RU2437173C2 - Optical head device and diffraction element, optical data device, computer, disc player, automobile navigation system, optical disc recording device and vehicle - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: optical head device includes a diffraction element which is divided into three regions. Phases of the grating of the left and right hand regions of the diffraction element for generating an additional beam differ from each other by 180 degrees. The central region of the diffraction element for generating an additional beam has a grating structure which differs from the structure of the left and right hand region, and divided into multiple regions to form different gratings which are different from each other.

EFFECT: use of a single diffraction element for discs with different track spacing to obtain a tracking error signal and preventing the fall of the amplitude value of that signal.

36 cl, 24 dwg

Description

FIELD OF THE INVENTION

The present invention relates to an optical information device for reproducing information from a medium for recording information represented by optical discs, or recording information on a medium for recording information; an optical head device for reproducing or recording information in an optical information device; and information equipment and system. The present invention also relates to a diffraction element used in said devices.

State of the art

Since a digital monofunctional disc (DVD) can record digital information with a recording density of about six times the recording density of a compact disc (CD), a DVD is known as an optical disc on which large data can be recorded. Recently, large-capacity optical discs have been required with an increase in the amount of information recorded on the optical disc. In order to obtain an optical disc with a large volume, the recording density of the information must be increased by reducing the optical spot generated by the light emitted to the optical disc when recording information on the optical disc and reproducing information recorded on the optical disc. Specifically, the optical spot can be reduced by the fact that the laser light of the light source has a short wavelength, and by increasing the numerical aperture (NA) of the objective lens. A wavelength of 660 nm (red) is used as the wavelength of the light source, the DVD using an objective lens having a numerical aperture (NA) of 0.6. In addition, a BD (cine ray disk) uses a light source having a wavelength of 405 nm and uses a lens lens having an NA of 0.85 to achieve a recording density five times that of modern DVDs.

In an optical information device for recording and reproducing at high density using a laser with a small wavelength by means of a blue laser, the usability of the device is further enhanced by providing a compatibility function with an existing optical disc, and cost-effectiveness is also increased.

A DVD-R disc (write-once DVD) having a track pitch of 0.74 μm, and a DVD-RAM disc (rewritable DVD) for recording both on the site (L) and in the groove (G) at 1, 3 microns coexist in a DVD using a red light source. Thus, it is important to stably perform track management on an optical disc with different track pitch even for equipment designed for DVDs, and, moreover, compatibility with CD and BD is also desirable.

In order to perform track control, a track offset value needs to be determined, and a track tracking error signal must be determined. One commonly used method for determining a track tracking error signal is a differential antiphase method (DPP method). The differential antiphase method is disclosed in Japanese Patent Laid-open Publication No. 7-272303 and is described below briefly with reference to FIG. 19 (Patent Document 1).

On Fig shows the configuration of the device of the optical head according to the prior art. The light beam 210 emitted by the light source 201 passes through the diffraction grating 204. The diffraction grating 204 creates conjugated diffracted light. The missed main beam and the diffracted additional beam are converted into parallel light by a collimator lens 203. The lens lens 205 converges the main beam and two additional rays, which are parallel light, onto the recording surface of the optical disk 227. The light reflected from the optical disk follows the same optical path in the opposite direction and enters the light detector 266. The lens of the lens moves in the direction of tracking the track, based on the error signal tslezhivaniya track received from the light detector 266, to perform track control.

The configuration of the diffraction grating (Fig. 19) is shown as a body layout, as in Figs. 20A and 20B. Fig. 20A is a front view, and Fig. 20B is a cross section. A diffraction grating 204 is obtained by periodically forming concave-convex portions on the surface of a transparent base material, such as glass, as shown in FIG. 20B. For simplicity, only the center line of the convex portion is shown in a front view in FIG. 20A. In this case, unless specifically indicated, for simplicity, only the center line of the convex part is shown in other drawings in the image of a concave-convex shape in front view. When a light beam is passed through a diffraction grating 204, conjugated ± one-dimensional diffracted light is generated and reduced on the recording surface of the optical disk 227 in the form of a main beam 211 and two additional rays 212, 213 through the lens 205 of the lens (Fig. 21). A recordable optical disc, such as DVD-RAM, has concave-convex grooves on the recording surface. “Concave-convex” refers to sites (L) and grooves (G). The diffraction grating 204 is controlled by rotation, as shown by the arrow in FIG. 20A, so that when the main beam 211 is flattened on a certain groove, additional beams 212, 213 are flattened at adjacent sites. When the antiphase signal generated by diffraction in the groove of the disk is determined from the main beam and the additional rays reflected and returned from the disk, the positive and negative signs of the antiphase signal become opposite for the main beam and additional rays. The track tracking error signal of the out-of-phase method is determined by differential calculation of the out-of-phase signal of the additional rays and the out-of-phase signal of the main beam. In this method, the distance in the tracking direction of the track (T) of the main beam and additional rays should be equal to the center-to-center distance of the platform and the groove, i.e. half step of the tracks, and thus the amplitude of the track tracking error signal is reduced when used with an optical disc with a different track pitch, such as DVD-RAM and DVD-R, which is a problem.

A diffraction grating designed to solve such a problem is shown in FIG. 22A (Japanese Patent Laid-Open Publication No. 9-81942 Patent Document 2). As shown in FIG. 22A, the diffraction grating 224 is divided into two halves by means of a dividing line parallel to the direction Y of the grooves. Assuming that the grating phase of the first diffraction grating region 2241 of the left side of the figure is a reference (0 degrees), the grating phase of the second grating region 2242 of the right side of the figure is 180 degrees. It is assumed that the phase shift of the lattice in the direction T is positive. At the moment, additional beams are symmetrically divided into halves (FIG. 22B). The additional rays 222 and 223 are located on the same groove as the main beam 221. In this case, the out-of-phase signals received from the additional rays 222 and 223 have opposite signs with respect to the main beam 221. Thus, the track tracking error signal in the method with an out-of-phase signal, it is determined by differential calculation of the out-of-phase signal of the additional rays and the out-of-phase signal of the main beam. In this method, the arrangement is such that the distance in the tracking direction of the track (T) of the main beam and the additional rays becomes 0, and thus, the amplitude of the track tracking error signal does not decrease due to disc differences, even when applied to optical discs, having different pitch tracks such as DVD-RAM and DVD-R. However, there is a problem that when the lens of the lens moves in the track tracking direction (T) as a result of following the track, the amplitude of the track tracking error signal at the destination decreases.

In addition, in order to prevent a decrease in the amplitude of the track tracking error signal as a result of moving the objective lens, a method is disclosed in Japanese Patent Laid-Open Publication No. 2000-145915 (Patent Document 3) and Japanese Patent Laid-open Publication No. 2006-4499 (Patent Document 4) . As shown in FIG. 23A, a third diffraction grating region 2343 having a 90 degree phase is disposed between the first diffraction grating 2341 having a 0 degree phase and the second diffraction grating region 2342 having a 180 degree phase. The signal amplitude in the state when the lens of the lens does not move as a result of following the track decreases in advance, and the decrease in the amplitude of the track tracking error signal in the state when the lens of the lens moves is eliminated by arranging another region in the middle part.

However, in the diffraction grating shown in FIG. 23A, the phase changes in a stepwise manner: 0 degrees, 90 degrees and 180 degrees in the order on the left side of the figure. The diagonal diffraction grating shown by the dotted line with double dots in FIG. 24 becomes the main component, and the additional rays have an uneven light intensity between the left and right additional rays (FIG. 23B). As shown in figv, when the location of the part where the intensity of the additional beam is large, the groove of the track should be optimally adjusted to maximize the DPP signal. Those. similarly to the method using the diffraction grating shown in FIGS. 20A and 20B, there is a problem that the optimal adjustment position (rotation angle) of the diffraction grating differs depending on the pitch of the optical pitch tracks, and it is difficult to obtain a stable track tracking error signal.

Therefore, at present, there is no way how to obtain the track tracking error signal by means of the optimal DPP method for optical disks having different track pitch using a single diffraction grating, or to eliminate the decrease in the amplitude of the track tracking error signal in the state when the lens of the lens is moving as a result of following the track.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an optical head and diffraction grating device that provides a track tracking error signal by means of an optimal DPP method for optical discs having different track pitch using a single diffraction element and eliminates a decrease in the amplitude of the track tracking error signal in a state when the lens of the lens moves as a result of following the path; as well as the creation of an optical information device; a computer; disc player; car navigation system; optical disc recorders; and vehicle.

To solve the tasks according to the present invention, the following configurations are proposed.

According to a first aspect of the present invention, there is provided an optical head device comprising a light source, a diffraction element for branching light coming from a light source into at least three light fluxes including a main beam that is transmitted without diffraction, and two additional beams that diffracted, the lens of the lens to reduce the three light fluxes on the recording surface of the optical disk, and a light receiver for receiving light, reduced on the recording surface of the optical disk using Inza lens and reflected by the optical disc and the photoelectric converting light into an electric signal, wherein

the diffraction element is divided into a first region of the diffraction grating, a second region of the diffraction grating formed by a second diffraction grating having a phase that differs substantially 180 degrees from the phase of the first diffraction grating located in the first region of the diffraction grating, and a central region located between the first a grating region and a second grating region;

the central region is further divided into a plurality of divided regions by means of a virtual dividing line; and

the central region has grating phases or vectors different from the grating phases and vectors of the first diffraction grating region and the second grating region, and the divided regions separated by a virtual dividing line are formed with diffraction gratings having a different phase and grating vector.

According to a second aspect of the present invention, there is provided an optical head apparatus of a first aspect in which a dividing line for dividing a central region extends in a direction orthogonal to the direction of passage of a groove of a track of the optical disc.

According to a third aspect of the present invention, there is provided an optical head apparatus of a first aspect in which the central region is divided into three or more divided regions.

According to a fourth aspect of the present invention, there is provided an optical head apparatus of a third aspect, in which diffraction gratings having different phases are formed in two divided regions from three or more divided regions of the central region; and

a diffraction grating with the same grating vector and the same phase as that of a diffraction grating formed in one of two divided regions is formed in at least one divided region from the remaining divided region.

According to a fifth aspect of the present invention, there is provided an optical head apparatus of a first aspect, wherein when a phase of a first diffraction grating formed in a first region of a diffraction grating is 0 degrees as a reference, a phase of a third diffraction grating formed in a divided region obtained by dividing a central region , and the phase of the fourth diffraction grating, formed in another divided region, have opposite polarities, but the same absolute value.

According to a sixth aspect of the present invention, there is provided an optical head device of a fifth aspect, wherein when the phase of the first diffraction grating formed in the first divided region is 0 degrees as a reference, the phase of the third diffraction grating is 90 degrees and the phase of the fourth diffraction grating is -90 degrees.

