WO1999017286A1

WO1999017286A1 - Non-mechanical recording and retrieval apparatus

Info

Publication number: WO1999017286A1
Application number: PCT/US1998/020436
Authority: WO
Inventors: Jerry W. Bohn
Original assignee: Bohn Jerry W
Priority date: 1997-09-30
Filing date: 1998-09-30
Publication date: 1999-04-08
Also published as: US6288995B1; AU9591898A

Abstract

A recording device is disclosed. The recording device (10) generates an electron beam (17) which selectively exposes portions of an electron-sensitive and/or UV light-sensitive film (28) to thereby record digital data on the film. A retrieval device is also disclosed. The retrieval device (100) selectively directs a generated electron beam (117) towards a predefined point on a target (131). The target is simultaneously exposed to a light pattern formed by shining UV light through exposed portions of an electron-sensitive and/or UV light-sensitive film (28) to thereby develop an output signal representative of digital data stored on the film at a location corresponding to the predefined point on the target.

Description

NON-MECHANICAL RECORDING AND RETRIEVAL APPARATUS

FIELD OF THE INVENTION

The present invention relates generally to recording and retrieval devices and,

more particularly, to a device for recording data on an electron-sensitive and/or UV

light- sensitive (e.g., x-ray mammography) film and a device for retrieving the

recorded data from the film.

BACKGROUND OF THE INVENTION

The storage and retrieval of digital data plays a significant role in many

areas of modern technology. For example, computers, compact disk players,

digital video disk players, digitized medical x-rays, and other devices all^"

utilize digital data. As such, each of these devices requires a medium for storing

digital data and, one or more mechanisms for storing and/or retrieving such data to

and from the storage medium.

Due to the critical role digital data plays in the operation of many devices, it is

essential to store such data in a manner that ensures reliable retrieval. In many

instances, it is also important to substantially optimize the speed at which such data

can be retrieved.

Heretofore mechanical devices have played a significant role in retrieval and

recording devices. By way of example, floppy disk drives, hard disk drives, compact

disk drives and digital video disk players, all require sophisticated mechanical

structures which rotate the storage medium during retrieval of digital data. However,

such mechanical devices are susceptible to premature failure. Indeed, in the typical case, the mechanical components of conventional storage and retrieval devices fail

long before the useful lives of the electronics and electrical components associated

with those devices have expired. Thus, there is a need for improved apparatus for

reliably storing and retrieving digital data from a storage medium.

There are many well known storage media for storing digital data. Exemplary

media include floppy disks, hard disks, compact disks, and digital video disks. Such

media can be read-only, such as is typically the case with compact disks and digital

video disks, or read-write, such as is typically the case with floppy disks and hard

disks.

Traditional storage media have suffered from certain drawbacks. For example,

some traditional storage media are expensive to manufacture. In addition, some

traditional storage media are limited in the amount of data they can store per unit of .

space they consume. For example, a traditional 3'/_. inch floppy disk can only store

1.44 megabytes of digital data. Thus, there is a need for an improved storage medium

that is relatively inexpensive to produce and copy, and which has improved data

storage density capabilities and a longer reliable lifespan. Some of these storage

media use magnetic technology which has a very short reliable lifespan. The cd

storage media may have a longer lifespan than the magnetic storage media, but its

reliable lifespan is also considerably shorter than the recently developed electron-

sensitive and/or UV light-sensitive film. SUMMARY OF THE INVENTION

In accordance with an aspect of the invention, an apparatus for recording

digital data on a film is provided. The apparatus includes a vacuum tube having first

and second ends; an electron gun disposed at the first end of the vacuum tube for

discharging a beam of electrons into the tube; and at least one set of focusing lenses

associated with the vacuum tube for focusing the electron beam discharged by the

electron gun. It also includes a support for securing a sheet of film at the second end

of the vacuum tube; a beam deflection system for directing the electron beam to

follow a controlled path; and, means for controlling the electron gun to adjust a

characteristic of

the electron beam to selectively expose portions of the film to thereby record digital

data on the film without moving the film.

In some embodiments, the apparatus is further provided with a faceplate

disposed at the second end of the vacuum tube and an anode disposed adjacent the

support externally to the vacuum tube.

In some embodiments, the beam deflection system comprises deflection

electrodes and a control circuit. In some such embodiments, the control circuit

comprises a synchronization generator.

In some embodiments, the control means comprises a control grid coupled to a

grid control circuit which modulate the electron beam between on and off states

representative of digital data. In such embodiments, the control means modulates the

beam to controUably switch between a natural threshold of radiation associated with a

faceplate disposed at the second end of the vacuum tube. In some embodiments, the control means exposes the portions of the film to

create a pattern of at least partially transparent spots corresponding to digital data.

