Electricity: measuring and testing – Magnetic – Displacement
Reexamination Certificate
2001-10-24
2004-04-06
Adams, Russell (Department: 2862)
Electricity: measuring and testing
Magnetic
Displacement
C324S207250
Reexamination Certificate
active
06717400
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to pulse signal generators.
2. Description of the Related Art
Pulse signal generators responsive to the position or speed of a moving object or a variety of operations have been used in the fields of automatic controls, and electrical and electronics equipment.
An example of the pulse signal generators of this type is a rotation detector that employs an electromagnetic, light pick-up, or Hole or magnetic reluctance element. The electromagnetic type, however, suffers from a low output at low speed rotations. The light pick-up type requires a broadband d-c amplifier and a dust-proof structure. The Hole or magnetic reluctance type requires a plurality of elements and an amplifier. Some elements of the light pick-up/Hole/magnetic reluctance type are too sensitive to temperatures to be used in the atmosphere that can have a large temperature change.
Consequently, where the rotation detector is used to detect the rotary speed or position of a crank or cam shaft of a car, it is impossible to detect very low to high speed rotations. In addition, it is necessary to provide an interface circuit for an engine control module. Moreover, the rotation detector is not suitable for use in automobiles where it can be exposed to temperature changes or noise. Furthermore, it is difficult for the rotation detector to make a stop/move decision (whether the car is at rest or in motion) when the power is on.
Japanese patent application Kokai No. 2000-101401 discloses a pulse signal generator that employ a magnetic element wire capable of producing large Barkhausen jumps to detect very low to high speed rotations. The pulse signal generator is able to resolve the above-mentioned problems but needs further improvements for use in automobiles.
For example, in order to increase the change of a magnetic field applied to the magnetic element wire under set and reset conditions, an adjusting yoke is attached to the rear face of the magnet, the length of the magnetic element wire is reduced below a half of the length of the magnet and yoke combined, the magnetic fields by a pair of magnets are made different by changing the power, volume, or shape of the magnets, the position of the magnetic element wire is changed relative to the magnets, or the magnets are tilted relative to each other.
Also, it is necessary to reduce the manufacturing cost and size of a unit, the time for assembly and adjustment, variations in the product quality, and the product yield. The pulse signal generator of JP 2000-101401, however, fails to meet these requirements.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention to provide a pulse signal generator capable of meeting such requirements as described above.
According to an embodiment of the invention there is provided a pulse signal generator comprising a magnetic element capable of producing large Barkhausen jumps; a generating unit for generating a magnetic field, which is changed by the object to be detected to cause the magnetic element to produce the large Barkhausen jumps, the generating unit consisting of a pair of elongated magnet/yoke combinations provided on opposite sides of the magnetic element such that their poles are oriented in opposite directions, forming a detecting area at an end thereof; a detecting unit for detecting the large Barkhausen jumps to produce a corresponding pulse signal; the magnetic element having a first length between a second length of the magnet/yoke combinations and a half of the second length and provided toward the detecting area; and an adjusting yoke movable along one of the elongated magnet/yoke combinations.
According to another embodiment of the invention there is provided a pulse signal generator comprising a magnetic element capable of producing large Barkhausen jumps; a generating unit for generating a magnetic field, which is changed by the object to be detected to cause the magnetic element to produce the large Barkhausen jumps, the generating unit consisting of a pair of elongated magnet/yoke combinations provided on opposite sides of the magnetic element such that their poles are oriented in opposite directions, forming a detecting area at an end thereof; a detecting unit for detecting the large Barkhausen jumps to produce a corresponding pulse signal; the magnetic element having a first length between a second length of the magnet/yoke combinations and a half of the second length and provided toward the detecting area; and the magnetic element being made movable such that a first distance between the magnetic element and one of the elongated magnet/yoke combinations and a second distance between the magnetic element and the other of the elongated magnet/yoke combinations are different.
According to sill another embodiment of the invention there is provided a pulse signal generator comprising a magnetic element capable of producing large Barkhausen jumps; a generating unit for generating a magnetic field, which is changed by the object to be detected to cause the magnetic element to produce the large Barkhausen jumps, the generating unit consisting of a pair of elongated magnet/yoke combinations provided on opposite sides of the magnetic element such that their poles are oriented in opposite directions, forming a detecting area at an end thereof; a detecting unit for detecting the large Barkhausen jumps to produce a corresponding pulse signal; the magnetic element having a first length between a second length of the magnet/yoke combinations and a half of the second length and provided toward the detecting area; and the magnetic element being made movable such that a first distance between the magnetic element and an upper edge of the elongated magnet/yoke combinations and a second distance between the magnetic element and a lower edge of the elongated magnet/yoke combinations are different.
REFERENCES:
patent: 5210490 (1993-05-01), Munch et al.
patent: 6566861 (2003-05-01), Ito et al.
patent: 0987522 (2000-03-01), None
patent: 0987523 (2000-03-01), None
Ito Tomoaki
Kubota Tadashi
Masuzaki Yasuhiro
Tanaka Masami
Adams Russell
Hirose Electric Co. Ltd.
Kanesaka & Takeuchi
Zaveri Subhash
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