JPH06111350A - Optical disc tilt detection device - Google Patents

Abstract

(57) [Abstract] [Purpose] In an optical disc tilt detection device used for a CD player, a video disc, etc., it is necessary to provide a light emitting element separately from an optical pickup, which solves the problem that the entire device becomes large. An object of the present invention is to provide a small-sized tilt detecting device capable of tilt detection using a light emitting element of an optical pickup. In order to achieve this object, the tilt detecting apparatus of the present invention applies a mirror 10 for tilting a part of the light emitted from a semiconductor laser 7 of an optical pickup together with an objective lens 9 and a prism 11 to an optical disk 1 and both The tilt of the optical disc 1 is detected by the amount of deviation of the image of the reflected light. With this tilt detection device,
Since the tilt of the optical disk 1 can be detected by using the semiconductor laser 7 which is the light emitting element of the optical pickup, the tilt of the optical disk can be detected by a small device without requiring a separate light emitting element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc tilt detecting device used for a CD player, a video disc and the like.

[0002]

2. Description of the Related Art When an optical disc such as a video disc is reproduced, the optical disc bends at the outer periphery, so that when the outer periphery of the optical disc is reproduced, the optical disc and an optical pickup for reproducing the optical disc are tilted and the quality of the reproduced signal is deteriorated. Deteriorates.

In order to prevent the deterioration of the reproduction signal due to the tilt of the optical disk, the tilt of the optical disk is detected by the tilt detection device, and the tilt signal of the optical pickup is tilted by the tilt signal thus detected to obtain the reproduction signal by correcting the tilt with the optical disk. There is.

A first conventional tilt detecting device for an optical disk is disclosed in, for example, Japanese Patent Application Laid-Open No. 02-044533. According to JP-A-02-044533,
Light from both ends of an objective lens using a hologram element is applied to an optical disc, and reflected light from the optical disc is received by light receiving elements provided at both ends of the objective lens to detect the tilt of the optical disc.

Next, a conventional example of a tilt detecting device for a second optical disk will be described with reference to the drawings.

FIG. 9 is a perspective view of such a conventional optical disc tilt detection device used in a video disc player. In FIG. 9, 1 is an optical disc, 2 is an optical pickup, and the optical pickup 2 is for reproducing information from the optical disc 1. Reference numeral 3 denotes an optical disc tilt detection device, which is configured on the optical pickup 2 and is arranged along the radial direction of the optical disc 1 based on the tilt of the optical disc 1 detected by the optical disc tilt detection device 3 with respect to the optical pickup 2 (see FIG. The optical disc 1 is inclined to correct the inclination of the optical disc 1).

FIG. 10 is a detailed side view of the optical disc tilt detecting device 3. In the figure, 5 is an LED as a light emitting element, which emits divergent light toward the optical disc 1. Reference numerals 6 and 7 denote light receiving elements, which are emitted from the LED 5,
The light reflected by the optical disk 1 is received on both sides of the LED 5.

In FIG. 10, (a) shows a state in which the optical disc 1 is not tilted, and the light emitted from the LED 5 is reflected on the optical disc 1 substantially evenly to the left and right to receive the light receiving elements 6, 7.
Incident on. At this time, the light amounts detected by the light receiving elements 6 and 7 are almost the same.

Next, when the optical disc 1 is tilted downward to the right with respect to the optical pickup 2 as shown in (b), the light amount of the light receiving element 6 located to the left of the light emitting element is smaller than that of the light receiving element 7 located to the right. Also increases, and a difference occurs in the light amount between the light receiving element 6 and the light receiving element 7. The inclination of the optical disc 1 can be detected by extracting this difference in light amount as the inclination signal of the optical disc 1.

In the state (c), the optical pickup 2 and the optical disc tilt detection device 3 are tilted to correct the tilt of the optical disc 1, and the light receiving elements 6 and 7 have the same amount of light. The tilt signal of the optical disc 1 becomes zero, which is equivalent to the state where the optical disc 1 has no tilt.