In some embodiments, the control means periodically records variable

coordinate values with the digital data to facilitate playback. In some such

embodiments, the variable coordinate values are referenced to a predefined location

on the film. Preferably, a reference target is recorded at the predefined location on the

film.

In any of the foregoing embodiments, the film can be either electron sensitive

or UV light sensitive. In embodiments, employing UV sensitive film, the apparatus

further includes a phosphor coated faceplate disposed adjacent the second end of the

vacuum tube, and the beam deflection system directs the electron beam across a

surface of the faceplate and the control means adjusts the beam characteristic to

selectively illuminate positions on the faceplate. The illuminated positions expose

corresponding locations of the film.

In accordance with another aspect of the invention, an apparatus for use with a

light source is provided. The apparatus is adapted for retrieving digital data stored on

a film. It includes a vacuum tube having first and second ends; an electron gun

disposed at the first end of the vacuum tube for discharging a beam of electrons into

the tube; and at least one set of focusing lenses associated with the vacuum tube for

focusing the electron beam discharged by the electron gun. The apparatus also

includes a support for securing a sheet of film at the second end of the vacuum tube

such that light from the light source passes through exposed portions of the film; a target for generating electrical signals when simultaneously exposed to light and

electrons; and a beam deflection system for directing the electron beam towards at

least one predefined location on the faceplate to retrieve data stored on the film

without moving the film.

Preferably, the apparatus further includes an output associated with the target

for coupling the electrical signals generated by the target to an external device. The

electrical signals are representative of digital data stored on the film.

Preferably, the apparatus is also provided with a faceplate disposed at the

second end of the vacuum tube, and the target is preferably implemented as an

electrode disposed on the faceplate. In such embodiments, the target generates

electrical signals when the electron beam traverses a spot on the target illuminated by

the light passing through an exposed portion of the film.

In some embodiments, the apparatus is further provided with an optical lens

for focusing the light passing through the exposed portions of the film on the target.

In some such embodiments, the lens is integrally focused with a faceplate disposed at

the second end of the vacuum tube.

Preferably, the apparatus is further provided with an output circuit coupled to

the target. The output circuit includes a power supply and a biasing resistor.

In some embodiments, the beam deflection system comprises a drive circuit

and a set of electrostatic grids. In such embodiments, the drive circuit may optionally

comprise a microprocessor, and/or the drive circuit may optionally drive the

electrostatic grids to cause the electron beam to traverse predefined locations of the faceplate. In some such embodiments, the predetermined locations are identified by

referencing a target location recorded on the film.

In some embodiments, the apparatus is provided with a map stored on the film

and identifying starting points of predetermined blocks of data on the film to facilitate

location of the predetermined blocks.

In some embodiments, the drive circuit drives the electrostatic grids to

playback a continuous stream of data stored on the film.

In some embodiments, the drive circuit comprises a generator to control a

retrieval rate to ensure an appropriate playback speed.

In some embodiments, the apparatus includes a light source disposed adjacent

the second end of the vacuum tube. Preferably, the light source comprises an

ultraviolet light.

In any of the foregoing embodiments, the film may comprise a write once,

read many film, and/or a write many, read many film.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a recording device constructed in

accordance with the teachings of the instant invention, utilizing an external anode.

FIG. 2 is a schematic illustration of another recording device constructed in

accordance with the teachings of the instant invention, utilizing a phosphor-coated

faceplate.

FIG. 3 is a block diagram illustrating exemplary applications for the recording

devices of FIGS. 1 and 2. FIG. 4 is a schematic illustration of an exemplary scanning technique.

FIG. 5 is a schematic illustration of a retrieval device constructed in

accordance with the teachings of the instant invention.

FIG. 6 is a block diagram illustrating exemplary applications for the playback

device of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Recording apparatus 10, 40 constructed in accordance with the teachings of

the instant invention are illustrated in FIGS. 1 and 2. As explained in detail below,

the recording apparatus 10, 40 are advantageously adapted to record data upon a

suitably positioned film such as electron-sensitive and/or UV light-sensitive film

without the assistance of mechanical devices. In other words, the apparatus provide

reliable and accurate means for recording digital data which do not suffer from the

susceptibility to mechanical failure typical of traditional recording apparatus.

