Coded data generation or conversion – Digital pattern reading type converter – Magnetic – inductive or capacitive
Patent
1999-10-14
2000-12-12
Young, Brian
Coded data generation or conversion
Digital pattern reading type converter
Magnetic, inductive or capacitive
H03M 122
Patent
active
061604992
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a magnetic encoder apparatus.
DESCRIPTION OF RELATED ART
Conventionally, as the first conventional example, as a gear type magnetic encoder, an encoder shown in FIG. 6 is used. In FIG. 6, a magnetic sensor 1 attached with a bias magnet 2 is oppositely arranged to a magnetic substance gear 81. Operations thereof will be described below. When the magnetic substance gear 81 is rotated and each cog approaches the magnetic sensor 1, magnetic flux from the bias magnet 2 easily pass through the gear, and the magnetic flux applied to the magnetic sensor 1 is increased. When the gear is further rotated and the cog goes away from the magnetic sensor 1, magnetic resistance is increased, and the magnetic flux applied to the magnetic sensor 1 is decreased. As described above, a change of magnetic flux due to a change of magnetic resistance is detected by the magnetic sensor 1 composed of magnetoresistive elements, and is converted into an electric signal. Further, the change of the electric signal is wave-shaped by a comparator 73 and a square wave is obtained. In this system, a gear is used and a change of reluctance of the magnetic circuit is utilized, and therefore this system is called a reluctance type.
As the second conventional example, an example as shown in FIG. 7 is disclosed (in Japanese Patent Publication No. 5-52584A). In this example, a rotation disk 10 which is a moving body, is integrally composed of a disk-like mask member 10d and a disk-like permanent magnet 9. The permanent magnet 9 is magnetized as a single pole in its axis direction, and structured to have a pair of magnetic poles on each side. The mask member 10d is made of soft magnetic substance, and on its peripheral portion, a plurality of slits are formed into ring-like arrangement with a predetermined pitch. According to this structure, in the mask member 10d, a slit portion 10c having high magnetic resistance, and a strip portion 10b having low magnetic resistance are alternately formed along the rotational direction of the rotation disk 10. Thereby, a magnetic pole 10a, in which magnetic flux from the permanent magnet 9 is alternately changed along the outer peripheral portion of the rotation disk 10, is formed. In the structure described above, when the rotation disk 10 is rotated, the magnetic flux affecting from the magnetic pole 10a to the magnetic sensor 1 is periodically changed, and a detection signal which is changed corresponding to the arrangement pitch of the magnetic pole 10a, is outputted from the magnetic sensor 1.
Incidentally, in the gear method as the first conventional example, it is necessary that a magnetic sensor is arranged at a position opposite to the gear, and therefore, there is a problem that a size in the diameter direction is increased, and further, only one kind of signal is obtained by the magnetic sensor. When it is necessary to obtain the other signals such as, for example, a reference signal, a pole sensor signal, or the like, it is required that another gear is prepared, or thickness of the gear is increased to form another cogs for another signal, resulting in a high production cost, which is a problem. Further, in the method in which the rotation disk is formed by integrating a mask member, on which magnetic shield slits are arranged, with the permanent magnet, as in the second conventional example, there is a problem that it is difficult to reduce the thickness of the rotation disk by the influence of a demagnetizing field of the permanent magnet.
DISCLOSURE OF THE INVENTION
The object of the present invention is to provide a thin type high performance encorder apparatus by which the production cost is lowered and plural kinds of signals can be detected, wherein the moving disk is formed into a magnetic thin plate using no permanent magnet, and a plurality of slit tracks are formed thereon, and a magnetic sensor is arranged corresponding to each slit track.
In order to achieve the above object, according to the present invention, there is provided
REFERENCES:
patent: 5625289 (1997-04-01), Daetz et al.
patent: 5774074 (1998-06-01), Cooper et al.
Arinaga Yuji
Murakami Satoshi
Suzuki Koji
Kabushiki Kaisha Yaskawa Denki
Young Brian
LandOfFree
Magnetic encoder apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Magnetic encoder apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magnetic encoder apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-221998