In this manner, the light from the LED 5 attached to the optical pickup 2 is directed to the optical disc 1, and the reflected light is compared with the amount of light received by the light receiving elements 6 and 7 provided on both sides of the LED 5 to obtain the optical disc 1. The inclination of can be detected.

[0012]

However, in such a first conventional structure, a light receiving element is newly provided at both ends of the objective lens in addition to the light receiving element for transmitting the information of the optical disk through the objective lens. Therefore, there is a problem that the entire device becomes large. In the second conventional example, L
Since it is necessary to separately provide the light emitting element of the ED 5 and the light receiving element 6, there is a problem that the entire device becomes large.

In the optical disc tilt detecting apparatus according to the present invention, the above-mentioned problems are solved and a light emitting element of an optical pickup,
It is an object of the present invention to provide a small-sized optical disc tilt detection device capable of tilt detection using a light receiving element.

[0014]

In order to achieve this object, the tilt detecting apparatus for an optical disk according to the present invention includes a tilt mechanism for tilting a part of light emitted from a light emitting element for reproducing information of an optical pickup together with an objective lens. The tilt of the optical disc is detected by detecting the amount of deviation of the image of the reflected light of the mirror and the reflected light of the two on the optical disc through the mirror and the transmitting means.

[0015]

With this optical disc tilt detecting device, the tilt of the optical disc can be detected by utilizing the light emitting element and the light receiving element for reproducing information from the optical pickup.
It is not necessary to separately provide a light emitting element or a light receiving element, and the tilt of the optical disc can be detected by a small device.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a side view of an optical disc tilt detecting apparatus according to an embodiment of the present invention. In the conventional example, the entire optical pickup 2 is tilted to correct the tilt of the optical disc 1, but in the present embodiment, the tilt of the optical disc 1 can be corrected by tilting only the objective lens. is doing.

In FIG. 1, reference numeral 1 is an optical disk, and the direction perpendicular to the paper surface is the radial direction. The other components in the figure are components of the optical pickup. Reference numeral 7 is a light emitting element of an optical pickup which is composed of a semiconductor laser, and 8 is a collimating lens which makes emitted light of the light emitting element 7 parallel light. Most of the center of the light emitted from the collimator lens 8 enters the objective lens 9 and is condensed on the optical disc 1.
The information on the optical disc 1 is reproduced. Collimating lens 8
And a part of the light that does not enter the objective lens 9 is guided to the optical disc 1 through a mirror 10 mounted beside the objective lens 9 and a prism 11 as a transmitting means, and plays a role of tilt detection.

FIG. 3 is an upper perspective view showing the structures of the objective lens 9, the mirror 10 and the prism 11. As shown in FIG. 3, the mirror 10 and the prism 11 are fixed to both ends of the objective lens 9 by fixing members 23 and can be tilted about the optical axis of the objective lens 9.

Returning to FIG. 1 again, the description will be continued. Mirror 1
0, the inclination direction of the prism 11 is along the radial direction of the optical disk 1 (in the direction of the arrow in the figure). Mirror 1
0 is inclined with respect to the objective lens 9 so that the reflected light is inclined outward (or may be inside) with respect to the incident optical axis of the objective lens 9. Further, the prism 11 has an emitting portion inclined with respect to the objective lens 9 so that the transmitted light is inclined outward (or may be inside) with respect to the incident optical axis of the objective lens 9.

Reference numeral 13 denotes a light receiving element, which receives the light returning from the objective lens 9, the reflected light of the mirror 10, and the light transmitted through the prism 11 and reflected by the optical disk 1 by separate divided light receiving elements. Details of the light receiving element 13 are described in an enlarged manner in FIG.

FIG. 2 is a front view of the light receiving element 13. Light returning from the objective lens 9 enters the r portion of the light receiving element 13 to form an image. The light reflected from the mirror 10 and returning returns has an optical axis tilted to the left outer side of the light returning from the objective lens 9, so that it is incident on the p portion outside the r portion and forms an image.

