JPH0279228A - Optical pickup device - Google Patents

Abstract

PURPOSE:To correctly detect the inclination of a signal reproducing position without providing another tilt sensor in order to detect the tilt error by providing an irradiation light separating means to separate the irradiation light from a light emitting element to a main beam and two sub-beams dislocating in a tracking direction against the main beam. CONSTITUTION:The irradiation light from a light emitting element 1 is separated to one main beam and two sub-beams with an irradiation light separating means 2, The two sub-beams are dislocated to both sides of the track direction against the main beam and the position, slightly deviated from both sides of the direction orthogonal to the tracking direction is irradiated therewith. The returning lights of sub-beams have their tracking errors detected by a tracking error detecting means, and the returning light of the main beam, has its difference in the light receiving quantity at a light receiving area detected by a pushable detecting means. A tracking error component is removed from the detected result and the tilt error is detected. Consequently, by using the optical system of an optical pickup device, the tilt error can be detected and the inclination of the signal reproducing position can be correctly detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical pickup device used in a CD [compact disk] player, an optical video disk device, etc.

[Conventional technology]

In an optical pickup device used in a CD player or the like, if a light beam is no longer incident perpendicularly to the disk surface due to, for example, a warped disk, coma aberration occurs in the light spot on the disk surface, causing interference from adjacent tracks. Crosstalk becomes more likely to occur.

Therefore, such optical pickup devices are sometimes provided with a tilt mechanism that adjusts the tilt angle according to the inclination of the disk surface so that the light beam is always irradiated perpendicularly to the disk surface.

When adjusting the tilt angle using this tilt mechanism,
Conventionally, a tilt sensor 41 as shown in FIG. 11 was provided near the objective lens of an optical pickup device, and the tilt of the disk surface was detected using this sensor.

This tilt sensor 41 includes a light emitting element 42 and a pair of light receiving elements 43 and 44.
are arranged to emit light toward the disk 45. Further, the light receiving elements 43 and 44 are arranged on both sides of the light emitting element 42 in the radial direction of the disk 45.

As a result, as shown in FIG. 11(a), the disk 4
5 has an upward curvature at its peripheral end, the light from the light emitting element 42 is reflected outward on the disk surface, so that the outer light receiving element 44 receives a larger amount of light. Also, the first
As shown in FIG. 1(b), when the circumferential edge of the disk 45 is curved downward, the light from the light emitting element 42 is reflected inward on the disk surface, so that the inner light receiving element 43
The amount of light received is greater. Therefore, these light receiving elements 43
- By inputting the output of 44 to the subtraction circuit 46 shown in FIG. 12, a tilt error signal corresponding to the inclination of the disk surface can be obtained.

[Problem to be solved by the invention]

However, if the tilt sensor 41 is provided separately from the optical pickup device as described above, the number of parts of the product will increase.

Furthermore, there is a slight deviation between the position on the disk 45 where the tilt sensor 41 detects the tilt and the position on the disk 45 where the light beam from the objective lens is actually irradiated and the recorded signal is reproduced. If the disk 45 has irregular warpage or the like, it is not possible to accurately detect the inclination of the disk surface.

For this reason, the conventional optical pickup device has a problem in that when attempting to detect a tilt error, the number of parts increases, leading to an increase in the cost of the product. In addition, in detecting a tilt error using the tilt sensor 41,
Another problem has arisen in that the inclination of the signal reproduction position on the record carrier cannot be accurately detected.

Here, a technique for detecting the tracking error signal TRE using a push-pull method, which is used by the present invention to solve this problem, will be explained based on FIG. 10.

As shown in FIG. 10(a), the laser beam that has passed through the half mirror 31 passes through the objective lens 32 to the disk surface 3.
The light is focused on 3. The return light from the disk surface 33 is reflected by the half mirror 31 via the objective lens 32, and is reflected by the light receiving areas 34a and 34b in the light receiving element 34.
irradiated on the border line.

