JPS61277007A - Apparatus for measuring surface deflection and warpage - Google Patents

Abstract

PURPOSE:To make it possible to measure the surface deflection and warpage of a medium to be measured in a non-contact state, by providing a means for measuring the surface deflection and warpage of the medium to be measured by the change in reflected light based on the variation in the spaced-apart distance between the medium to be measured and a pickup head. CONSTITUTION:A measuring means is constituted of a focus stracking difference signal detection part 54, a focus servo drive circuit 55, a linearizing circuit 56, a peak/ bottom detection circuit 57 and a rotation detection sensor 33. A timing disc 32 is fixed to a spindle motor 2 so as to be integrally rotated along with said motor 2 and the rotation detection sensor 33 for detecting the timing disc 2 is provided. A signal at every one rotation of an optical disc is outputted from the rotation detection sensor 33 and the peak/bottom detection circuit 57 inputs the outputs of the linearizing circuit 56 and the rotation detection sensor 33 to detect the max. value and min. value of the feedback signal at every one rotation of the optical disc. The difference between the max. value and min. value during one rotation of the optical disc comes to surface deflection quantity and the difference between the max. value and min. value in the entire measuring surface region of the optical disc comes to warpage quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a surface runout and warpage measuring device that automatically measures surface runout and warpage of a disk disk such as an optical disk, a hard disk, or a compact disk.

[Technical background of the invention and its problems]

When recording or reproducing information on an optical disk or the like, an objective lens of an optical head is moved up and down to focus a laser beam onto the optical disk.

By the way, if the surface runout 9 warpage of the optical disk is large, it becomes difficult to follow the vertical movement of the objective lens, causing problems in recording and reproducing information.

Therefore, we have conventionally measured the surface runout and warpage of optical discs.
Quality control is normally in place to ensure that non-standard products are not shipped.

Here, a conventional surface runout 9 warpage measuring device is shown in FIG.

In this measuring device, a stylus 12 and an iron piece 13 are placed on a base 17.
A balance rod 10 is supported by a support 11. Further, the spindle motor 2 is attached to a motor fixing base 4, and an optical disk 1 is supported on the motor shaft and held by a disk holding cap 3.

The motor fixed base 4 has a bearing 5 and is movable on a slide rail 8 fixed on the base 17, and can be moved in a straight line by a rack gear 7, a reversible motor controller 9, and a reversible motor 6. It is driven as follows. Note that rotation control of the spindle motor 2 is performed by a spindle motor control driver 16.

The lower surface of the optical disk 1 is in contact with the stylus 12, and the iron piece 13 is moved up and down according to the amount of surface runout 5 of the optical disk 1 according to the lever principle. A proximity sensor 14 is mounted on the top of this iron piece 13.
is fixed, and a change in the distance between the proximity sensor 14 and the iron piece 13 is detected and the amount of change is plotted on a recorder 15.

However, since this measuring device measures surface run-out and warpage by contact with the optical disc 1, it may cause scratches on the surface of the optical disc 1, wear of the stylus 12 during long-term measurement, or slight damage to the surface of the optical disc 1. There were problems with the responsiveness of the amount of change, speeding up of measurement time, vibration, etc.

[Object of the Invention] The present invention has been made in view of the above-mentioned circumstances, and is capable of measuring surface runout with high precision and good responsiveness by non-contact measurement of surface runout and warpage of a medium to be measured.

The object of the present invention is to provide a warpage measuring device.

[Summary of the invention]

To achieve the above object, the present invention provides a pickup head that irradiates electromagnetic energy to a rotationally driven medium to be measured and detects the reflected energy; and a measuring means for measuring surface runout and warpage of the medium to be measured based on changes in the reflected light based on changes in the separation distance between the medium to be measured and the pickup head. It is something.

[Embodiments of the invention]

Hereinafter, the present invention will be explained with reference to an illustrated embodiment.

FIG. 1 is a block diagram of a data communication system including a surface runout 9 warpage measuring device according to the present invention. This data communication system consists of an evaluation room 100, a computer room 101, and a sputtering room 102. The surface runout 5 in the evaluation chamber 100
The warp measuring device 37 and the lower-level computer 45 are configured to perform optical communication via the optical fiber cable 103 and the R3-232 CI/F box 44. In addition, the lower computer 45 in the evaluation room 100 and the computer room 1
It communicates with the host computer 46 in 01 using a telephone line 102 or the like.

Further, the R3-232 CI/F box 44 in the evaluation chamber 100 and the pinhole counter measurement device 51 and film transmission/reflection measurement device 102 in the sputtering chamber 102 are optically communicated via an optical fiber cable 104. It has become.

FIG. 2 is a front view of the control rack 18 of the surface runout and warpage measuring device 37, and the P
WA rack unit 38, display module and keyboard unit 39, switch operation panel unit 1
-40, detection mechanism unit 41. A pen recorder unit 42, a power supply unit 43, etc. are arranged.

Next, the details of the surface runout 1 warpage measuring device 37 are shown in FIGS. 3 and 4.
This will be explained with reference to the drawings. 3 is a schematic sectional view of the detection mechanism unit 41 of the control rack 18 in FIG. 2, viewed from the side, and FIG. 4 is a block diagram of the detection circuit. A traverse forward/reverse cylinder 23 is attached to 20, and the operation of the traverse forward/reverse cylinder 23 allows the sub-base 21 to move in and out of the control rack 18.

