DE1916958A1 - Method and device for the direct recording of light patterns - Google Patents

Description

April 1, 1969 Gzx / goe

LITTON INDUSTRIES, Inc

Method and device for the direct recording of light patterns.

The invention relates to a method for the direct recording of light patterns and in particular to a method for the direct recording of light patterns by selective dielectric heating of recording material, generally sheet material, for recording of temperatures according to the light pattern intensities predetermined size. The invention is specifically a method of recording light patterns, with in the area a photoconductive plate exposed to light pattern intensities of predetermined magnitude, high frequency electrical Fields through the adjoining receiving sheet material

leads Y ^ so that the resulting potential gradients in the receiving sheet material this for temperature recording in areas which are determined by the incident light pattern, dielectrically heat.

In one embodiment of the present invention, the receiving sheet material is in the form of visibly variable, thermosensitive sheets between a photoconductive plate and a conductive plate placed. Mainly during exposure to a light pattern on the photoconductive plate, but at least during its life Their change in conductivity becomes a Viechs el voltage predetermined size and frequency between photoconductive and conductive

tending plate. The conductivity pattern on the photoconductive Plate, which has been generated by light pattern intensities of a predetermined size, causes the electric field between the two plates is guided so that the resulting potential gradient the recording sheet in areas of the plane of the recording sheet, which were determined by the light pattern, in a predetermined Visibly change time through dielectric heating.

In a second embodiment of the invention, spaced apart Electrodes to which an alternating voltage of a predetermined magnitude and frequency is to be applied, with respect to a photoconductive one Plate and a parallel recording sheet so arranged that the electric field between the electrodes runs in the planes of the photoconductive plate and the receiving sheet. As in the first embodiment, the photoconductive plate is a Exposed to light patterns and during the lifetime of the conductivity change the AC voltage is applied. As a result, the conductivity pattern in the photoconductive plate, which generated by light pattern intensities of a predetermined size the electric field between the electrodes in such a way that the resulting potential gradient the recording sheet in Heat areas in the plane of the recording sheet dielectrically in a predetermined time, which is determined by the light pattern became.

A feature of the invention is the fact that the receiving sheet, or the recording sheets, to a recording temperature

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can be dielectrically heated to produce positives or negatives of a light pattern, which is incident on an adjacent photoconductive Plate falls. The difference between positive and negative is made by controlling the level of lighting that creates the light pattern determined, achieved.

This happens due to the fact that a light pattern is made up of areas is composed of low and high intensity, and due to the discovery that a recording sheet is at recording temperature is heated and thereby marked, opposite areas of the photoconductive plate which only have light pattern intensities have been exposed to a certain size. However, there is no marking against areas of the photoconductive plate, which Light pattern intensities of a magnitude that are either was lower or higher than the predetermined size the Light intensity is at which marking occurs. If accordingly the intensity of the illumination of certain areas of a light pattern is set above or below the predetermined size, and the intensity of the illumination of other areas determining the light pattern is increased up to the predetermined size or is reduced, there is a reversal of the marked areas.

In the second embodiment, according to their arrangement the inhibiting effect of light intensities that are higher than the predetermined intensity, a marking of the recording sheet to promote areas of the photoconductive plate which are not exposed to any light or light of any intensity

80984 * 7, 4; <,

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which is lower than the predetermined intensity. However, the marking of these areas is favored if they are adjacent Areas of the photoconductive plate simultaneously light of a predetermined intensity, a so-called marking intensity, were exposed.

This invention is thus generally concerned with a method P1 and a device for recording light patterns using high frequency energy, with high frequency electric fields being passed through areas of a recording sheet which correspond to the light pattern intensities on a photoconductive plate
fall, are selected so that the resulting potential gradients only on those areas of the recording sheet
Dielectrically heat the recording temperature, which, in the plane
of the recording sheet, can be determined by light pattern areas that are different from other areas.

According to the invention a device is used which contains a photoconductive plate, the changes in conductivity due to incident light patterns act to the effect that a high-frequency electric field, which is passed through it, is deformed in such a way that the potential gradients that arise from the discontinuity of the field thus generated, Heat parts of an adjacent recording sheet to recording temperature, the areas of which
are thermally changed in the plane of the sheet, according to the incident light pattern, which dielectric energy there
drives through

BAD ORIG? | Sjal " ^/ "

1918958

According to one feature of the invention, an arrangement is provided, in which a flat photoconductive plate is adjacent to spaced apart Electrodes are held to form a corresponding pattern of leadthroughs as a result of an applied light pattern in the plane of a photoconductive plate and a recording sheet, which rests thereon, for the lines of the electrical Generate flux that arises between the electrodes when a high-frequency voltage is applied to the electrodes.

