JPH08285874A - Reference signal generator and rotational information detector employing the same - Google Patents

Abstract

PURPOSE: To obtain a reference signal generator, and a rotational information detector employing it, which can generate a reference signal at the time of recording the information for detecting the circumferential direction of a disc or positioning the disc highly accurately utilizing a Doppler signal and an index signal obtained through an optical head. CONSTITUTION: Luminous flux from a light source means 2 impinges on the plane to be detected of a rotating object 1. Scattering light from the object 1 subjected to Doppler shaft is detected by a photodetector 201 which delivers a signal to a Doppler signal processing circuit 21. A Doppler signal pulse from the circuit 21 impinges, along with the luminous flux from a light source means 2, on an index mark smaller than the diameter of luminous flux put on a part of the rotating object 1 while having diffuse reflectance different from that of the plane to be detected. Scattering light from the index mark is detected by a photodetector 201 which delivers a signal to an index processing circuit 22. A reference signal is produced using an index signal from the circuit 22 at the time of recording the positioning information on the rotary object.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reference signal generator and a rotation information detector using the reference signal generator. For example, a reference signal used when recording positioning information on a rotating disk-shaped or cylindrical rotating object is used. Using a so-called Doppler signal and an index signal obtained by one optical head based on the rotation speed of a rotating object, a reference signal generating device for recording positioning information on the rotating object and the reference signal generating device are used. It is suitable for writing the positioning information of the rotation information detecting device.

[0002]

2. Description of the Related Art Conventionally, a disk coated with a magnetic material has been used as a storage / reproducing means used in an information processing apparatus such as a computer. When a signal (information) is magnetically written on this disk using a magnetic head, it is necessary to previously write information for positioning the magnetic head on the disk. Therefore, in addition to the original writing head for information, a dedicated clock head is used, and an unused area on the disk,
A high frequency pulse is recorded mainly in the outermost circumference. Various devices have been proposed in which information for positioning is written on a disk based on the pulse.

FIG. 7 is a schematic view when the circumferential direction (angle direction) of a disk is divided into a plurality of areas. In the figure, 1
Is a disk to be divided. The figure shows a state in which the disk 1 is divided into N equal parts. The area from point a to point b represents one area when divided. Here, the division does not necessarily have to be at equal intervals, but normally it is required to be at equal intervals and spatially accurate division, in other words, accurate division.

The area where information is recorded is written for each area on a concentric circular track on a disk in a portion on the donut (a portion excluding the black portion in the drawing) from the inner circumference to the outer circumference. One concentric circle is divided into a plurality of areas (a to b represent one of them), and the head of each area is a portion for writing information for positioning and the remaining portion is a portion for recording actual information. is there. As shown in the figure, the head positions of the respective areas are arranged at the same angular positions of the concentric circles, that is, on the radii, and for positioning purposes, the information is also written on the radii of the concentric circles in phase. The positioning is performed by reading the positioning information (servo pattern) written at the beginning of each area. For this reason, the divided area is required to be accurately divided between the concentric circles without displacement.

FIG. 6 is a schematic view of a main part of a conventional positioning information recording device. In the figure, 1 is a disk, which is rotated by a spindle motor (not shown). Reference numeral 12 is a clock head which writes a time-accurate clock pulse in an unused area of the disk 1 and reads the clock pulse. 1d is the recorded clock pulse signal. A counter (counter means) 3 counts the detected pulses from the clock head 12. Four
Is a one-round pulse number memory, which stores the number of pulses for one round of the disk 1. 5 is the division number data, 1 of disk 1
It shows how many times the lap is divided.

Reference numeral 6 denotes a divider, which is a one-cycle pulse number memory 4
Is divided by the number of divisions N from the division data 5 to obtain the number of division pulses per division area. Reference numeral 7 is a divided pulse number memory, which stores the number of pulses per divided region. Reference numeral 8 is a comparator, which compares the number of divided pulses with the value of the counter and outputs a divided reference pulse in the divided area.

A signal processing unit 9 writes and reads data through the magnetic head 11. 10 is a voice coil motor (hereinafter referred to as "VCM"),
The magnetic head 11 is driven in the radial direction of the disk 1. The magnetic head 11 writes and reads data.
In the figure, thin lines represent pulse signals and thick lines represent data buses.

In the figure, a time-accurate clock pulse from a clock pulse circuit (not shown) is written in the unused area of the disk 1 by the clock head 12 for the disk 1 rotating by the spindle motor. The number of clock pulses for one cycle is predetermined, and the writing is performed by changing the frequency of the clock pulse until the writing of the correct number of pulses is performed.

Next, the clock head 12 reads out the written clock pulses, counts them by the counter 3, and stores the pulse number in the one-round pulse number memory 4. This value is the divider 6
Is divided by the division number from the division number data 5 and is stored in the division pulse number memory 7 as the number of pulses per area.

The number of pulses counted by the counter 3 is compared with the number of pulses per region by the comparator 8. The comparator 8 counts the number of pulses in one region and sends the number of pulses at this time to the signal processing unit 9 as a reference pulse. At the same time, a clear pulse is sent to the counter 3 to prepare to count the next divided area from 0.

When the signal processing unit 9 receives the reference pulse for division, the magnetic head 11 writes a signal based on the clock pulse on the disk 1 to divide the region. The VCM 10 sequentially positions the magnetic heads 11 at predetermined intervals in the radial direction by a radial positioning device (not shown). And the magnetic head 11
Thus, radial divisional reference position signals are formed on the concentric circles of the disk 1 at equal angles.

[0012]

In the positioning writing apparatus shown in FIG. 6, since the clock pulse is based on time, the fluctuation of the rotation speed directly affects the accuracy of the position reference signal. In order to reduce the influence of the fluctuation of the rotation speed and increase the resolution, the rotation of the disk may be delayed only when writing the clock pulse, which causes the throughput not to be increased. Further, there is a problem in that the clock head may come into contact with the disk to make a defective product.

As described above, in the conventional positioning information recording apparatus, when the accuracy of generating the reference signal is increased, there is a problem that the rotational speed is changed and many defective products are generated due to a contact accident.

According to the present invention, by appropriately processing the Doppler signal and the index signal obtained from the optical head, it is possible to easily obtain a reference signal for highly accurately detecting and positioning an angle in the circumferential direction of a disk or the like. It is an object of the present invention to provide a reference signal generator capable of performing the above and a rotation information detecting device using the same.

[0015]

The reference signal generator according to the present invention comprises: (1-1) Scattering by causing a light beam from a light source means to be incident on a surface to be inspected of a rotating object and receiving a Doppler shift from the rotating object. Light is detected by a photodetector, and a Doppler signal pulse obtained by inputting a signal from the photodetector to a Doppler signal processing circuit and a luminous flux from the light source means are provided on a part of the rotating object. Having a diffuse reflectance different from the diffuse reflectance of the inspection surface, and incident on an index mark smaller than the diameter of the light flux, the scattered light from the index mark is detected by the photodetector, and from the photodetector. Is used to obtain a reference signal for recording the positioning information on the rotating object by using the index signal obtained by inputting the signal to the index processing circuit.

In particular, (1-1-1) has counter means for counting the Doppler signal pulses,
A pulse signal for starting and ending counting is determined for the counter means, the number of Doppler signal pulses between the pulse signals for starting and ending counting is stored in the first storage means, and the Doppler stored in the first storage means. The number of signal pulses is divided by the number of divisions by which the angular direction of the rotating object is divided into a plurality of regions by the dividing means, the divided number of pulses is stored in the second storage means, and the number of pulses stored in the second storage means and the The divided reference pulse is generated by comparing the number of Doppler signal pulses counted by the counter means with the comparison means, the angular direction of the rotating object is divided into a plurality of areas by using the divided reference pulse, and positioning is performed in the plurality of areas. Use the Doppler signal pulse as a reference signal when writing information for.

(1-1-2) The rotating object has a ring-shaped reflection region and an index mark in the ring-shaped reflection region which has a diffuse reflectance different from that of the reflection region and smaller than the diameter of the incident light beam. And detecting the index signal from the scattered light from the index mark by the photodetector to determine the counting start pulse and the counting end pulse for the counter means.

(1-1-3) The index signal processing circuit has a low-pass filter, a high-pass filter, an amplifier circuit, a level detector and an index generator, and the cut-off frequencies of both filters are set to the speed of the rotating object. Make an informed decision and obtain an index signal from this.

(1-1-4) The photodetector detects a Doppler signal based on the Doppler shift of scattered light generated from the rotating object when the light beam from the light source means is incident on the rotating object. When the reference signal for recording the positioning information on the rotating object is generated using the Doppler signal, the rotating object has a ring-shaped diffuse reflection area centered on the rotation axis and an index mark. And so on.

(1-2) A light beam from the light source means is made incident on an object, and a Doppler signal based on the frequency shift of scattered light subjected to the Doppler shift from the object and an index signal as a reference of the object are generated. It is characterized in that it is detected by one optical head, and a reference signal for recording positioning information is generated by a Doppler signal and an index signal from the optical head.

(1-3) The light beam from the light source means is made incident on the surface to be inspected of the rotating object, the scattered light which has undergone the Doppler shift from the rotating object is detected by the photodetector, and the scattered light from the photodetector is detected. A Doppler signal pulse obtained by inputting a signal to the Doppler signal processing circuit is used to index the rotating object into a plurality of regions in the angular direction by index signals obtained based on two or more index marks provided on the circumference of the rotating object. And is used as a reference signal when writing information for positioning in the plurality of regions.

In the rotation information detecting device of the present invention, (2-1) the light beam from the light source means is incident on the surface to be inspected of the rotating object, and the scattered light which has undergone the Doppler shift from the rotating object is detected by the photodetector. When detecting the rotation information of the rotating object from the Doppler signal pulse signal obtained by inputting the signal from the photodetector to the Doppler signal processing circuit, the Doppler signal pulse and the light flux from the light source means are detected. An index signal obtained by entering an index mark provided on a part of a rotating object, detecting scattered light from the index mark by the photodetector, and inputting a signal from the photodetector to an index processing circuit. Is used to obtain a reference signal when recording the positioning information on the rotating object.

In particular, (2-1-1) has counter means for counting the Doppler signal pulses,
A pulse signal for starting and ending counting is determined for the counter means, the number of pulses of the Doppler signal between the pulse signals for starting and ending counting is stored in the first storage means, and the pulse stored in the first storage means is stored. The number is divided by the number of divisions into which the angular direction of the rotating object is divided into a plurality of areas by the division means, the divided number of pulses is stored in the second storage means, and the pulses stored in the second storage means and the counter means The divided reference pulse is generated by comparing the counted number of Doppler signal pulses with the comparison means, the angular direction of the rotating object is divided into a plurality of regions by using the divided reference pulse, and positioning is performed in the plurality of regions. Use the Doppler signal pulse as a reference signal when writing information.

(2-1-2) The rotating object has a ring-shaped reflection region and an index mark in the ring-shaped reflection region which has a diffuse reflectance different from that of the reflection region and which is smaller than the diameter of the incident light beam. And detecting the index signal from the scattered light from the index mark by the photodetector to determine the counting start pulse and the counting end pulse for the counter means.

(2-1-3) The index signal processing circuit has a low-pass filter, a high-pass filter, an amplifier circuit, a level detector and an index generator, and the cut-off frequencies of both filters are set to the speed of the rotating object. Make an informed decision and obtain an index signal from this.

(2-1-4) The photodetector detects the Doppler signal based on the Doppler shift of scattered light generated from the rotating object when the light beam from the light source means is incident on the rotating object. When the reference signal for recording the positioning information on the rotating object is generated using the Doppler signal, the rotating object has a ring-shaped diffuse reflection area centered on the rotation axis and an index mark. And so on.

(2-2) A light beam from the light source means is made incident on the rotating object, and it serves as a reference for the rotating object and a Doppler signal based on the frequency shift of scattered light subjected to the Doppler shift from the rotating object. The index signal is detected by one optical head, and when detecting the rotation information of the rotating object from the Doppler signal from the optical head, a reference signal for recording positioning information is generated by the Doppler signal and the index signal. It is characterized by that.

(2-3) The light beam from the light source means is made incident on the surface to be inspected of the rotating object, the scattered light subjected to the Doppler shift from the rotating object is detected by the photodetector, and the scattered light from the photodetector is detected. When detecting the rotation information of the rotating object from the Doppler signal pulse obtained by inputting the signal to the Doppler signal processing circuit, the Doppler signal pulse is based on two or more index marks provided on the circumference of the rotating object. The index signal thus obtained is used to divide the rotating object into a plurality of regions in the angular direction and to use as a reference signal when writing information for positioning in the plurality of regions.

[0029]

Embodiment 1 FIG. 1 is a schematic view of the essential portions of Embodiment 1 of the present invention. This embodiment shows a case where the present invention is applied to a servo track writer of a hard disk.

In the figure, 1 is a disk (rotating object), which is rotated by a spindle motor (not shown). Reference numeral 2 denotes an optical head, which irradiates the disc with laser light from a light source means, detects diffused light from the disc and amplifies it to generate a signal including a Doppler signal and an index signal based on the rotation speed of the disc 1. are doing. A counter means (counter) 3 counts the Doppler signal pulses detected by the Doppler signal processing circuit 21. Reference numeral 4 denotes a memory (one-round pulse number memory) as a first recording means, which stores the number of pulses for one round of the disk 1.

Reference numeral 5 is division number data, and represents how many divisions the disk 1 makes for one revolution. A divider 6 divides the contents of the memory 4 by the division number N from the division number data 5 to obtain the number of pulses per divided area. 7 is a memory (divided pulse number memory) as a second recording means,
The number of pulses (the number of divided pulses) per divided area is stored. Reference numeral 8 is a comparator, which has a divided pulse number and a counter 3
And outputs the division reference pulse for the division area. A signal processing unit 9 writes and reads data through the magnetic head 11.

A voice coil motor (VCM) 10 drives the magnetic head 11 in the radial direction of the disk 1. The magnetic head 11 writes and reads data. In the figure, thin lines represent pulse signals and thick lines represent data buses.

The Doppler signal pulse detected by the optical head 2 and obtained by the Doppler signal processing circuit 21 has a frequency proportional to the speed (rotation speed) of the object (disk) being irradiated. In this embodiment, angle information is obtained by counting the Doppler signal pulses.

Now, when the optical head 2 is fixed, the circumference C on the disk 1 is to be measured. Even if there is eccentricity in the rotation of the spindle motor, the length of one round is the same, and the number of Doppler signal pulses corresponding to this circle is constant regardless of fluctuations in the rotation speed. Further in the present invention,
Since the information for positioning is written in the finally used state, basically no problem of eccentricity remains.

In order to count the number of Doppler signal pulses for one round, a signal serving as a rotation reference is required. As a method therefor, an index mark 18 having a diffuse reflectance different from the diffuse reflectance of the disk 1 and smaller than the incident light flux is provided at one location on the circumference C. The index mark 18 is detected by the optical head 2 and a pulse signal (clear latch signal) for starting and ending counting is obtained from the index signal obtained from the index signal processing circuit 22. The counter means 3 counts the number of pulses between the reference signals.

The count pulse number from the counter means 3 is stored in the one-round pulse number memory 4. This value is divided by the division number data 5 by the divider 6 and stored in the division pulse number memory 7 as the number of pulses per area. When the number of pulses per divided area does not become an integer, adjustment is made so that it becomes an integer within the range of 1 pulse.

For example, if the integer value rounded down to the right of the decimal point is n and m = 1 pulse number- (n × N), N-m n-pulse regions and m-n + 1 pulse regions are formed. .

For example, when the number of pulses for one round is 3003 and the number of divisions is N = 30, 3003 ÷ 30 = 100.1 Therefore, n = 100, and m = 3003− (100 × 30) from the above formula. = 3 This gives 3 101 pulse regions and 27 100 pulse regions.
It is divided into 30 in the pulse region. Therefore, the divided pulse number memory 7 is in the form of a table of divided numbers and the corresponding pulse numbers.

Although the method using the Doppler signal pulse as it is has been described in the present embodiment, if the number of pulses is further increased or decreased by an electrical or signal processing means, the same as the clock pulse of the conventional example is explained. You can also take a method.

The number of pulses counted by the counter means 3 is compared with the number of pulses per region by the comparator 8. The comparator 8 sends the divided reference signal to the signal processing unit 9 when counting the pulses for one area. At the same time, a clear latch signal is sent to the counter means 3 to prepare for counting the next area.

When the signal processing unit 9 receives the divided reference signal, the magnetic head 11 writes the positioning information on the disk 1 using the Doppler signal pulse as the reference signal. VCM
10 is sequentially positioned by a radial direction positioning device (not shown) at predetermined intervals in the radial direction, and thereby radial positioning information is formed on the concentric circles of the disk 1 at equal angles (equal intervals).

In the figure, the optical head 2 is perpendicular to the disk 1, but it need not be vertical if a Doppler signal can be obtained, and it is positioned horizontally or obliquely with respect to the rotation axis. Is also good. The ring-shaped diffused reflection area C of the disc 1 according to the present embodiment is formed in advance on the disc 1 or is attached later.

In this embodiment, the surface of the hard disk may be mirror-finished. At this time, the Doppler signal is difficult to obtain from the hard disk surface.
Therefore, in the present embodiment, the Doppler signal detection ring 16 is used.
Is attached to a portion outside the recording area of the disk 1 corresponding to the circumference C. The detection ring 16 may be attached at any position as long as it can obtain the Doppler pulse from the laser light and can cover the portion hit by the laser light.

In this embodiment, the detection ring 16 is provided with an index mark (rotational reference area) 18 serving as a rotation reference. The index mark 18 does not affect the Doppler output of the optical head 2 that receives the laser light. On the other hand, an index signal processing circuit 22 for detecting the index mark 18 is provided, and the output from the index signal processing circuit 22 is input to the counter means 3 as a pulse signal (clear latch signal) for starting and ending counting.

In this embodiment, a reference position signal (clear latch signal) can be obtained from one optical head 2, and each time the magnetic head 11 is positioned, the first division is started from the reference position signal. When there is a timing difference between the output from the comparator 8 of the final Nth divided area and the rotation reference signal for each rotation, it is determined that the writing of the divided positioning information has failed, and the magnetic head 11 is moved to the next step. Instead of moving to the track, after erasing, the division is redone.

In this embodiment, the method of sticking the detection ring 16 including the index mark (rotational reference area) 18 has been described, but the detection ring 16 is prepared by forming the reflection area for the Doppler pulse when the hard disk is manufactured.
Alternatively, a ring-shaped detection portion including the index mark (rotational reference area) 18 may be formed in advance, or only the area of the detection ring 16 may be formed and the index mark (rotation reference area) may be formed. Reference area) 18
May be attached.

Next, the index mark 1 according to this embodiment
The size of 8 will be described.

FIG. 2 is an explanatory diagram of the size of the index mark to be written on the test object when the index forming means forms the index mark on the test object in the present invention.

In the figure, reference numeral 18 is an index mark, and 114a and 114b are spot diameters of the laser light flux with which the object to be inspected is irradiated. Index mark 1
8 is a spot 114a where two light beams from the light source means intersect.
And 114b.

2A shows the index mark 18 horizontally long in the moving direction, FIG. 2B shows the index mark 18 vertically long in the moving direction, FIG. 2C.
Shows an example in which the index mark 18 is round. Further, the index mark to be written is such that its diffuse reflectance is low or high, which is different from the diffuse reflectance of the test object.

FIG. 3 is a block diagram of essential parts of a method for obtaining the Doppler signal pulse and the index signal in this embodiment.

In the figure, 21 is a Doppler signal processing circuit, 2
Reference numeral 2 is an index signal processing circuit. Reference numeral 201 denotes a photodetector, which detects both the scattered light that has undergone the Doppler shift from the test object (moving object) irradiated with the speed measurement light beam and the scattered light from the index mark, and outputs the output signal. It is output as S. A first amplifier 202 amplifies the output signal S from the photodetector 201.
The amplifier 202 includes a Doppler signal and an index signal according to the speed of the object to be inspected, and outputs the signal as a signal according to the amount of diffused reflected light from the object to be inspected.

Reference numeral 203 denotes a second amplifier, which is the first amplifier 2
The Doppler signal from 02 is amplified to a certain level. Reference numeral 204 denotes a bandpass filter that removes noise of the Doppler signal from the second amplifier 203. Reference numeral 205 denotes a waveform shaper, which binarizes the Doppler signal from the bandpass filter 204. 206
Is a frequency oscillator, and outputs the binarized Doppler signal from the waveform shaper 205 as a continuous signal.

In the present embodiment, the Doppler signal processing circuit 21
Based on the binarized Doppler signal pulse (Doppler frequency F) from, the movement information of the moving object is detected based on the equation described later.

Reference numeral 207 is a high-pass filter (HPF), which removes the fluctuation of the signal due to the surface property of the object to be inspected from the signal corresponding to the light quantity of the diffuse reflected light including the index signal from the first amplifier 202. . 208 is a low pass filter (LPF), and a high pass filter (H
The Doppler signal and high frequency noise from the PF) 207 are removed. A third amplifier 209 amplifies the index signal from the low pass filter 208. Two
A detector 10 detects a signal corresponding to the index mark from the signal from the third amplifier 209 and uses it as an index mark detection signal.

Reference numeral 211 denotes an index generator, which outputs an index signal of a certain width from the index mark detection signal from the detector 210. The index signal processing circuit 22 determines the cutoff frequency of the high-pass filter 207, the low-pass filter 208, etc. (band-pass filter) based on the speed information of the rotating object, and the index generator 211 obtains a predetermined index signal from this. .

Next, the method of detecting and generating the index signal in this embodiment will be described with reference to FIG. In FIG. 3, including the index signal from the first amplifier 2,
The signal corresponding to the light amount of the diffusely reflected light includes low-frequency signal fluctuations and other wideband noise due to the change of the reflected light amount due to the surface property of the object to be inspected as shown by the signal waveform 2a in FIG.

Therefore, the HPF 207 removes the fluctuation of the signal due to the surface property of the object to be inspected, and then the LPF 208 removes the high frequency noise due to the Doppler signal or the like.
Then, the index signal is efficiently amplified by the third amplifier 209 to obtain a signal like the signal waveform 2b in FIG.

In the detector 210 for detecting the signal level by such processing, it becomes easy to set the signal detection level corresponding to the index mark on the basis of the output level of the third amplifier 209, thereby eliminating malfunction. You can The index generator 211 sets the output width t of the signal output when the index detection signal 2c detected by the detector 210 is input, and outputs the index signal from this.

Further, in this embodiment, the cutoff frequencies of the HPF 207 and the LPF 208 are set based on the speed information of the rotating object. This allows the third amplifier 209 to efficiently amplify the index signal. The cut-off frequency can be calculated as shown in FIG. 4 if the size of the index mark, the diameter of the laser beam and the speed of the object to be measured are known.
Since the width of the index signal of the graph 2a of 1 can be calculated, it can be easily determined.

Further, the width of the index mark is made smaller than the spot diameter at which the two light beams intersect, which has almost no effect on the level of the Doppler signal and prevents the measurement accuracy from deteriorating.

FIG. 5 is a schematic view of a main part of an optical system of the optical head 2 according to the present invention.

In the figure, reference numeral 100 is a schematic view of a main part of the optical head 2 using the Doppler effect. Reference numeral 101 is a laser, 102 is a collimator lens, 1 is an object to be measured as a moving object, 110 is a diffraction grating with a grating pitch d, 1
Reference numerals 21 and 122 denote convex lenses (lens systems) having a focal length of f, and are arranged as shown in the figure. The distance from the diffraction grating 110 to the lens 121 is a, and the lens 122 is
Letting b be the distance from the object to be measured 1, a and b satisfy the relationship of a + b = 2f.

Laser light from the laser diode 101 having a wavelength λ of about 0.68 μm is collimated by the collimator lens 10.
2 becomes a parallel light flux 103 with a diameter of 1.2 mmφ,
The light enters perpendicularly to the grating arrangement direction of the transmission type diffraction grating 110 having a grating pitch d of 3.2 μm. At this time, the ± 1st-order diffracted lights 105a and 105b are emitted at a diffraction angle θ ₁ = 12 °.

The light beams 105a and 105b have a focal length f (=
When incident on a 15 mm) convex lens 121, light fluxes 113a and 113b as shown in the figure are obtained. Luminous flux 113a, 1
When 13b enters another convex lens 122 separated by 2f (= 30 mm), parallel rays 114a and 114b are obtained again, and a spot diameter of 1.2 mmφ is formed at an angle equal to the diffraction angle θ ₁ from the diffraction grating 110 described above. Become speed V (m
The disk 1 as an object to be measured is irradiated at m / sec).

The convex lens 12 reflects scattered light from the measured object 1.
2 and the condensing lens 108 make the photodetector 201 efficient.
The light signal is condensed on the light receiving unit 201a of (1) and the optical signal containing the Doppler signal shown in the expression (a1) is detected. And Figure 3
The velocity information of the object to be measured 1 is obtained via a calculation means (not shown) that receives an output from the Doppler signal processing circuit having the configuration shown in FIG.

F = 2V / d = V / 1.6 (kHz) (a1) Here, a = 10 mm and b = 20 mm, where b is relatively long and the working distance is large. The speed of installation of the speedometer is increased.

If the wavelength λ of the laser light from the laser diode 101 changes, then dsin θ =
The diffraction angle θ changes in accordance with λ, but the Doppler signal does not change. Further, in this device, the positions of the two light flux spots are also immovable. That is, the object to be measured 1 is set to the arrangement shown in FIG. 5, the positions of the spots of the two light fluxes on the object to be measured 1 are immovable, and the positional deviation between the spots does not occur. The crossing condition is maintained and good Doppler and index signals are obtained.

FIG. 8 is a block diagram of essential parts of the second embodiment of the present invention. This embodiment shows a case where the present invention is applied to a servo track writer of a hard disk.

The same blocks (elements) as those of the first embodiment shown in FIG. 1 are assigned the same numbers and their explanations are omitted. The difference from Example 1 is that two or more index marks are provided in the diffuse reflection area. The index signal is used as a division reference signal, and the Doppler signal pulse is used as a reference signal when writing positioning information.

As shown in the lower part of FIG. 8, the index mark 18 is provided on the detection ring 16 in advance. When using a part of a rotating object as a diffuse reflection area, an index mark is put on the rotating object, or a sticker or the like that functions as an index mark is attached to form an index mark.

If two or more index marks are arranged in advance in a precise positional relationship, the counter means 3, the one-round pulse memory 4, the division number data 5, the divider 6, the division pulse number memory 7, and the comparator 8 will be described. Is unnecessary and the circuit configuration can be simplified. Other Doppler signal detection and index signal detection are the same as in the first embodiment.

[0073]

As described above, according to the present invention, by appropriately processing the Doppler signal and the index signal obtained from the optical head, the angle detection and positioning in the circumferential direction of the disk or the like can be performed with high accuracy. Therefore, it is possible to achieve a reference signal generator that can easily obtain a reference signal and a rotation information detection device using the reference signal generator.

In addition, according to the present invention, the scattered light including the Doppler signal and the index signal from the rotating object is detected by one photodetector for detecting the Doppler signal, and the signal from the photodetector is detected. The index signal is obtained together with the Doppler signal by processing using a signal processing circuit with an appropriate configuration, and the rotation information of the rotating object can be detected with high accuracy by a simple configuration, and it is affected by the fluctuation of the rotation speed. It is possible to achieve a reference signal generator for writing highly accurate position information without contact.

By using such an apparatus according to the present invention, it is possible to prevent the Doppler signal from being affected even if the index mark is formed on the object to be inspected. Further, the index signal can be accurately obtained even if the rotation speed of the object to be measured changes.

In addition to this, according to the present invention, by providing a ring-shaped reflection region in a part of the rotating object, a Doppler signal can always be obtained regardless of the rotating state of the rotating object. By detecting the index signal from the index mark and determining the start and end of counting and the reference pulse signal, the clear latch signal can be obtained for each rotation. By having the ring-shaped diffusion region and the index mark, it is possible to realize a rotating object capable of angle division using the Doppler signal pulse as described above. In particular, it is possible to obtain an effect that the angle can be detected with high accuracy in a non-contact manner without being affected by the fluctuation of the rotation speed.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between an index mark and a spot light flux according to the present invention.

FIG. 3 is a block diagram of a main part of the first embodiment of the present invention.

FIG. 4 is an explanatory diagram of an index signal detection method according to the present invention.

FIG. 5 is a schematic view of a main part of an optical head according to the present invention.

FIG. 6 is a block diagram of a main part of a conventional positioning information writing device.

FIG. 7 is an explanatory diagram for dividing the circumference of the disk into a plurality of areas.

FIG. 8 is a schematic view of the essential portions of Embodiment 2 of the present invention.

[Explanation of symbols]

 1 Disk (Rotating Object) 2 Optical Head 3 Counter Means 4 1-Pulse Pulse Memory 5 Divided Number Data 6 Divider 7 Divided Pulse Number Memory 8 Comparator 9 Signal Processing Unit 10 Voice Coil Motor (VCM) 11 Magnetic Head 16 Detection Ring 18 index mark (rotational reference area) 21 Doppler signal processing circuit 22 index signal processing circuit 100 optical system of optical head 101 light source means 201 photodetector 202 first amplifier 203 second amplifier 204 bandpass filter 205 waveform shaper 206 frequency generator 206 207 High-pass filter 208 Low-pass filter 209 Third amplifier 210 Detector 211 Index generator

Claims (14)

[Claims] 1. A light beam from a light source means is incident on a surface to be inspected of a rotating object, scattered light subjected to Doppler shift from the rotating object is detected by a photodetector, and a signal from the photodetector is detected by Doppler. The Doppler signal pulse obtained by inputting to the signal processing circuit and the light flux from the light source means have a diffuse reflectance different from the diffuse reflectance of the surface to be inspected provided on a part of the rotating object, and the light flux Incident on an index mark smaller than the diameter of the index mark, the scattered light from the index mark is detected by the photodetector, and the signal from the photodetector is input to the index processing circuit to obtain an index signal. A reference signal generator for obtaining a reference signal for recording positioning information on the rotating object. 2. A counter means for counting the Doppler signal pulses, comprising:
A pulse signal for starting and ending counting is determined for the counter means, the number of Doppler signal pulses between the pulse signals for starting and ending counting is stored in the first storage means, and the Doppler stored in the first storage means. The number of signal pulses is divided by the number of divisions by which the angular direction of the rotating object is divided into a plurality of regions by the dividing means, the divided number of pulses is stored in the second storage means, and the number of pulses stored in the second storage means and the The divided reference pulse is generated by comparing the number of Doppler signal pulses counted by the counter means with the comparison means, the angular direction of the rotating object is divided into a plurality of areas by using the divided reference pulse, and positioning is performed in the plurality of areas. 2. The reference signal generator according to claim 1, wherein the Doppler signal pulse is used as a reference signal when writing information for writing. 3. The rotating object has a ring-shaped reflection area and an index mark in the ring-shaped reflection area, which has a diffuse reflectance different from that of the reflection area and is smaller than a diameter of an incident light beam. 3. The reference signal generator according to claim 2, wherein the photodetector detects an index signal from the scattered light from the index mark to determine the pulse for starting and ending the counting for the counter means. 4. The index signal processing circuit includes a low-pass filter, a high-pass filter, an amplifier circuit, a level detector, and an index generator, and the cutoff frequencies of both filters are determined based on the speed information of the rotating object. 4. The reference signal generator according to claim 1, wherein the index signal is obtained from the index signal. 5. The photodetector detects a Doppler signal based on a Doppler shift of scattered light generated from a rotating object when a light beam from a light source means is incident on the rotating object, and the Doppler signal is utilized. 7. When generating a reference signal for recording positioning information on the rotating object, the rotating object has a ring-shaped diffuse reflection area centered on the rotation axis and an index mark. 1, 2, 3 or 4 reference signal generators. 6. A light beam from a light source means is incident on an object,
A Doppler signal based on the frequency shift of scattered light that has undergone the Doppler shift from the object and an index signal serving as a reference of the object are detected by one optical head, and by the Doppler signal and the index signal from the optical head, A reference signal generator for generating a reference signal for recording positioning information. 7. A light beam from a light source means is made incident on a surface to be inspected of a rotating object, scattered light subjected to Doppler shift from the rotating object is detected by a photodetector, and a signal from the photodetector is detected by Doppler. A Doppler signal pulse obtained by inputting to a signal processing circuit is divided into a plurality of regions in the angular direction by an index signal obtained based on two or more index marks provided on the circumference of the rotating object. A reference signal generator used as a reference signal when writing information for positioning in the plurality of regions. 8. A light beam from a light source means is incident on a surface to be inspected of a rotating object, scattered light subjected to Doppler shift from the rotating object is detected by a photodetector, and a signal from the photodetector is detected by Doppler. When detecting the rotation information of the rotating object from the Doppler signal pulse signal obtained by inputting to the signal processing circuit, the Doppler signal pulse and the light flux from the light source means are made incident on an index mark provided in a part of the rotating object. Then, the scattered light from the index mark is detected by the photodetector, and the positioning information is recorded on the rotating object using the index signal obtained by inputting the signal from the photodetector to the index processing circuit. A rotation information detecting device, wherein a reference signal of time is obtained. 9. A counter means for counting the Doppler signal pulses, comprising:
A pulse signal for starting and ending counting is determined for the counter means, the number of pulses of the Doppler signal between the pulse signals for starting and ending counting is stored in the first storage means, and the pulse stored in the first storage means is stored. The number is divided by the number of divisions into which the angular direction of the rotating object is divided into a plurality of areas by the division means, the divided number of pulses is stored in the second storage means, and the pulses stored in the second storage means and the counter means The divided reference pulse is generated by comparing the counted number of Doppler signal pulses with the comparison means, the angular direction of the rotating object is divided into a plurality of regions by using the divided reference pulse, and positioning is performed in the plurality of regions. 9. The rotation information detecting device according to claim 8, wherein the Doppler signal pulse is used as a reference signal when writing information. 10. The rotating object has a ring-shaped reflection region and an index mark in the ring-shaped reflection region, which has a diffuse reflectance different from that of the reflection region and is smaller than a diameter of an incident light beam. 10. The rotation information detecting device according to claim 9, wherein the photodetector detects an index signal from the scattered light from the index mark to determine the counting start and counting end pulses for the counter means. 11. The index signal processing circuit includes a low-pass filter, a high-pass filter, an amplifier circuit, a level detector, and an index generator, and cutoff frequencies of both filters are determined based on velocity information of the rotating object. The rotation information detecting device according to claim 8, 9 or 10, wherein the index signal is obtained from this. 12. The photodetector detects a Doppler signal based on a Doppler shift of scattered light generated from a rotating object when a light beam from a light source means is incident on the rotating object, and the Doppler signal is utilized. 7. When generating a reference signal for recording positioning information on the rotating object, the rotating object has a ring-shaped diffuse reflection area centered on the rotation axis and an index mark. 8, 9, 10 or 11 rotation information detecting device. 13. A Doppler signal based on a frequency shift of scattered light that is caused by a Doppler shift from the rotating object when a light beam from a light source means is incident on the rotating object, and an index signal serving as a reference of the rotating object. Is detected by one optical head, and when the rotation information of the rotating object is detected from the Doppler signal from the optical head, a reference signal for recording positioning information is generated by the Doppler signal and the index signal. And a rotation information detecting device. 14. A light beam from a light source means is made incident on a surface to be inspected of a rotating object, a scattered light subjected to Doppler shift from the rotating object is detected by a photodetector, and a signal from the photodetector is detected by Doppler. When detecting the rotation information of the rotating object from the Doppler signal pulse obtained by inputting to the signal processing circuit,
The Doppler signal pulse is provided on the circumference of the rotating object 2
The rotating object is divided into a plurality of regions in the angular direction by an index signal obtained based on one or more index marks, and is used as a reference signal when writing information for positioning in the plurality of regions. Rotation information detection device.