At this time, if the laser beam focused on the disk surface 33 accurately illuminates the center of the track, each light receiving area 3
The amount of light returned to 4a and 34b becomes equal. but,
If the laser beam does not illuminate the center of the track,
The diffraction effect due to the bits or groups on the disk surface 33 becomes asymmetrical, resulting in a difference in the amount of light returned to each of the light receiving areas 34a and 34b. Therefore, each of these light receiving areas 34a
- By sending the output of 34b to the subtraction circuit 35 and taking the difference between the two, it is possible to obtain a tracking error signal THE corresponding to the tracking deviation.

However, as shown in FIG. 10(b), the disk surface 3
3 is tilted, the optical axis of the returned light will be shifted, so that the center of the luminous flux of this returned light will be accurately aligned with the light receiving area 3.
The irradiation will no longer occur on the boundary line between 4a and 34b. As a result, even when the laser beam is irradiating the center of the track,
Substantially, there is a difference in the amount of light received by each of the light receiving areas 34a and 34b, and the subtraction circuit 35 outputs the same tracking error signal TRE as in the case where there is a tracking error. Therefore, the detection of the tracking error signal TRE using this push-pull method has the disadvantage that erroneous detection occurs when a tilt error occurs.

The present invention takes advantage of the drawbacks of this push-pull method. That is, it utilizes the phenomenon that if tracking is accurate, the detection result by the push-pull method will indicate a tilt error.

[Means to solve the problem]

In order to solve the above problem, an optical pickup device according to the invention as set forth in claim 1 irradiates the record carrier with the irradiation light emitted from the light emitting element, and also irradiates the return light reflected by the record carrier. In an optical pickup device that irradiates light onto a light-receiving element, the irradiated light from the light-emitting element is shifted from the main beam to both sides in the track direction, and also slightly shifted to both sides in the direction perpendicular to the track direction. irradiated light separating means separates the irradiated light into two sub-beams; and a light-receiving element having separate light-receiving areas receives the return light of the two sub-beams reflected by the record carrier, and detects the difference in the amount of received light. A tracking error detection means for detecting a tracking error by taking a push-pull detection means that receives light with each light-receiving element having an individual light-receiving area and takes a difference in the amount of light received by each light-receiving area; and a push-pull detection means based on the tracking error detected by the tracking error detection means. Remove tracking error components from the results,
It is characterized by having a tilt error detection means for detecting only tilt errors.

Further, in the optical pickup device according to the invention recited in claim 2, in the configuration of the invention recited in claim 1, the push-pull detection means detects the return light of the main beam reflected by the record carrier. The light-receiving element is divided into two light-receiving areas by a dividing line substantially along the track direction, and the light is received on the boundary line between the two light-receiving areas, and the difference in the amount of light received in each light-receiving area is calculated.

[For production]

The irradiation light emitted from the light emitting element is separated into one main beam and two sub beams by the irradiation light separation means.

The separation of this irradiation light is usually ±1 from the O-order diffracted light of the diffraction grating.
This is done by using the next diffracted light.

The two separated sub-beams are irradiated onto the record carrier. At this time, the two sub beams are irradiated to positions that are shifted to both sides in the track direction with respect to the main beam and also slightly shifted to both sides in a direction perpendicular to the track direction. Therefore,
When these sub-beams reflect on the record carrier, the diffraction effects of the bits or groups change in opposite directions depending on the deviation from the track of the main beam. Then, the returned lights of these sub beams are received by a light receiving element having individual light receiving areas by a tracking error detecting means, and a tracking error is detected by taking the difference in the amount of each received light. That is, this tracking error detection means detects a tracking error using the conventional three-beam method.