According to a seventh aspect of the present invention, there is provided an optical head apparatus of a first aspect, wherein when the phase of the first diffraction grating formed in the first region of the diffraction grating is 0 degrees as a reference, the phase of each diffraction grating formed in each divided region of the central region is, essentially 0 degrees on average.

According to an eighth aspect of the present invention, there is provided an optical head apparatus of a third aspect, wherein when the phase of the first diffraction grating formed in the first divided region is 0 degrees as a reference, the central region is divided into four or more divided regions, forming a diffraction grating having a phase -120 degrees, a diffraction grating having a phase of -60 degrees, a diffraction grating having a phase of +60 degrees, and a diffraction grating having a phase of +120 degrees.

According to a ninth aspect of the present invention, there is provided an optical head device comprising a light source, a diffraction element for branching light coming from a light source into at least three light fluxes, an objective lens for converging three light fluxes on an optical disc recording surface, and a light receiver for receiving light brought together on the recording surface of the optical disk by the objective lens and reflected by the optical disk, and photoelectric conversion of light into an electrical signal l, and

the diffraction element is divided into a first diffraction grating region, a second diffraction grating region formed with a second diffraction grating having a phase that differs substantially 180 degrees from the first diffraction grating located in the first diffraction grating region, and a central region located between the first the region of the diffraction grating and the second region of the diffraction grating, wherein

a diffraction grating having a direction different from that of the first diffraction grating and the second diffraction grating is formed in the central region.

According to a tenth aspect of the present invention, there is provided an optical head arrangement of a ninth aspect, in which a third diffraction grating formed in a divided region obtained by dividing a central region and a fourth diffraction grating formed in another divided region are diffraction gratings having a direction different from the first diffraction grating and the second diffraction grating, and have an angle formed with the direction of passage of the grooves of the track opt disk, opposite signs relative to each other.

According to an eleventh aspect of the present invention, there is provided an optical head device comprising a light source, a diffraction element for branching light coming from a light source into at least three light fluxes, an objective lens for converging three light fluxes on an optical disc recording surface, and a light receiver for receiving light brought together on the recording surface of the optical disc by means of a lens of the lens and reflected by the optical disc, and photoelectric conversion of light into electrical signal, moreover

the diffraction element is divided into a first diffraction grating region, a second diffraction grating region formed with a second diffraction grating having a phase differing substantially 180 degrees from the phase of the first diffraction grating located in the first diffraction grating region, and a central region located between the first region of the diffraction grating and the second region of the diffraction grating, wherein

a diffraction grating having a grating pitch different from the grating spacing of the first diffraction grating and the second diffraction grating is formed in the central region.

According to a twelfth aspect of the present invention, there is provided an optical head arrangement of a tenth aspect in which a diffraction grating formed in a central region is a diffraction grating having a smaller grating pitch than the first diffraction grating and the second diffraction grating.

According to a thirteenth aspect of the present invention, there is provided an optical head device of any one of the first, ninth and eleventh aspects, in which the width of the central region is from 10% to 40% of the projection diameter on the diffractive element of the effective diameter of the objective lens.

According to a fourteenth aspect of the present invention, there is provided an optical head device of any one of the first, ninth, and eleventh aspects, wherein the light source is a two-wavelength light source for emitting red light and infrared light.

According to a fifteenth aspect of the present invention, there is provided an optical head device of the fourteenth aspect, in which the width of the central region is less than or equal to 30% of the projection onto the diffraction element of the effective diameter of the lens aperture.

According to a sixteenth aspect of the present invention, there is provided an optical head device of any one of the first, ninth, and eleventh aspects, further comprising a blue light source.

According to a seventeenth aspect of the present invention, there is provided a diffraction element mounted on an optical head device including a light source, an objective lens for converging light coming from a light source on a recording surface of an optical disc, and a light receiver for receiving light reduced on a recording surface of the optical disc by means of an objective lens and reflected by the optical disk, and photoelectric conversion of light into an electrical signal, the diffraction element branching the light, and coming from the light source into at least three light fluxes, including the main beam, which is transmitted without diffraction, and two additional rays, which are diffracted,

the diffraction element is divided into a first diffraction grating region, a second diffraction grating region formed with a second diffraction grating having a phase differing substantially 180 degrees from the phase of the first diffraction grating located in the first diffraction grating region, and a central region located between the first region of the diffraction grating and the second region of the diffraction grating, wherein

the central region has grating phases or vectors different from the grating phases and vectors of the first diffraction grating region and the second diffraction grating region, and the divided regions separated by a dividing line are formed with diffraction gratings having different phase and grating vector.

According to an eighteenth aspect of the present invention, there is provided a diffraction element of the 17th aspect, in which a dividing line for dividing the central region extends in a direction orthogonal to the direction of passage of the groove of the track of the optical disc.

According to a nineteenth aspect of the present invention, there is provided a diffraction element of the 17th aspect, in which the central region is divided into three or more divided regions.

According to a twentieth aspect of the present invention, there is provided a diffraction element of the 19th aspect, in which diffraction gratings having different phases are formed in two divided regions from three or more divided regions of the central region, wherein

a diffraction grating with the same grating vector and the same phase as that of a diffraction grating formed in one of two divided regions is formed in at least one divided region from the remaining divided region.

According to a twenty-first aspect of the present invention, there is provided a diffraction element of the 17th aspect, wherein when the phase of the first diffraction grating formed in the first region of the diffraction grating is 0 degrees as a reference, the phase of the third diffraction grating formed in the divided region obtained by separation the central region, and the phase of the fourth diffraction grating, formed in another divided region, have opposite polarities, but the same absolute value.

According to a twenty-second aspect of the present invention, there is provided a diffraction element of the 21st aspect, wherein when the phase of the first diffraction grating formed in the first divided region is 0 degrees as a reference, the phase of the third diffraction grating is 90 degrees and the phase of the fourth diffraction grating is -90 degrees.

According to a twenty-third aspect of the present invention, there is provided a diffraction element of the 17th aspect, in which, when the phase of the first diffraction grating formed in the first region of the diffraction grating is 0 degrees as a reference, the phase of each diffraction grating formed in each divided region of the central region, essentially equal to 0 degrees on average.

According to a twenty-fourth aspect of the present invention, there is provided a diffraction element of the 20th aspect, wherein when the phase of the first diffraction grating formed in the first divided region is 0 degrees as a reference, the central region divided into three or more regions is provided with a diffraction grating having a phase of -120 degrees, a diffraction grating having a phase of -60 degrees, a diffraction grating having a phase of +60 degrees, and a diffraction grating having a phase of +120 degrees.

According to a twenty-fifth aspect of the present invention, there is provided a diffraction element mounted on an optical head device including a light source, an objective lens for converging light coming from a light source on an optical disc recording surface, and a light receiver for receiving light reduced on an optical recording surface a disk by means of a lens of the lens and reflected by the optical disk, and photoelectric conversion of light into an electrical signal, the diffraction element branches out Emanating from the light source into at least three light beams including a main beam that is transmitted without diffraction, and two additional beams that are diffracted, wherein

the diffraction element is divided into a first diffraction grating region, a second diffraction grating region formed with a second diffraction grating having a phase differing substantially 180 degrees from the phase of the first diffraction grating located in the first diffraction grating region, and a central region located between the first region of the diffraction grating and the second region of the diffraction grating, wherein

a diffraction grating having a direction different from that of the first diffraction grating and the second diffraction grating is formed in the central region.

According to a twenty-sixth aspect of the present invention, there is provided a diffraction element of the 25th aspect, in which the third diffraction grating formed in the divided region obtained by dividing the center region and the fourth diffraction grating formed in the other divided region are diffraction gratings having a direction different from the direction of the first diffraction grating and the second diffraction grating, and have an angle formed with the direction of passage of the groove ki optical disc with opposite signs to each other.

According to a twenty-seventh aspect of the present invention, there is provided a diffraction element mounted on an optical head device including a light source, an objective lens for converging light coming from a light source on a recording surface of an optical disc, and a light receiver for receiving light reduced on a recording surface of an optical the disk by means of a lens of the lens and reflected by the optical disk, and photoelectric conversion of light into an electrical signal, the diffraction element branches with is emitted from the light source into at least three light beams including a main beam that is transmitted without diffraction, and two additional beams that are diffracted, wherein

the diffraction element is divided into a first diffraction grating region, a second diffraction grating region formed with a second diffraction grating having a phase differing substantially 180 degrees from the phase of the first diffraction grating located in the first diffraction grating region, and a central region located between the first region of the diffraction grating and the second region of the diffraction grating, wherein

a diffraction grating having a grating pitch different from the grating spacing of the first diffraction grating and the second diffraction grating is formed in the central region.

According to a twenty-eighth aspect of the present invention, there is provided a diffraction element of the 27th aspect, in which the diffraction grating formed in the central region is a diffraction grating having a smaller grating step than the grating step of the first diffraction grating and the second diffraction grating.

According to a twenty-ninth aspect of the present invention, there is provided an optical information device comprising:

an optical head device according to any one of the first to 16th aspects;

drive for rotating an optical disk; and

an electrical circuit for receiving a signal received from the optical head device and controlling and driving an engine, an optical lens and a laser light source based on the signal.

According to a thirtieth aspect of the present invention, there is provided an optical information device of the 29th aspect, in which

the out-of-phase signal obtained by receiving an additional beam at the light receiver and calculated by photoelectric conversion is amplified with a gain K1 and subtracted by the out-of-phase signal obtained by receiving the additional beam on the light receiver and processed by the photoelectric conversion to be used as a track tracking error signal; and

the gain coefficient K1 is fixed after adjustment at a value at which the change in the track tracking control signal becomes smaller when the lens of the lens moves in a direction perpendicular to the direction of passage of the groove of the track of the optical disc.

According to a thirty-first aspect of the present invention, there is provided an optical information device of the 29th aspect, in which a focus error signal obtained by receiving an additional beam at a light detector and calculated by a photoelectric conversion is amplified with a gain K2 and added to the focus error signal obtained by receiving additional beam at the light detector, and is processed using photoelectric conversion for use as a si Nala focus error for the focus control.

According to a thirty-second aspect of the present invention, there is provided a computer, comprising:

optical information device of the 29th aspect;

input device or input terminals for inputting information;

an arithmetic device for performing arithmetic operations based on information entered from an input device or information reproduced from an optical information device; and

an output device or output terminals for displaying or outputting information inputted from an input device, or information reproduced from an optical information device, or the result of an arithmetic operation performed by an arithmetic device.

