US3711860A

US3711860A - Arc discharge recording apparatus with pigment carrier

Info

Publication number: US3711860A
Application number: US00146746A
Authority: US
Inventors: L Medlar
Original assignee: Honeywell Inc
Current assignee: Honeywell Inc
Priority date: 1971-05-25
Filing date: 1971-05-25
Publication date: 1973-01-16
Anticipated expiration: 1990-01-16

Abstract

A high speed recording system has a belt of dielectric material with an aperture therein and a drive means for the belt to move the aperture across a recording surface of a recording medium along a recording line. A pigment carrier is positioned between the belt and a first electrically conductive surface with the pigment carrier and the recording surface being coextensive with the recording line. A second electrically conductive surface for supporting the recording medium is positioned on the other side of the recording medium from the dielectric belt and is, also, arranged to extend along the path of the moving aperture. A selectively operable high voltage generating means is connected between the first and second electrically conductive surfaces to induce an electrical discharge therebetween through the pigment carrier, the moving aperture and the recording surface. This electrical discharge transfers some of the pigment from the carrier to the recording surface to produce a visible permanent recording. The recording medium can be driven to produce two axes of relative motion between the recording surface and the moving aperture whereby the aperture path encompasses the recording surface by a succession of parallel recording lines.

Description

United States Patent [191 Medlar Jan. 16, 1973 ARC DISCHARGE RECORDING APPARATUS WITH PIGMENT [57] ABSTRACT CARRIER A high speed recording system has a belt of dielectric [75] Inventor: Lewis A. Medlar, Oreland, Pa. material with an aperture therein and a drive means for the belt to move the a erture across a recording [73] Asslgnee: Honeywell Mmneapohs surface of a recording medi iim along a recording line. [22] Filed: May 25, 197] A pigment carrier is positioned between the belt and a first electrically conductive surface with the i ment [2H 'Appl' 146746 carrier and the recording surface being coelzt nsive with the recording line. A second electrically conduc- [52] US. Cl. ..346/74 S, 346/33 S, 346/46 tive surface for supporting the recording medium is [51] Int. Cl. ..G0ld 15/08 positioned on the other side of the recording medium [58] Field of Search....346/74 E, 74 ES, 74 EB, 74 S, from the dielectric belt and is, also, arranged to ex- -346/74 SB, 74 SC, 33 S, 46, 140, 105 tend along the path of the moving aperture. A selectively operable high voltage generating means is con- [56] References Cited nected between the first and second electrically conductive surfaces 'to induce an electrical discharge UNITED STATES PATENTS therebetween through the pigment carrier, the moving 3,599,225 8/l971 Babaoff ..346/74 ES aperture and the recording Surfaee- ThiS electrical 2,90l,374 8/1959 Gundlach ..346/74 ES discharge transfers some of the pigment from the car- 2,639,96S 5/1953 Holcomb ..346/33 S rier to the recording surface to produce a visible per- 3,2l2,93l 10/1965 Kubota et al ..346/74 ES manent recording, The recording medium can be 2,739,865 3/1956 Willey i -345/33 s driven to produce two axes of relative motion between 3,427,633 2/l969 Waterman ..346/74 S Primary Examiner-Bernard Konick Assistant Examiner-Jay P. Lucas Attorney-Arthur H. Swanson et al.

the recording surface and the moving aperture whereby the aperture path encompasses the recording surface by a succession of parallel recording lines.

9 Claims, 5 Drawing Figures HIGH-VOLTAGE coMPARAToR+ GENERATOR ARC DISCHARGE RECORDING APPARATUS WITH PIGMENT CARRIER BACKGROUND OF THE INVENTION The high speed recording of data to produce a permanent visual record is an essential operation in many process control systems as well as being of general utility in scientific research and product design and development fields. In order to provide a high speed recorder having a low initial cost while avoiding the high enertia of mechanical recorders, such as a typewriter, the prior art recorder designs have usually used either electrostatic fields of high potential spark discharges to effect a recording operation. Examples of prior art electrostatic type recording devices are shown in U.S. Pat. Nos. 2,967,082 of H. Epstein and 3,413,654 of R. K. Strong. High potential, or spark, type prior art recorders are shown in US. Pat. Nos. 2,647,033 of H. T. Fouse and 2,963,336 of H. I. Chambers et al.