Further, the main beam is also irradiated onto the record carrier and becomes a returned light. The return light of the main beam is first divided by the push-pull detection means according to claim 1 at a dividing line substantially along the track direction, and then each light beam is divided by a light receiving element having an individual light receiving area. Light is received. To divide the light beam in this manner, an optical system such as a diffraction element whose diffraction area is divided by dividing lines along the horizontal track direction is used. This push-pull detection means is characterized by the difference in the amount of light received in each light-receiving area.The push-pull detection means according to claim 2 guides the luminous flux of the return light of the main beam onto the light-receiving element without dividing it. However, the light-receiving element in this push-pull detection means has a light-receiving area divided by a dividing line substantially along the track direction.
The returned light is irradiated onto the boundary line between the two light receiving areas.

Therefore, it is possible to obtain the same output from each light-receiving area as in the case of the push-pull detection means according to claim 1 above.

These push-pull detection means all have the same configuration as the tracking error detection means using the conventional push-pull method, and as shown in FIG. 10(b),
This detection result makes it possible to detect a tilt error.

However, the detection result by the push-pull detection means also includes a tracking error component based on the original push-pull method. However, the tracking error detection by the tracking error detection means is hardly affected by the tilt error. Therefore, the tilt error detection means removes the tracking error component from the detection result of the push-pull detection means based on the tracking error detected by the tracking error detection means, thereby detecting only the tilt error.

This tilt error detection means can detect a tilt error by directly removing the tracking error component of the tracking error detection means from the detection result of the push-pull detection means, for example, by signal processing. Furthermore, the tracking control of the optical pickup device is performed based on the detection of the tracking error by the tracking error detection means, and the tilt error can also be detected by removing high frequency components (for example, 1) (Z or higher) from the detection results by the tilt error detection means. It is possible to detect only However, when tracks are formed in a spiral shape on a disk such as a CD, the tracking error includes a DC offset component, and the slide control of the optical pickup device is performed based on this DC offset. Become. Therefore, in this case, the DC offset component is also removed from the detection result by the push-pull detection means.

Therefore, according to the invention described in claims 1 and 2, a tilt error can be detected using the optical system of the optical pickup device, so there is no need to provide a separate tilt sensor. Furthermore, since the tilt error is detected from the return light of the main beam, the tilt of the signal reproduction position on the record carrier can be accurately detected.

[Embodiment 1] An embodiment of the invention set forth in claim 1 will be described below with reference to FIGS. 1 to 3.

As shown in FIG. 1, in front of the light emitting element 1 in the optical pickup device of this embodiment, diffraction elements 2 and 3, a collimating lens 4, and an objective lens 5 are arranged, and the laser beam emitted from the light emitting element 1 is is condensed onto the disk 6 as irradiation light. Further, a light receiving element 7 is arranged adjacent to the light emitting element 1.

As shown in FIG. 2, the diffraction element 2 has one type of diffraction region 2a formed therein. This diffraction region 2a is made up of a diffraction grating that uses the O-order diffracted light of the irradiated light from the light emitting element 1 as a main beam and separates the ±1st-order diffracted light into two sub beams from this main beam. The optical axes of these two sub beams are shifted from the main beam to both sides in the track direction on the disk 6, and also slightly shifted to both sides in the radial direction.

The diffraction element 3 is formed with two types of first diffraction regions 3a and second diffraction regions 3b, which are divided into two regions by a dividing line along the track direction.

The collimating lens 4 is a lens for converting the irradiated light from the light emitting element 1 that has passed through the diffraction elements 2 and 3 into parallel light beams. The objective lens 5 is a lens for condensing this irradiation light onto the disk 6.

Further, these lenses 4 and 5 are adapted to guide the returned light from the irradiated light reflected by the disk 6 to the diffraction element 3 again.

The light-receiving element 7 has a central light-receiving area divided into two parts by a dividing line along the radial direction, and a first light-receiving area 7 on the outside thereof.
a is formed. The inner light-receiving area divided into two is further divided into two by a dividing line along the track direction, forming a second light-receiving area 7b and a third light-receiving area 7c, respectively. Further, a fourth light receiving region 7d and a fifth light receiving region 7e are formed on both sides of the light receiving regions 7a to 7C during the daytime, respectively.

