US3154369A - Information recording and developing apparatus - Google Patents

Description

H. R. DAY, JR

Filed Sept. 20, 1961 INFORMATION RECORDING AND DEVELOPING APPARATUS I) 'H'HHllum 7 ill ntor-1- dr'o/ol 2213 His Atto ,5 'Dey.

United States Patent 3,154,369 INFURMATHQN RECGRDTNG AND DEVELGPHNG APPARATUS Harold R. Day, In, Saratoga, N.Y., assignor to General Electric Company, a corporation of New York Filed Sept. 20, 1961, Ser. No. 139,461 6 Claims. (Cl. 346-77) The present invention relates to improved apparatus for recording information particularly on a thermoplastic medium. The invention relates particularly to improved cooling of the recording medium after it has been heated and subjected to the information containing electric charge pattern.

In copending Glenn application Serial No. 8,842, filed February 15, 1960, now US. Patent No. 3,113,179, entitled Method, Apparatus and Medium for Recording, and assigned to the assignee of this application, is described and claimed an apparatus, method and medium for recording information in the form of minute thicl'- ness deformations in a thermoplastic layer produced by establishing a charge pattern having a density distribution corresponding to the information to be recorded and rendering the thermoplastic sufiiciently liquid to be deformed and to retain the deformation upon cooling. inasmuch as a preferred form of applying the electric charge pattern is with an electron beam, it is highly desirable to provide an apparatus in which the entire electron beam path is highly evacuated to avoid difficulties with arcing of the electrodes which generate and control the beam and to minimize electron scattering due to collision with gases which would otherwise be present in the beam path. As far as the operation of the electron beam writing apparatus is concerned, a good vacuum, for example, less than one micron and preferably in the order of .01 micron to .1 micron is desirable. However, such a good vacuum effectively eliminates any cooling of the medium by gaseous conduction and accordingly greatly retards the cooling process, thus rendering difiicult the development solidifying of the recording medium in the same recording apparatus as the one where the exposure to the electron beam takes place. In accordance with an important aspect of the present invention a region of significantly higher pressure, in the order of 500-2000 microns or higher, is provided to enhance the cooling of the recording medium and this region is separated from the beam path by a path which substantially restricts the flow of gases and renders it relatively easy to maintain this significant pressure differential between the region of the beam path and the region where the cooling takes place. In other words, the recording apparatus involves a separation of the beam path from the cooling region by a sufficiently restricted gas flow path to maintain the desired pressure levels for the information writing by the electron beam and the enhanced cooling of the tape by gaseous conduction. A relatively small pressure of 500 2000 microns is sufficient to provide a very substantial increase in cooling rate, i.e., in the order of 10,000 times the cooling available at the high vacuum preferable for the electron beam path without substantially increasing the problems of evacuation.

In Glenn, Jr., et al. application Serial No. 139,460, now Patent No. 3,116,962, filed concurrently herewith, is described and claimed a method and apparatus for enhancing the cooling of the tape after it is heated and subjected to the information containing electron beam in accordance with which the tape passes through a restricted passage into a region of higher pressure. The present invention is an improvement on the invention of the aforesaid Glenn et al. application and provides a particularly simple and effective construction for subjecting a tape to an increased pressure while at the same time minimizing the gas admitted to the chamber where the heating and recording takes place and in this way minimizes the load imposed on the evacuating apparatus. Accordingly, it is an important object of the present invention to provide new and improved recording apparatus, particularly with respect to the enhanced cooling of a previously heated recording medium without interference with the maintenance of a good vacuum in the region of recording.

Further objects and advantages of my invention will become apparent from the following detailed description taken in connection with the accompanying drawing and its scope which will be pointed out in the appended claims. In the drawing:

FIG. 1 is an elevational view of recording apparatus embodying my invention with the cover open showing the internal construction of theapparatus;

FIG. 2 is a sectional view taken along the line 22 of FIG. 1, and

FIG. 3 is a partial sectional view taken along the line 33 of FIG. 2.