A typical prior art electrostatic recording process involves the use of a contrasting material called a toner which is applied to electrically charged areas defining the record on a recording surface to provide a visible indication of these areas. A subsequent fixing of the toner to the recording surface is effective to produce a permanent visible record. The need for the generation and application of electrostatic fields as well as the distribution and fixing of the toner material has prevented the electrostatic recorder from achieving a completely satisfactory recording operation. On the other hand, the spark type recorder is limited to either using a pretreated recording medium exhibiting an augmented sensitivity to the recording spark (which medium increases the expense of recording) of decreasing the recording speed to allow sufficient time for the high voltage recording spark to blacken an ordinary paper recording medium. In both cases, the physical deterioration of the recording medium in the vicinity of the spark produced mark is a limiting factor on the recording density as well as the frequency response of the recording process due to the time required for the physical alteration of the physical structure of the recording medium by the recording spark. Accordingly, it is desirable to provide a high speed recorder which obviates the aforesaid disadvantages of the prior art electrostatic and high voltage spark recorders while produce a permanent and immediately visible recording without the need'of a specially prepared recording medium. v I

An object of the present invention is to provide an improved high speed recorder for producing an immediately visible permanent record.

Another object of the present invention is to provide an improved high speed recorder capable of multitrace recording.

SUMMARY OF THE INVENTION In accomplishing these andother objects, there has been provided, in accordance with the present invention, a recording system having a moving belt of dielectric material with an aperture therein. The belt is positioned between and in a mutually parallel relationship with a recording surface of a recording medium and a pigment carrier carrying a recording pigment. An electrically conductive support means is positioned in contact with the recording medium on the other side from the recording surface. A selectively operable high voltage generating means is arranged to induce an electrical discharge through the pigment carrier, the aperture in the dielectric belt and the recording surface to the electrically conductive support means. The recording pigment is transferred by the electrical discharge from the pigment carrier to the recording surface to produce a visible recording thereon.

BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of the present invention may be had when the following detailed description is read in association with the accompanying drawings, in which:

FIG. 1 is a pictorial representation of a recording system embodying the present invention,

FIG. 2 is an enlarged cross-section of a part of the structure shown in FIG. 1, and

FIG. 3 is an enlarged cross-section of another part of the structure shown in FIG. 1.

FIG. 4 is a partial representation of a multi-color pigment carrier suitable for use with the recording system shown in FIG. 1. 2

FIG. 5 is a partial representation of a multi-color pigment carrier suitable for use with a modified embodiment of the recording system shown in FIG. 1.

DETAILED DESCRIPTION Referring now to FIG. 1 in more detail, there is shown a pictorial representation of a high speed recorder structure embodying the present invention. A dielectric web is shown in the form of an endless belt, or ribbon, 12 supported in a generally rectangular loop by four support rollers l4, l6, l8 and 20. The belt 12 is driven along the loop by any suitable drive means, e.g., one of the support rollers, such as roller 14, may be connected to a suitable drive means as described hereinafter. A second generally rectangular loop is formed by a recording pigment carrier shown as an inked band, or ribbon, 22 supported on four

rollers

24, 26, 28 and 30. The ink band 22 can, similarly, be driven by one of its support rollers, e.g., roller 24 may be connected to a drive means which is, also, described more fully hereinafter. A portion of the path of the belt 12 and a portion of the path of the inked band 22 are arranged to be parallel to each other and in close relative priximity to each other andto a recording surface 34A of a recording medium 34.

Thus, the dielectric web 12 and the ink band 22 are each arranged as endless ribbons encircling a recording medium 34 with the dielectric web 12 and the'ink band 22 being further arranged in a layered configuration in parallel planes in front of the recording surface 34A of the recording medium 34. Specifically, the dielectric web 12 is positioned immediately adjacent to the recording surface 34A, and the ink band 22 is located on the other side of the web 12 from the surface 34A. An elongated electrode 32 is positioned. on the other side of the ink band 22 from the dielectric web 12 and is arranged to be in contact with the ink band 22. The electrode 32 is arranged to extend from sideto side of the recording surface 34A along the path of the dielectric web 12 and over a recording line on the recording surface 34A. A second electrode 36 is positioned on the other side of the recording medium 34 from the side to side of the recording medium 34 in a manner similar to that of the first electrode 33 while providing a sliding support for the recording medium 34.