According to a thirty-third aspect of the present invention, there is provided an optical disc player comprising:

optical information device of the 29th aspect; and

an information-image decoder for converting an information signal received from an optical information device into an image.

According to a thirty-fourth aspect of the present invention, there is provided an automobile navigation system comprising:

optical information device of the 29th aspect;

an information-image decoder for converting an information signal received from an optical information device into an image; and

position sensor.

According to a thirty-fifth aspect of the present invention, there is provided an optical disc recording apparatus comprising:

optical information device of the 29th aspect; and

image-information encoder for converting image information into information to be recorded by the optical information device.

According to a thirty-sixth aspect of the present invention, there is provided a vehicle, comprising: an optical information device of the 29th aspect, a vehicle body assembled with an optical information device, and a power generation unit for generating power for moving a vehicle body.

According to a thirty-seventh aspect of the present invention, there is provided an optical head device including a light source, a diffraction element for branching light coming from a light source into at least three light fluxes, including a main beam that is transmitted without diffraction, and two additional of the beam that are diffracted, an objective lens for converging three light fluxes on the recording surface of the optical disk, and a light receiver for receiving light reduced on the recording surface of the optical disk a lawsuit through the lens of the lens and reflected by the optical disk, and photoelectric conversion of light into an electrical signal; moreover

the diffractive element includes a first divided region, a second divided region, a third divided region and a fourth divided region;

a first diffraction grating is formed in the first divided region;

a second diffraction grating having a phase differing substantially 180 degrees from the phase of the first diffraction grating is formed in a second divided region;

a third diffraction grating having a phase differing substantially by -90 degrees from the phase of the first diffraction grating is formed in a third divided region; and

a fourth diffraction grating having a phase differing substantially +90 degrees from the phase of the first diffraction grating is formed in the fourth divided region.

According to a thirty-eighth aspect of the present invention, there is provided a diffractive element used in an optical head including a light source, a diffractive element for branching light coming from a light source into at least three light fluxes including a main beam that is transmitted without diffraction , and two additional beams that are diffracted, an objective lens for converging three light fluxes on the recording surface of the optical disk, and a light receiver for receiving light brought on top recording an optical disc by means of an objective lens and reflected by the optical disc, and photoelectric conversion of light into an electrical signal; moreover

the diffractive element includes a first divided region, a second divided region, a third divided region and a fourth divided region;

a first diffraction grating is formed in the first divided region;

a second diffraction grating having a phase differing substantially 180 degrees from the phase of the first diffraction grating is formed in a second divided region;

a third diffraction grating having a phase differing substantially by -90 degrees from the phase of the first diffraction grating is formed in a third divided region; and

a fourth diffraction grating having a phase differing substantially +90 degrees from the phase of the first diffraction grating is formed in the fourth divided region.

Effect of the invention

According to the present invention, the effect of both obtaining a track tracking error signal by an optimal DPP method with respect to an optical disc with a different track pitch using only one diffraction element is provided, and eliminating a decrease in the amplitude of the track tracking error signal in a state when the lens of the lens moves as a result following the track.

Those. the signal amplitude in the state when the lens of the lens does not move as a result of following the track decreases in advance, and the decrease in the amplitude of the track tracking error signal in the state when the lens of the lens moves is proportionally eliminated by arranging the divided regions forming diffraction gratings different from the diffraction gratings of the first the area of the diffraction grating and the second region of the diffraction grating in the Central region located between the first region of the diffraction grating and the second th region of the diffraction grating. In addition, the phase change is prevented in a stepwise manner over the entire surface of the diffraction grating by dividing the central region located between the first region of the diffraction grating and the second region of the diffraction grating into a plurality of divided regions and arrangements of diffraction gratings having different phases from each other, thereby achieving that the corresponding additional rays have a light distribution line symmetrical in the direction (track tracking direction) of emescheniya optical head relative to the symmetrical line along a direction substantially parallel to the projections in the direction of passage of the optical disc.

Brief Description of the Drawings

These and other aspects and features of the present invention will become apparent from the following description, taken in conjunction with preferred embodiments with reference to the accompanying drawings, in which:

1 schematically depicts a configuration of an optical head device according to a first embodiment of the present invention;

Figa - depicts the configuration of a diffraction element mounted on the device of the optical head of Fig.1, according to the invention;

Fig. 2B is a view of the information spot on the optical disk when using the diffraction grating of Fig. 2A, according to the invention;

3 schematically depicts a configuration of an optical head device according to a second embodiment of the present invention;

Fig. 4A shows the transmission region of the main beam and the secondary beam when the diffraction grating shown in Fig. 2A is mounted on the optical head device of Fig. 3 according to the invention;

Fig. 4B is a view of the information spot on the optical disk when the diffraction grating of Fig. 4A is used on the optical head device of Fig. 3 according to the invention;

Figure 5 depicts the configuration of a diffraction element mounted on the device of the optical head of figure 3, according to the invention;

Fig. 5B is a view of the information spot on the optical disk when the diffraction grating of Fig. 5A is used, according to the invention;

6A depicts a diffraction grating configuration of a third embodiment of the present invention;

Fig. 6B is a view of the information spot on the optical disk when the diffraction grating of Fig. 6A is used, according to the invention;

7A shows a diffraction grating configuration of a fourth embodiment of the present invention;

Fig. 7B is a view of the information spot on the optical disk when the diffraction grating of Fig. 7A is used, according to the invention;

Fig. 8A shows a diffraction grating configuration of a fifth embodiment of the present invention;

Fig. 8B is a view of the information spot on the optical disk when the diffraction grating of Fig. 8A is used, according to the invention;

Fig. 9A shows a diffraction grating configuration of a sixth embodiment of the present invention;

Fig. 9B is a view of the information spot on the optical disc when the diffraction grating of Fig. 9A is used, according to the invention;

10 schematically depicts an example configuration of a light detector used in combination with an additional beam diffraction element in an optical head device of each embodiment of the present invention;

11 schematically depicts another example of a configuration of a light detector used in combination with an additional beam diffraction element in an optical head device of each embodiment of the present invention;

12 shows a configuration of an optical head device according to another embodiment of the present invention;

Fig.13 schematically depicts the configuration of a light detector mounted on the optical head device shown in Fig.12, according to the invention;

Fig.14 schematically depicts the configuration of an optical information device assembled with the optical head device of Fig.12, according to the invention;

Fig - General view of a computer assembled with the optical information device of Fig.14, according to the invention;

Fig. 16 is a perspective view of an optical disc player and an automobile navigation system assembled with the optical information device of Fig. 14, according to the invention;

FIG. 17 is a perspective view of an optical disc recorder assembled with the optical information device of FIG. 14, according to the invention; FIG.

Fig. 18 is a configuration of a vehicle assembled with the optical information device of Fig. 14, according to the invention;

Fig. 19 shows a configuration of a known optical head device;

Figa - front view of the configuration of the diffraction element of the optical head device shown in Fig.19;

Fig. 20B is a cross-sectional view illustrating a configuration of a diffraction element of the optical head device shown in Fig. 19;

Fig. 21 is a view of an information spot on an optical disk in a known optical head device;

Figa - front view depicting the configuration of the diffraction element of the known device of the optical head;

FIG. 22B is a view of the information spot on the optical disk when the diffraction grating shown in FIG. 22A is used;

23A is a front view showing a configuration of a diffraction element of a known optical head device;

FIG. 23B is a view of the information spot on the optical disk when the diffraction grating shown in FIG. 23A is used;

Figa depicts the state of change of the diffraction phase, which becomes the main component of the diffraction element of the optical head device shown in figa;

24B is a view of the information spot on the optical disc when the diffraction grating shown in FIG. 24A is used.

The best embodiments of the invention

First Embodiment

1 shows a configuration of an optical head device according to a first embodiment of the present invention.

The light beam 14 emitted by the light source 12 (for example, a red light source) is passed through a diffraction element 31 that diffracts some light (partial diffraction), and then is reflected in the beam splitter 3000 and has a parallelism converted (for example, essentially to parallel light) by means of a collimator lens 70, whereby the light beam 14 is brought together on the recording surface of the optical disc 27, such as DVD-R and DVD-RAM, etc. through a transparent base material of approximately 0.6 mm using the lens 25 of the lens, forming an additional spot on the optical disk 27. The light beam reflected by the recording surface of the optical disk 27 passes through the same light path in the opposite direction, passes through a beam splitter 3000 and then branches in a direction different from the direction to the light source 12, and, at the same time, astigmatism is provided. The light beam is photoelectrically converted by the light receiver 10 to receive electrical signals to obtain an information signal, a servo signal (a focus error signal for focus control and a track tracking error signal for controlling track tracking). If the amplifier circuit is integrated in the light detector 10, a satisfactory information signal is obtained having a high signal to noise ratio (S / N), and in addition, miniaturization of the optical head device is realized and stability is achieved.

Although not shown, the optical head can be thinned by tilting the optical axis in a direction perpendicular to the optical disc, such as DVD-R and DVD-RAM, by positioning a raising mirror between the collimator lens 70 and the lens 25 of the lens.

On figa presents the configuration of the diffraction element 31 mounted on the device of the optical head of figure 1. 2A, the dotted line is a boundary line that virtually depicts the boundary 3108 of the diffraction grating region. The diffraction grating in each region of the diffraction grating has a center line of the convex portion shown by a solid line. The step of the diffraction grating is designed accordingly by arranging the diffraction element 31.

The direction T is the direction perpendicular to the optical axis of the light beam and essentially perpendicular to the projection on the direction of the groove of the track of the optical disk (not shown), and the Z direction is the direction of the optical axis (direction perpendicular to the plane of the drawing) of the light beam. The T axis represents the direction of movement of the optical head device when recording or reproducing the inner periphery and the outer periphery of the optical disc and represents the direction in which the lens of the lens moves in accordance with the following along the track. The Y axis represents a direction perpendicular to the Z axis and the T axis, and represents a direction substantially parallel to the projection onto the direction of passage of the grooves of the track of the optical disc. In the above description, projection is performed, including mirror handling, etc. along the optical axis of the light ray.