The first diffraction region 3a of the diffraction element 3 is a diffraction grating for condensing the first-order diffracted light in the return light of the main beam onto the boundary line between the second light-receiving region 7b and the third light-receiving region 7c of the light-receiving element 7. Consisting of This first diffraction region 3a is
The first-order diffracted light in the return light of the two sub-beams is also focused on the fourth light-receiving area 7d and the fifth light-receiving area 7e, respectively. Further, the second diffraction region 3b of the diffraction element 3
consists of a diffraction grating for condensing the first-order diffracted light in the return light of the main beam onto the first light-receiving region 7a of the light-receiving element 7. The second diffraction region 3b focuses the first-order diffracted light in the return light of the two sub-beams onto the fourth light-receiving region 7d and the fifth light-receiving region 7e, respectively, similarly to the first diffraction region 3a. It looks like this.

Outputs 5a-3e of each of these light-receiving areas 7a-7e in the light-receiving element 7 are sent to a signal detection circuit shown in FIG. This signal detection circuit is composed of two adder circuits 8a and 8b and three subtraction ports IW8c to 8e. Outputs 5b-3c of the second light-receiving area 7b and third light-receiving area 7c are output from an adding circuit 8a and a subtracting circuit 8, respectively.
d. Further, the output Sa of the first light receiving area 7a is input to an addition circuit 8b and a subtraction circuit 8c. The output of the addition circuit 8a is connected to the other inputs of the addition circuit 8b and the subtraction circuit 8c. Furthermore, the fourth light receiving area 7d and the fifth light receiving area 7d
The outputs Sd and Se of the light receiving area 7e are input to a subtraction circuit 8e. Then, the adder circuit 8b outputs a reproduction information signal RF by the following calculation.

RF=Sa+Sb+Sc Further, the subtraction circuit 8c outputs a tilt error signal TLE by the following calculation.

TLE=(Sb+Sc)-3a Furthermore, the subtraction circuit 8d outputs a focus error signal FE by the following calculation.

FE-3b-3c Further, the subtraction circuit 8e outputs a tracking error signal THE by the following calculation.

TRE=Sd-3e The operation of the optical pickup device configured as described above will be explained.

The irradiated light from the light emitting element 1 passes through the diffraction elements 2 and 3 and is focused onto the disk 6 via the collimating lens 4 and the objective lens 5. At this time, the diffraction area 2 of the diffraction element 2
The O-order diffracted light that has passed through a is directed to the disk 6 as a main beam.
The light is focused on the top. Also, ±
The first-order diffracted light is also focused on the disk 6 as two sub-beams. However, these sub beams are focused at positions that are shifted back and forth in the track direction with respect to the focused position of the main beam on the disk 6 and slightly shifted in and out of the radial direction. Note that for this irradiation light, the diffraction element 3 uses only the O-th order diffracted light in each of the diffraction regions 3a and 3b.

The return light of each beam reflected on this disk 6 passes through an objective lens 5 and a collimating lens 4 to a diffraction element 3.
pass through. Each diffraction region 3a of this diffraction element 3
- The first-order diffracted light in 3b is focused on each of the light receiving regions 7a to 7e in the light receiving element 7, respectively. Note that for this returned light, the diffraction element 3 uses only the first-order diffracted light in each of the diffraction regions 3a and 3b.

At this time, the return light of the main beam that has passed through the first diffraction region 3a is focused on the boundary line between the second light receiving region 7b and the third light receiving region 7C. Here, the return light of the main beam that has passed through the first diffraction region 3a becomes one of the light beams obtained by dividing the luminous flux by a dividing line along the track direction. Therefore, the outputs 5b-3c of the second light receiving area 7b and the third light receiving area 7c
By inputting this into the subtraction circuit 8d in the signal detection circuit and taking the difference, the focus error signal FE can be detected by a kind of Knifezi method.