According to a further feature of the invention is a device for recording with the help of selective dielectric heating of a visible changeable heat sensitive on riahuiblat tes provided. Positive or negatives of a light pattern are generated as required by controlling the lighting level through the light pattern, falling on the photoconductive plate. This will be preferred Guides in the record sheet for a high-frequency electric Field created.

Looking at the various features and embodiments, dicj have been mentioned so far, the present invention can be used as a method for printing, marking, doubling, recording or the like by generating visible patterns on thermally changeable dielectric .material on the cradle selective application a high-frequency electrical Viechseifield on such areas of the material can be considered which correspond to the pattern, with the high-frequency electrical chemical field of sufficient intensity has to be thermal by dielectrically generated heat

90984S / U32 _{BAD O} r, q, NAL

To produce changes due to the molecular friction, resulting in a change in the appearance of the corresponding to the light niuster Areas result. Here, a light pattern is applied to a photoconductive element according to the desired pattern, whereby the high-frequency alternating electric field is guided into the material with the help of the photoconductive element. The best Results are achieved when the material is polar-dielectric. It is understood that the photoconductive element is a high frequency Alternating field with discontinuities in the field intensity causes at points that by means of the conductivity pattern the correspond to the desired pattern that was built up by the application of the light pattern therein. The material is made for a specific Time exposed to the field to change the appearance of those areas of the material exposed to high field intensities are. In this case, those areas that are exposed to low field intensities are essentially not changed. As a result, lead at locations within an extensive surface area of the photoconductive element, the highly conductive areas of this element relatively high field intensities in the material where the dielectric material is to be changed, in order to make markings on it to leave according to the pattern you want. In contrast, relatively low field intensities are found in areas of low conductivity of the photoconductive element provided in the remaining part of the extended surface area.

According to an embodiment mentioned above, the high-frequency alternating field between an electrode that has the

90984B / .U32,

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includes photoconductive element, and another electrode is generated. The impedance conditions for the field are set so that relatively high and relatively low impedance points for the field can be created by projecting an image of the desired pattern onto the photoconductive element. The material is placed between the photoconductive element and the other electrode, thereby exposing the material to the field. In practice one uses two parallel, essentially flat electrodes, one of which is the photoconductive element in the form of a photoconductive one Includes layer which, as a result of the projection of the image, has areas which have relatively low impedance paths for the Field, and other areas that have relatively high impedance paths for the field. The areas match the desired pattern. At least one layer thermally changeable dielectric material is placed between the electrodes. The field is created between the electrodes. In this way, a field distribution is generated that is composed of areas relatively higher and relatively low field intensity.

According to another embodiment also mentioned above, the high-frequency alternating field is via the photoconductive

we'd at

Element led. The impedance conditions for the field are set in such a way that locations with relatively high and relatively low impedance for the field are created by projecting an image of the desired diameter onto the photoconductive element. That Material is in contact with the photoconductive element. The management of the •! • ktria «h« n field is achieved in particular by w «ch-

9 0 9 8 k 5 / · U 3 }. BATH ORIGINAL

Selective potentials between a pair of elongated electrodes in a plane along the plane of the phot sliding element and the Materials are applied.

The choice between working conditions that lead to a positive or a negative is made by either maximum light intensities of the light pattern on the photoconductive end Element are applied in the area in which the marking occurs, thereby producing a negative of the light pattern, or that minimal light intensities of the light pattern on the photoleitendo Element are applied in the area, in the marking {Stands to thereby create a positive of the light pattern. In both cases, the total lighting level applied to the photoconductive element falls, controlled in such a way that light of a predetermined intensity, the marking intensity, an impedance matching between adjacent areas of the photoconductive element and the material, when this causes the electrical Field is exposed to a predetermined frequency. This will caused dielectric heating of the photoconductive element and lowered its impedance to a negligible value. In practice this is suitably achieved by having at least one pre-irradiation light source for control of the entire lighting level is used. In particular, if the total light intensity level that of one or more additional Light sources is supplied, causes an illumination of the photoconductive elements in the range of intensities at which Marking occurs is in areas of high intensity level

90984 5 / U 3 2 bad original

the applied light pattern the total lighting level in areas of impedance mismatch between the photoconductive Element and material raised »This prevents marking of the material in areas of high intensity of the light pattern, so that a positive of the light pattern is created.