The diffraction element 31 is divided into regions by means of a dividing line (dashed line) parallel to the direction Y of the groove (Fig. 2A), thereby forming diffraction gratings. Assuming that the grating phase of the first diffraction grating region 3101 on the left side of the figure is a reference (0 degrees), the grating phase of the second diffraction grating region 3102 on the right side of the figure is 180 degrees. The offset in the Y direction of the grating phase is positive. The central region 3109 between the first diffraction grating region 3101 having a 0 degree phase and the second diffraction grating region 3102 having a 180 degree phase is divided into regions by a dividing line 3108 extending in the T direction, whereby a third diffraction grating region 3103 having a phase 90 degrees, and a fourth diffraction grating region 3104 having a phase of -90 degrees are arranged in the Y direction. In other words, a region 3109 between the first diffraction grating region 3101 and the second diffraction region 3102 the lattice constant is further divided into a plurality of regions and the phase gratings divided areas 3103, 3104 take values with opposite signs, for example +90 degrees and -90 degrees. The lattice phase is in the range of -180 degrees to +180 degrees, in the present embodiment. Since the phase has a periodicity at which one period is 360 degrees, the phase can be indicated in other ranges by adding or subtracting integer multiples of 360 degrees. For example, when the lattice phase is indicated in the range from 0 degrees to 360 degrees, 360 degrees is added only when the phase is negative, whereby the lattice phase of the divided region 3104 of the present embodiment becomes the same as the phase indicated as 270 degrees. The lattice phase is indicated in the range from -180 degrees to +180 degrees, as described below. The signal amplitude in the state when the lens of the lens does not move as a result of following the track decreases in advance, and the decrease in the amplitude of the track tracking error signal in the state when the lens of the lens moves is proportionally eliminated by arranging diffraction gratings different from diffraction gratings 3103, 3104 the gratings of the first diffraction grating region 3101 and the second diffraction grating region 3102 in the central region 3109 located between the first diffraction grating region 3101 and Torah grating region 3102. The phase change is prevented in a stepwise manner over the entire surface of the diffraction element 31, while the distribution of the amount of light in which the additional beams 33, 34 are linearly symmetrical in the T direction with respect to the symmetric line in the Y direction is obtained by forming regions obtained by dividing the central region 3109, located between the first region 3101 of the diffraction grating and the second region 3102 of the diffraction grating, for a plurality of regions and locations of diffraction gratings with tlichayuschimisya phases from each other. Specifically, as shown in a simplified form in FIG. 2B, each additional beam has the form of a divided into two beams, since the level lines of the magnitude of the light are shown. According to the configuration of the present invention, an execution effect is achieved, i.e. receiving the track tracking error signal by the optimal DPP method with respect to the optical disc 27 with a different track pitch using a single diffraction element 31, and eliminating the decrease in the amplitude of the track tracking error signal in the state when the lens of the lens moves as a result of following the track.

An essential feature of the invention disclosed in the present example is to divide the lattice region into at least first to fourth regions, where at least a third region and a fourth region are located between the first region and the second region, wherein a phase of +90 degrees and -90 degrees is assigned respectively, the third region and the fourth region, assuming that the lattice phase of the first region is a reference (0 degrees), and the phase of the second region is 180 degrees. In other words, four types of phase gratings having phases differing by 90 degrees are formed from the first region to the fourth region. The above effect is achieved due to this feature.

The lattice structure is shown, which is linear and with the same period and in the same direction. This means that the direction and size of the lattice vector are equal. However, the present invention is not limited to an example with the same lattice vector. The grating, which is the basis for the phase change, may be bent, the period of the grating may be partially changed, or the direction of the grating may be partially changed to change the wave front of the additional beam to the desired wave front. Thus, the effect of reducing off-axis aberrations of the objective lens is achieved. Off-axis aberration is an aberration that is created when the beam enters the lens diagonally.

The width in the T direction of the central region 3109 located between the first diffraction grating region 3101 and the second diffraction grating region 3102 is respectively 10% to 40% of the projection diameter (hereinafter referred to as effective diameter) in the plane of the diffraction grating 31 for the main beam limited hole located near the lens of the lens in relation to red light. Unless otherwise indicated, it is the same for subsequent embodiments. Changing the signal during lens shift can thus be eliminated while guaranteeing the signal intensity obtained from the additional beam by determining the width in the direction T.

In the above embodiment, the central region 3109 located between the diffraction grating region 1 and the diffraction grating region 2 is divided into multiple regions to provide two regions of the third diffraction grating region 3103 and the fourth diffraction grating region 3104, using a dividing line 3108 extending in the T direction, but can be divided by means of a dividing line running in the Y direction instead of the T direction to arrange a plurality of areas in the T direction. The region can split with an intermediate angle between the Y direction and the T. direction. In this case, an effect can also be achieved that the phase change is eliminated in a stepwise manner over the entire surface of the diffraction grating 31, and additional rays 33, 34 approach the light distribution line symmetrical in the T direction with respect to the symmetrical line in the Y direction. This is also true for subsequent embodiments.

Second Embodiment

Due to limitations on the external shape of the optical head device, the diffraction element for generating additional rays used instead of the diffraction element 31 in FIG. 1 must be located close to the light source 12 and at a distance from the collimator lens 70, as in position 3100 (FIG. 3). With this arrangement, the required effective diameter of the diffraction element 3100 is reduced, and the external shape is miniaturized, and thus, the material costs of the diffraction element 3100 are reduced.

In this case, the region from which the additional beam is generated in the diffraction element 3100 is different from the region where the main beam is generated, and the region 402 of the generation of the additional beam 242 and the region 403 of the generation of the additional beam 243 are shifted in the Y direction relative to the transmission region 401 of the main beam 214, as shown in figa. This is because the additional beam is diffracted light, and the optical axis is inclined relative to the main beam, whereby the projection position of the limited hole located near the objective lens in the additional beam is shifted from the projection position of the objective lens in the main beam. The generation regions are displaced because an additional beam, which is diffracted light, is deflected in a direction different from the direction of the main beam. Therefore, the amount of displacement of the generation region determined by the product of the angle and distance becomes larger than the larger distance to the limited hole located near the objective lens from the diffraction element, i.e. closer to where the diffraction element is located to the light source. Since the diameter of the light beam or the display of a limited hole is small, the closer the diffraction element is to the light source, the greater the proportionality of the displacement relative to the diameter of the beam. Focusing on the region 403 of generating the additional beam 243, the additional beam 243 in the region between the first region 3101 of the diffraction grating having a phase of 0 degrees and the second region 3102 of the diffraction grating having a phase of 180 degrees is generated mainly by the third region 3103 of the diffraction grating, having a phase of 90 degrees. Thus, the additional beam 243 has a diffraction grating phase of 0 degrees, substantially 90 degrees and 180 degrees to the left, and the phase changes in a stepwise manner. Thus, locally there is a state close to the example of the prior art shown in figa, 23B.

Focusing on the region 402 for generating the additional beam 242, the additional beam 242 in the region between the first region 3101 of the diffraction grating having a phase of 0 degrees and the second region 3102 of the diffraction grating having a phase of 180 degrees is generated mainly by the fourth region 3104 of the diffraction grating, having a phase of -90 degrees. In addition, the phase of the second diffraction grating region 3102 is -180 degrees, taking into account a 360 degree periodicity. Thus, the additional beam 242 has a phase of the diffraction element of 0 degrees, essentially −90 degrees and −180 degrees to the left, and the phase changes in a stepwise manner. Thus, locally there is a state close to the example of the prior art shown in figa, 23B.

Since the phases of the diffraction gratings of the areas for generating additional rays have a stepped form, the additional beam is asymmetric (Fig. 4B), and there is a shift in the track tracking error signal through the antiphase method in the main beam and the additional beam, and the magnitude of the shift fluctuates depending on the step tracks of the optical disc and cannot be adjusted using a constant correction value.

To avoid such a problem, the central region 3119 located between the first diffraction grating region 3111 and the second diffraction grating region 3112 is divided into a plurality of regions of three or more by two or more virtual boundary lines 3118 to obtain diffraction gratings 3113, 3114 having many kinds of phases in the present embodiment (FIGS. 5A and 6A). On figa and subsequent line of the convex part of the diffraction grating is omitted to simplify for the grating in the same direction as the step. If only the phase of the diffraction grating is shown, it is assumed that the step and direction of the grating in the same region are constant.

The diffraction grating 3110 (Fig. 5A) divides the center region 3119 between the first region 3111 of the diffraction grating having a phase of 0 degrees (reference) and the second region 3112 of the diffraction grating having a phase of 180 degrees into five regions by four dividing lines 3118 extending into direction T, where the three regions represent the third region 3113 of the diffraction grating having a 90 degree phase, and the remaining two regions represent the fourth region 3113B of the diffraction grating having a phase of -90 degrees.

According to such a configuration, the additional beam generation region 4310 and the additional beam generation region 4210 3310 substantially equally include a diffraction grating region 3A having a 90 degree phase and a diffraction grating region 3B having a −90 degree phase, and thus , additional beam 3310 and additional beam 3410 are symmetrical (FIG. 5B). Therefore, the effect of fulfilling both conditions, i.e. how to obtain a track tracking error signal by means of an optimal DPP method for an optical disc having different track steps using a single diffraction element, and to eliminate the decrease in the amplitude of the track tracking error signal in a state in which the lens of the lens moves as a result of following the track. The number of divided areas using the dividing line 3118, passing in the direction T, is not limited to five, but simply should be three or more, and thus may be more than five.

Third Embodiment

The diffraction grating 3120 according to the third embodiment of the present invention is used instead of the diffraction element 31 in FIG. As shown in FIG. 6A, the diffraction element 3120 divides the center region 3129 between the first diffraction grating region 3121 having a 0 degree phase and the second diffraction grating region 3122 having a 180 degree phase into seven regions through six dividing lines 3128 extending in the direction T, to obtain third regions 3123 of the diffraction grating having a phase of 60 degrees, fourth regions 3124 of the diffraction grating having a phase of 120 degrees, fifth regions 3125 of the diffraction grating having a phase of -120 degrees, and a sixth region ST 3126 diffraction grating having a phase of -60 degrees. According to the present configuration, the additional beam generation region 4320 and the additional beam generation region 4220 3320 substantially equally include diffraction grating regions whose phases are opposite to each other, and thus the additional beam 3320 and the additional beam 3420 are symmetrical (figv). Therefore, the effect of fulfilling both conditions, i.e. how to obtain a track tracking error signal by the optimal DPP method with respect to an optical disc having a different track pitch using a single diffraction element, and to eliminate the reduction in the track tracking error signal in a state where the lens of the lens moves while tracking the track. The number of areas to be divided by dividing line 3128, passing in the direction T, is not limited to seven and may be more. The phase of the diffraction grating formed in the central region 1329 between the region 1 of the diffraction grating and the region 2 of the diffraction grating forms a grating having phases of opposite signs, or the average value of the phase of the diffraction grating formed in the central region 3129 simply needs to be substantially 0 degrees, and is not necessarily limited to ± 60 degrees, ± 90 degrees, ± 120 degrees, etc.