Further, the return light of the main beam that has passed through the second diffraction region 3b is focused on the first light receiving region 7a. Here, the return light of the main beam that has passed through the second diffraction region 3b becomes the other light beam obtained by dividing the luminous flux by the dividing line along the track direction. Therefore, if the difference between the result of adding the outputs 5b-sC of the second light receiving area 7b and the third light receiving area 7C in the adding circuit 8a and the output Sa of the first light receiving area 7a is calculated in the subtracting circuit 8C, Tilt error signal TL by push-pull method
E can be detected. This tilt error signal TL
E includes a component representing information on the original tracking error due to the push-pull method and a component representing information on the tilt error affected by the tilt of the disk 6. In addition,
By adding the output Sa of the first light receiving area 7a in the adding circuit 8b to the addition result of the adding circuit 8a, the reproduced information signal RF can be detected.

Furthermore, the return light of the sub-beams that have passed through these diffraction regions 3a and 3b are focused on the fourth light receiving region 7d and the fifth light receiving region 7e, respectively. Therefore, these fourth light receiving areas 7
d and the output 5d-3e of the fifth light receiving area 7e is subtracted by a circuit 8e.
The tracking error signal TRE can be detected by the three-beam method by inputting the signals and calculating the difference.

The tracking error signal TRE obtained by this three-beam method is hardly affected by tilt errors, so if tracking control is performed based on this tracking error signal TRE, the tracking error of the optical pickup device will be only small fluctuations. Therefore, by passing the tilt error signal TLE through an integrator and extracting only extremely low frequency components below 1) Accurate tilt control can be performed by feeding back the error signal TLE to the tilt mechanism to adjust the tilt angle of the optical pickup device.However, for discs 6 with spiral tracks such as CDs, In this case, the tracking error includes a DC offset component for slide control of the optical pickup device. Therefore, in this case, the DC offset component is further removed from the tilt error signal TLE.

As a result, in this embodiment, the tilt error signal TLE can be detected by only making slight changes to the light-receiving area pattern of the light-receiving element 7 and the signal detection circuit in the conventional optical pickup device. In addition, this tilt error signal TLE
can be detected directly from the main beam return light.

[Embodiment 2] Another embodiment of the invention set forth in claim 1 will be described based on FIGS. 4 to 6.

As shown in FIG. 4, in front of the light emitting element 11 in the optical pickup device of this embodiment, a diffraction element 12, a collimating lens 14, and an objective lens 15 are arranged, and the laser beam emitted from the light emitting element 11 is irradiated. The light is focused onto the disk 16. Further, a light receiving element 17 is arranged adjacent to the light emitting element 11.

Here, since the constituent members other than the diffraction element 12 corresponding to the diffraction elements 2 and 3 are the same as those in the first embodiment, their explanation will be omitted.

The diffraction element 12 has diffraction gratings formed on both sides of a sufficiently thick substrate. As shown in FIG.
A first diffraction region 12a is formed. This first diffraction region 12a is the diffraction region 2 of the diffraction element 2 in Example 1.
It consists of the same diffraction grating as a, and is designed to separate the irradiated light from the light emitting element 11 into one main beam and two sub beams.

Collimating lens 14 on the substrate of this diffraction element 12
On the surface of the example, two types of second diffraction regions 12b and third diffraction regions 12c are formed by dividing the region into two by a dividing line along the track direction. These second diffraction regions 1
2b and the third diffraction region 12c are the first diffraction region 3a and the second diffraction region 3 of the diffraction element 3 in Example 1, respectively.
It is made of the same diffraction grating as b, and is designed to irradiate the light receiving element 17 with the return light from the disk 16. Furthermore, the light receiving regions 17a to 17e on the light receiving element 17 illuminated by the second diffraction region 12b and the third diffraction region 12c are also the same as in the first embodiment, as shown in FIG.

Therefore, the operation of the optical pickup device of this embodiment is similar to that of the first embodiment, and therefore, only slight changes can be made to the light-receiving area pattern of the light-receiving element 7 and the signal detection circuit in the conventional optical pickup device. , the tilt error signal TLE can be detected. Further, this tilt error signal TLE can be directly detected from the return light of the main beam. Moreover, in this embodiment, one diffraction element 1
Since the diffraction element 2 has the same function as the two diffraction elements 2 and 3, it can contribute to reducing the number of parts of the optical pickup device.