The dielectric web 12 is provided with a plurality of apertures 38 therein. The apertures 38 may be spaced from each other along the length of the dielectric web 34A. The dielectric web 12 and the ink band 22 can be driven either in the same direction or in opposite directions by a drive arrangement as described above usingany suitable drive means such as an electrical motor 44 having an'output shaft 45 connected to the web drive pully 14 and a geardrive 46 coupling the motor shaft 45 to the hand drive pulley 24.

7 In order to produce a longitudinal recording on the recording surface 34A of the recording medium 34, the recording medium 34 is advanced by any suitable means (not shown) in a plane parallel to the layered planes of the dielectric band 12 and the inked band 22 in a direction perpendicular to the motion of the dielectric web 12 and ink band 22. The aforesaid relationships of the recording elements are shown more clearly in FIG. 2 in an enlarged cross-section of a portion of the apparatus shown in FIG. 1 and taken along line 2- 2. Thus, in FIG. 2 it may be seen that the dielectric band 12 passes between the recording surface 34A of the recording medium 34 and the inked band 22. Additionally, the first electrode 32 is shown in contact with the inked band 22 and on the opposite side of the inked band 22 from the dielectric web 12. Further, the second electrode 36 is shown in contact with the surface of the recording medium 34 on the opposite side from the to therecording surface 34A. A representative aperture 38 is shown in the dielectric web 12 in FIG. 2 for purposes of illustration to complete the operative association of the recording elements.

Referring to FIG. 1 again, there is shown a signal generating means 48, e.g., an alternating current generator, connected to the motor shaft 45 and arranged to be driven by the motor 44. The output signal from the generating means 48 is rectified by a rectifier circuit 50 and, subsequently, filtered by a filter circuit 52. The filtered signal is, then, applied to an integrating circuit 54 including a resistor 56 and a capacitor 58.

The output of the integrating circuit which is representative of the potential across the integrating capacitor 58 is applied as one input signal to a voltage comparing means 64..A second input signal to the voltage'comparing means 64 is obtained from an input terminal 66 output circuit of the high voltage generating means 68 is connected between the first electrode 32 and the second electrode 36. A switch means 70 is connected across the integrating capacitor 58 of the integrator 54 and is selectively operated by a switching means 72 to selectively interrupt an integrating operation by the integrator 54. The switching means 72 is positioned adjacent to the band 12 and is arranged to sense the position of the dielectric band 12 as hereinafter described.

In operation, the apparatus of the embodiment of the invention shown in FIG. 1 is arranged to produce a recording waveshape 72 on the recording surface 34A representative of an input signal applied to the input terminals 66. The dielectric band 12 and the ink band 22 are driven in their respective rectangular loops by the motor 44 which may be energized by any suitable source (not shown). Concurrently, the recording medium 34 is driven past the moving dielectric band 12, as previously discussed, by any suitable drive means which may be connected to the drive motor 44 or driven by a separate motor means. The use of the motor 44 to drive the recording medium 34 would simplify the problem of maintaining a predetermined relationship between the speeds of the dielectric band 12, the ink band 22 and the recording medium 34 in order to achieve a desired recording representation. The recording 73 is composed of a series of closely spaced dots, or particles, of the recording ink from the ink band 22. The ink is transferred to the recording surface 34 by an electrical discharge between the first electrode 32 and the second electrode 36 through the hole 38 in the dielectric band 12. Specifically, a high voltage pulse is applied between the

electrodes

32 and 36 by the high voltage generator 68 to produce an electrical arc discharge. This discharge takes place between the

electrodes

32 and 36 at the point of least resistance. lnasmuch as the dielectric band 12 is made ofa high resistance material, e.g., polytetrafluorethylene, the arc discharge is limited to the area of the hole 38 in the dielectric band 12. The arc discharge also takes place, however, through the ink band 22 and the recording medium 34. However, it should be noted that the dura tion and intensity of the arc discharge are selected to minimize direct marking of the recording surface 34A by the arc discharge while emphasizing the transfer of the pigment from the pigment band 22. In order to reduce the potential required from the high voltage generator 68, the recording medium 34 and the ink band 22 may be made slightly electrically conductive to reduce the overall resistance of the arc discharge path. The cross sectional view in FIG. 2 clearly shows the relationship of the first and

second electrodes

32 and 36 and the intermediate relationships of the aperture 38, the dielectric band 12 the recording medium and the ink band 22 in the arc discharge path, as described above. The arc discharge, which ordinarily takes place in a fraction of a microsecond, propels a measure of ink from the ink band 22 to the recording surface 34A to produce the recording curve 73 as a succession of closely spaced dots or particles of recording ink. Since there are no reciprocating parts involved in'this printing process, the recording speed is only limited by the linear velocity of the aperture 38 in the dielectric sheet 12.

The production of the high voltage pulse from the high voltage generating means 68 is timed with the movement of the aperture 38 across the recording surface 34A in order to produce the recording line 73 representative of an input signal applied to the input terminals 66. Specifically, the input signal to be recorded is compared by the comparator 64 with a ramp signal generated by the integrator 54. The duration of the ramp signal is determined by the selective operation of the switch means 70 by the switching means 72. The switching means 72 is arranged to sense the arrival of the aperture 38 at the start of its sweep across the recording medium 34A to open the switch 70 to initiate an integrating operation by the integrator 54. Subsequently, the switching means 72 is arranged to sense the occurrance of the position of an aperture 38 at the end of its sweep across the recording surface 34A to close the switch means 70 whereby to terminate the integrating operation of the integrator 54 by discharging the integrating capacitor 58. Thus, the duration of the ramp signal is substantially equal to the time required for a single sweep by the aperture 38 of the recording surface 34A.

A suitable embodiment of the switching means 72 is shown in FIG. 3. As depicted in FIG. 3, the dielectric band 12 is provided with a plurality of selectively located deposits of magnetic material shown as magnetic material deposit 74 in FIG. 3. Each of the deposits of magnetic material 74 is arranged to interact with a pick-up head 75 to produce an output signal from the pick-up head 75. This output signal is amplified by an amplifier 76 and is applied to the complementing input of a flip-flop 78 to change the state of the flip-flop 78. Thus, the occurrence of each output signal from the pick-up head 75 is indicative of the passage of a magnetic deposit past the pick-up head 75 and is arranged to change the state of the flip-flop 78 between its logical l and 0 states. A relay coil 80 is connected to one output, e.g., the 1 output, of the flip-flop 78 to be energized thereby. Accordingly, when the flip-flop 78 is in its logical 1 state the relay 80 is energized, and, conversely, when the flip-flop 78 is in its logical zero state the relay 80 is deenergized. The relay 80 is arrangedto operate the switch means 70 to selectively discharge'the capacitor 58.

The placement of the magnetic material deposit 74 on the dielectric band 12 with respect to the apertures 38 is predetermined to effect a switching operation of the switch means 70 whereby the ramp signal from the integrator 54 is started as each of the apertures 38 on the dielectric band 12 starts its sweep across the recording surface 34A, and the ramp is terminated when that one of the aperture 38 reaches the end of its sweep across the recording surface 34A and before the next aperture starts its sweep of the recording surface 34A. Thus, each of the apertures 38 has two deposits of magnetic material associated with it, and the deposits 74 are arranged to allow a discharge of the capacitor 58 between successive sweeps' of the recording surface 34A by successive ones of the apertures 38. In order to provide sufficient time for the operation of the switch 70, the deposits 74 could be arranged to trigger a discharge operation before an aperture 38 has fully left the recording surface 34A and to start a charging operation after a successive aperature has started its sweep of the recording surface 34A. Using such a timing arrangement of the deposits 74, a narrow longitudinal strip along each longitudinal edge of therecording surface 34A would be excluded from the recording operation.

The input signal to the integrator 54 is obtained, as previously discussed, from a generating means 48 attached to the output shaft 45 of the motor 44. The generating means 48 is arranged to produce an output signal which is linearly proportional to the rotational speed of the output shaft 45. This output signal is an alternating current signal which is rectified and filtered before being applied to the integrator 54 as a direct current signal to be integrated. Accordingly, any change in the speed of the motor 44 which would also effect the speed of the dielectric band 12 is translated into a corresponding change in the output of the generating means 48 to produce a change in the slope of the ramp signal being generated by the integrator 54. For example, if the motor 44 increases its speed, the output of the generating means 48 is also increased and the direct current input signal for the integrator 54 has a higher magnitude to induce the ramp to reach its final value in a shorter period of time which maintains the ramp waveshape in synchronism with the higher speed of the dielectric web 12. The comparator 64 compares the ramp signal from the integrator 54 with the input signal applied to the input terminal 66. When an equality between these compared signals is detected by the comparator 64, the comparator 64 is arranged to trigger the high voltage generator 68 to produce an arc discharge between the first and

second electrodes

32 and 36. Thus, the recorded curve 73 is representative of the instantaneous magnitude of the input signal applied to the input terminals 66 during one sweep of the recording surface 34A by one of the apertures 38.

The apparatus of the present invention is shown in FIG. 1 as a single point recorder for purposes of illustration, however, it should be noted that this recording apparatus can be easily adapted to perform a multipoint recording function. A single color multipoint recording operation can be effected by multiplexing a plurality of input signals to the input terminals 66. The number of multiplexed input signals in this method of operation is equal to the number of apertures 38 in the dielectric web 12. Further, the application of each input signal to the input signals is synchronized with the arrival of a respective one of the apertures at the start of its sweep across the recording surface 34A. Thus, each of the input signals is recorded by a corresponding one of the apertures 38. In order to distinguish the plurality of waveshapes by this process from each other, the apertures 38 may each be of a characteristic shape different from the shapes of the other ones of the apertures 38. The different aperture shapes would produce correspondingly shaped ink dots to allow an easy identification of a recorded waveshape. The space between the dots forming any one of the plurality of recording lines would be increased over that in the single waveshape recording unless the speed of the recording medium is decreased to compensate therefor inasmuch as the recording apparatus is being time shared among the multiplexed input signals. On the other hand, the apparatus of the present invention may be adapted to produce a multicolor, multipoint recording with each color being coordinated to a corresponding input signal and waveshape recording. For example, as shown in FIG. 4, an ink web 82 may be divided into a plurality of transverse sections 82a, 82b, and 820 with each section containing ink of a different color. Each of the color sections 82a, 82b, and 820 is located adjacent to one of the apertures 38 in the dielectric belt 12. Further, the normal speed of the dielectric band 12 and the ink band 82 are synchronized whereby each of the apertures 38 is continually aligned with a corresponding one of the color sections on the ink band 82. The input signals to the input terminals 66 would, in such an embodiment, be multiplexed in a manner similar to that discussed above for a single color multipoint recording to present a different input signal for recording during each sweep of an aperture across the recording surface 34A. Thus, each input signal would be recorded by a corresponding one of the apertures 38 in a respective color on the recording surface 34A with the number of input signals being multiplexed and recorded corresponding to the number of apertures 38 and to the color sections of the ink band 82. In order to utilize all of the inked area of a color section on the ink band 82, the drive for the ink band 82 may include an intermittent mechanism to periodically align a new area of a color section with their respective one of the apertures 38 whereby during the operative life of the ink band 82, each of the apertures 38 would traverse its respective color section to more completely utilize the ink stored sections 83a to83d on the ink band 83. Further, a

dielectric web would be provided with a group of apertures therein at each aperture location on the dielectric web with each of-th'e apertures in a group being aligned 8311 on the ink band 83. In this'inulti-point system, the electronic recording circuitry shown in FIG. 1 including the integrator 54, the comparator 64, and the high voltage generator 68 could be duplicated for eachinput signaland each of the input signals could be applied to a respective oneof-theduplicate circuits with each of the high voltage generator 68 output circuits being connected to a respective one of the first electrodes 38a to 382i and a common connection to the second electrode 36. Alternatively,'this multipoint systemcould be arrangedwith a single electronic recording circuit of the type shown in FIG. 1. and the input signals could be multi-plexed before being applied sequentially to the input terminals 66,and the'output of the high voltage generator could be synchronously multiplexed along with'the input signals to distribute the high voltage pulses in sequence among the plurality of first electrodes 38a to 38d.

Accordingly, it may be seen that there has been provided, in accordance with the present invention, a high speed recorder for producing an immediately viewable with a corresponding one of the color sections 83a to dielectric web and said pigment permanent record and having multipoint recording capabilities. I

The embodiments of the invention in which an exclusive property of privilege is claimed are defined as follows:

l. A recorder comprising a pair of electrodes,

a movable dielectric web located between said electrodes, an aperture in said web, a recording pigment carrier extending along a path of said aperture, and positioned between said electrodes, means supporting a recording medium between said electrodes and parallel to the path of said aperture in said dielectric web, and an electric arc discharge means connected to said electrodes means and responsive to an input signal to be recorded to produce an arc discharge between said pair of electrodes and through said aperture, said recording medium, and said pigment carrier for selectively propelling said recording pigment in said pigment carrier by said arc discharge onto said recording medium to immediately form a visible record thereon, wherein said dielectric web is located adjacent to a recording surface of said recording medium and said pigment carrier is on the other side of said dielectric web from said recording medium.

2. The recorder as set forth in claim 1 wherein said dielectric web is in the form of an endless belt havinga plurality of apertures therein with said apertures being uniformly separated by a distance corresponding to the width of a recording line on said recording medium.

3. A recorder as set forth in claim 2 wherein said pigment carrier includes a plurality of successive transverse areas having respective'pigment characteristics with each area extending along said pigment carrier for a distance corresponding to the length of a recording line and including means for synchronizing each of said plurality of apertures with a corresponding one of said transverse areas.

4. A recorder as set forth in claim 2 wherein said pigment carrier includes a plurality of adjacent longitudinal areas haying respective pigment" characteristics and wherein'one 'of said electrodes extends across the width of said pigment carrier and the other one of said electrodes includes a plurality of electrode bars, each I of said bars being longitudinally aligned with a corresponding one of said longitudinal areas and wherein said arc discharge means is connected to said one elec-v trode and to all of said electrode bars and includes means for selectively producing an arc discharge between said one electrode and a selected one of said electrode bars. I

5. The recorder as set forth in claim 2 wherein said recording pigment carrier is in the form of an endless movable band. v

6. The recorder as set forth in claim 5 wherein said recording medium. 1

7. A recorder as set forth in claim 1 wherein said are discharge means includes means for generating a ramp signal, means for comparing said ramp signal with an input signal to be recorded to produce an output signal representative of an equality between said compared signals, and a high voltage generating means responsive to said output signal to produce a high voltage potential between said pair of electrodes. 8

carrier encircle said means for generating a ramp signal includes means responsive to the position of said movable web to initiate a ramp signal upon the occurrence of a predetermined position of said movable web.

Claims

1. A recorder comprising a pair of electrodes, a movable dielectric web located between said electrodes, an aperture in said web, a recording pigment carrier extending along a path of said aperture, and positioned between said electrodes, means supporting a recording medium between said electrodes and parallel to the path of said aperture in said dielectric web, and an electric arc discharge means connected to said electrodes means and responsive to an input signal to be recorded to produce an arc discharge between said pair of electrodes and through said aperture, said recording medium, and said pigment carrier for selectively propelling said recording pigment in said pigment carrier by said arc discharge onto said recording medium to immediately form a visible record thereon, wherein said dielectric web is located adjacent to a recording surface of said recording medium and said pigment carrier is on the other side of said dielectric web from said recording medium.

2. The recorder as set forth in claim 1 wherein said dielectric web is in the form of an endless belt having a plurality of apertures therein with said apertures being uniformly separated by a distance corresponding to the width of a recording line on said recording medium.

3. A recorder as set forth in claim 2 wherein said pigment carrier includes a plurality of successive transverse areas having respective pigment characteristics with each area extending along said pigment carrier for a distance corresponding to the length of a recording line and including means for synchronizing each of said plurality of apertures with a corresponding one of said transverse areas.

4. A recorder as set forth in claim 2 wherein said pigment carrier includes a plurality of adjacent longitudinal areas having respective pigment characteristics and wherein one of said electrodes extends across the width of said pigment carrier and the other one of said electrodes includes a plurality of electrode bars, each of said bars being longitudinally aligned with a corresponding one of said longitudinal areaS and wherein said arc discharge means is connected to said one electrode and to all of said electrode bars and includes means for selectively producing an arc discharge between said one electrode and a selected one of said electrode bars.

5. The recorder as set forth in claim 2 wherein said recording pigment carrier is in the form of an endless movable band.

6. The recorder as set forth in claim 5 wherein said dielectric web and said pigment carrier encircle said recording medium.

7. A recorder as set forth in claim 1 wherein said arc discharge means includes means for generating a ramp signal, means for comparing said ramp signal with an input signal to be recorded to produce an output signal representative of an equality between said compared signals, and a high voltage generating means responsive to said output signal to produce a high voltage potential between said pair of electrodes.

8. The recorder as set forth in claim 7 and including means for driving said dielectric web and said pigment carrier band and for producing an output signal linearly related to the speed of said dielectric band for application as an input signal to said integrator means.

9. A recorder as set forth in claim 7 wherein said means for generating a ramp signal includes means responsive to the position of said movable web to initiate a ramp signal upon the occurrence of a predetermined position of said movable web.