Further, the light transmitted through the prism 11 and reflected by the optical disc 1 and returning returns to the right of the r portion because the optical axis of the light returning from the objective lens 9 is tilted to the outer right side. It is incident on the outer q portion to form an image. By appropriately matching the tilt of the mirror 10 and the tilt angle of the exit surface of the prism 11, the reflected light with respect to the incident light of the objective lens 9 is
The light receiving element 13 can be tilted outward by the same angle.
The p section and the q section can be arranged at positions substantially opposite to the r section, which facilitates adjustment of the light receiving element 13.

Now, the p and q parts of the light receiving element 13 are wedge-shaped, and the image of the received light is partly incident on the wedge-shaped slope and partly offset. When the image of the light being received moves in the direction of arrow X in the figure, the amount of received light changes.

Reference numeral 14 denotes a differential amplifier which outputs the difference in the amount of received light between the p section and the q section as a tilt detection signal of the optical disk 1.

The operation of the optical disc tilt detecting device will be described with reference to FIG. FIG. 4 is an operation explanatory view of the optical disc tilt detection apparatus of the present invention, which is 90 ° from FIG.
A side view from the rotational direction, that is, the circumferential direction of the optical disc 1 and an image on the light receiving element 13 are described according to the operation.

FIG. 4A shows a state before the optical disc 1 is tilted. When observed from the direction along the circumferential direction of the optical disc 1, the light reflected by the mirror 10 also passes through the prism 11 and is reflected by the optical disc 1. The emitted light also returns to the light receiving element 13 substantially perpendicularly to the optical disc 1, and returns to the p section and the q section of the light receiving element 13, respectively. At this time, the light amounts of the p portion and the q portion are almost equal. Therefore, the slope signal output from the differential amplifier 14 is almost zero.

In FIG. 4 (b), the optical disc 1 is in a state of being inclined downward to the right. In the case of (b), since the light transmitted through the prism 11 is reflected by the tilted optical disk 1, it returns with tilting to the left with respect to the optical axis of the mirror 10. Therefore, the image of the light received by the q portion of the light receiving element 13 moves to the left in the figure.

At this time, the quantity of light received by the q-portion of the light-receiving element 13 is smaller than the quantity of light received by the p-section, so that a positive output is obtained as a tilt detection signal from the differential amplifier 14 which outputs the difference in light quantity. It will be.

FIG. 4C is a state diagram when the tilt of the optical disc 1 is corrected by tilting the objective lens 9 based on the tilt signal in FIG. 4B. When the objective lens 9 is tilted by the same amount as the optical disc 1, the mirror 10 is tilted together with the objective lens 9, and therefore the optical axis reflected and returned by the mirror 10 is also tilted.
The light transmitted through the prism 11 and reflected by the optical disc 1 returns with the same inclination as the optical axis.

Therefore, since the light returning to the p section of the light receiving element 13 is also shifted to the left side in the figure, the amounts of light received by the p section and the q section become equal again, and the same output as (a) is output to the differential amplifier 1
4 is output as a tilt signal.

As described above, the light of the semiconductor laser 7 of the optical pickup used for reproducing information from the optical disc 1 is applied to the optical disc 1 through the mirror 10 and the prism 11 which are inclined together with the objective lens 9, and the reflected light of both is received by the light receiving element. It is possible to detect the tilt of the optical disc 1 without separately providing a light emitting element by guiding the light to the position 13 and detecting the image shift amount. In the above description, the case where the optical disc 1 is tilted downward to the right has been described, but the same operation is performed only when the optical disc 1 is tilted downward to the left but the left and right sides are reversed.

Further, by tilting the reflecting surfaces of the mirror 10 and the prism 11, the p portion and the q portion can be arranged near the r portion of the light receiving element 13, and the r, p and q portions of the light receiving element 13 can be arranged. Can be formed on one semiconductor substrate, and the size of the device can be reduced.