Referring now to the drawing, 1 have shown my invention embodied in a thermoplastic recording apparatus including a generally rectangular box-like housing 10 having a hinged cover 11 which closes against a suitable sealing gasket 12 extending completely around the housing on the upper edge of the side walls thereof. The chamber provided by the housing 10 is evacuated by one or more large vacuum ports 13 connected to a suitable vacuum system. A supply of the recording medium which is in the form of a flexible tape 14 is provided in the recorder on a supply reel 15. The tape passes from the supply reel 15 to a guide pulley 16, past a heater assembly 17 which provides a source of heat adjacent an extended surface of the tape and may, for example, be made up of a resistance heater element spaced closely to the tape as described in more detail in the aforementioned Glenn, Jr., et al. application. After the tape is heated to the point where the thermoplastic layer thereof is sufliciently liquid to permit it to be readily deformed by the electrostatic forces which may be readily obtained by a charge pattern obtained from an electron beam, it passes over a plurality of guide pulleys 13 to the recording station 19 where the thermoplastic surface is scanned by an electron beam produced and controlled by the beam forming and controlling apparatus designated generally by the numeral 20 and housed within the spaced partition members 21 supported from the back of the housing it The tape is exposed to the beam in a manner to be described in more detail later in the specification, to scan across the tape as the tape is moved to produce a raster having a pattern of deformations corresponding to the information to be recorded. The tape then passes over a drive sprocket 22 and a guide pulley 23 from which it passes around the circumference of a cooling drum or wheel 24 and engagement with which is guided by an assembly 25 including a pair of guide rollers 26 closely spaced to one another and to the periphery of the cooling drum 24. Assembly 25 also includes a pair of arms 27 which normally do not engage the tape but which serve to insure that the tape remains reasonably well centered on the cooling drum. The drum 24 is provided with a pair of side flanges 28 for guiding the tape and may be further recessed as shown from the surface to provide a very shallow chamber to receive air or other gas such as dry nitrogen, for example, from the plurality of radially extending passages or ducts 3t communicating with the recess and extending inwardly to the inner bore of the drum. While the additional recess 29 may be provided, it should be a very shallow recess and in fact may be dispensed with entirely since the thin film of air that is provided between the face of the drum and the tape is of sufficient thickness to provide for enhanced cooling and the cooling is acutely decreased as the layer of air becomes thicker.

The drum 24 is rotatably mounted from a hub 31 secured in vacuum-tight relation to the back of the recorder housing 10. The drum 24 rotates on the hub 31 on a pair of suitably retained ballbearing assemblies 32 and is maintained in substantially vacuum-tight relation by means of a pair of O-rings 33. The hub provides for the introduction of a small amount of gas to the drum 24- by means of the axially extending duct or passage 34 communicating by means of radial passage 35 to an annular recess 36 which communicates with the inner ends of the radial ducts 30 of the drum 24. It is to be noted that the hub 31 is provided with a valve member 37 which is biased radially outwardly by a spring 38 to close the duct or ducts 30 in the drum 24 which communicates with the portion of the drum periphery near the rollers 26 which is not covered by the tape. This valve action prevents the direct passage of air into the interior of the vacuum housing so that only the air leaking from underneath the tape is introduced into the vacuum housing and with suitable capacity evacuating apparatus and an exhaust port 13 of good size, no difficulty is encountered in maintaining the housing at the desired vacuum for the electron beam writing. The overall rate of flow of air to the interior of the cooling drum may, as will be readily understood, be controlled by a suitable valve (not shown) for controlling the introduction of air into the passage 34.

At this point it is believed desirable to describe briefly the nature of a tape suitable for use in such a recorder. As best seen in FIG. 2, the tape may be a three-layer composite structure including a backing or support layer 39, a transparent conducting layer 40, and a thin thermoplastic layer 41, which may terminate short of the marginal portions of the tape in which openings 42 are provided to provide for engagement with the driving sprocket 22. While the particular materials and construction of the tape are not, by themselves, a part of the present invention and they may be made in accordance with the teachings of aforementioned Glenn, In, application Serial No. 8,842, filed February 15, 1960, a specific example of a tape suitable for use in the present invention is one in which the backing layer 39 is of an optical grade of polyethylene terephthalate available under the name of Cronar. The backing layer may be up to 4 mils in thickness, for example. The transparent conducting layer 40 may be formed in accordance with any of the known processes for forming a thin transparent conducting coating and may, for example, be accomplished by a copper iodide film. The thermoplastic layer which is the information storage layer may be a medium molecular weight polystyrene having a thickness in the range of .2 to 2 mils thick. The optimum thickness of the thermoplastic layer depends to some extent on the spacings of the information containing deformations and the thickness should be for best results equal to or less than the spacings between the adjacent depressions or deformations.