[Embodiment 3] An embodiment of the invention described in claim 2 will be described based on FIGS. 7 to 9.

As shown in FIG. 7, a diffraction element 22 and a half mirror 23 are arranged on the side of the light emitting element 21 in the optical pickup device of this embodiment. Also, this half mirror
Above the lens 23, there is a collimating lens 24 and an objective lens 2.
5 is placed. Laser light emitted from the light emitting element 21 is used as irradiation light and is focused onto the disk 26 via these optical systems. Further, a light receiving element 27 is arranged below the half mirror 23 via a cylindrical lens 28 .

Here, the diffraction element 22 is the diffraction element 2 in Example 1.
It is the same structural member as , and the irradiation light from the light emitting element 21 is
The book is separated into a main beam and two sub-beams. The half mirror 23 is an optical system for separating the optical axis of irradiated light and the optical axis of returned light.

As shown in FIG. 8, the light-receiving element 27 has a central light-receiving area divided into four by two dividing lines along the track direction and the radial direction, forming first to fourth light-receiving areas 27a to 27d, respectively. has been done. According to these light receiving areas 27a to 27d, the focus error signal FE can be detected from the returned light irradiated via the cylindrical lens 28 based on the astigmatism method. In addition,
The reproduction information signal RF can also be obtained from the outputs of these light receiving areas 27a to 27d.

Moreover, the output S a of these light receiving areas 27a to 2,7d
z S d is input to a tilt error signal detection circuit shown in FIG. This tilt error signal detection circuit includes two adder circuits 28a and 28b and 1
The subtraction circuit 28c detects the tilt error signal TLE by performing the following calculation.

TLE=(Sa+5d)-(Sb+Sc), that is, the first
The light receiving area 27a, the fourth light receiving area 27d, the second light receiving area 27b, and the third light receiving area 27c are located on both sides of the central light receiving area divided into two by a dividing line along the track direction. Through the above calculation, it becomes possible to detect the tilt error signal TLE based on the push-pull method, as in the case of the first embodiment.

Furthermore, a fifth light receiving area 27e and a sixth light receiving area 27f are formed on both sides of the light receiving areas 27a to 27d, respectively. The fifth light receiving area 27e and the sixth light receiving area 27f are the fourth light receiving area 7d and the fifth light receiving area 27f in the first embodiment.
Corresponding to the light receiving area 7e, the tracking error signal TRE can be detected by the three-beam method.

As a result, in this embodiment, the tilt error signal TLE can be detected by only making slight changes to the signal detection circuit in the conventional optical pickup device using the half mirror 23. Further, this tilt error signal TLE can be directly detected from the return light of the main beam.

〔Effect of the invention〕

As described above, the optical pickup device according to the invention described in claim 1 irradiates the record carrier with the irradiation light emitted from the light emitting element, and also emits the return light reflected by the record carrier. In an optical pickup device that irradiates light onto a light-receiving element, the irradiated light from the light-emitting element is shifted from the main beam to both sides in the track direction, and also slightly shifted to both sides in the direction perpendicular to the track direction. An irradiation light separating means separates the irradiation light into two sub-beams, and a light-receiving element having a separate light-receiving area receives the return light of the two sub-beams reflected by the record carrier, and the difference in the amount of received light is detected. A tracking error detection means detects a tracking error by detecting a tracking error, and a tracking error detection means that divides the returned light of the main beam reflected by the record carrier by a dividing line substantially along the track direction, and separately separates each divided light beam. push-pull detection means that receives light with each light-receiving element having a light-receiving area and calculates the difference in the amount of light received by each light-receiving area, and a detection result of the push-pull detection means based on the tracking error detected by the tracking error detection means. The tilt error detection means removes the tracking error component from the tilt error component and detects only the tilt error.

