JPS62121936A - Optical tracking device - Google Patents

Abstract

PURPOSE:To prevent an improper tracking, to check out reading and writing actions several times and to improve accuracy by irradiating plural beams as plural spots on the prescribed tracking guide. CONSTITUTION:Since a means 1 emitting plural lights 4a and 4b is used as a light source, they can be irradiated as plural spots A and B on an optical recording medium 7. Accordingly, the spots A and B almost simultaneously scan the same tracking guide, and a factor such as cracks on the medium 7, which develops an improper tracking, is immediately detected to switch a normal tracking signal, etc. Then correct information is read out and an improper tracking is prevented. Moreover the spots A and B read or write optical information, check out each recorded information twice to improve accuracy.

Description

[Detailed Description of the Invention] <Technical Field of the Invention> The present invention relates to an optical tracking device used for writing and reading optical information on optical cards, optical disks, etc., and particularly relates to a device for preventing mistracking. It is something.

<Summary of the Invention> The present invention is configured to use a plurality of beams for one information recording section (track guide) to read and write optical information to and from an optical recording medium. This provides an optical tracking device that can prevent mistrunking caused by scratches on optical recording media, improve reading and writing accuracy, and can also be applied to dramatically improve writing and reading speeds. It is something to do.

<Background of the Invention> Conventionally, a single beam is used to read and write optical information recorded on an optical recording medium. FIG. 9 shows the overall configuration of a conventional optical tracking device, and FIG. 10 shows the configuration of its detector. In FIG. 9, one beam 54 emitted from a laser diode 51 is collimated by a collimating lens 52, transmitted through a polarizing beam splitter 53 to become p-polarized light, and further transmitted through a 174-wave plate 55 to an objective lens 56. The light is focused on the optical recording medium 57 and irradiated as one spot. The beam 54 reflected by the optical recording medium 57 travels in the opposite direction and passes through the objective lens 56 and further through the 1/4 wavelength +ri 55 .

The reflected beam that has passed through the 174 wavelength plate 55 is converted from p-polarized light to S-polarized light, is reflected within the polarizing beam splitter 53 on the return path, and travels on an optical path different from the incident optical path. The light is then converged by the spherical lens 59 and the cylindrical lens 60, and detected as an optical output signal by the detector 58 placed in front of them.

FIG. 10 shows the configuration of the detector 58.

In the illustrated example, the part that detects light is composed of four divided sensor sections 58a, 58b, 58c, and 58d, and the output signals from these sensor sections are a, b, and c.
, d, a focus signal S indicating each information for reading or writing, a focusing signal F for determining whether the light is accurately focused on the optical recording medium 57, and a focus signal F for determining whether the light is accurately focused on the optical recording medium 57; Each of the tracking signals T for determining whether or not a predetermined information recording section (track guide) of the optical recording medium is accurately scanned is detected and each signal is output.

In addition, in FIG. 10, 61, 62, 63, 64° 67 indicate adders, and 65, 66 indicate subtracters.

According to this conventional method, as shown in FIG. 11, when a cause of mistracking, such as a scratch 67, occurs on the optical recording medium 57, a light spot 68 is placed before and after the scratch 67 in areas other than the predetermined information recording area 69. There was a problem that caused so-called mistracking 70.71, which is the erroneous scanning of the recording section 72.73. <Objective of the Invention> The present invention is intended to solve the above problem, and aims to An object of the present invention is to provide an optical tracking device that can prevent mistracking by irradiating a trunking guide with a plurality of spots, and can check writing and reading to improve their accuracy.

<Structure and Effects of the Invention> In order to achieve the above object, the present invention provides an apparatus for writing and reading optical information in an optical information recording section on an optical recording medium, which includes: (a) a light emitting means that emits a plurality of lights; , (b) an objective lens that converges a plurality of lights emitted from the light emitting means and irradiates each of the lights onto the optical information recording section of the optical recording medium, and (C) an objective lens that focuses each of the lights that are reflected or transmitted through the optical recording medium. It was decided to include a light detection means for detection.

According to this configuration, since a light emitting means that emits a plurality of lights is used as a light source, a plurality of beams can be irradiated onto the optical recording medium as a plurality of spots. Therefore, multiple spots scan back and forth within the same trunking guide, and even if there are scratches or other causes of mistracking on the optical recording medium, this will be detected immediately and tracking will always be normal. Mistracking can be prevented by switching to a signal or the like and reading the correct information. Furthermore, since the optical information is read or written using the plurality of spots, each piece of recorded information (bit signals, etc.) can be read and written while double-checking at all times, which improves the accuracy of the reading and writing. It has a remarkable effect.

<Description of Embodiments> FIG. 1 shows a first embodiment of an optical tracking device according to the present invention. Although the illustrated example is of a type that detects a reflected beam from an optical recording medium, the present invention is not limited to this, and can be applied to a type that detects a transmitted beam of an optical recording medium.