Further features of the method according to the invention include the use of a plate-shaped photoconductive element and of ordinary thermosensitive dielectric material or otherwise from ordinary paper. The thermal change caused by dielectrically applied heat in ordinary paper is generated, consists in a darkening, hedged by at least partial charring,

In the context of the invention, a device for generating is more visible Markings or patterns of markings provided on dielectric material, which due to the application of heat in its Appearance can be changed, such as paper, heat-sensitive Material or similar dielectric materials, in particular a device for printing, marking, recording and / or Duplicate, whereby a high-frequency alternating electric field is built up. This field has discontinuities in field intensity in places that correspond in their shape to that of the pattern that is to be generated. Means are provided for dielectric Exposing material to the field. This is a permanent one Change in appearance caused by dielectrically generated heat in those areas of the material which the

909846 / U32

BATH ORIGINAL,

Exposed to high intensity field. The device contains a photoconductive element onto which the desired image is projected. The conductivity pattern that is so in the photoconductive Element formed creates the discontinuities in the field intensity of the pattern. Usually a plate-shaped photoconductive element used, which forms part of an electrode, which is made of a layer of conductive transparent material between a layer of insulating transparent. Material and a layer of photoconductive, usually insulating material is composed. Then the high-frequency alternating electrical field between the conductive transparent layer and a built up another electrode. The recording material is located between these. On the other hand, a pair of electrodes that is jointly spaced along the photoconductive element, be applied to concentrate the flow of the high frequency electric lifechself eldes through the photoconductive element, wherein at least one sheet of thermally alterable dielectric material, such as paper or thermally sensitive recording material, is applied to the photoconductive element. Advantageously A complete arrangement usually contains one dormant oscillator, which can be excited for short periods of time, which are sufficient to cause thermal changes in appearance of the dielectric material only at the points exposed to a high intensity field. Optimal results are achieved when the frequency of the oscillator is substantially corresponds to the frequency at which the loss factor of the material has a maximum »

BATH

909 * 4-8 / 1432

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Additional features of the device according to the invention include arrangements for projecting an image of the desired pattern
on the photoconductive element, for holding sheets of the
Reproduction material in contact with the photoconductive element, and lighting arrangements in addition to the image of the

Light pattern a pre-exposure intensity on the photoconductive

ο in.
Align the element, The importance of the use of arrangements for the application of additional pre-exposure sources lies in the fact that the pre-exposure intensity is set, or so adjustable, that light intensities of a magnitude are produced
which cause a change in the impedance of the photoconductive element in the direction of adaptation to the impedance of the receiving material | in this way heat is generated in the photoconductive element and thus its impedance is reduced to a negligible value, whereby the increased voltage on adjacent parts of the non-metallic material heats them dielectrically and thermally
changes.

Further features, advantages and possible applications of the new invention emerge from the accompanying illustrations of exemplary embodiments on as well as from the following description.

Show it:

Fig. 1 is a schematic representation of the basic elements of a
first embodiment of the invention, later than
"Parallel plate arrangement" (one recording sheet is in the working position),

909 8 /, 5 / U32

- ϊ C - \ · ■: - * ■ - ': \ i> X. ~ - BAD ORIGINAL

FIG. 2 is a view similar to that of FIG. 1, in which a light pattern reflected from a document and directed onto the photoconductive plate, the light intensities are set so that a negative of the document is recorded,

FIG. 3 is a view similar to that of FIG. 1, in which a light pattern is incident on the photoconductive plate, the light intensities being impinged on by a pre-exposure source an intensity can be raised that the recording material is marked in the areas not affected by the pattern, while, through simultaneous application high light intensity that prevents marking in areas hit by the pattern the result that positives of the document are accepted,

ψ Fig. k shows an electrical equivalent circuit diagram of the parallel plate mounting arrangement and Fig. 1,