Also, in the foregoing description of the tape handling apparatus, it should be pointed out that the thermoplastic layer 39 of the tape faces the electron beam apparatus as it passes over the pulley 19. Accordingly, this layer of the tape faces toward many of the other tape handling pulleys and it will be appreciated that these pulleys are recessed throughout a substantial portion of the central face area so as not to engage the recording area of the thermoplastic surface.

While the electrodes for forming the electron beam and controlling it to impart the information containing deformations to the tape surface by themselves form no part of the present invention, it is believed well to deode 42, an apertured control grid 4-3, an apertured accelerating electrode or anode 44. The beam thus formed and accelerated passes between a pair of vertical deflection plates 45 and between the opposed electrodes of three pairs of generally cylindrical electrodes 46, 47 and 48 and impinges the thermoplastic medium as it passes over the roller 19.

The particular control imposed on the electron beam and as a result the particular type of information recorded on the medium as deformations thereof is not important to the present invention. The apparatus described, however, is suitable for impressing color television picture information on the medium in which case the energization of the electrodes may be in accordance with the disclosure of my copending application Serial No. 119,712, filed June 26, 1961. For example, the horizontal deflection which determines the width of the tape which is subjected to the beam may be produced by a deflection voltage supplied to the pair of cylindrical electrodes 46. The electrodes 47 may also be supplied with the horizontal focusing voltage. The electrodes 47 are also employed for subjecting the beam to the voltage for velocity modulating the horizontal sweep in accordance with the color information of two color components, for example, red and blue. The electrodes 48 are supplied with the vertical focusing voltage, i.e., the voltage for focusing the beam in the direction of the tape travel. The electrodes 45, as described in that application, are energized by a voltage of relatively high frequency and an amplitude which varies with the amplitude of the other color (green) to be recorded. This varies the charge density along the raster line in accordance with the amplitude of the green signal voltage. As will be understood, the movement of the tape is synchronized with the horizontal sweep voltage and the velocity of tape movement correlated with the sweep frequency to determine the vertical ra'ster dimension. This arrangement produces two sets of orthogonally arranged light controlling deformations which may be used in conjunction with suitable optics such as those shown in the aforesaid application Serial No. 119,712 to reproduce the color picture.

In the operation of the preferred embodiment of my invention described above, the system is evacuated by the vacuum equipment connected with the exhaust port 13 and the heater element 17 energized so that, as the tape 14 is driven past the heater, and the recording station at 19 it becomes heated to a state sufliciently liquid so that it is deformed by the electrostatic forces produced by the charge pattern established by the electron beam. As the deformed tape passes over the surface of the drum 24 the gas pressure in the confined region between the face of the drum and the tape increases substantially over that existing in the recording region and preferably to a pressure in the order of 500 to 2000 microns. With this increased pressure heat is transferred readily to the drum 24 by gaseous conduction and by remaining in contact with the drum as it makes one revolution the tape is adequately cooled so that it may pass to the takeup reel and be stored without damage to the information containing deformations. The action of the valve 37 in maintaining the duct or ducts 30 which are not closed by the tape, closed at the inner end, insures that no direct and large volume passage of gas into the vacuum chamber occurs. This invention makes possible a simple and efficient recording apparatus in which the tape is heated, subjected to the electron beam, cooled and rolled on a storage reel, all in a single recorder housing.

While a particular embodiment of my invention has been described it will be apparent to those skilled in the art that many changes and modifications may be made without departing from my invention in its broadest aspects and I aim therefore in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. Apparatus for recording information on a recording medium including a thermoplastic recording surface in the form of thickness deformations of the thermoplastic surface comprising a vacuum chamber electron beam producing means in said chamber for producing an information containing electron beam, heating means in said chamber, means for transporting the tape to be recorded upon past said beam producing means and said heating means to produce deformations of the heated thermoplastic layer which vary in accordance with the information contained in the beam, a drum having a passage extending to the face thereof, means introducing a gaseous medium into said passage, and means directing the recording medium over a substantial part of the circumference of said drum to enhance the cooling thereof as a result of the increased gas pressure between the tape and drum as compared to the pressure of said chamber, the recording medium substantially closing said passage to minimize the gas admitted to said vacuum chamber.

