Static information storage and retrieval – Recirculation stores – Magnetic
Reexamination Certificate
1998-04-08
2001-05-22
Zarabian, A. (Department: 2824)
Static information storage and retrieval
Recirculation stores
Magnetic
C365S066000, C365S171000
Reexamination Certificate
active
06236586
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a memory cell, which is formed on a semiconductor substrate constituted of silicon, or the like. This invention also relates to a method of inputting and outputting information.
2. Description of the Prior Art
With the increased use of the Internet in recent years, there has arisen a strong demand for computers, particularly personal computers (hereinbelow referred to as the “PC”), and rapid advances have been made in the related techniques. Also, the market requires products, which have as high a performance as possible and are as cheap as possible, and research has continuously been carried out in order to satisfy the requirements of the market.
One of important factors for determining the performance of computers is a storage device. Currently popular storage devices are semiconductor storage devices, which comprise a semiconductor substrate constituted of silicon, or the like, and memory cells formed on the semiconductor substrate. In order for a storage device to have a high performance, the storage device should primarily satisfy the requirements in that the inputting and the outputting of information can be carried out quickly, in that the memory should have a large capacity, and in that the stored information can be retained with a high stability. It will be possible for computers to take constitutions in accordance with various requirements of the market. However, if both of the requirements for the quick operation and the large capacity are to be satisfied, the cost cannot be kept low. The cost can be kept low by compromising on either one of the two requirements.
In the currently most popular main body memories of PC's, cache memories and main memories are constituted of random access memories (RAM's). As the RAM's, dynamic random access memories (DRAM's) and static random access memories (SRAM's) are used.
The DRAM's have a larger capacity per unit area than SRAM's and can be produced at a low cost. However, the DRAM's have the drawbacks in that, since the takeout of stored information is carried out by the discharging of electric charges, a long time is required to output the stored information, and electric charges must always be supplied (refreshed). With the SRAM's, the takeout of stored information is carried out by the discrimination of the state of a multivibrator. Therefore, with the SRAM's, refreshing operations need not be carried out, and the stored information can be read quickly. However, the SRAM's have the drawbacks in that, due to their complicated structures, the capacity per unit area is smaller than in the DRAM's, and the cost cannot be kept low.
Accordingly, in an ordinary constitution of PC memories, the SRAM's are employed as the cache memories, the DRAM's are employed as the main memories, and the cost is thereby restricted.
Also, with the DRAM's and the SRAM's, the stored information is lost when the electric power source is turned off, and therefore necessary information must be stored on other storage devices, such as disks. Memories, which have the characteristics such that the stored information may not be lost when the electric power source is turned off, include flash memories. However, due to the necessity of a high voltage for the information inputting operation, a limitation on the capacity, and the cost, the flash memories cannot sufficiently satisfy the aforesaid requirements of the current market.
SUMMARY OF THE INVENTION
The primary object of the present invention is to provide a micro magnetic core memory, which serves as a memory cell constituting a storage device capable of satisfying requirements for a main body RAM of a computer in that the inputting and the outputting of information can be carried out quickly, in that a high degree of integration can be achieved easily and a storage device having a large capacity can be produced at a low cost, and in that the stored information can be retained with a high stability without being lost when the supply of electric power is turned off.
Another object of the present invention is to provide a method of inputting and outputting information, in which the micro magnetic core memory is utilized.
The present invention provides a micro magnetic core memory, comprising:
i) a magnetic core, which serves as a storage medium,
ii) a coil, which is located in close vicinity to the magnetic core and magnetizes the magnetic core, and
iii) a sensor, which is located in close vicinity to the magnetic core and detects polarity of magnetization of the magnetic core.
The present invention also provides a method of inputting and outputting information, comprising the steps of:
i) employing a magnetic core, which is a magnetic material, as a storage medium,
ii) locating at least one coil with respect to one magnetic core, the coil serving to magnetize the magnetic core,
iii) magnetizing the magnetic core by the coil, information being thereby written into the magnetic core,
iv) locating at least one sensor with respect to one magnetic core, the sensor serving to detect polarity of magnetization of the magnetic core, and
v) detecting the polarity of magnetization of the magnetic core by the sensor, the stored information being thereby read from the magnetic core.
The micro magnetic core memory in accordance with the present invention serves as a memory cell for constituting a storage device, which takes on the form of an RAM primarily like a DRAM and a SRAM. The micro magnetic core memory in accordance with the present invention has the same advantages as those of the DRAM and the SRAM. Also, with the micro magnetic core memory in accordance with the present invention, as in a flash memory, the stored information is not lost when the electric power source is turned off.
Therefore, in the method of inputting and outputting information, the magnetic core is employed as a storage medium, at least one coil is located with respect to one magnetic core, the magnetic core is magnetized by the coil, and information is thereby written into the magnetic core. Further, at least one sensor is located with respect to one magnetic core, the polarity of magnetization of the magnetic core is detected by the sensor, and the stored information is thereby read from the magnetic core.
In a fundamental constitution of the memory cell, the coil may be wound around the magnetic core, and the sensor may be located in close vicinity to the magnetic core. As the sensor, a thin-film sensor, such as a giant magnetic resistor (GMR) or a magnetic resistor (MR), which is easy to process and has a high resolution, may be employed.
Accordingly, the micro magnetic core memory in accordance with the present invention has the simple structure and does not require complicated structures, such as trenches and stacks. Thus the micro magnetic core memory in accordance with the present invention can be easily integrated to a high degree and can constitute a large-capacity RAM device at a low cost.
In cases where a storage device is produced by integrating the micro magnetic core memory in accordance with the present invention, for example, the magnetic material of a silicon crystal, such as garnet, is appropriate as the material of the magnetic core. Also, as the thin-film sensor for reading the stored information, the GMR or the MR is appropriate. Therefore, mass production of the storage device can be carried out with approximately the same processes as those for the conventional LSI's, and the like.
The micro magnetic core memory in accordance with the present invention has good effects in that it can constitute the storage device having the performance described below.
(1) The inputting and the outputting of information can be carried out quickly.
(2) A high degree of integration can be achieved easily, and a storage device having a large capacity can be produced at a low cost.
(3) The stored information is not lost when the supply of electric power is turned off.
The stora
Nixon & Peabody LLP
Studebaker Donald R.
Zarabian A.
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