In FIG. 1, the light emitting means for emitting a plurality of lights is, for example, an array laser diode 1 having two separate light emitting points within one laser diode. This 2
The radiation beams 4a and 4b from the two light emitting points have optical axes slightly different from each other and travel along separate optical paths. The beams 4a and 4b are first incident on the collimating lens 2, collimated there, and then incident on the polarizing beam splitter 3. This polarizing beam splitter 3 is configured to transmit, for example, p-polarized light but reflect S-polarized light, and the p-polarized light components of the two beams 4a and 4b are transmitted through this polarizing beam splitter 3. After that, it is further incident on the 174 wavelength plate 5,
The p-polarized light exits the 174-wave plate 5 as circularly polarized light. The light emitted from the 174-wavelength plate 5 enters the objective lens 6 substantially perpendicularly, and after being converged there, it is irradiated onto an optical recording medium 7 such as an optical card or an optical disk in the form of a spot. In the figure, A and B indicate the irradiation positions of these spots, which are irradiated in the same optical information recording section (track guide) provided on the optical recording medium 7 in front and back in series.

The reflected light from the optical recording medium 7 travels in the opposite direction, passes through the objective lens 6 and then the quarter-wave plate 5, and enters the polarizing beam splitter 3 again. The beams 4a and 4b reflected at this time become S-polarized light by passing through the quarter-wave plate 5 twice in a round trip. Therefore, the beams 4a and 4b are reflected within the polarizing beam splitter 3 on the return path and proceed along an optical path different from the incident optical path (the optical path to the left in FIG. 1), and the The light is detected by the detector 8 as its optical output signal.

Note that the spherical lens 9 and the cylindrical lens 10 are optical systems for converging the reflected beams 4a and 4b onto the detector 8. Further, in FIG. 1, arrow X indicates the scanning direction of this optical tracking device, and arrow Y indicates the moving direction of the optical recording medium 7, respectively.

FIG. 2 shows an example of the configuration of the detector 8. Detector 8 in the illustrated example
In FIG. 2(1), the upper half is 8A for detecting the optical spot (A), and the lower half is 8B for detecting the optical spot B, each of which is divided into four sensor sections 81a and 8lb.
, 81c, and 81d. In these detectors 8, the imaging state when the focus is on is as shown in FIG.
8 l b, 81 c.

81d, but when the image is out of focus, it becomes an ellipse as shown in FIG. 3(3). Therefore, the adder 13 adds the outputs a and d of the sensor sections 81b and 81d located diagonally, and similarly the adder 12 adds the outputs a and b of the sensor sections 81a and 81c. 12. The subtracter 15 calculates the output difference of 13, and uses this as the focusing signal F.

Output as F2. This focusing signal F+, F
When t is zero, it is determined that the focus state is proper, and if it is not zero, the focus is adjusted by adjusting the objective lens 6.

On the other hand, by further adding the outputs of the adders 12 and 13 in an adder 17, it is possible to obtain each information (pit information) S+ and SZ for writing and reading on the optical recording medium 7.

Furthermore, the outputs (a) and (c) of the sensor units 81b and 81c located on one side with respect to the scanning direction d is added by an adder 14, and these adders 11
．． 14 can be calculated by a subtracter 16 to detect the tracking signal T,,T,.

FIG. 3 shows the state of tracking by two spots A and B in correspondence with the sensor sections 81a to 81d of the detector 8. In the figure, three track guides 21
, 22 and 23, and the beams 4a and 4b are scanned in series on the track guide 22 in the center as two separated spots A and B.

First, FIG. 3+1) shows a state in which both the light spots A and B are within the tracking guide 22 and are not covered by the scratch 24. In this case, the above-mentioned focusing signal, tracking signal, The pit signal is
Each signal S, , T, , F, from spot A will be adopted.

FIG. 3(2) shows a state where spot A is inside the scratch 24 and spot B is on the track guide 22.
In this case, the level of the output signal SI of Spora) A is 2.
4, the output decreases significantly, so this decrease in output is shown in Figure 2 (
1) is detected by the threshold circuit 18. This S
When the output of , becomes below a certain threshold, the switching circuit 19
20, T2 is selected as the tracking signal and F2 is selected as the focusing signal, and as a result, S2 is adopted as the output signal of the optical information recorded on the track guide 22.

As the scanning progresses further, as shown in Figure 3 (3),
When the light spot A escapes from the scratch 24, the output signal S1 of the spora l-A becomes larger than the threshold value, so the threshold circuit 18 detects this and switches the switching circuit 19.
．． 20 is switched in the opposite manner to the above. As a result, T1 is again selected as the tracking signal and Fl is selected as the focusing signal, and as a result, S is selected as the output signal. In this way, mistracking caused by mistracking factors such as scratches can be completely prevented.