As mentioned above, the recording apparatus 10, 40 are preferably employed

to record data on an electron-sensitive and/or UV light-sensitive film. Although the

commercially available film sold by Sterling Diagnostic Imaging Corp. under the

tradename MicroVision-C is presently preferred in this role, persons of ordinary skill

in the art will readily appreciate that other films could likewise be employed without

departing from the scope of the invention. There are films that are superior than the

above-mentioned film. However, such films are proprietary to the U.S. Government

at the present time. As film technology improves with respect to resolution and

speed, the density of data stored on the film can be increased. Density is based on the

resolution of the film. High-resolution film requires longer exposure to the electron

beam; whereas low-resolution film requires less exposure time of the electron beam.

Therefore, low-resolution film can be scanned at a faster scanning rate. An inherent

property of electron-sensitive and/or UV light-sensitive film is: as the resolution

(density) increases, the speed decreases. Therefore, to record very large quantities of data on the film, the recording cannot be done in real time. This is not a critical

factor for most data such as videos and music. However, when it is critical to record

in real time, the quantity of data that can be recorded, decreases. Some of the speed

limitations can be compensated for by increasing the film processing time. There are

other films that are used for laser imaging that do not use liquid processing (e.g.,

carbon granules) and, therefore, do not require any processing time. This type of film

can also be used without departing from the scope or spirit of the invention. In any

event, the film is preferably selected such that exposure to electrons and/or UV light

(and further chemical processing) causes a darkening or lightening of the exposed

sections.

For the purpose of providing a suitable environment for developing and

controlling an electron beam, the recording apparatus 10, 40 are each provided with a

vacuum tube 12 of conventional design. The vacuum tube 12 preferably comprises a

cathode-ray tube, similar to the low energy charged-induced voltage alterations

(LEVICA) scanning electron microscope developed by Sandia National Laboratory.

As shown in FIGS. 1 and 2, the vacuum tubes 12 include a sealed volume which has

had substantially all air removed therefrom by a pump or the like. Such vacuum tubes

are commonly used in television and scanning x-ray microscopes and will not be

further discussed here.

To generate an electron beam, the recording apparatus 10, 40 are each further

provided with an electron gun 14 comprising a filament 16, a cathode 13, an anode

18, and a control grid 15. The filament 16 of each gun 14 is coupled to a source of highly regulated and controlled voltage via a lead 20. The voltage should be

sufficient to generate enough heat to excite the cathode 13 to cause a high electron

flow. As shown in FIGS. 1 and 2, when suitably energized, the electron guns 14 will

each develop and discharge a beam 17 of electrons into their respective vacuum tube

12.

The discharged electrons are focused into a very fine beam 17 by electrostatic

beam focusing and condensing lenses 22. In the preferred

embodiment three such lenses 22 are provided for each tube 12, but other numbers of

lenses could also be employed. Regardless of the number of lenses selected, the

lenses 22 preferably generate one or more electrostatic fields which deflect and focus

the electron beam 17. As will be appreciated by those of ordinary skill in the art, the

lenses 22 can be implemented as either capacitive or inductive devices without

departing from the scope of the invention. Electrostatic focusing is preferred because

it achieves: 1) minimum geometric distortion (because of a more uniform field); 2)

low shading; 3) uniform resolution over the scanned area; 4) shorter flyback

(because no resonant energy is stored in the deflection coil); 5) high registration

stability (because of no heating of deflection electrodes compared to the heating of

deflection coils); and 6) no eddy-currant losses and resultant line-start nonlinearity.

As shown in FIG. 1, the end of the vacuum tube 12 opposite the electron gun

14 is sealed by a high quality, substantially flat faceplate 24. In the embodiment

shown in FIG. 1 , a film support 26 comprising an external anode 27 is disposed

adjacent this faceplate 24 such that a sheet of film 28 supported thereon can be positioned adjacent, and preferably in contact with, the faceplate 24. The close

proximity between the film 28 and the faceplate 24 maximizes the effectiveness of the

electron beam's radiation.

The apparatus 40 shown in FIG. 2 is substantially the same as the apparatus 10

shown in FIG. 1 , except that the faceplate 24 of the apparatus 40 has an ultra-fine

phosphorus coating 41 and the film support 26 of the apparatus 40 does not have an

external anode 27. In recording apparatus 10, it is necessary to place an anode

outside the vacuum tube 12 to increase the intensity and the quantity of the electrons.

As a safety precaution, but not necessary for the scope of this invention, the external

anode 27 may be at the same potential as the earth, and all other voltages negative

according to their normal function. Because of the ultra-fine phosphorus coating, the

apparatus 40 does not require the external anode 27.