Fourth Embodiment

In another embodiment, an example of a diffraction element located in a region forming a diffraction grating with a grating vector different from the diffraction grating vector of the diffraction grating region 1 and the diffraction grating region 2 in the central part located between the first region of the diffraction grating and the second region of the diffraction grating is described. An example of using a diffractive element instead of a diffractive element 31 in FIG. 1 is described below with reference to FIG. The diffraction element 3130 (FIG. 7A) divides the center region 3139 between the first region 3131 of the diffraction grating having a phase of 0 degrees and the second region 3132 of the diffraction grating having a phase of 180 degrees into five regions by four dividing lines 3138 extending in the T direction, where three regions represent the third region 3133 of the diffraction grating, having a center line of the convex part diagonally from right to down in FIG. 7A, and the other two regions represent the fourth region 3134 of the diffraction grating, th center line of the convex portion diagonally left-downward in Figure 7A. Those. the directions of the grating vector of the first diffraction grating region 3131, the second diffraction grating region 3132, and the central region 3139 change. In the present configuration, diffracted light of the central region 3139 located between the first diffraction grating region 3131 and the second diffraction grating region 3132 is emitted at positions different from the positions additional rays 3330, 3430, as in diffracted light 3530 and diffracted light 3630 in FIG. 7B on the recording surface of the optical disc. Similarly, when the optical disk reflects and irradiates the light detector, the light is emitted at positions different from the positions of the additional beams 3330, 3430. Thus, the beam passing through the central region 3139 does not contribute to the formation of the out-of-phase signal, and the signal amplitude decreases in advance when the lens of the lens does not move as a result of tracking the track. Therefore, a decrease in the amplitude of the track tracking error signal in the state when the lens of the lens is moving proportionally is excluded. The additional beam 3330 and the additional beam 3430 are symmetrical, as shown in FIG. 7B, and thus, the effect of fulfilling both conditions, i.e. how to obtain a track tracking error signal by means of an optimal DPP method with respect to an optical disk having a different track pitch using a single diffraction element, and to eliminate the decrease in the amplitude of the track tracking error signal in the state when the lens of the lens moves as a result of following the track. The number of areas to be divided by a dividing line passing in the T direction is not limited to five, and may be more.

Fifth Embodiment

The diffraction element 3140 (FIG. 8A), used instead of the diffraction element 31 in FIG. 1, forms a third diffraction grating region 3143 having a step different from that of the first diffraction grating region 3141 and the second diffraction grating region 3142, in the center region 3149 between the first a diffraction grating region 3141 having a phase of 0 degrees and a second diffraction grating region 3142 having a phase of 180 degrees. Even if the direction of the center line of the convex part of the diffraction grating located in the third diffraction grating region 3143 is the same as the direction of the first diffraction grating region 3141 and the second diffraction grating region 3142, the magnitude of the grating vector is different since the step is different. The direction of the center line of the convex part may vary. In the present configuration, diffracted light transmitted through a central region 3149 located between the first diffraction grating region 3141 and the second diffraction grating region 3142 is emitted at positions different from the positions of the additional beams 3340, 3440, as in diffracted light 3540 and diffracted light 3640 in FIG. .8V on the recording surface of the optical disc. Similarly, when the optical disk reflects and irradiates the light detector, the light is emitted at positions different from the positions of the additional beams 3340, 3440. Thus, the beam passing through the central region 3149 does not contribute to the formation of an out-of-phase signal, and the signal amplitude decreases in advance, when the lens of the lens does not move as a result of following the track. Therefore, a decrease in the amplitude of the track tracking error signal in the state when the lens of the lens is moving proportionally is excluded. The additional beam 3340 and the additional beam 3440 are symmetrical, as shown in FIG. 8B, and thus, the effect of fulfilling both conditions, i.e. how to obtain a track tracking error signal by the optimal DPP method with respect to an optical disc having a different track pitch using a single diffraction element, and to eliminate the decrease in the amplitude of the track tracking error signal in a state when the lens of the lens moves as a result of following the track. In addition, the central region 3149 located between the first diffraction grating region 3141 and the second diffraction grating region 3142 can be divided into regions by a dividing line (not shown) extending in the T direction, forming diffraction gratings with different pitch.

Sixth Embodiment

A method for determining a track tracking error signal by means of a DPP method is sometimes used with a method for determining a focus error signal by a differential astigmatism method. Patent Document 5 of PCT Publication WO 2004/097815 discloses a method for differential astigmatism and for improving a defocus characteristic of a focus error signal by means of a differential astigmatism method. The diffraction grating divides the diffraction grating for generating an additional beam into four regions, wherein the phase of the neighboring regions differs by 180 degrees, and the opposite phases are set to the same phase. In such a diffraction grating, the additional beam is divided into four, and when the additional beam is located in the same groove as the main beam on the recording surface of the optical disk, the antiphase signal of the additional beam has a polarity opposite to that of the main beam, thus realizing DPP- way. In addition, crosstalk of the out-of-phase signal component for the focus error signal is suppressed by detecting and adding a focus error signal using the astigmatism method from both the main beam and the secondary beam.

In the additional beam generation diffraction grating described in Patent Documents 3 and 4, only one region is intended for a part of the grating having a phase of 0 degrees and a part of the grating having a phase of 180 degrees.

As shown in FIG. 9A, in the present embodiment, the left side diffraction region 3151 of the diffraction element 3150 used instead of the diffraction element 31 in FIG. 1 is divided into regions by a border 3158L extending in the direction T to A of the diffraction grating region 3151A and To the grating region 3151B, where the grating phase of the grating region A is 0 degrees, and the phase of the grating region B is 180 degrees. In addition, the diffraction region 3152 of the right side of the diffraction grating 3150 is divided into regions by a boundary 3158R extending in the T direction into a diffraction grating region 3152A A and a diffraction grating region 3152B, the diffraction grating phase A of the diffraction grating region 3152A being 180 degrees, and the phase In the region 3152B of the diffraction grating is equal to 0 degrees. The left-side diffraction region 3151A diffraction grating region 3151 and the right-side diffraction region 3152A diffraction region 3152A have diffraction grating phases differing by 180 degrees relative to each other, and the left-side diffraction region 3151B diffraction grating region 3151B and the B diffraction grating region 3152B regions 3152 of the right side have diffraction grating phases differing by 180 degrees relative to each other, and thus the polarity of the antiphase signals of the main beam and additional beam are also opposite. Similarly, for Patent Document 5, the defocus characteristic of the focus error signal is also improved by the differential astigmatism method, and crosstalk of the out-of-phase signal component for the focus error signal is suppressed. An aspect of the present example is that the central region 3159 is located between the left side diffraction region 3151 and the right side diffraction region 3152, which is different from the patent documents described above. The effect of eliminating the decrease in the amplitude of the track tracking error signal in a state in which the lens of the lens moves as a result of following the track by arranging the central region 3159 is achieved. A specific configuration of the central region 3159 may be any one of the above embodiments.

Light receiver

The following describes a light detector used in combination with an additional beam generating diffraction element according to an embodiment of the present invention. FIG. 10 shows an example of a separation configuration of a light detection region of the light detector 10 suitable for determining a focus error signal by a differential astigmatism method and determining a track tracking error signal by a DPP method. In Fig. 10, the Y, T, Z axes are common with those shown in Fig. 1. The structure of the light detector 10 is shown when viewed from the side opposite to the surface onto which the light beam enters. The light receiving region 20 for receiving the main beam is also divided into four, and the focus error signal (FE) is determined using the astigmatism provided by passing through the beam splitter 3000. Expressing the name of each divided region as the intensity of the output signal, the FE can be calculated according to equation 1.

(1) FE = (20A + 20C) - (20B + 20D)

(one)

A track tracking error signal may also be obtained by the so-called phase difference method or the antiphase method. The track tracking signal by the phase difference method is obtained by comparing the phase of the change in the temporal intensity of the signal 20A + 20C and 20B + 20D. The track tracking error signal by the antiphase method of the main beam (TERP) is calculated according to equation 2.

(2) TERR = (20A + 20V) - (20C + 20D)

(2)

The light receiving regions 21, 22 receive an additional beam. The track tracking error signal by the differential antiphase method can be determined by calculating the antiphase signal of the light receiving region 20, the focus error signal by the astigmatism method can be determined from the light receiving regions 21, 22 and calculated by the focus error signal received from the light receiving region 20, to remove crosstalk from the track signal.

The track tracking error signal TEDPP by the differential antiphase method is calculated according to equation 3.

(3), TEDPP = (20A + 20B) - (20C + 20D) -K1 [(21A + 21B) - (21C + 21D)] - k1 [(22A + 22B) - (22C + 22D)]

(3)

where K1 is a constant. By properly determining the constant K1, fluctuation of the track tracking error signal is prevented by the antiphase method when the lens of the lens moves in the T direction as a result of following the track. The reason for the fluctuation of the track tracking error signal when the lens of the lens moves in the T direction is the movement of the light beam along the light detector 10 when the field picture moves in the far zone. Since the main beam and the additional beam are equally affected by the movement of the field picture in the far zone, K1 is set so as to eliminate the ratio of the light value of the main beam and the light value of the additional beam. Specifically, an optical disk without grooves is prepared, focus control is performed, and the lens of the lens is forcedly moved in the T direction to determine the value of K1, so that the change in TEDPP becomes sufficiently small. The value of K1 should be changed for each step of the tracks of the optical disk in patent document 3, but it is preferable that the value of K1 is determined more correctly in accordance with the distribution of the light value of the picture in the far zone of the light beam and the diffraction efficiency of the diffraction element for diffraction of the additional beam. Therefore, K1 is preferably constant, unique to the device, for example, by installing a half-variable resistor on the optical head device or the substrate of the optical information device circuit, and shipping after adjusting the gain of the amplifier.

The focus error signal FED by the differential astigmatism method is calculated according to equation 4.

(4), FED = (20A + 20C) - (20B + 20D) -K2 [(21A + 21C) - (21B + 21D)] - K2 [(22A + 22C) - (22B + 22D)]

(four),

where K2 is a constant. Crosstalk from the track signal to the focus error signal is eliminated by determining the constant K2. In particular, since the antiphase DVD-RAM signal is large, K2 is preferably set so that crosstalk from the track signal to the focus error signal becomes minimal with respect to the DVD-RAM disc. Focus control is performed on a DVD-RAM disc, and the lens of the lens is forced to move in the direction T to determine the value of K2, so that the change in the FED signal of the focus error becomes quite small. Similarly, K1, K2 is preferably constant, unique to the device, for example, by installing a half-variable resistor on the optical head device or the substrate of the optical information device circuit, and shipping after adjusting the gain of the amplifier.

In DVD-R, DVD-RW, DVD-ROM, since the antiphase signal is relatively small, the switching circuit according to the type of optical disc is located in the optical information device, so that the focus error signal uses FE of equation 1 and uses FED of equation 4 only for DVD-RAM to switch signals.