FIG. 4 shows an example of a circuit configuration added to the configuration of the detector 8 to improve reading accuracy. The output signal S
1 and S2 are output signals outputted by scanning the same tracking guide 22, so they have the same content. Then, the output signal St detected first is sent to the delay circuit 4.
1 to match the time timing with the other output signal S2, and then input the output of the delay circuit 41 and the output signal S2 to the exclusive OR circuit 42 to determine whether or not they match. That's what I do. As a result, when the outputs S and 82 do not match, an error signal E can be obtained as the output of the exclusive OR circuit 42, and reading can be double checked to improve reading accuracy. Of course, this additional configuration can also be applied to the configuration example t5 in FIG. 5, which will be described later.

In the above embodiment, two spots A and B are irradiated back and forth on the same track guide, but these two spots A and B are irradiated by different spots A and B as shown in FIG.
4. Can be placed in parallel on 1 and 23. Figure 6 shows the electrical and electrical wiring of the detector 8 in this case.
Since its circuit configuration is the same as that in FIG. 2, corresponding configurations are given the same reference numerals and their illustrations will be omitted.

FIG. 7 shows another embodiment of the Luz according to the present invention, in which an in-the-diode 35 having one light emitting point as a light emitting means for emitting a plurality of lights and a diffraction grating 36 are bonded together.
It is made using waza. Regarding this implementation 1. - put it aside,
Optical spot A of beams 4a and 4b formed on optical recording medium 7.

Y5 (Δ1) between B is Δ+ = f tan (5in-'nλ/d) [However,
"=focal length of objective lens 6.

n=order of diffraction image λ=350 wavelength of laser diode d=grating interval of diffraction grating]. Note that the other configurations are the same as the embodiment shown in FIG. 1, including the collimating lens 2. Polarizing beam splitter 3.1
/4 wavelength plate5. Objective lens 6° Optical recording medium 7. Detector 8
1 spherical lens9. It includes a cylindrical lens 10.

FIG. 8 shows still another embodiment, in which two laser diodes 37 and 38 having a single light emitting point are used as light emitting means for emitting a plurality of lights. In this embodiment, a beam splitter 39 that transmits the beam 4a from the laser diode 37 and reflects the beam 4b from the laser diode 38 is connected to the polarizing beam splitter 3.
is placed in front of. In this embodiment, the optical spots A of the beams 4a and 4b formed on the optical recording medium 7,
The interval (Δ2) of B is as follows: Δ2=ftan θ [where f=focal length of the objective lens 6.

θ=angle of inclination of laser diode 38]. In addition,
The other configurations are the same as the embodiment shown in FIG. 1, with the collimating lens 2. Polarizing beam splinter 3. 1/4 wavelength plate 5.
Objective lens 6° Optical recording medium 7. Detector 89 Spherical lens 9
．． It includes a cylindrical lens 10.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of an embodiment of this invention, FIG. 2 is a diagram showing an example of the configuration of a detector applied to this invention, FIG. 3 is a diagram showing a tracking state of this invention, Figure 4 shows an example of a circuit configuration that is additionally used to improve reading accuracy, Figure 5 shows another example of tracking, and Figure 6 shows the configuration of a detector applied to the example in Figure 5. Figure 7 showing an example
8 and 8 are views showing other embodiments of the present invention, and FIG.
10 is a diagram showing the configuration of a detector applied to the conventional example, and FIG. 11 is a diagram showing the state of mistracking in the conventional example. 1.35.37.38...Array laser diode 6...Objective lens 7...Optical recording medium 8...
...Detector 36...Diffraction grating patent Applicant: Tateishi Electric Co., Ltd./Figure 1) 2/7 Ray Rebe Quiet Device 6) 5734 7. U-27. □、1. show. Δ sweet 4111 4ka @ bribe □ purchase 60.4 fang, 7G mu1

Claims (7)

[Claims] (1) Writing optical information to the optical information recording section on the optical recording medium,
A reading device comprising: a light emitting means that emits a plurality of lights; an objective lens that converges the plurality of lights emitted from the light emitting means and irradiates each of the lights onto an optical information recording section of an optical recording medium; and the optical recording medium. An optical tracking device comprising: a light detection means for detecting each light reflected or transmitted through the light. (2) The optical tracking device according to claim 1, wherein the optical recording medium is an optical card. (3) The optical tracking device according to claim 1, wherein the optical recording medium is an optical disc. (4) The optical tracking device according to claim 1, wherein the light emitting means is a laser diode. (5) The optical tracking device according to claim 1 or 4, wherein the light emitting means is an array laser diode having two separate light emitting points within one laser diode. (6) The optical tracking device according to claim 1 or 4, wherein the light emitting means is a plurality of laser diodes. (7) The optical tracking device according to claim 1, wherein the light emitting means is a combination of one laser diode and a diffraction grating.