Fig. 5 is also an electrical equivalent circuit diagram corresponding to Fig. 1 showing series equivalent circuits of each circuit path of Fig. K ;

Fig. 6 is a graph showing the change in the size of the

Series equivalent impedance of the photoconductive layer with changes in the resistance value of the photoconductive layer due to changes in the light intensity

9 0 98 U. / 1 A3 / _ / _

BATH

- 13 reflects the situation,

Fig. 7 are graphs showing the relationship of energy output in the

photoconductive layer and changes in the receiving sheet in the resistance value of the photoconductive layer when the light intensity changes,

8 shows a schematic representation of a second embodiment ^{according to the invention, hereinafter} referred to as "lf two-wire arrangement", with a receiving sheet in the working position,

Fig. 9 is a view similar to that of Fig. 8 showing the receptacle of a positive of a light pattern,

Figure 10 is a view similar to that of Figure 8, do the pickup reproduces a negative of a light pattern,

Fig. 11 is a schematic diagram showing the electrical

Equivalent to the two-wire take-up arrangement of FIG. 8 represents

Fig. 12 is a schematic diagram showing the circuit with the series equivalents of the parallel circuits of Fig, II represents, and

9098 4-5 / 1432 BAD ORIGINAL

. - Ik -

13 is a view similar to that of FIG. 9, which shows the recording of a positive of a light pattern using a pre-exposure source of marking intensity, since this arrangement also has the effect of reducing the recording time. ■ - ^: ■:; ; . ■: - ·.

In the following drawings, the same reference symbols denote before or corresponding elements in the various figures. Fig.l shows a recording material in the form of a recording sheet 15. The ■ recording sheet is preferably made or consists of polar, dielectric material, which has a loss factor with a peak value at a certain frequency. In contrast, non-polar dielectric materials are characterized by a loss factor which is essentially constant and relatively low over the entire frequency range. Preferably, the Aufrialimemater consists ial from one or more Papierblätterri l6, of "which each one wärmeeinpf has in ^ lethal covering layer 17, WEL f before visibly chemically modified or becomes transparent when its temperature to a specific uptake temperature, the so-called marker temperature increases, This exposes the colored surface of the paper carrier sheet, and such receiver sheets are known in the trade as thermographic copier paper.

The work Δ ¥ that is required to obtain the temperature T of a Material to increase by an amount _Λ T, i.e. from the ambient temperature to a specific recording temperature, the marking

90984B / U32 BAD OR ₁ G ₁ NAL

tion temperature at which, according to the invention, a visible change occurs is calculated according to the following well-known equation:

Aw »M.s. At. (ο)

Here, M means the mass of a material volume of an area A. and a thickness d multiplied by the density, and S the specific Warmth of the material.

In order to accomplish this work in a certain time t, an effort (V work / time unit) of MS / \ T is required.

t borrowed. Thus the required performance is:

Al « ms Δt . (ι)

The power dissipated in the dielectric material is represented by the following equation:

L _d = E ² «XCd _f . (2)

HiorbP * is L dip voltage or the potential gradient across a unit of material in area A, a thickness of "d" and a dielectric constant e, ο 2 (| -fold »the frequency f, d is the loss factor of the material at the applied

Frequency and C (» KAe ) the capacity of the unit cube of the mate
terials.

If one equates the required power «j L with the consumed power L jr and dissolves for / \ T , one obtains the

BATH ORIGINAL

- 16 -following equation:

Δτ » ^{e2 w 0} V. (3)

M s

Thus, the dielectric heating or increasing the Temperature of a recording sheet or sheets to a specific recording temperature in a given time a predetermined .Combination of voltage and frequency} the higher the frequency, the lower the voltage and vice versa. The upper limit of the voltage is determined by the breakdown voltage of the recording sheet given which is to be dielectrically heated. The loss factor of the receiving sheet material is preferably at selected frequency or near a maximum.