A disk holding lifting cylinder 22 that holds the optical disk 1 and can move up and down is fixed on the sub-base 21. Further, within the control rack 18, a spindle motor 2 serving as rotational driving means is disposed below the stop position of the disc hold elevating cylinder 22, and a disc cap 27 is disposed above. Then, the sub-base 21 moves to the back of the control rack 18, and then the disk hold elevating cylinder 22 holding the optical disk 1 descends to place the optical disk 1 on the spindle motor 2. Thereafter, the cap approach lift motor 26 is driven to lower the disk cap 27 and lock the optical disk 1 to the spindle motor 2. As shown in FIG. 4, the spindle motor 2 is rotationally controlled by a scan scale detector 2A, a spindle motor controller 2B, and a spindle motor driver 2C.

A pickup radar 31 is arranged below the optical disc 1 placed on the spindle motor 2. This pickup head 31 is movable along the radial direction of the optical disc 1. For this purpose, the pickup head 3I is connected to the linear guide 28 and the ball screw 2.
9, and horizontally moves the pickup head 31 by rotating the ball screw 29 by a head scan motor 30. Note that this head scan motor 30 is driven by a scan motor driver 30A. It has become. and,
The above linear guide 28, ball screw 29, head scan motor 30, and scan motor driver 30A constitute a moving means.

Further, this pickup head 31 is driven by a semiconductor laser power supply 53 shown in FIG. 4 to irradiate a laser beam onto the coated surface located inside the optical disk 1, and detects the reflected light with a photodiode detector. It is something. Then, a focus tracking difference signal detection section 54 detects a focus difference signal based on this reflected light. The focus servo drive circuit 55 controls energization of the focus lens coil in the pickup head 31 based on the focus difference signal to maintain a constant distance between the film-applied surface of the optical disk l and the focus lens of the pickup head 31. That's what I do. In the device of this embodiment,
A feedback signal controlling the focus lens coil is detected as an amount of surface wobbling via a linearization circuit 56. Note that the output of this linearization detection circuit 56 is transmitted to the pen recorder 3 in the pen recorder unit 42.
4. The measured values are input to the printing device 1/F35 and plotted. Further, the focus tracking difference signal detection section 54, the focus servo drive circuit 55, the linearization circuit 56, the peak/bottom detection circuit 57, and the rotation detection sensor 33 constitute a measuring means. Further, a timing disk 32 that rotates integrally with the spindle motor 2 is fixed to the spindle motor 2, and a rotation detection sensor 33 that detects the timing disk 32 is provided. And this rotation detection sensor 3
3 outputs a signal for each revolution of the optical disc 1. The peak/bottom detection circuit 57 receives the outputs of the linearization circuit 56 and the rotation detection sensor 33 and detects the maximum value and minimum value of the feedback signal for each revolution of the optical disc 1. This optical disc 1
The difference between the maximum and minimum values during one rotation is the amount of surface runout.

Also, the maximum value within the entire measurement surface of the optical disc.

The difference between the minimum values is the amount of warpage. The output of the peak/bottom detection circuit 57 is transferred to the CPU 36 and stored in the memory. After the measurement is completed, the CPU 36 processes the data stored in the memory and displays the amount of surface runout 9 and the amount of warpage on the display module 39 of the control rack 18 . Further, the CPU 36 transfers the above data to the lower-level computer 45, compares it with a specified value that has been previously input to the lower-level computer 45, and displays the determination result on the display module 39. Furthermore, the measurement data and judgment results are transferred from the lower computer 45 to the upper computer 46.
The lower computer 45 can display or print out the measurement data and judgment results at any time.

As described above, the device of this embodiment can measure surface runout and warpage without contacting the optical disk l, which is the medium to be measured, and has better response than conventional contact-type measuring devices. Therefore, measurement accuracy is improved, and problems such as wear and vibration of the measuring part do not occur. Furthermore, the measurement results can be automatically processed by the operator simply by setting the medium to be measured once, which greatly reduces the burden on the operator.

Note that the present invention is not limited to the above-mentioned embodiments, and various modifications can be made within the scope of the gist of the present invention. For example, the light source for the light to be irradiated onto the medium 1 to be measured from the pickup head 31 is not limited to a semiconductor laser. L
When an ED is used as a light source, its luminous flux is narrowed down and the incident angle θ1
A position sensor may be used to measure the separation distance using the relationship between the reflection angle θ2 and the reflection angle θ2. Alternatively, the same surface runout occurs even if a capacitive sensor is used.

Warpage can be detected. Further, in a broad sense, it is possible to detect surface runout 1 warpage by irradiating the medium to be measured with electromagnetic energy and detecting changes in reflected energy due to surface runout 9 warpage.

Further, in the embodiment described above, surface runout is controlled based on a feedback signal that controls the movement of the focus coil.

Although the method was used to measure warpage, it is also possible to measure surface runout 1 warpage using the focal difference signal itself.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a surface runout 2 warpage measuring device that can measure surface runout 9 warpage of a medium to be measured without contact.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a data communication system including a surface runout 2 warpage measuring device according to the present invention, FIG. 2 is a front view of the surface runout 2 warpage measuring device, and FIG. Schematic sectional view, Figure 4 is a block diagram of the detection circuit, Figure 5 is a block diagram of the detection circuit.
The figure is a schematic explanatory diagram of a conventional contact-type surface runout 2-curvature measuring device. 1...Measurement medium, 2...Rotation drive means, 28.2
9.30.30A...Moving means 31...Pickup head, 33.54,55,56.57...Measuring means.

Claims (1)

[Claims] A pickup head that irradiates electromagnetic energy to a rotationally driven medium to be measured and detects the reflected energy; a moving means that moves the pickup head along a rotation radius direction of the medium to be measured; An apparatus for measuring surface runout and warpage, comprising measuring means for measuring surface runout and warpage of a medium to be measured based on changes in the reflected energy based on changes in the separation distance from the pickup head.