In the apparatus 40, the striking of the electron beam 17 against the

phosphorus coating causes the phosphor to glow, thereby emitting photons (light)

which expose the film. Because blue (UV) phosphorus has a high photon output, it is

preferred for use in the coating.

For the purpose of directing the electron beam 17 along a predefined path, the

vacuum tube 12 is further provided with an electrostatic beam deflection system

comprising electrostatic electrodes 30 coupled to a control circuit 34. Control circuit

34 preferably energizes the electrostatic electrodes 30 to thereby direct the beam 17

along a continuous path across the surface of the faceplate 24. In the preferred

embodiment, four electrostatic electrodes 30 are provided (one on each side of the vacuum tube 12), and the control circuit 34 is implemented by a suitably programmed

synchronization generator. However, persons of ordinary skill in the art will readily

appreciate that other numbers of electrostatic electrodes and/or other implementations

of the control circuit 34 could also be employed without departing from the scope of

the invention. The focusing and intensity of the electron beam must be adjusted for

the distance the beam travels from side to side and top to bottom as it scans the film

28 in apparatus 10, and/or the phosphorus coating 41 in apparatus 40. The adjusting

is done through programming of the software in the control circuit 34.

In order to encode the electron beam with data to be recorded on the film 28,

the recording apparatus is provided with a grid control circuit 32. The control grid 15

is preferably used to modulate the electron beam 17 between "on" and "off states

representative .of digital data to be recorded. Preferably, the electron beam 17 will

not be completely turned off during recording. On the contrary, the beam is

preferably generated on a continuous basis but modulated by the control grid 15 to

selectively and controUably switch between slightly above and slightly below the

natural threshold of radiation for the film/faceplate combination (e.g., the level of

voltage for which any less will not expose the film 28). In other words, the control

grid 15 is adapted to modulate the beam 17 in accordance with a stream of data bits to

be recorded, such that beam 17 exposes a corresponding pattern of points on the film

28 as the scanning electrostatic electrodes 30 direct the beam along its continuous

path. Preferably, the film 28 is selected such that the pattern of exposed sections

created by the modulated beam 17 comprises a pattern of at least semi-transparent spots. The semi-transparent spots can transmit UV light having a wavelength falling

within a range of predefined wavelengths. The non-exposed sections of the film will

preferably prevent light (photons) from passing.

The recording devices 10, 40 are particularly well suited for recording digital

data. As those skilled in the art will readily appreciate, the recording devices 10, 40

can be programmed to record digital " 1 "s as a dark spot (i.e., an unexposed section of

film) and "0"s as an at least semi-transparent spot, or vice versa, without departing

from the scope of the invention. As those skilled in the art will further appreciate, the

number of bytes that can be recorded on a given sheet of film by the recording

apparatus is dependent upon the size of the electron beam, the size of the film, the

resolution of the film, and the speed of the film. It is, therefore, preferable to match

the size of the beam 17 to the resolution of the film 28 to maximize the amount of

data a sheet of film of a given size can record. When the above-noted presently

preferred film is employed, it is preferred that the electron beam be focused to one

micron or less at its tip such that the exposed sections of the film have a radius of

approximately one-half micron. When the preferred criteria are followed, it is

estimated that a microfiche-sized piece of film will hold approximately fifty gigabytes

of data.

As mentioned above, the electron beam is preferably not turned off during

recording thereby avoiding "splattering" of the beam and, thus, unwanted exposure of

the film 28 which might otherwise be caused by turning the beam on and off. As also

mentioned above, the movement of the beam 17 is preferably continuous across the film 28, thereby preventing exposure of the same spot twice. A preferred path for

movement of the beam 17 across a rectangular film sheet 28 is shown in FIG. 4.

Preferably, the path is completely continuous with no breaks. The dashes and dots in

FIG. 4 are representative of "Ons (l's)" and "Offs (O's)". Preferably, the physical

width between horizontal paths is the same as the space between successive bits

("Ons" and "Offs"). Those skilled in the art will, however, appreciate that other

paths, including, without limitation, discontinuous and/or circular paths, could also

be employed without departing from the scope of the invention.

In order to facilitate subsequent playback or retrieval of the recorded

data, the recording device is preferably programmed to imprint a target, symbol or

pattern at a predefined location on the film. The target, symbol or pattern is then

understood to represent a predefined reference location on the film (such as 0, 0 in an

x , y rectangular coordinate system), which can be

subsequently used to randomly locate and retrieve data stored at any desired

point on the film as explained below. Preferably, the reference target is located in a

corner of the film sheet at a starting point for recording data.