Other examples of light detector configurations

The following describes a light detector used in combination with an additional beam generating diffraction element according to the aforementioned embodiment of the present invention, capable of reproducing or recording not only a DVD, but also a CD. It is assumed that the light source 12 in FIG. 1 is a light source with two wavelengths for emitting not only red light, but also infrared light. As described in Japanese Patent Publication No. 7-98431 (Patent Document 6), with the region divided to the inner periphery and the outer periphery, the objective lens 25 converges the light passing through both the inner and the outer periphery of the DVD, and performs the convergence light passing only through the inner periphery of the CD. Playback and recording of both CD and DVD is realized through the use of a light detector 1000 (FIG. 11). 11, the light detection regions 20, 21, 22 act in the same way as the light detector 10 shown in FIG. 10. The light detector 1000 is further arranged in the light detection regions 23, 24, 25 for receiving infrared light. The light detection region 23 is divided into four, and the light detection regions 24, 25 are divided into two. Similar to how the light receiving region 20 receives red light, infrared light is received by the light detecting region 23, and a focus error signal is detected by the astigmatism method and a track tracking error signal by the antiphase method or the phase difference method. When recording on a CD-R or CD-RW, a track tracking error signal by the DPP method is determined using the output of the light detection regions 24, 25. The TEDPPCD signal of the track tracking error by the DPP method is determined by calculating equation 5.

(5), TEDPPCD = (23A + 23B) - (23C + 23D) -K3 (24A-24B) -K3 (25A-22B)

(5),

where K3 is a constant. The fluctuation of the track tracking error signal is prevented by the antiphase method when the lens of the lens moves in the T direction as a result of following the track by determining the constant K3. The cause of the fluctuation of the track tracking error signal when the lens of the lens moves in the T direction is the movement of the light beam through the light detector 1000, since the picture moves in the far zone. Since the main beam and the additional beam are equally affected by the movement of the picture in the far zone, K3 is set so as to cancel the ratio of the light value of the main beam and the light value of the additional beam. Specifically, an optical disk without grooves is prepared, focus control is performed, and the lens of the lens is forcedly moved in the T direction to determine the K3 value, so that the change in TEDPPCD becomes small enough. The value of K3 is preferably determined in accordance with the distribution of the light value of the picture in the far zone of the light beam and the diffraction efficiency of the diffraction element for diffraction of the additional beam. Therefore, K3 is preferably constant, unique to the device, for example, by installing a half-variable resistor on the optical head device or the substrate of the optical information device circuit, and shipping after adjusting the gain of the amplifier. Since the diffraction element described in the previous embodiments is used as the diffraction element for generating an additional beam in the present application, a satisfactory DPP signal can even be obtained on a CD in which the track pitch is significantly different from the track pitch of the DVD. However, since the effective diameter of the infrared light is approximately 3/4 of the effective diameter of the red light, the width of the region between the diffraction grating region 1 and the diffraction grating region 2 of the additional beam generating element is preferably less than or equal to 30% of the effective diameter (lens projection lens) red light. As previously described, the width is preferably 10% to 40% in the optical head for DVDs, the width of the region between the diffraction grating region 1 and the diffraction grating region 2 of the additional beam generating element is preferably 10% to 30% from the effective diameter (projection of the objective lens) of red light to also meet both requirements when playing a CD.

Optical head device

The following describes an optical head device capable of reproducing or recording not only DVDs, but also CDs and BDs. 12, the direction T is the direction perpendicular to the optical axis of the lens 9 of the lens and substantially perpendicular to the direction of the groove of the track of the optical disk (not shown), and the direction Z is the direction of the optical axis of the lens 34, 41 of the lens, i.e. . focus direction (direction perpendicular to the plane of the drawing). The T axis represents the direction of movement of the optical head device when recording and reproducing the inner periphery and the outer periphery of the optical disc. The Y axis represents a direction perpendicular to the Z axis and the T axis, and represents a direction substantially parallel to the direction of the groove of the track of the optical disc in the position of the lens 9 of the lens. A mirror reversal configuration can be adopted in which the T axis and Y axis change direction or rotate 90 °, 180 °, 270 °.

A light beam 2 of linearly polarized light emitted from a first short wavelength light source (for example, a blue light source) is reflected by a separation film by polarization on a surface of a parallel flat plate 3 and passed through a hologram element 4. Reflective hologram (not shown) formed in a region that does not shield the incident light for the objective lens 9 remote from the optical axis of the hologram element 4, and the signal of the control device for stabilizing the light intensity is obtained without increasing the number of components by receiving the reflected diffracted light on the light detector 10 and controlling the light intensity of the light beam 2.

The light beam 1, passed through the hologram element 4, is converted into a luminous flux, the divergence of which is significantly increased by the wraparound lens 5. The wraparound lens 5 has the effect of a concave lens and converts the angle of the light source 1 from the part of the hole of the lens 9 of the lens, i.e. the numerical aperture (NA) on the side of the light source is converted from small NA near the light source to large NA on the side of the collimator lens 7. The light beam 2 is converted to close to parallel by the collimator lens 7, and the optical axis deviates in the direction of the Z axis perpendicular to the optical disk by means of a raising mirror 8. The lens 9 of the lens passes a light beam 2 through a transparent base material of about 0.1 mm, thinner than 0.6 mm, and converts a light beam 2 on a recording surface of a high density optical disc and such as BD. The collimator lens 7 makes the rays of light close to parallel, i.e. the lens weakens the degree of divergence, or can be configured using the combined two lenses. When moving the collimator lens 7 in the direction of the optical axis to correct spherical aberration, if the collimator lens 7 is configured with two lenses, only one of the two lenses needs to be moved. The quarter-wave plate 18 changes linearly polarized light into circularly polarized light. A ray of light reflected on the recording surface of the optical disk follows the path of the original light in the opposite direction and is converted into linearly polarized light in the direction perpendicular to the direction when it leaves the light source 1, using a quarter-wave plate 18, and passed through a branching element, such as a parallel flat plate 3 having a polarization separation film formed on the surface together with one part of a light beam diffracted by a hologram about element 4, forks in a direction different from the direction to the light source 1, and is photoelectricly converted by the light receiver 1010, so that electrical signals are obtained for receiving an information signal and a servo signal (focus error signal for focus control, i.e., a tracking signal and a focus servo signal to control track tracking).

A light beam 15 emitted by a second light source 12 (for example, an infrared light source) is passed (with partial diffraction) through a diffraction element 13 to diffract some part of the light to form an additional spot on the optical disk, and is passed through a wedge 6 having a wedge-shaped cross section shape, and has parallelism provided by a collimator lens 7 (for example, in essentially parallel light), and the optical axis is deflected by means of a raising mirror 9 in a direction perpendicular to a disc, such as a compact disc (CD), having a lower recording density than BD. The objective lens 9 passes a light beam 14 through a transparent base material of about 1.2 mm and converges the light beam 14 on the recording surface of the optical disc. The light beam reflected by the recording surface of the optical disk follows the path of the original light in the opposite direction, branches out in a direction different from the direction of the light source 12, using a branching element, such as a polarization separation film, located on the surface on the side of the collimator lens 7 of the wedge 6, and is photoelectrically converted by the light receiver 1010 similarly to the light beam 1, so that electrical signals are obtained for receiving an information signal and a servo signal ( Igna focus error for the focus control, the tracking signal for tracking control). If the amplifier circuit is integrated in the light detector 10, a satisfactory information signal is obtained having a high signal to noise ratio (S / N), and miniaturization and thinning of the optical head device is achieved, and stability is achieved.

In addition, in order to play or record a third optical disc (e.g., DVD) having an intermediate recording density of two types of optical discs, a third red light source is located near the light source 12, and a beam splitter located near the light source 12 may be provided, to combine the light paths with an infrared light source, but if the light source 12 is a light source with two wavelengths to emit a light beam with two wavelengths of red light and infrared Of the light, a beam splitter is optional, and the number of components is reduced.

A red light beam 15 emitted from the light source 12 reaches the objective lens 9, similarly to red light, and passes through a transparent base material of about 0.6 mm and is reduced on the recording surface of an optical disc such as a DVD using the objective lens 9. Like red light, the light beam reflected by the recording surface of the optical disc follows the path of the original light in the opposite direction, and the electrical signals for receiving an information signal and a servo signal (focus error signal for focus control, track tracking signal for controlling track tracking) are obtained by light receiver 10.

Typically, in order to branch the optical path, a cubic-type beam splitter can be used in which two triangular transparent elements are connected, but the number of components can be reduced if a parallel flat plate or wedge is used as it in the present invention and material costs are reduced. If a beam splitter from a single element is located in the path of non-parallel light from the light source to the objective lens to transmit light, a wedge 6 (Fig. 12) is used to prevent astigmatism, and the angle of incidence of the optical axis is preferably less than 45 degrees. Aberration can still occur due to manufacturing error, even if the above is taken into account. Thus, in the example shown in FIG. 1, the light beam 2 to be reduced on the optical disk having the highest density is reflected without passing through either of the two beam splitters in the path of the non-parallel light from the light source 1 to the collimator lens 7. Thus Thus, satisfactory reproduction of the signal and recording of the signal on an optical disc having the highest density, such as BD, can be realized.

The lens 9 of the lens is fixed in a predetermined position of the drive mechanism (not shown) for microscopic movement of the lens of the lens. The lens lens drive device (lens lens drive mechanism) provides microscopic movement of the lens 9 of the lens both in the focusing direction Z, orthogonal to the recording surface of the optical disc, and in the tracking direction Y of the track of the optical disc.

When using a lens 9 of a lens with a NA of 0.85, or with a larger numerical aperture for reproducing or recording BD and the like, spherical aberration is largely created with respect to the thickness of the transparent base material filled from the surface onto which the light enters to the optical disk, to the information recording surface when recording or playing back on the optical disk, since the numerical aperture is large. In the present example, the degree of convergence of light scattering from the collimator lens 7 to the lens 9 of the lens is changed by moving the collimator lens 7 in the direction of the optical axis of the collimator lens 7. When the degree of convergence of the diffusion of light entering the lens of the lens changes, spherical aberration changes, and thus spherical aberration arising due to the difference in thickness of the base material is corrected using it. The optical head device shown in FIG. 12 is configured with a drive device 11 for moving the collimator lens 7 in the direction of the optical axis of the collimator lens 7. Specifically, a stepper motor, brushless motor, or the like. used as a drive device 11. A holder 17 for holding a collimator lens 7, a guide shaft 16 for guiding the movement of the holder 17, and a gear (not shown) for transmitting the driving force of the drive motor 11 to the holder 17 are located in the optical head device. The holder 17 for holding the collimator lens 7 can be molded in one piece with the collimator lens 7, whereby when molding in one piece reduces the number of components of the device of the optical head.