Furthermore, the mirror 10 and the prism 1
By setting the tilt angles of the mirror 10 and the prism 11 so that the optical axis of the light transmitted through the optical disc 1 and reflected by the optical disc 1 is substantially the same as the optical axis of the incident light of the objective lens 9, Since the p section and the q section can be arranged in contrast to the r section on the element 13, the adjustment of the light receiving element 13 can be facilitated.

Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 5 shows the second embodiment of the present invention.
It is a side view which shows the Example of. In FIG. 5, 9 is an objective lens, 10 is a mirror, and 11 is a prism, which is tilted with respect to the optical disc 1 about the optical axis of the objective lens 9 as in the first embodiment.

The difference from the first embodiment is that the light reflected by the half mirror 21 as the optical separating means is guided to the objective lens 9, and the light transmitted through the half mirror 21 is reflected by the fixed mirror 15 to make the mirror 10. And that the mirror 10 and the prism 11 are made of the same member.

Similar to the first embodiment, since the objective lens 9, the mirror 10 and the prism 11 are inclined together with the objective lens, the inclination of the optical disk 1 can be detected by the same light receiving element.

Further, by separating the light by the half mirror 21 and sending the transmitted light to the mirror 10 and the prism 11, the mirror 10 and the prism 11 can be arranged side by side in the vicinity of the center of the incident light. Since the amount of light that can be used for detection increases, it is possible to improve the detection accuracy of the tilt signal of the optical disc 1.

Furthermore, by forming the mirror 10 and the prism 11 with the same member, the number of components can be reduced,
The configuration can be simplified.

Next, a third embodiment will be described with reference to the drawings. FIG. 6 is a side view showing the configuration of the objective lens, mirror and prism used in the third embodiment. In FIG. 6, the mirror 10 and the prism 11 are integrally formed by performing mirror processing and prism processing, respectively, by inclining the mirror portion outside the circumference of the objective lens 9 to the left and right.

FIG. 7 is a top view of the objective lens 9. In FIG. 7, the left outer periphery of the objective lens 9 is the mirror 1
0, a prism 11 is integrally formed on the right outer circumference of the objective lens 9.

If such an integrally molded objective lens 19 is used instead of the objective lens 9 and constructed as shown in FIG. 1, the tilt of the optical disc 1 can be detected as in the first embodiment.

Further, since the mirror 10, the prism 11 and the objective lens 9 are integrally molded, the number of parts can be reduced and the structure can be further simplified.

Next, a fourth embodiment of the present invention will be described. FIG. 8 shows a light receiving element 13 used in the fourth embodiment of the present invention.
3 is a circuit diagram showing a configuration of a tilt signal detection circuit. FIG.

In the light receiving element of FIG. 2, the q portion of the light receiving element 13 which receives the light which is transmitted through the prism 11 and reflected by the optical disk 1 and returned is formed from a wedge shape to a square shape.

The total light amount B returning from the optical disk 1 after passing through the prism 11 is detected by the adding amplifier 17, and is divided by the light amount A of the wedge portion by the divider 20 to obtain A /
B is calculated. The tilt detection signal is obtained by detecting this output and the amount of reflected light from the mirror 10 received by the p section of the light receiving element 13 by the differential amplifier 14.

By dividing the amount of light of the wedge portion of the light receiving element 13 by the total amount of light that is transmitted through the prism 11 and reflected from the optical disc 1, the light image is obtained regardless of the variation in the reflectance of the optical disc 1. Can be detected, and the inclination can be detected regardless of the reflectance of the optical disc 1 by taking the difference from the p portion.

In the first embodiment, the prism 1
1 is fixed to the fixing member 23 together with the objective lens 9 and tilted together with the objective lens, but the prism 11 may be fixed closer to the semiconductor laser 7 than the objective lens 9.

[0049]

As described above, in the optical disc tilt detection apparatus of the present invention, the light of the light emitting element 7 of the semiconductor laser optical pickup used for reproducing information from the optical disc 1 is passed through the mirror 10 and the prism 11 which are tilted together with the objective lens 9. The light reflected by the optical disk 1 and the reflected light of
By detecting the shift amount of the image by guiding to, the tilt of the optical disc 1 can be detected without separately providing a light emitting element or a light receiving element.