Further, in the optical pickup device according to the invention set forth in claim 2, in the invention set forth in claim 1, the push-pull detection means substantially detects the return light of the main beam reflected by the record carrier. The light-receiving element is divided into two light-receiving regions by dividing lines along the track direction, and is configured to receive light on the boundary line between the two light-receiving regions, and to calculate the difference in the amount of light received by each light-receiving region.

With these configurations, tilt errors can be detected using the optical system of the optical pickup device. Also,
Since the tilt error is detected from the return light of the main beam, the tilt of the signal reproduction position can be detected accurately.

Therefore, the optical pickup device according to the invention described in claims 1 and 2 eliminates the need to provide a separate tilt sensor for detecting tilt errors, and reduces the cost of the product due to an increase in the number of parts. This has the effect that it can be prevented. Moreover, by detecting this tilt error, the tilt of the actual signal reproduction position on the record carrier can be accurately detected.

[Brief explanation of the drawing]

1 to 3 show an embodiment of the invention as set forth in claim 1, in which FIG. 1 is a front view showing the configuration of an optical pickup device, and FIG. 2 is a front view showing the configuration of an optical pickup device. FIG. 3 is a block diagram of the signal detection circuit. 4 to 6 show other embodiments of the invention as set forth in claim 1, in which FIG. 4 is a front view showing the configuration of an optical pickup device, and FIG. 5 is a diffraction element. FIG. 6 is a perspective view and a plan view showing the arrangement of light receiving elements. 7 to 9 show an embodiment of the invention as set forth in claim 2, in which FIG. 7 is a front view showing the configuration of the optical pickup device, and FIG. 8 is a front view showing the configuration of the optical pickup device. FIG. 9, a plan view showing the arrangement, is a block diagram of a tilt error signal detection circuit. FIG. 10 is for explaining tracking error detection using the push-pull method, and FIG. 10 (a) is a front view showing the configuration of the optical pickup device when there is no tilt error, and FIG. 10 (b) is a front view showing the configuration of the optical pickup device when there is no tilt error. FIG. 2 is a front view showing the configuration of the optical pickup device when a tilt error occurs. Fig. 11 and Fig. 12 show a conventional example, Fig. 11 shows the configuration of the tilt sensor, and Fig. 11 (a) is a front view when the circumferential edge of the disk is curved upward. , FIG. 12(b) is a front view when the circumferential edge of the disk is warped downward, and FIG. 12 is a block diagram of a tilt error signal detection circuit. 1, 11, and 21 are light emitting elements, 2, 12, and 22 are diffraction elements (irradiated light separation means), 6, 16, and 26 are disks (record carriers), and 7, 17, and 27 are light receiving elements. Patent applicant Sharp Co., Ltd. Figure 1

Claims (1)

[Scope of Claims] 1. In an optical pickup device that irradiates irradiation light emitted from a light emitting element onto a record carrier and irradiates return light reflected from the record carrier onto a light receiving element, comprising: irradiation light separating means for separating irradiation light into a main beam and two sub-beams that are shifted to both sides in the track direction with respect to the main beam and slightly shifted to both sides in a direction perpendicular to the track direction; 2 reflected by the carrier
A tracking error detection means detects a tracking error by receiving the return light of the sub-beam of the book by a light-receiving element having an individual light-receiving area and taking the difference in the amount of received light, and a main beam reflected by the record carrier. Regarding the return light of Push-pull detection means; and tilt error detection means for removing a tracking error component from the detection result of the push-pull detection means and detecting only a tilt error based on the tracking error detected by the tracking error detection means. Characteristic optical pickup device. 2. The push-pull detection means receives the return light of the main beam reflected by the record carrier on the boundary line between both light-receiving regions in the light-receiving element, which has divided the light-receiving region by a dividing line that runs approximately in the track direction, and 2. The optical pickup device according to claim 1, wherein the optical pickup device calculates the difference in the amount of received light.