In Fig. 1, a photoconductive plate is shown which forms an electrode assembly 18. This has a transparent Gla · - or mica pad 19 with a conductive transparent coating \ 21. In the transparent conductive coating 21 is a photoconductive normally insulating layer 22, which in one embodiment, the phosphorescent substance Sylvania P-20 in a mixing ratio of 2.5: 1 with acrylic resin 100 (Union Carbide: LKSA / OIOO). This photoconductive, normally insulating layer is applied to a fine thickness on the order of about 80 micrometers (0.003 inch) and has a dielectric constant of 3. The plate-shaped arrangement 18 can suitably be held in a frame (not shown). The recording sheet 15 is preferably used with its heat-sensitive cover

90984 5 / U3 2 BAD original

- 17 -

train 17 of the electrode 18 facing and in direct contact with the Layer 22 arranged. The photoconductive element in the form of the layer 22 together with the conductive coating 21 on the glass plate 19 on the one hand and a conductive element or plate 23 in direct contact with the receiving sheet on the other hand form plate electrodes and complete the layer structure, which is referred to as a parallel plate arrangement.

A high-frequency constant voltage source 2k can be applied to the electrodes for a specific time t, which is predetermined by an electronic timer 25. During this time, recording must be carried out while the photoconductive electrode assembly 18 is exposed to a light pattern to be recorded. The source 2k can be in the form of a Hartley oscillator.

Referring to Figure 1, there is an original document 26 which is to be replicated should, shown. The surface of the document has dark areas 27 and white or lighter areas 28, which both together determine a light pattern. If the original document of lamps is illuminated, the light reflected therefrom is passed through a lens 30 onto the photoconductive layer 22 of the electrode arrangement l8 projected. If, as in Fig. 2, the same original 26 to be copied, the intensity of the from the white areas reflected light has a predetermined intensity, generally denoted as G, and higher than that reflected from areas 27 and a voltage V of a predetermined magnitude and a frequency f are applied to the electrodes l8 and 23 for the time t,

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is the resistance of the photoconductive, usually insulating Layer 22 in areas struck by light of intensity G, with the result in a yet to be described Way that very much lowers the density of the electric flow through areas of the recording sheet which abut areas of the layer 22 which have been struck by light of intensity G, increases. In this way, the potential gradient or voltage drop across these areas of the receiving sheet is essentially achieved the value E and is thus large enough to bring the recording sheet to the recording temperature at the frequency used to heat up in a time t. The heat developed in this way produces a beneficial effect Markings in the layer 17 of the recording material sheet in areas 31 (FIG. 2) corresponding to the document areas 28 (Fig. L). That is, the recording material in opposite Areas of the photoconductive plate 22 exposed to light of an intensity G, is marked, creating a negative of the light pattern projected from the original document 26 became.

Whenever the intensity of the ambient light is higher than the intensity G of the light which causes the marking to become the photoconductive electrode assembly 18 is normally shielded from ambient light. However, if the level of ambient light is lower than the intensity G of the light required to effect the marking or recording the arrangement 18 not to be shielded from the ambient light. ... - / -

909845/1432 /. ^ß AD original

Venn, as in FIG. 3t, the photoconductive electrode arrangement 18 is illuminated by lamps 32, which are solely for light of marking intensity G and the electrode arrangement 18 is simultaneously exposed to the light reflected from the document 26 in which the light reflected from the white areas 28 has a higher intensity, generally referred to as G, in this way, the latter prevents marking of the recording sheet in the areas of the photoconductive layer 22 which are exposed to light an * intensity G was hit. Then that is recorded

Original-

Pattern a positive of the light pattern projected from the »document became.

To explain this behavior, the parallel plate arrangement of FIG. 1 can be represented in an electrical equivalent circuit diagram according to FIG. K when considering the paths through an elementary area from the plate 21 to the plate 23. In Fig. K , each effective path through such an elementary region contains a parallel RC element 33, which reproduces the electrical behavior of the material of the photoconductive layer 23, in series with a parallel RC element 3 ^ i which reproduces the properties of the receiving sheet material . Typically, the reactance value X of the photoconductive layer is essentially equal to the reactance

tank value X of the recording sheet. The dark resistance value R, c _r ph

the photoconductive layer is greater than the resistance value R of the recording sheet and both, R and R, are with the applied High frequencies greater than the corresponding reactance values

X and X. At 100 megahertz, the frequency at which the loss- ^C ph ^C r

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factor for typical receiver sheet materials is close to its peak, and considering a light struck elemental area of 0.25 cm by 0.25 ^cm (0.1 inch by 0.1 inch) area and a thickness of layer 22 and receiver sheet 15 of about ÖO micrometers (0.003 inch) each and takes a value of about 3 for the dielectric constants of the photoconductive layer and the receiving sheet, these parameters have the following values; ,