To further facilitate retrieval of recorded data, the control grids 15 of the

recording devices 10, 40 are preferably programmed to modulate the beam 17 to

record a coordinate value defined relative to the reference target for every predefined

unit of data recorded on the film. For example, to record the digital byte "00000000"

when the next section of film available for recording is at (1,0) in an x, y coordinate

system, the apparatus 10, 40 would record two coordinate values such as "001" and "000" followed by the byte "00000000". While the predefined unit can comprise any

convenient size or group of data bits, in the preferred embodiment the predefined unit

comprises eight bits or a byte of data. Similarly, while any desired coordinate system

could be employed, in the presently preferred embodiment, an x, y coordinate system

keyed to the above-noted reference point is utilized.

In order to provide a convenient means for loading film into the recording

apparatus 10, 40, a conventional mechanical transport mechanism (not shown) can be

provided for each apparatus 10, 40. As will be appreciated by those skilled in the art,

the transport mechanism can be implemented in any number of ways without

departing from the scope of the invention. By way of example, not limitation, it can

be implemented as a sliding drawer in a manner analogous to a conventional loading

tray in a single disk compact disk player. The mechanism can be motor driven or

manually powered. Optionally, film support 26 can form part of the transport

mechanism. For instance, the film support 26 may comprise the sliding drawer.

Exemplary environments of use for the recording apparatus 10, 40 are

illustrated generally in FIG. 3. As shown in that figure, the recording apparatus 10, 40

can be used with both analog and digital sources 43 and 44. Exemplary analog

sources 43 include, without limitation, analog televisions, video cassette recorders,

and/or audio devices. Exemplary digital sources 44 include, without limitation, a cd-

rom, a floppy disk drive, a hard disk drive, a computer, a digital video disk player

and/or a digital television. In any event, since in the preferred embodiment, the recording apparatus 10,

40 are used to record digital data, the grid control circuit 32 is preferably provided

with digital data via a digital input circuit 46 which

comprises grid and beam control circuitry 32 and 34, conventional digital processing

circuitry 33, and conventional encoding and error correction circuitry 35. As shown

in FIG. 3, digital sources 44 can be directly connected to the digital input circuit 46.

A conventional analog to digital converter 48 is employed to digitize the output of the

analog source 43 for the digital input circuit 46. Digital input circuit 46 preferably

conditions received input signals for use by the grid control circuit 32. For example,

the input circuit 46 can filter and step received signals to appropriate voltage levels for

use in apparatus 10, 40.

As will be appreciated by those skilled in the art, the physical size of the film

and of the recording apparatus 10, 40 are determined by the intended application. For

example, they can be miniaturized or constructed at a microfiche size. Similarly, the

film can have a sheet format or be constructed

as a coiled strip. Both the size and format are selected to accommodate the desired

quantity and access rate of the data to be stored and retrieved. In one presently

contemplated embodiment, a 5 inch by 5 inch square film sheet is employed.

A retrieval apparatus 100 constructed in accordance with the teachings of the

invention is illustrated in FIG. 5. As explained in detail below, the retrieval apparatus

100 is adapted to retrieve and output data stored on a film, such as the film 28

processed by the recording apparatus 10, 40. As with the recording devices 10, 40, other than an optional film transport device, the retrieval apparatus 100 operates

without the use of mechanical devices and, thus, does not suffer from the

susceptibility to mechanical failure characteristic of prior art retrieval systems which

rely on moving mechanical structures for operation.

The core of the retrieval apparatus 100 is fashioned after a vidicon diode gun

camera tube, with positive grid 115 added before the final beam-defining aperture. As

with the recording apparatus 10, 40, the retrieval apparatus 100 is provided with a

vacuum tube 112. Also like the recording apparatus 10, 40, the vacuum tube 112 of

the retrieval apparatus 100 includes an electron gun 114 including a filament 116, a

cathode 111, a control grid 113, a beam-forming grid 119, an anode 118, a lead 120

coupled to a voltage supply, focusing lenses 122, scanning grids 130, and a glass

faceplate 124. Unlike a vidicon camera tube, this tube utilizes grid control circuitry to

develop a highly defined and intense electron stream. Preferably, the focusing

electrostatic grids 122 focus the electron beam 117 to a tip of one micron; or a

dimension which is selected to match the resolution of the film 28.

In order to generate electrical signals representative of the data stored on the

film 28, the retrieval apparatus 100 is provided with a target 131. Target 131 is a

conventional structure included in commercially available vidicon diode gun camera

tubes. In particular, it comprises an electrode deposited on the surface of glass plate

124. The electrode is coated with a very thin layer of micro-fine UV photo-

conductive material. As is conventional, target 131 is adapted to become conductive

only when a spot on the electrode is contacted by an electron beam 117 of suitable intensity, and the UV photo-conductive material associated with that same spot is

sufficiently excited by UV light. As explained below, that UV light is provided by

shining UV light through an exposed film 28 such that a pattern of UV light

corresponding to the data recorded on the film 28 shines on the target 131. Then, as

the electron beam 117 traces a path across the target 131 , the target 131 outputs a

series of electrical signals corresponding to the data stored on the film 28. Very high

frequency UV light is used because of its very short wavelength and high photon

stream.

In order to locate a light pattern corresponding to the pattern recorded on film

28 on the target 131, a UV light source 180 and an optical lens 182 are provided. As

shown in FIG. 5, the UV light source 180 is positioned beneath film 28, and optical

lens 182 is located between film 28 and glass plate 124 such that the UV light source

180 and optical lens 182 provide a back lighting system which illuminates the target

131 at only the spots where the film has been exposed. Preferably, the light source

180 is a UV black light with a wavelength of 10 to 50 nm.

Although the face plate 124 and the optical lens 182 could be implemented as

separate devices, in the preferred embodiment those structures

are integrally formed. When the plate 124 and the lens 182 form an integral structure,

the plate 124 and the film should be substantially the same size. The integral

plate/lens will preferably transmit parallel light with minimal, if any, light scattering.

Despite the foregoing, those skilled in the art will appreciate that the separate lens 182

and faceplate 124 approach would be advantageous in applications where it is desirable to focus UV light from a relatively large film onto a target 131 of smaller

size than the film within the refracting properties of an optical lens.

Preferably, the film 28 is supported by a frame or the like which does not

interfere with UV light transmission through the operative portions of the film. If

desired, a transport mechanism for loading film such as that described in connection

with the recording apparatus 10, 40 can be provided.

As shown in FIG. 5, target 131 is coupled to an output circuit 190. The output

circuit 190 comprises a power supply 192 coupled to a biasing resistor 194, and a

capacitor 196 acting as a low pass filter. As the electron beam 1 17 traverses the

surface of the target 131, a series of electrical pulses corresponding to spots where

light passed through the film 28 will be generated and output by circuit 190.

In some embodiments, the electrostatic beam control system 122 is provided

with a suitably programmed, microprocessor-based drive circuit. The drive circuit

preferably drives the electrostatic grids 130 to locate and

retrieve the data stored at predetermined locations identified via the reference target

and stored coordinates mentioned above. Such an apparatus shortens retrieval times

and renders the retrieval apparatus 100 "random access" in that data at any location on

the film 28 can be retrieved independently of the remainder of the data stored on the

film 28.

In other embodiments, the drive circuit associated with the electrostatic grids

130 causes the electron beam 117 to continuously trace the path of the stored data

from the starting point at the data path towards the end. Such an approach is advantageous in applications such as video or audio playback where continuous

playback is the dominant mode of operation. Fast forwarding and/or skipping features

can likewise be programmed into the drive circuit such that, upon request from a user,

the retrieval apparatus 100 skips ahead through the stored data. If such features are

included, the film 28 is preferably provided with a map near the beginning of the data

path which identifies the starting points (e.g., the starting coordinates) of certain

groups of data. Providing such a map advantageously enables a user to skip ahead to

predefined locations in the film. This approach permits a user to skip songs, for

example, when the film 28 stores audio recordings.

Regardless of the drive circuit implementation selected, the drive circuit

preferably includes an internal generator which controls the playback or retrieval rate

to ensure appropriate playback speed. Where playback rate is significant, the

appropriate rate is preferably stored on the film 28 and, after retrieval, is used by the

internal generator of the drive circuit to playback data at the required rate.

As will be appreciated by those skilled in the art, light source 180 can be

implemented in many ways without departing from the scope of the invention.

However, it is presently preferred that a substantially even light is employed behind

the film 28, and, thus, on target 131. It is also preferred that the light source provide

ultraviolet light . A Black Light, UV fluorescent light, satisfies these conditions and,

thus, is presently preferred in the role of the light source 180.

FIG. 6 illustrates exemplary environments of use for the retrieval apparatus

100. As shown in that figure, the retrieval apparatus 100 is coupled to suitable interface circuitry 145 of a digital output circuit 146. The digital output circuit 146

includes beam control and grid control circuitry 132, conventional error correction

circuitry 133, conventional data decoding circuitry 134, and a conventional CPU and

system management circuit 135. The digital output circuit 146 can be coupled

directly to a digital device 144 such as a computer, or a digital television.