2. Apparatus for recording information on a recording medium including a thermoplastic recording surface in the form of thickness deformations of the thermoplastic surface comprising a vacuum chamber, electron beam producing means in said chamber for producing an information containing electron beam, heating means in said chamber, means for transporting the medium to be recorded upon past said beam producing means and said heating means to produce deformations of the heated thermoplastic layer which vary in accordance with the information contained in the beam, a ported drum having a circumferentially extending recess in the face thereof, means introducing a gaseous medium into said recess, and means directing the recording medium over a substantial part of the circumference of said drum to enhance the cooling thereof as a result of the increased gas pressure between the tape and drum as compared to the pressure of said chamber, the recording medium substantially clos ing said recess to thereby minimize the gas admitted to said vacuum chamber.

3. Apparatus for enhancing the cooling of a tape having information recorded thereon in the form of thickness deformations of the surface of the tape comprising a vacuum chamber, a drum rotatedly mounted in said chamber, a plurality of passages in said drum extending outwardly to the face thereof, means introducing gas into said passages, means directing the tape over a substantial part of the circumference of said drum to enhance the cooling thereof as a result of the increased gas pressure between the tape and drum as compared to the pressure of said chamber While minimizing the gas admitted to said vacuum chamber, and valve means for closing all of said passages communicating with said face in a region not covered by said tape.

4. Apparatus for enhancing the cooling of a tape comprising a vacuum chamber, a member in said vacuum chamber, means directing the tape over a face of said member, a passage in said member extending to the face thereof, and means introducing a gaseous medium into said passage to enhance the cooling of said tape While minimizing the amount of gaseous medium introduced into said chamber.

5. Apparatus for enhancing the cooling of a tape comprising a vacuum chamber, a member in said vacuum chamber having a recess of substantial length in a face thereof, means directing the tape over said face to substantially close the recess and means introducing a gaseous medium to said recess to enhance the cooling of said tape While the closure of said recess by the tape minimizes the amount of gaseous medium introduced into said chamber.

6. Apparatus for recording information on a recording medium including a thermoplastic recording surface in the form of thickness deformations of the thermoplastic surface comprising a vacuum chamber, electron beam producing means in said chamber for producing an information-containing electron beam, heating means in said chamber, means in said chamber for transporting the tape to be recorded upon past said beam producing means and said heating means to produce deformations of the heated thermoplastic layer which vary in accordance with the information contained in the beam, a member in said vacuum chamber, means directing the tape over a face of said member, a passage in said member extending to the face thereof, and means introducing a gaseous medium into said passage to enhance the cooling of said tape while minimizing the amount of gaseous medium introduced into said chamber.

References Cited in the file of this patent UNITED STATES PATENTS 2,391,451 Fisher Dec. 25, 1945 2,519,728 Alexander Aug. 22, 1950 2,559,412 Dungler July 3, 1951 2,563,119 Kelley Aug. 7, 1951 2,616,961 Groak Nov. 4, 1952 3,113,179 Glenn Dec. 3, 1963

Claims (1)

1. APPARATUS FOR RECORDING INFORMATION ON A RECORDING MEDIUM INCLUDING A THERMOPLASTIC RECORDING SURFACE IN THE FORM OF THICKNESS DEFORMATIONS OF THE THERMOPLASTIC SURFACE COMPRISING A VACUUM CHAMBER ELECTRON BEAM PRODUCING MEANS IN SAID CHAMBER FOR PRODUCING AN INFORMATION CONTAINING ELECTRON BEAM, HEATING MEANS IN SAID CHAMBER, MEANS FOR TRANSPORTING THE TAPE TO BE RECORDED UPON PAST SAID BEAM PRODUCING MEANS AND SAID HEATING MEANS TO PRODUCE DEFORMATIONS OF THE HEATED THERMOPLASTIC LAYER WHICH VARY IN ACCORDANCE WITH THE INFORMATION CONTAINED IN THE BEAM, A DRUM HAVING A PASSAGE EXTENDING TO THE FACE THEREOF, MEANS INTRODUCING A GASEOUS MEDIUM INTO SAID PASSAGE, AND MEANS DIRECTING THE RECORDING MEDIUM OVER A SUBSTANTIAL PART OF THE CIRCUMFERENCE OF SAID DRUM TO ENHANCE THE COOLING THEREOF AS A RESULT OF THE INCREASED GAS PRESSURE BETWEEN THE TAPE AND DRUM AS COMPARED TO THE PRESSURE OF SAID CHAMBER, THE RECORDING MEDIUM SUBSTANTIALLY CLOSING SAID PASSAGE TO MINIMIZE THE GAS ADMITTED TO SAID VACUUM CHAMBER.

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