It is prevented that the collimator lens 7 inadvertently moves with respect to inertia by accelerating and decelerating the speed when the entire optical head device moves in the direction of the inner and outer periphery of the optical disc by the fact that the optical axis of the collimator lens 7 is not parallel to the Y axis, as in the present application.

The objective lens 25 converts infrared light 15 in the innermost peripheral portion near the optical axis through a transparent base material of about 1.2 mm low density optical disc 28, such as CD. The lens lens 25 also converts the red light 14 to the middle peripheral part of the range, one size wider than the innermost peripheral part, through the transparent base material of about 0.6 mm of the optical disc 27, such as a DVD. The lens lens 25 converges the blue light 2 within the effective diameter through a transparent base material of about 0.1 mm or thinner than a high density optical disc 26, such as BD.

Therefore, in order to reduce the corresponding light transmitted through the transparent base material of various thicknesses, a diffractive element is effectively used, as described in Japanese Patent Laid-Open No. 7-98431 (Patent Document 6). The diffractive element has a structure of the innermost peripheral part, the middle peripheral part and the outermost peripheral part, which are discontinuous, so that the innermost peripheral part converges through the base material of any thickness, and the outermost peripheral part performs information only when it is passed through the material substrates 0.1 mm thick or thinner. As one example, the design becomes easier by using a light source with different wavelengths, as described above. The CD uses infrared light, the DVD uses red light, and the BD uses blue light, and the correction of spherical aberration due to the thickness of the base material and switching the restricted hole according to the type of disc is achieved by the fact that the diffraction angle of the initially diffracted light of the diffraction element differs depending by wavelength.

FIG. 13 shows an example of dividing a light detection area of a light detector 1010 suitable for detecting a focus error signal by an astigmatism method. On Fig shows a picture that is visible from the side opposite to the surface onto which the light beam enters in the light detector 1010. The light receiving areas 20, 21, 22, 23, 24, 25 are denoted by the same positions for areas acting in the same way as the light detector 1000 of FIG. 11, with respect to red light and infrared light. The light receiving region 20 receives blue light and red light. The light receiving region 20 is divided into four and determines a focus error signal using the astigmatism generated by the parallel flat plate 3. The track tracking signal can also be obtained by the so-called phase difference method and the antiphase method. The light receiving regions 21, 22 receive an additional beam diffracted when the red light passes through the diffraction element 13. The track tracking error signal by the differential antiphase method is determined by calculating the light receiving region 20 by the antiphase signal, the focus error signal by the astigmatism method is determined from light receiving regions 21, 22 and is calculated using the focus error signal received from the light receiving region 20 to The method of differential astigmatism removes crosstalk from a track signal. By positioning the diffraction element between the light source 1 and the parallel flat plate 3, the signal of the additional beam can be detected from the light receiving regions 21, 22 in blue light, like red light.

The light receiving regions 23, 24, 25 receive infrared light. The center-to-center distance of the light-receiving regions 20 and 23 is set to the value obtained by multiplying the magnification factor realized by the wrapping lens 5 by the distance between the light emission points of red light and infrared light in the light source 12. Assuming that the center-to-center distance of the light-receiving regions 20 and 21 is L1, and the center-to-center distance of the light-receiving regions 23, 24 is L2, the ratio of L1 and L2 is set to be equal to the ratio “red light wavelength: infrared light wavelength”. The light receiving region 23 is divided into four, and the focus error signal is determined using astigmatism created by the parallel flat plate 3. A track tracking signal can also be obtained by the so-called phase difference method and the antiphase method. The light receiving regions 24, 25 receive an additional beam diffracted when infrared light passes through the diffraction element 13. The track tracking signal by the differential antiphase method is determined by calculating the light receiving region 23 using the antiphase signal. In the present application, the diffraction element described in previous embodiments, such as diffraction element 31, 3100, is used as diffraction element 13. Thus, an effect of kt like obtaining the tracking error signal by the DPP-method suitable for an optical disc with different track pitch using a single diffraction element, and elimination of magnitude reduction in the tracking error signal amplitude state when the objective lens is moved as a result of following the track.

The number of components of a semiconductor component is reduced by arranging a plurality of light receiving regions on one light detector or one semiconductor crystal and photoelectric conversion of different wavelengths.

Optical information device

An example configuration of an optical information device using the optical head device of the present invention is also shown in FIG. On Fig optical disks 26, 27, 28 are located on the supporting disk 182 and rotate by the motor 164. The optical head device shown in Fig, is used for the device 155 of the optical head. The optical head device 155 is roughly moved by the optical head drive device 151 to a track where the required information is present on the optical disc.

The optical head device 155 delivers a focus error signal (focus error) or a track tracking error signal to the electric circuit 153 in accordance with the relative position of the optical disk 26. The electric circuit 153 supplies a signal for microscopic movement of the lens of the lens to the optical head device 155 under the action of the focus error signal or a track tracking error signal. Under the influence of the signal, the optical head device 155 performs servo focusing and focus tracking control on the optical disk and also reads, writes (writes) or erases information regarding the optical head device 155.

The optical information device 157 of the present embodiment is assembled with the optical head device shown in FIG. 12, and thus has the advantage of stably recording or reproducing a plurality of optical discs having different recording densities using one optical head device.

A computer

The following describes a computer installed with the optical information device 167 shown in Fig.14. The computer, optical disc player or optical disc recorder with the optical information device of FIG. 14 or using the recording and reproducing method described above stably records or reproduces various types of optical discs, and thus can be used for a wide range of applications.

FIG. 15 shows a computer 300 including an optical information device 167 shown in FIG. 14, an input device 365, such as a keyboard, mouse, and touch pad, for inputting information, an arithmetic device 364, such as a central processing unit (CPU) ) to perform a calculation based on information input from the input device and information read from the optical information device 167 and an output device 361, such as a cathode ray tube, a liquid crystal display device, and a printer for displaying information, such as the result of computing an arithmetic device.

Optical disc player

The configuration of the housing of the optical disc player assembled with the optical information device shown in Fig. 14 is shown in Fig. 16. FIG. 16 shows an optical disc player 321 including an optical information device 167 shown in FIG. 14 and an information-image conversion device (eg, decoder 366) for converting an information signal received from the optical information device into an image. This configuration is also used as a car navigation system by adding a position sensor, such as a global navigation and positioning system (GPS), and a central processing unit (CPU). It is also possible option obtained by adding a display device 320, such as a liquid crystal monitor.

Optical disc recorder

The configuration of the housing of the optical disc recording apparatus assembled with the optical information device shown in FIG. 14 is shown in FIG. The optical disc recorder shown in FIG. 17 includes an optical information device 167 shown in FIG. 14 and an image-information conversion device (eg, encoder 368) for converting image information into information to be recorded on an optical disk optical information device. It is desirable that the part that has already been recorded can also be reproduced by turning on the information-image conversion device (decoder 366) to convert the information signal received from the optical information device into an image. An output device 361, such as a cathode ray tube, a liquid crystal display device, a printer, and the like, may also be installed. to display information.

Vehicle

A vehicle with an optical information device 167 shown in FIG. 14 is described below. The configuration of the vehicle body layout assembled with the optical information device shown in Fig. 14 is shown in Fig. 18. In Fig. 18, the optical information device 167 is an optical information device 167 in Fig. 14. The vehicle body 131 is provided with an optical information device 167. A power generation unit 134 and a fuel storage unit 135 for storing fuel to be supplied to the power generation unit 134 and / or a power source 136 are also mounted in the vehicle body 131. Therefore, it is possible to stably obtain information from various types of optical discs while in a moving body by installing the optical information device 167 on the vehicle body. Alternatively, information may be recorded. The vehicle body 131 further includes wheels 133 for traveling if it is a train or a car. In the case of a car, there is a handle 130 for changing the direction of movement.

In addition, a large number of optical discs can easily be used by installing the device 138 automatic disk changer or block 139 placement of optical discs on the body 131 of the vehicle. An arithmetic device 164 for processing information received from the optical disk for acquiring an image, a semiconductor memory 137 for temporarily storing information, and a display device 142 may be installed to reproduce image information from the optical disk. Sound and music can be reproduced from the optical disc by installing an amplifier 140 and a speaker 141. When installing a position sensor such as GPS 132, together with map information played from the optical disc, the current position and direction of movement can be recognized as the image displayed on a display device 142 or sound output from the loudspeaker 141. In addition, information from outside can be received and further used with information of the optical disc through the block 143 without wired connection.

The output device 361 and the liquid crystal display monitor 320 are shown in FIGS. 15, 16 and 17, but the output terminals can be installed where the output device 361 and the liquid crystal monitor 320 can obviously be in separately sold product types without being housed therein. An input device is not shown in FIGS. 16 and 17, but a product may also be provided with an input device such as a keyboard, touch panel, mouse, remote control device, and the like. An input device may be sold separately and may be in a form that includes only input terminals.

Industrial applicability

An optical head device according to the present invention can record and reproduce numerous types of optical discs having different thicknesses of the base material, response wavelength, recording density and the like, and a compatible optical information device using the optical head device can manipulate an optical disc of various standards such as CD, DVD and BD. Therefore, the application can be expanded to various systems for storing information, such as a computer, an optical disc player, an optical disc recorder, a car navigation system, an editing system, a data server, an audiovisual component, a vehicle, and the like.

Corresponding advantages are achieved by combining appropriately arbitrary embodiments from the numerous embodiments described above.

Although the present invention has been fully described in connection with its preferred embodiments with reference to the accompanying drawings, it should be noted that various changes and modifications are apparent to those skilled in the art. Such changes and modifications should be understood as being included in the scope of the present invention defined in the attached claims, if they do not depart from it.