Alternatively, the digital output circuit 146 can be coupled through a conventional

digital to analog converter 148 to an analog device 142 such as an analog television,

or a stereo amplifier.

As mentioned above, the presently preferred embodiments of the recording

and retrieval apparatus 10, 40, 100 employ MicroVision-C film, a mammography film

with excellent resolution. Since after exposure, this film cannot be erased, it is

intended for write once, read many type applications. For example, this film could be

used as an alternative to compact disks for storing audio data, or as an alternative to

digital video disks, laser disks, or VHS tapes for storing video/audio data such as

movies. If, however, it is desired to use the recording and retrieval apparatus 10, 40,

100 in write many, read many applications, an emulsion such as that used in the

Magneto Optical Disk by Imation, Inc. of St. Paul, MN, which retains its sensitivity

to an electron beam after multiple exposures wherein, where applicable, successive

exposures reverses the effect of predecessor exposures, could be employed. Such an

emulsion would be positioned in a magnetic field during the re-write process. The

noted emulsion would need to be modified to be electron-sensitive, not thermal-

sensitive. Eastman Kodak and Sterling Diagnostic Imaging Corp. both sell such an electron-sensitive and UV light-sensitive emulsion to the public. When such an

emulsion is utilized, exemplary applications of the recording and playback apparatus

include replacing a floppy disk drive and/or a hard disk drive.

In summary, persons of ordinary skill in the art will appreciate that improved

data recording and retrieval apparatus have been disclosed. Among the advantages

enjoyed by the improved apparatus are: the ability to store more data per unit of media

volume (e.g., greater data density storage) than prior art devices; recording and near

instant random access retrieval of data (e.g., near-zero "seek-time"); enhanced

durability as mechanical parts which can wear out,

become misaligned, or require maintenance, are not used in recording or retrieving

data from a suitably positioned film; universality of the data storage film (e.g., the

same piece of film can be employed to store and retrieve data by disparate devices

such as a computer, an audio system and a video system, and data stored by one such

device can be retrieved and used by another); economic manufacturability using

existing facilities and existing methods of mass distribution; and ease of mass-

duplication (e.g., as with conventional photographic film, the film 28 (exposed or

otherwise) could be mass-duplicated for a few cents per copy. The amount of data

that can be stored in this system is limited only by the bandwidth of the light source,

by the resolution of the target material on the faceplate of the electron retrieval tube,

by the resolution and speed of the electron-sensitive film and/or UV light-sensitive

film, and by the resolution of the phosphor coating on the faceplate. As these limitations are reduced, the capacity of data for a 35 mm square film could be

increased in excess of 5 tera-bytes.

Those skilled in the art will further appreciate that, although the invention has

been described in connection with certain embodiments, there is no intent to limit the

invention thereto. On the contrary, the intention of this application is to cover all

modifications and embodiments fairly falling within the scope of the appended claims

either literally or under the doctrine of equivalents.

Claims

What Is Claimed Is:

1. An apparatus for recording digital data on a film comprising:

a vacuum tube having first and second ends;

an electron gun disposed at the first end of the vacuum tube for

discharging a beam of electrons into the tube;

at least one set of focusing lenses associated with the vacuum tube for

focusing the electron beam discharged by the electron gun;

a support for securing a sheet of film at the second end of the vacuum tube;

a beam deflection system for directing the electron beam to follow a controlled

path; and,

means for controlling the electron gun to adjust a characteristic of

data on the film without moving the film.

2. An apparatus as defined in claim 1 further comprising a faceplate

support externally to the vacuum tube.

3. An apparatus as defined in claim 1 wherein the beam deflection system

comprises deflection electrodes and a control circuit.

4. An apparatus as defined in claim 3 wherein the control circuit comprises

a synchronization generator.

5. An apparatus as defined in claim 1 wherein the control means comprises

a control gird coupled to a grid control circuit which modulate the electron beam

between on and off states representative of digital data.

6. An apparatus as defined in claim 5 wherein the control means

modulates the beam to controUably switch between a natural threshold of radiation

associated with a faceplate disposed at the second end of the vacuum tube.

7. An apparatus as defined in claim 1 wherein the control means exposes

the portions of the film to create a pattern of at least partially transparent spots

corresponding to digital data.

8. An apparatus as defined in claim 1 wherein the beam remains in an on

state throughout the recording process.

9. An apparatus as defined in claim 1 wherein the controlled path is

continuous.

10. An apparatus as defined in claim 1 wherein the control means

periodically records variable coordinate values with the digital data to facilitate

playback.

11. An apparatus as defined in claim 10 wherein the variable coordinate

values are referenced to a predefined location on the film.

