the hologram optical element 4 is disposed is not limited to the position of the present embodiment, and for example, a configuration in which the hologram optical element 4 is disposed between the beam splitter 2 and the light receiving element 7 may be employed.

  The optical pickup device of the present invention is an optical pickup device that can adjust the position of a light receiving element using a signal from a light receiving region arranged in the light receiving element, and is an arrangement of the light receiving region provided in the light receiving element. However, the sensitivity of the signal when performing the position adjustment can be increased. For this reason, in the optical pickup device of the present invention, it is possible to accurately adjust the position of the light receiving element. Further, when increasing the sensitivity of position adjustment, the number of parts is not increased unnecessarily, and the size of the light receiving element is not increased unnecessarily.

These are the figures for demonstrating the structure of the hologram optical element of this embodiment, and are the schematic diagrams which showed typically the structure of the surface in which the diffraction pattern was formed. These are explanatory drawings showing the correspondence between the 0th-order light and ± 1st-order light generated through the hologram optical element and the light receiving element. These are figures which show the state which the position of the light receiving element shifted | deviated to the rotation direction. These are the schematic diagrams which showed the structure of the optical system of the conventional optical pick-up apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 4 Hologram optical element 6 Objective lens (focusing means)
8 Optical recording medium 8a Recording surface 9 1st area 10 2nd area 11 0th order light 12a, 13a + 1st order light 12b, 13b -1st order light 14 0th order light receiving area (RF signal detection area)
15a, 15b Track error signal detection area 16a, 16b Focus error signal detection area 17 Center of light beam 18a First dividing line 18b Second dividing line 19 Optical axis of 0th-order light

Claims (5)

A light source, a focusing means for focusing the light beam emitted from the light source on the recording surface of the optical recording medium, a light receiving element for receiving the reflected light reflected by the recording surface, and the focusing means and the light receiving element. A hologram optical element disposed between and diffracting the reflected light to generate diffracted light,
The light receiving element includes an RF signal detection region for detecting an RF signal, a focus error signal detection region for detecting a focus error signal, and a track error signal detection region for detecting a track error signal. In the optical pickup device to be arranged,
The hologram optical element is divided into two regions, a first region and a second region, by a first dividing line passing through the center of the reflected light, and both the first and second regions are Divided into two regions by a second parting line orthogonal to the first parting line and passing through the center of the luminous flux,
The focus error signal is detected by a spot size detection method,
The RF signal detection region is one light receiving region that receives zero-order light that passes through the hologram optical element,
Each of the focus error signal detection area and the track error signal detection area is composed of two independent light receiving areas, and the hologram optical element at the position of the light receiving element is sandwiched between the RF signal detection areas. Arranged alternately in a direction parallel to the diffraction direction of the diffracted light with respect to the optical axis of the transmitted 0th-order light,
The first region is formed such that ± primary light generated when the reflected light passes through the first region is received by being distributed to the focus error signal detection region and the track error signal detection region, In the second area, the ± first-order light generated when the reflected light passes through the second area is different from the ± first-order light received from the first area. An optical pickup device formed so as to be received by being distributed to the track error signal detection region. A light source, a focusing means for focusing a light beam emitted from the light source on a recording surface of an optical recording medium, a light receiving element for receiving reflected light reflected by the recording surface, and the focusing means and the light receiving element. A hologram optical element disposed between and diffracting the reflected light to generate diffracted light,
In the optical pickup device in which the light receiving element includes at least a focus error signal detection region for detecting a focus error signal and a track error signal detection region for detecting a track error signal.
The hologram optical element is divided into two regions, a first region and a second region, by at least one first dividing line passing through the center of the reflected light.
The focus error signal detection region and the track error signal detection region are both composed of two independent light receiving regions, and the diffraction with respect to the optical axis of the zeroth order light transmitted through the hologram optical element at the light receiving element position. Arranged alternately in a direction parallel to the diffraction direction of light,
The first region is formed such that ± primary light generated when the reflected light passes through the first region is received by being distributed to the focus error signal detection region and the track error signal detection region, In the second area, the ± first-order light generated when the reflected light passes through the second area is different from the ± first-order light received from the first area. An optical pickup device formed so as to be received by being distributed to the track error signal detection region.   3. The optical pickup device according to claim 2, wherein the focus error signal is detected by a spot size detection method.   In the light receiving element, one zero-order light receiving region for receiving the zero-order light is arranged at the center of a column in which the focus error signal detection region and the track error signal detection region are arranged side by side. The optical pickup device according to claim 2 or 3, wherein:   The first and second regions are both divided into two regions by a second dividing line that is orthogonal to the first dividing line and passes through the light beam center. The optical pick-up apparatus of any one of these.

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