[Brief description of drawings]

FIG. 1 is a side view of an optical disk tilt detection device according to a first embodiment.

FIG. 2 is a front view of the light receiving element of the first embodiment.

FIG. 3 is an upper perspective view of the optical disc tilt detection device according to the first embodiment.

FIG. 4 is an operation explanatory view of the optical disc tilt detection apparatus according to the first embodiment.

FIG. 5 is a side view of an optical disc tilt detection device according to a second embodiment.

FIG. 6 is a side view of an objective lens according to a third embodiment.

FIG. 7 is a top view of an objective lens according to a third example.

FIG. 8 is a light receiving element and detection circuit diagram of a fourth embodiment.

FIG. 9 is a perspective view of a second conventional optical disc tilt detection device.

FIG. 10 is a detailed side view of a second conventional optical disc tilt detection device.

[Explanation of symbols]

 1 Optical Disc 2 Optical Pickup 7 Light Emitting Element 9 Objective Lens 10 Mirror 11 Prism 13 Photosensitive Element 14 Differential Amplifier 20 Divider 21 Half Mirror

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toru Nakamura 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (9)

[Claims] 1. A light emitting element, an objective lens for condensing light of the light emitting element onto an optical disk, a mirror for reflecting a part of the light of the light emitting element and tilting together with the objective lens, and a light of the light emitting element. A transmissive unit that transmits a part of the light and guides it to the optical disc, a first light receiving element that receives the image of the light that is transmitted through the transmissive unit and reflected by the optical disc, and a light image that is reflected by the mirror. The difference between the light amount change amount of the second light receiving element and the first light receiving element due to the movement of the light image and the light amount change amount of the second light receiving element according to the movement amount of the light image is output. Optical disc tilt detection device consisting of a differential amplifier. 2. The optical disk tilt detecting apparatus according to claim 1, wherein the light receiving element has a geometric structure in which a light receiving area changes along the moving direction of the image of the received light. 3. The optical disk tilt detecting device according to claim 1, wherein the transmitting means is a prism for tilting the optical axis of the transmitted light. 4. The tilt detecting device for an optical disk according to claim 1, wherein the mirror has a tilt that tilts the reflected light with respect to the optical axis of the objective lens. 5. The tilt detecting device for an optical disk according to claim 1, wherein the tilts of the reflected light which is transmitted from the transmitting means and reflected from the optical disk and the light which is reflected from the mirror have the same angle. 6. The optical disk tilt detecting device according to claim 1, wherein the transmitting means and the mirror are made of the same member. 7. The optical disk tilt detecting device according to claim 1, wherein the transmitting means, the mirror, and the objective lens are formed of the same member. 8. A light emitting element, an objective lens for condensing the light of the light emitting element onto an optical disc, an optical separating means for separating a part of the light quantity of the light of the light emitting element guided to the objective lens, Part of the light emitted from the optical separation means is reflected,
A mirror that tilts together with the objective lens, a transmissive unit that transmits a part of the light emitted from the optical separation unit and guides it to the optical disc, and a first image that receives the image of the light that is transmitted through the transmissive unit and reflected by the optical disc. Of the second light receiving element, the second light receiving element for receiving the image of the light reflected by the mirror, the amount of change in the amount of light accompanying the movement of the light image of the first light receiving element, and the second light receiving element of the second light receiving element. An optical disc tilt detection device comprising a differential amplifier that outputs a difference in the amount of change in the amount of light depending on the amount of movement of the image of the received light. 9. The light-receiving element comprises a first element having a geometric structure in which a light-receiving area changes along the moving direction of the image of the light to be received, and a second element for detecting the total amount of light of the image of the light. 2. The optical disk tilt detection device for an optical disk according to claim 1, further comprising a divider which is composed of an element and which divides the first received light amount by the second received light amount.