12. An apparatus as defined in claim 11 wherein a reference target is

recorded at the predefined location on the film.

13. An apparatus as defined in claim 1 further comprising means for

loading film into the apparatus.

14. An apparatus as defined in claim 1 wherein the film is electron

sensitive.

15. An apparatus as defined in claim 1 wherein the film is UV light

sensitive.

16. An apparatus as defined in claim 15 further comprising a phosphor

coated faceplate disposed adjacent the second end of the vacuum tube, wherein the

beam deflection system directs the electron beam across a surface of the faceplate and the control means adjusts the beam characteristic to selectively illuminate positions on

the faceplate, and wherein the illuminated positions expose corresponding locations of

the film.

17. An apparatus as defined in claim 1 wherein the at least one set of

focusing lenses comprise electrostatic focusing lenses.

18. An apparatus as defined in claim 1 wherein the beam deflection system

comprises an electrostatic system.

19. For use with a light source, an apparatus for retrieving digital data

stored on a film comprising:

a vacuum tube having first and second ends;

an electron gun disposed at the first end of the vacuum tube for discharging a

beam of electrons into the tube;

at least one set of focusing lenses associated with the vacuum tube for

focusing the electron beam discharged by the electron gun;

a support for securing a sheet of film at the second end of the vacuum tube

such that light from the light source passes through exposed portions of the film;

a target for generating electrical signals when simultaneously exposed to light

and electrons; and a beam deflection system for directing the electron beam towards at least one

predefined location on the faceplate to retrieve data stored on the film without moving

the film.

20. An apparatus as defined in claim 19 further comprising an output

associated with the target for coupling the electrical signals generated by the target to

an external device, wherein the electrical signals are representative of digital data

stored on the film.

21. An apparatus as defined in claim 19 wherein the beam deflection system

comprises deflection electrodes and a control circuit.

22. An apparatus as defined in claim 21 wherein the control circuit

comprises a synchronization generator.

23. An apparatus as defined in claim 19 further comprising means for

loading film into the apparatus.

24. An apparatus as defined in claim 19 wherein the film is electron

sensitive.

25. An apparatus as defined in claim 19 wherein the film is UV light

sensitive.

26. An apparatus as defined in claim 19 wherein the at least one set of

focusing lenses comprise electrostatic focusing lenses.

27. An apparatus as defined in claim 19 wherein the bean deflection system

comprises an electrostatic system.

28. An apparatus as defined in claim 19 further comprising a faceplate

disposed at the second end of the vacuum tube and wherein the target comprises an

electrode disposed on the faceplate.

29. An apparatus as defined in claim 28 wherein the target generates

the light passing through an exposed portion of the film.

30. An apparatus as defined in claim 19 further comprising an optical lens

31. An apparatus as defined in claim 30 wherein the lens is integrally

focused with a faceplate disposed at the second end of the vacuum tube.

32. An apparatus as defined in claim 19 wherein the support comprises a

frame.

33. An apparatus as defined in claim 19 further comprising an output circuit

coupled to the target, the output circuit including a power supply and a biasing

resistor.

34. An apparatus as defined in claim 19 wherein the beam deflection system

comprises a drive circuit and a set of electrostatic grids.

35. An apparatus as defined in claim 34 wherein the drive circuit comprises

a microprocessor.

36. An apparatus as defined in claim 34 wherein the drive circuit drives the

electrostatic grids to cause the electron beam to traverse predetermined locations of

the faceplate.

37. An apparatus as defined in claim 36 wherein the predetermined

locations are identified by referencing a target location recorded on the film.

38. An apparatus as defined in claim 19 further comprising a map stored on

the film and identifying starting points of predetermined blocks of data on the film to

facilitate location of the predetermined blocks.

39. An apparatus as defined in claim 34 wherein the drive circuit drives the

electrostatic grids to playback a continuous stream of data stored on the film.

40. An apparatus as defined in claim 34 wherein the drive circuit comprises

a generator to control a retrieval rate to ensure an appropriate playback speed.

41. An apparatus as defined in claim 19 further comprising a light source

disposed adjacent the second end of the vacuum tube.

42. An apparatus as defined in claim 41 wherein the light source comprises

an ultraviolet light.

43. An apparatus as defined in claim 19 wherein the film comprises a write

once, read many film.

44. An apparatus as defined in claim 19 wherein the film comprises a write

many, read many film.

45. An apparatus as defined in claim 1 wherein the film comprises a write

once, read many film.

46. An apparatus as defined in claim 1 wherein the film comprises a write

many, read many film.