Claims (36)

1. An optical head device, comprising: a light source; a diffraction element for branching the light emanating from the light source into at least three light fluxes, including a main beam that is transmitted without diffraction, and two additional rays that are diffracted; an objective lens for converging three light fluxes on an optical disc recording surface; and a light receiver for receiving light brought together on the recording surface of the optical disk using an objective lens and reflected by the optical disk, and photoelectric conversion of light into an electrical signal,
the diffraction element is divided into a first diffraction grating region, a second diffraction grating region formed with a second diffraction grating having a phase substantially 180 ° different from a phase of the first diffraction grating located in the first diffraction grating region, and a central region located between the first region of the diffraction grating and the second region of the diffraction grating;
the central region is further divided into a plurality of divided regions by means of a virtual dividing line; and
the central region has grating phases or vectors different from the grating phases and vectors of the first diffraction grating region and the second diffraction grating region, and the divided regions separated by the dividing line are formed with diffraction gratings having a different phase or grating vector. 2. The optical head device according to claim 1, wherein the dividing line for dividing the central region extends in a direction orthogonal to the direction of passage of the groove of the track of the optical disk. 3. The optical head device according to claim 1, wherein the central region is divided into three or more divided regions. 4. The optical head device according to claim 3, in which diffraction gratings having different phases are formed in two divided regions from three or more divided regions of the central region; and
a diffraction grating with the same grating vector and the same phase as the diffraction grating formed in one of two divided regions is formed in at least one divided region from the remaining divided region. 5. The optical head device according to claim 1, wherein when the phase of the first diffraction grating formed in the first region of the diffraction grating is 0 ° as a reference, the phase of the third diffraction grating formed in the divided region obtained by dividing the center region, and the phase of the fourth diffraction grating, formed in another divided region, have opposite polarities, but the same absolute value. 6. The optical head device according to claim 5, wherein when the phase of the first diffraction grating formed in the first divided region is 0 ° as a reference, the phase of the third diffraction grating is 90 °, and the phase of the fourth diffraction grating is -90 °. 7. The optical head device according to claim 1, wherein when the phase of the first diffraction grating formed in the first region of the diffraction grating is 0 ° as a reference, the phase of each diffraction grating formed in each divided region of the central region is essentially , 0 ° on average. 8. The optical head device according to claim 3, in which, when the phase of the first diffraction grating formed in the first divided region is 0 ° as a reference, the central region is divided into four or more divided regions and includes a diffraction grating having a phase -120 °, a diffraction grating having a phase of -60 °, a diffraction grating having a phase of + 60 °, and a diffraction grating having a phase of + 120 °. 9. An optical head device, comprising: a light source; a diffraction element for branching the light emanating from the light source into at least three light fluxes; an objective lens for converging three light fluxes on an optical disc recording surface; and a light receiver for receiving light brought together on the recording surface of the optical disk by the objective lens and reflected by the optical disk, and photoelectric conversion of light into an electrical signal,
the diffraction element is divided into a first diffraction grating region, a second diffraction grating region formed with a second diffraction grating having a phase substantially 180 ° different from a phase of the first diffraction grating located in the first diffraction grating region, and a central region located between the first region of the diffraction grating and the second region of the diffraction grating; and
a diffraction grating having a direction different from that of the first diffraction grating and the second diffraction grating is formed in the central region. 10. The optical head apparatus of claim 9, wherein the third diffraction grating formed in the divided region obtained by dividing the center region and the fourth diffraction grating formed in the other divided region are diffraction gratings having a direction different from that of the first diffraction grating and the second diffraction grating, and have an angle formed with the direction of passage of the grooves of the track of the optical disk, with opposite signs relative to dr yn friend. 11. An optical head device, comprising: a light source; a diffraction element for branching the light emanating from the light source into at least three light fluxes; an objective lens for converging the three light fluxes on the recording surface of the optical disc and a light receiver for receiving light brought together on the recording surface of the optical disc by the objective lens and reflected by the optical disc, and photoelectric conversion of light into an electrical signal, wherein
the diffraction element is divided into a first diffraction grating region, a second diffraction grating region formed with a second diffraction grating having a phase substantially 180 ° different from a phase of the first diffraction grating located in the first diffraction grating region, and a central region located between the first region of the diffraction grating and the second region of the diffraction grating; and
a diffraction grating having a grating pitch different from the grating spacing of the first diffraction grating and the second diffraction grating is formed in the central region. 12. The optical head device of claim 10, wherein the diffraction grating formed in the central region is a diffraction grating having a smaller grating pitch than the first diffraction grating and the second diffraction grating. 13. The device of the optical head according to any one of claims 1, 9 and 11, in which the width of the Central region is from 10% to 40% of the diameter of the projection on the diffraction element of the effective diameter of the objective lens. 14. The optical head device according to any one of claims 1, 9 and 11, wherein the light source is a light source with two wavelengths for emitting red light and infrared light. 15. The optical head device according to 14, in which the width of the Central region is less than or equal to 30% of the projection diameter on the diffraction element of the effective diameter of the lens aperture. 16. The optical head device according to any one of claims 1, 9 and 11, further comprising a blue light source. 17. A diffraction element mounted on an optical head device including a light source, an objective lens for converging light coming from the light source onto the recording surface of the optical disk, and a light receiver for receiving light brought together on the recording surface of the optical disk through the lens lens and reflected by the optical disk, and photoelectric conversion of light into an electrical signal, and the diffraction element branches the light coming from the light source into at least three light eye, comprising a main beam which is passed without diffraction, and two additional beams that are diffracted, wherein
the diffraction element is divided into a first diffraction grating region, a second diffraction grating region formed with a second diffraction grating having a phase substantially 180 ° different from a phase of the first diffraction grating located in the first diffraction grating region, and a central region located between the first region of the diffraction grating and the second region of the diffraction grating; and
the central region has grating phases or vectors different from the grating phases and vectors of the first diffraction grating region and the second diffraction grating region, and the divided regions separated by the dividing line are formed with diffraction gratings having a different phase or grating vector. 18. The diffraction element according to claim 17, wherein the dividing line for dividing the central region extends in a direction orthogonal to the direction of passage of the groove of the track of the optical disk. 19. The diffraction element of claim 17, wherein the central region is divided into three or more divided regions. 20. The diffraction element according to claim 19, in which diffraction gratings having different phases are formed in two divided regions from three or more divided regions of the central region; and
a diffraction grating with the same grating vector and with the same phase as that of a diffraction grating formed in one of two divided regions is formed in at least one divided region from the remaining divided region. 21. The diffraction element according to claim 17, wherein when the phase of the first diffraction grating formed in the first region of the diffraction grating is 0 ° as a reference, the phase of the third diffraction grating formed in the divided region obtained by dividing the center region and the phase the fourth diffraction grating, formed in another divided region, have opposite polarities, but the same absolute value. 22. The diffraction element of claim 21, wherein when the phase of the first diffraction grating formed in the first divided region is 0 ° as a reference, the phase of the third diffraction grating is 90 ° and the phase of the fourth diffraction grating is -90 °. 23. The diffraction element of claim 17, wherein when the phase of the first diffraction grating formed in the first region of the diffraction grating is 0 ° as a reference, the phase of each diffraction grating formed in each divided region of the central region is substantially 0 ° on average. 24. The diffraction element according to claim 20, wherein when the phase of the first diffraction grating formed in the first divided region is 0 ° as a reference, the central region is divided into four or more regions and includes a diffraction grating having a -120 phase °, a diffraction grating having a phase of -60 °, a diffraction grating having a phase of + 60 °, and a diffraction grating having a phase of + 120 °. 25. A diffraction element mounted on an optical head device including a light source, an objective lens for converging light coming from a light source onto an optical disc recording surface, and a light detector for receiving light brought together on an optical disc recording surface by an objective lens and reflected by the optical disk, and photoelectric conversion of light into an electrical signal, and the diffraction element branches the light coming from the light source into at least three light eye, including the main beam, which is passed without diffraction, and two additional beam which is diffracted; moreover
the diffraction element is divided into a first diffraction grating region, a second diffraction grating region formed with a second diffraction grating having a phase substantially 180 ° different from a phase of the first diffraction grating located in the first diffraction grating region, and a central region located between the first region of the diffraction grating and the second region of the diffraction grating; and
a diffraction grating having a direction different from that of the first diffraction grating and the second diffraction grating is formed in the central region. 26. The diffraction element of claim 25, wherein the third diffraction grating formed in the divided region obtained by dividing the central region and the fourth diffraction grating formed in the other divided region are diffraction gratings having a direction different from that of the first diffraction lattice and the second diffraction grating, and have an angle formed with the direction of passage of the grooves of the tracks of the optical disc, with opposite signs relative to each other . 27. A diffraction element mounted on an optical head device including a light source, an objective lens for converging light coming from a light source onto an optical disc recording surface, and a light receiver for receiving light brought together on an optical disc recording surface by an objective lens and reflected by the optical disk, and photoelectric conversion of light into an electrical signal, and the diffraction element branches the light coming from the light source into at least three light eye, including the main beam, which is passed without diffraction, and two additional beam which is diffracted; moreover
the diffraction element is divided into a first diffraction grating region, a second diffraction grating region formed with a second diffraction grating having a phase substantially 180 ° different from a phase of the first diffraction grating located in the first diffraction grating region, and a central region located between the first region of the diffraction grating and the second region of the diffraction grating; and
a diffraction grating having a grating pitch different from the grating spacing of the first diffraction grating and the second diffraction grating is formed in the central region. 28. The diffraction element according to claim 27, wherein the diffraction grating formed in the central region is a diffraction grating having a smaller grating step than the grating step of the first diffraction grating and the second diffraction grating. 29. An optical information device comprising:
an optical head device according to any one of claims 1 to 16;
an engine for rotating an optical disk; and
an electrical circuit for receiving a signal received from the optical head device and controlling the engine drive, the optical lens and the laser light source based on the signal. 30. The optical information device according to clause 29, in which the antiphase signal obtained by receiving an additional beam at the light detector and calculated using the photoelectric conversion is amplified with a gain K1 and subtracted by the antiphase signal obtained by receiving the additional beam at the light receiver and processed using photovoltaic conversion for use as a track tracking error signal; and in which
the gain coefficient K1 is fixed after adjustment at a value at which the change in the track tracking control signal becomes smaller when the lens of the lens moves in a direction perpendicular to the direction of passage of the groove of the track of the optical disc. 31. The optical information device according to clause 29, in which the focus error signal obtained by receiving an additional beam at the light detector and calculated using the photoelectric conversion is amplified with a gain K2 and added to the focus error signal obtained by receiving the additional beam on the light receiver and processed by photoelectric conversion to use as a focus error signal to control focus. 32. A computer containing:
optical information device according to clause 29;
input device or input terminal for inputting information;
an arithmetic device for performing an arithmetic operation based on information input from an input device or information reproduced from an optical information device; and
an output device or an output terminal for displaying or outputting information inputted from an input device, or information reproduced from an optical information device, or the result of an arithmetic operation performed by an arithmetic device. 33. An optical disc player comprising:
optical information device according to clause 29; and
an information-image decoder for converting an information signal received from an optical information device into an image. 34. An automobile navigation system comprising:
optical information device according to clause 29;
an information-image decoder for converting an information signal received from an optical information device into an image; and
position sensor. 35. A device for recording on optical disks, comprising:
optical information device according to clause 29 and
image-information encoder for converting image information into information to be recorded by the optical information device. 36. A vehicle containing the optical information device according to clause 29, a vehicle body assembled with an optical information device, and a power generation unit for generating power for moving the vehicle body.

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