JPH0437294Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The invention relates to a developing device that irradiates a disc-shaped information recording medium with laser light, monitors the intensity ratio of the diffracted light, and performs optimal development processing. .

(Prior Art) FIG. 3 shows an example of a developing device to which the present invention can be applied. A disk-shaped information recording medium 1 recorded with a laser beam or the like is rotated by a motor 3 provided on a spinner 2. The developer is sprayed from the nozzle 4. Further, the laser beam 5 from the laser source 6 is irradiated from the back surface of the information recording medium 1. As the development progresses, the outline of the groove (pit) shape becomes clearer and diffracted lights 7, 8, and 9 are generated. Since the formed groove (pit) row is considered to be a type of diffraction grating, information on the groove width and groove depth can be obtained from the calculation table 13 from the respective diffracted light intensity ratios. That is,
The groove width is determined from the value of the diffracted light intensity ratio I ₂ /I ₁ of the 1st-order light and the 2nd-order light, and the diffracted light intensity ratio of the 0th-order light and the 1st-order light is
The groove depth is determined from the values of I ₁ /I ₀ and the above-mentioned I ₂ /I ₁ . Therefore, an optimal groove shape can be obtained by stopping development at a predetermined intensity ratio value.

Incidentally, the position of the detector that receives the diffracted light of a predetermined order is determined by the track pitch of the information recording medium 1 and the wavelength of the irradiated laser beam. That is, if P is the track pitch, λ is the wavelength of the laser beam, and m is the order of the diffracted light, the diffraction angle φm is expressed by the following equation.

φm=sin ⁻¹ (mλ/P) (1) For example, when P=1.6 μm and λ=633 nm, the first-order light diffraction angle is 23.3° and the second-order light diffraction angle is 52.3°.

(Problems to be Solved by the Invention) However, the track pitch of the disk-shaped information recording medium in which the present developing device is used is not always constant. For example, in the case of a video disc on which video signals are recorded, the track pitch is approximately 1.7 μm, and in the case of recording high-density code data, the track pitch is approximately 1.6 μm.
It becomes the following bitch. Although various track pitches are conceivable for the information recording medium, it is desirable to be able to process them with the same developing device from the viewpoint of cost and reliability. However, in the case of a general developing device, the position of the detector that receives the diffracted light is arranged so that it can only receive light at a limited pitch, which has the disadvantage that the diffracted light with a different track pitch may deviate from the detector. ing. This tendency is particularly remarkable for secondary light having a large diffraction angle.

(Means for solving the problem) The present invention moves various information recording media to the same position by moving the detector that receives the diffracted light to a predetermined position even when the diffraction angle differs depending on the track pitch value. It is designed so that it can be processed by a developing device.

(Example) The principle of the present invention will be explained with reference to FIG. 1st and 2nd order light 8 diffracted by the information recording medium 1;
The diffraction angles of 9 are the values of φ ₁ =sin ⁻¹ (λ/P) and φ ₂ =sin ⁻¹ (2λ/P), respectively, from equation (1).

Here, the intersection point 3 of the laser beam 5 and the information surface 1a
Let Q 1 and Q ₂ be the points where the circumference 30 having an arbitrary radius R centered on 1 intersects with the first-order diffracted light 8 and the second-order diffracted light ₉ . Then, from the above formula, the 0th order light 7
The distances x ₁ and x ₂ from the optical axis to points Q ₁ and Q ₂ are respectively x ₁ = Rsinφ ₁ = R·λ/P x ₂ = Rsinφ ₂ = R·2λ/P. Therefore, if the values of P, R, and λ are constant, the relationship is x ₂ = 2x ₁ , and even if the track pitch is different, the detector position for secondary light reception is always the same as the detector position for primary light. All you have to do is move to a position that is twice that.

FIG. 1 shows an embodiment of the present invention. Arms 16 and 17 are fixed to rack gears 14 and 15, and detectors 11 and 12 are supported on the arms 16 and 17, respectively, so as to be slidable and rotatable in the vertical direction through elongated holes 16a and 17a. 12 is movable on the circumference 30 so that the light receiving surface always faces the intersection 31. The pinion gears 18 and 19 are fixed to the shaft of the motor 20, and have a tooth ratio of 2. That is, the arm 17 moves twice as much as the arm 16 with respect to the rotation of the motor shaft. The diffracted light 22 is -1st-order light having the same diffraction angle as the diffracted light 8, and depending on the position where the position sensor 21 is irradiated with this diffracted light 22, the output corresponding to the track pitch of the recording medium 1 is controlled by the motor. It is added to the drive circuit 23.

According to the above configuration, the position sensor 2
By predetermining the rotation speed of the motor shaft for the output of 1, the detectors 11 and 12 for receiving diffracted light can
is automatically moved on the circumference by the motor 20 to the optimum position so that the distance ratio between the 0th order diffracted light 7 and the optical axis is always 1:2, so the 1st and 2nd order diffracted lights 8 and 9 are always It is possible to make the light incident perpendicularly to the center of the detection surfaces of the detectors 11 and 12. It goes without saying that various other well-known means can be applied to the means for moving while keeping the distance ratio constant.

(Effects) According to the present invention, even in various information recording media with different track pitches, the detector that receives the diffracted light is always placed at the optimum position, and stable development processing can be carried out.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing an embodiment of the present invention;
The figure is an explanatory diagram of the principle, and FIG. 3 is a schematic diagram showing an example of a developing processing apparatus to which the present invention can be applied. 1... Recording medium, 10, 11, 12... Detector, 16, 17... Arm.

Claims (1)

[Scope of utility model registration request] It has first and second detectors that irradiate the optically recorded information recording medium on the disk with a laser beam, monitor the intensity of the first- and second-order diffracted light, and performs development processing according to the intensity of the diffracted light. In the developing device, means for obtaining a position detection output according to the irradiation position of the first or second order diffracted light, and first and second detectors that connect the optical axis of the zeroth order diffracted light of the irradiated laser light and the first and second detectors. first and second detector moving means for adjusting the second distance according to the position detection output, and the amount of change in the second distance is twice the amount of change in the first distance. A developing device for a recording information medium, characterized in that: