JP2000065600A - Rotary state detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a pattern with a simple method and at the same time securely detect a rotary state by applying light to a rotator where surface is machined so that patterns with a different reflection factor, a reflection direction, distance from a rotary shaft, and the like can be formed and detecting the intensity of reflection light. SOLUTION: A pattern 31 is formed on the side surface of a drum-shaped rotator 30, and a pattern part has a lower light reflection factor or the like than other parts. In a laser light source 32 for constituting detection circuits 15-19, a laser beam is applied to a side surface where the pattern 31 of the rotator 30 is formed by a semiconductor laser element for generating an infrared laser beam. A photosensor 33 incorporates a photo detector such as a photodiode and is combined with such optical device as a lens, thus outputting a signal with the intensity of reflection light from the rotator 30. A mechanism control processor 20 converts the output from analog to digital, compares the digital data with a specific threshold, calculates the starting and ending time of a projecting part, a recessed part, or an inclined part, and further calculates the rotary angle and speed of the rotator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotational state detecting device, and more particularly to a rotational state detecting device capable of reliably detecting a rotational state by a simple method.

[0002]

2. Description of the Related Art Conventionally, in a tape backup device such as a VTR or a data recorder, a rotation state detecting device is provided to control a rotating body such as a drum, a capstan, and a reel motor provided in the device. ing. For example, Japanese Unexamined Patent Publication No. Hei 7-13069 discloses that a disk substrate has irregularities (servo marks) corresponding to servo signals for tracking.
, A magnetic film is formed on the surface, and a servo mark is read by a magnetic head. In addition, a magnetic film is formed on the surface, a control pattern is written and read with a magnetic head, a magnet is installed and a coil is detected, and a black and white pattern is printed or affixed to the surface of the rotating body by printing or attaching a label. And a method of detecting the pattern by an optical sensor.

[0003]

As described above, in the conventional rotation state detection method, a magnetic film, a magnet, a paint,
It was necessary to add some substance to the surface of the rotating body, such as a label, or write a pattern. Therefore, in the case of a magnetic film, a magnetizing device or a magnetized state inspection device requires a printing label / paint and a dark place to detect reflected light, which complicates the process. there were. In addition, if a deviation of the magnetization pattern or a deviation of the coating occurs at the time of manufacturing, there is a problem that the detection accuracy is deteriorated and the device is broken down due to separation due to aging. Further, for example, in the conventional magnetization pattern detection method, it is necessary to dispose the magnetic head very close to the surface of the rotating body, and there is a problem that foreign matter is caught. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art, and to provide a rotation state detection device in which a pattern is formed by a simple method and a rotation state can be reliably detected.

[0004]

According to the present invention, there is provided a rotating state detecting device, wherein a surface is processed so that at least one of a reflectance, a reflecting direction, and a distance from a rotation axis is different in pattern. It is characterized by comprising a body, light source means for irradiating the rotating body with light, and detecting means for detecting the intensity of reflected light from the rotating body. According to the present invention, a pattern is formed on the surface of a rotating body made of metal, for example, by a processing method such as machining or etching, so that the process is simplified, and an extra substance is attached to the surface of the rotating body, Since there is no need to write a pattern, the number of components and manufacturing equipment are reduced, and there is no risk of pattern displacement or peeling.

[0005]

Embodiments of the present invention will be described below in detail. FIG. 1 is a block diagram showing a configuration of a control circuit of a mechanism part of a VTR to which the present invention is applied. The apparatus includes a drum motor 10, a capstan motor 11, an S reel motor 12, a T reel motor 13, other mechanical operation control motors (not shown), a motor such as a rotary encoder 14 for detecting a mechanical deck and a tape loading position, and a rotation. A mechanism device having a body is mounted. In order to smoothly transport the tape and always correctly control the rotation of the drum having the recording / reproducing head, each of the rotating bodies has a detecting device 15 to 19 for detecting a rotational position (angle). It is installed. The mechanism control processor 20 calculates values such as the number of rotations, the position, and the angle based on a detection signal from each of the motors 10 to 13 or the rotary encoder 14 based on an instruction from a control device (not shown) that controls the entire apparatus. Feedback control is performed via the drive circuits 21 to 24 so that the value becomes a desired value.

FIG. 2 is an explanatory view showing a first embodiment in which a pattern is formed on the surface of a drum. For example, the present invention can be implemented when the rotating body is in the form of a drum, or by mounting a detection drum on a rotating shaft. A pattern 31 (represented by a vertical line) is formed on the side surface of the drum 30. As will be described later, the pattern portion has, for example, a lower reflectance of light than other portions. Laser light source 3 constituting detection circuits 15 to 19
Reference numeral 2 denotes a semiconductor laser element that generates, for example, infrared laser light, and irradiates the laser light to the side surface of the drum 30 on which the pattern 31 is formed. The optical sensor 33 incorporates a light detecting element such as a photodiode, for example, and outputs an intensity signal of reflected light from the drum 30 in combination with an optical system device such as a lens.

FIG. 3 is an explanatory view showing a second embodiment in which a pattern is formed on the surface of a disk. The second embodiment is the same as the first embodiment except that the drum is a disk and the pattern is formed on the upper surface of the disk. In addition,
2 and 3, the shapes of the drum and the disk such as the radius and length are arbitrary, and the positions of the laser light source 32 and the optical sensor 33 are drawn away from the pattern formation surface. The position of the optical sensor 33 may be very close to the pattern.

FIG. 4 is an explanatory diagram showing a first embodiment of a pattern in which a pattern in which the distance and the reflection direction change is formed. In this embodiment, irregularities as shown are provided on the surface of the metal drum 30 or the disk 40. Such irregularities can be formed by a known method such as cutting, pressing, casting, etching, or the like. The finish of the pattern surface may be uniform, or, for example, the reflectance of the laser beam may be different for each of the convex portion 50, the concave portion 51, and the inclined portion 52.

In the lower part of FIG. 4, the output waveform of the intensity signal of the laser beam detected by the optical sensor 33 corresponding to the pattern disclosed in the middle is disclosed. Convex part 50
In, since the distance between the light source 32 or the sensor 33 and the pattern surface is short, the amount of light reaching the optical sensor 33 is large, and the output signal level becomes high. On the other hand, in the concave portion 51, the distance becomes longer, and the output signal level decreases.
In the inclined portion 52, the main reflection direction of the laser light is in a direction other than the optical sensor 33, so that the level is further reduced.

The mechanism control processor 20 shown in FIG. 1 converts the output signal into a digital signal, converts the analog signal into a digital signal, and compares it with a predetermined threshold value.
2 can be calculated, and the position (rotation angle) and speed of the rotating body can be calculated.

If the optical system of the optical sensor 33 is focused on the surface of the convex portion 50, the concave portion 51 will not be in focus, and the level difference will be further increased. Further, when the laser light source is irradiated obliquely to the pattern surface as shown in the figure, the irradiation position is different between the convex portion and the concave portion. Therefore, for example, if the focal point of the optical system of the optical sensor 33 is set to the irradiation position of the projection 50, the position is shifted in the projection, so that the level difference also increases.

FIG. 5 is an explanatory view showing a second embodiment of a pattern in which a pattern in which the reflectance changes is formed. This embodiment is an example in which a low reflectance portion 60, a medium reflectance portion 61, and a high reflectance portion 62 are repeatedly formed on the surface of a drum or a disk. Such a pattern, for example, etching and laser processing on the surface finished to high reflectivity,
It can be formed by reducing the reflectance of a specific area by performing a press working or the like.

In FIG. 5, the middle pattern shows a state in which the pattern surface is viewed from the vertical direction, and there is no step on the pattern surface as in the first embodiment. In addition, in order to separate the regions of each reflectance, a narrow region having a different reflectance from both sides may be provided between the respective regions.

In the lower part of FIG. 5, the output waveform of the intensity signal of the laser beam detected by the optical sensor 33 corresponding to the pattern disclosed in the middle is disclosed. In the low reflectance section 60, the amount of light reaching the optical sensor 33 is small, and the output signal level is low. On the other hand, the high reflectance portion 62
In, the output signal level increases.

The mechanism control processor 20 shown in FIG. 1 converts the output signal into a digital signal, converts the analog signal into a digital signal, compares it with a predetermined threshold value, and thereby obtains a low reflectance section 60, a medium reflectance section 61, and a high reflectance section 62. , The start and end times can be calculated, and the position (rotation angle) and speed of the rotating body can be calculated. Further, for example, the direction of rotation can also be determined based on which of the higher and lower reflectance portions comes after the middle reflectance portion 61.

FIG. 6 is an explanatory view showing a third embodiment of a pattern in which a pattern whose reflection direction changes is formed. FIG.
(A) is a pattern in which a groove 70 having a V-shaped cross section is provided as a pattern in a direction perpendicular to the rotation direction of the surface of the rotating body.
A laser light source 32 and an optical sensor 33 (not shown)
Are installed so that the output signal level becomes high in portions other than the groove 70. In the portion of the groove 70, the output signal level decreases similarly to the inclined portion 52 of FIG. 4 of the first embodiment of the pattern. FIG. 6B shows a pattern in which a projection 71 having a V-shaped cross section is provided in a direction perpendicular to the rotation direction of the surface of the rotating body. Also in this embodiment, the output signal level is reduced at the protrusion 71 in the same manner as in the case of the groove 70.

In the embodiment described above, the pattern may be provided in all regions on the circumference or may be provided only in a specific region. When providing a pattern in all areas,
For example, a pattern in which only one appears on the circumference, that is, the length of the convex portion 50 in the first embodiment or the low reflectivity portion 60 in the second embodiment is changed by one, or the groove 70 in the third embodiment is changed. Alternatively, a pattern in which the distance between the protrusions 71 is changed by one is provided, and the absolute position (angle) of the rotating body can be detected by detecting the pattern.

Although the embodiments of the present invention have been disclosed above, the present invention may have the following modifications. In the embodiment, three types of embodiments of a combination of patterns having different distances and reflection angles, a pattern having different reflectances, and a pattern having different reflection angles have been disclosed. The pattern can be formed by one of the rates, or any combination of two or all three. In the example,
Although an example using a laser light emitting element as a light source has been disclosed,
By optimizing the light emitting / receiving element and the optical path, any light source such as an LED, a lamp, and a discharge tube can be used. In addition to metal, plastic can be used as the material of the object used for the rotating body, and a substance in which the crystal orientation is changed periodically instead of physical processing can be used for the same purpose. In this case, there is a possibility that the cost can be further reduced as compared with the physical processing. In the embodiment, the example in which the present invention is applied to the tape backup device is disclosed, but the present invention is applicable to any device having a rotating body.

[0019]

As described above, in the present invention,
In a system that detects the rotation speed of a rotating part, a physical uneven pattern is formed on the surface by machining or etching without adding other substances to the rotating body,
Since the pattern is detected by the optical sensor, the formation of the pattern on the surface of the rotating body can be replaced with easier physical processing or chemical processing, which simplifies the manufacturing process and also prevents the pattern from being displaced or separated. There is an effect that can be. Further, as compared with the detection by the conventional magnetic head, the distance between the rotating body and the detection unit can be made wider, so that the foreign substance can be prevented from being caught, and the binary detection can be increased to the multi-value detection. There is also an effect that the rotation can be determined. Further, the same detection device and signal processing method can be used for a plurality of types of rotating bodies, so that there is an effect that the number of types of components can be reduced and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a mechanism control circuit of a VTR according to the present invention.

FIG. 2 is an explanatory view showing a first embodiment in which a pattern is formed on a drum surface.

FIG. 3 is an explanatory view showing a second embodiment in which a pattern is formed on the disk surface.

FIG. 4 is an explanatory diagram showing a first embodiment of a pattern in which a pattern in which the distance and the reflection direction change is formed.

FIG. 5 is an explanatory diagram showing a second embodiment of a pattern in which a pattern in which the reflectance changes is formed.

FIG. 6 is an explanatory view showing a third embodiment of a pattern in which a pattern whose reflection direction changes is formed.

[Explanation of symbols]

10: drum motor, 11: capstan motor, 12
.. S reel motor, 13 T reel motor, 14 rotary encoder, 15-19 detection circuit, 20, mechanism control processor, 21-24 drive circuit, 30 drum, 31, 41 pattern, 32 laser light source , 33 ...
Optical sensor, 40 ... disk

Claims (3)

[Claims] A rotating body having a surface processed so that at least one of a reflectance, a reflecting direction, and a distance from a rotation axis forms a different pattern; light source means for irradiating the rotating body with light; A rotation state detection device, comprising: detection means for detecting the intensity of light reflected from the rotating body. 2. The apparatus according to claim 1, further comprising calculation means for inputting output information of said detection means and calculating at least one of an angular velocity, a linear velocity, a rotation position, a rotation angle, and a rotation direction of the rotating body. The rotation state detecting device according to claim 1, wherein 3. The rotation state detecting device according to claim 1, wherein the pattern is formed by machining or etching.