Dynamic information storage or retrieval – Specific detail of information handling portion of system – Electrical modification or sensing of storage medium
Reexamination Certificate
2002-03-06
2004-02-03
Hindi, Nabil (Department: 2655)
Dynamic information storage or retrieval
Specific detail of information handling portion of system
Electrical modification or sensing of storage medium
Reexamination Certificate
active
06687210
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an information storage apparatus and methods of writing, reading and erasing information using the same, and more particularly, to a high-density information storage apparatus using electron emission and methods of writing, reading and erasing information using the same.
2. Description of the Related Art
Recently, as recording media enabling high-density recording are developed, devices using them have been developed. Information storage apparatuses with a high-density information recording medium such as CDs or DVDs write information to the high-density recording medium, or read or erase information from the high-density recording medium using a laser. Accordingly, it is preferable to use a short-wavelength laser beam which can reduce the area of a beam spot formed on the surface of a high-density recording medium in order to write information to the high-density recording medium.
Since there is a limit in decreasing the wavelength of a laser beam, the performance of information storage apparatuses for writing, reading and erasing information using a laser beam is also limited.
Meanwhile, vertical magnetic recording apparatuses which use a probe instead of a laser for writing, reading and erasing information have limited storage performance depending on the size of the probe.
Therefore, there have been provided alternative methods of bringing a tip, which is used for a scanning probe microscope (SPM) or an atomic force microscope (AFM), in contact with or close to a recording medium to write, read or erase information. The AFM falls under the SPM and uses atomic force between a tip and a sample. However, such methods have problems with abrasion and vibration of a tip and slow recording and writing speed.
FIG. 1
is a schematic diagram of a disc apparatus using a conventional SPM probe. Referring to
FIG. 1
, the disc apparatus includes a disc
8
, a head
9
, and an optical system
100
. The disc
8
includes a circular substrate
8
a,
an electrode layer
8
b
formed on the circular substrate
8
a,
and a ferroelectric layer
8
c
formed on the electrode layer. The head
9
includes a microtip
9
a
for writing information by polarizing the ferroelectric layer
8
c
and for plying the surface of the disc
8
by an amount corresponding to a quarter of the wavelength of light in a vertical direction from the surface of the disc
8
according to the polarity of the dielectric polarization to read information, and a reflective unit for reflecting light. The optical system
100
recognizes a difference in optical path attendant on the vertical reciprocating motion of the head
9
to detect the recording information.
For the disc
8
, the electrode layer
8
b
and the ferroelectric layer
8
c,
to which information is written using dielectric polarization, are sequentially stacked on the circular substrate
8
a.
The head
9
is realized as an SPM probe. The head
9
includes a microtip
9
a,
a reflector
9
b
for reflecting light, and an arm
9
c
for supporting the microtip
9
a
and the reflector
9
b.
The optical system
100
includes a laser diode, i.e., a light source
1
, a collimating lens
2
for converting light emitted from the light source
1
into a parallel beam, a beam splitter
3
for transmitting light and reflecting light reflected from the disc
8
, an objective lens
5
for focusing light onto a track of the disc
8
to a diffraction limit, a focusing lens
4
for focusing the reflected light, and a photodetector
7
for converting the focused reflected light into an electrical signal.
The disc apparatus operates according to the following principle. When a slight portion of a ferroelectric film deposited on an electrode plate is polarized using a microtip electrode, the polarized portion can be discriminated from an unpolarized or reverse polarized portion by moving the microtip
9
a
to which a predetermined voltage is applied and understanding a difference in electrostatic force therebetween. Accordingly, a different magnitude of electrostatic force is applied to the microtip
9
a
of the head
9
, to which the predetermined voltage is applied, according to the degree of polarization on the surface of the disc
8
. The electrostatic force raises or drops the microtip
9
a
by &lgr;/4. Only light having an optical path difference of &lgr;/2 is split by the beam splitter
3
to be incident to the photodetector
7
and then detected by the photodetector
7
.
As described above, in the SPM technique of measuring phenomena acting between a probe and a sample using physical instruments and laser beams, it is required that the tip of the probe be extremely close to the sample, and the tip be very sharp. Accordingly, the tip is easily worn away. When the tip is worn away or vibrates, the distance between the tip point and the sample changes, which makes it difficult to precisely write or read information. In addition, a high degree of dependence on the flatness of a recording medium results in relatively low information writing or reading speed.
SUMMARY OF THE INVENTION
To solve the above-described problems, it is a first object of the present invention to provide an information storage apparatus for overcoming a problem of abrasion or vibration of a member such as a tip used for writing and reading information, preventing information writing and reading speed from dropping, and storing much more information in a unit area.
It is a second object of the present invention to provide methods of writing, reading and erasing information using the above information storage apparatus.
To achieve the first object of the invention, there is provided a high-density information storage apparatus including a lower electrode, a photoconductive layer and a recording medium sequentially provided on the lower electrode, a conductive layer converting unit for making the photoconductive layer conductive, a data write and read unit for writing data to the recording medium or reading data from the recording medium, a data loss preventing unit for preventing loss of data during data write and read operations, and a power supply connected to the lower electrode and the data write and read unit, for supplying voltage necessary for reading and writing data.
Here, the recording medium is a material layer in which the conductivity changes when charged particles are injected thereto and is realized as an amorphous dielectric substrate. The data write and read unit is a charged particle emitting unit which writes data by injecting charged particles into the recording medium and reads data by detecting charged particles emitted from the recording medium.
The high-density information storage apparatus further includes a gate between the charged particle emitting unit and the recording medium. The gate allows only some of the charged particles emitted from the charged particle emitting unit (the recording medium) to reach the recording medium (the charged particle emitting unit).
The power supply includes a first power supply for applying a predetermined voltage between the lower electrode and the gate, and a second power supply for applying a predetermined voltage between the gate and the charged particle emitting unit.
The charged particle emitting unit includes an emitter for emitting charged particles, and an emitter holder connected to the power supply and disposed above the recording medium, for controlling the motion of the emitter.
In addition, the data loss preventing unit is a charged particle control unit for controlling charged particles emitted from the emitter so that they reach a predetermined region of the recording medium directly below the emitter or controlling charged particles emitted from the recording medium so that they reach the emitter directly above the recording medium. The data loss preventing unit is realized as a magnet. Here, the magnet includes a first magnet provided above the emitter holder and a second magnet provided below the lower electrode. The first and second magnets
Choi Won-bong
Kim Byong-man
Yoo In-kyeong
Burns Doane , Swecker, Mathis LLP
Hindi Nabil
Samsung Electronics Co,. Ltd.
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