R, (dark or ambient light) «■ 3 x 10 0hm

H'll.ß KiI. ohm

X = 700 ohms ^C _P h

X = 700 ohms. c

Fig. 5 shows the series equivalent circuit of the photoconductive layer and the receiving sheet material in each path of an elementary region, the one to the photoconductive. Layer and the recording sheet belonging parallel circuits 33 and 3k on

* an equivalent resistance value R and an equivalent reactance

verri ligern ^et *

value X Yi where the values R and X are represented in a known manner by eq eq eq

the following expressions are intended:

r2

R.
eq a R. S. R. RX C. X
eq ² ₊ X ²
C. -JR ² X
C. 2 X ²
C.

(4) (5)

9 0 9 8 U S / 1 A 3, BAD

In these equations, if R> X:

· 'C

x ²

^R _ett - __ £ _ and X »-JX ^eÜ R ^C eq ^C

and thus the series impedance:

X ² Z = c - jX (6)

³ R ^C

if: R.
eq R a ^X c « X
C.
eq so follows: _z R.
⁼ 2 and and thus: R.
⁼ 2 .J ₃

rf R <X, then it follows:

R * R and X a -rrJ

eq c X

¹ eq c

and thus: . _D 2

Z _o -R ^ p-. (8th)

S Λ

Since, as mentioned above, the resistance value of the recording sheet R is greater than its reactance value at the frequency used,

the

so is the equivalent impedance Z of the recording sheet when you consider the

r uses the recording sheet parameters of the above formulas}

X ²

r r constant * - / ··

909845/1432 'sad original

The resistance value of the photoconductive layer, however, changes inversely with the light intensity and when the resistance value could be brought below the value of their reactance value at the frequencies used, the size of the equivalent series impedance would be Z of the photoconductive insulating layer, such as

^S ph
shown in curve 35 of Fig. 6, at a relatively low

Value compared to the magnitude of the equivalent series impedance Z

^ (Equation 9) of the receiving sheet material. Thus appears in essence the total voltage V across the recording sheet impedance Z and takes effect on the recording sheet at a time t

r
To heat the recording temperature dielectrically. Consequently, the naturally expected mode of operation of the parallel plate arrangement is the generation of negatives, ie the marking of the recording material which is in contact with those areas of the photoconductive layer that have been struck by the light (FIG. 2).

So far, however, no commercially available photoconductive material ψ has been found whose resistance value, even when exposed to very high light intensities, can be brought to values that approach their reactance value, let alone is significantly lower than their reactance value at frequencies in the applied 100 megahertz range . In Fig. 6, the curve 35 represents the course of

_ and

Z on a semi-logarithmic scale ^ R, on a logarithmic scale

^S ph ^pn

Scale represents, and the dotted line kl divides the curve 35 in the

Point at which the value of R. is equal to the value X. Since every-

^pc ph

but, as mentioned above, R, cannot be brought to this value by the action of light, the impedance value Z remains the photo-

ph /

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BAD OMGiHAL

conductive layer within the area of curve 35 on the right side of the line ^ l in Fig. 6 high and the voltage division between the impedances of the photoconductive layer and the receiving sheet in the circuit of FIG. 5 takes place so that the voltage drop across the Aufaahmeblattimpedanz Z, whose

r constant magnitude is represented by the dotted line 38,

is insufficient for marking.

In the absence of a photoconductive material, its resistance value can be brought below its heactance value, which is at mega-Hertz frequencies is very low, this process can affect the light-struck areas of the photoconductive sheet "" Do not selectively heat the layer dielectrically.

In experimental tests, the resistance value of the photoconductive Bringing down layer 22 with spots of high intensity G, it was unexpectedly found that the recording material has been marked in areas that are on areas of the layer 22 outside of the point. This means that there are areas that one lower intensity G were marked. These lower intensity G was due to a halo of light around the light spot high intensity generated. The halo was evidently formed from internal healing in the glass or was caused by ambient light of intensity G. In this way it was found that the Material problem in the parallel system arrangement due to regulation the exposure level could be solved. Here is a Light intensity ü selected at which, as is now believed,

909 8 4b / ι43 2,

BATH ORIGINAL

the energy output in the photoconductive layer has a maximum. This promotes the heating of the photoconductive layer, to make their resistance value lower than their reactance value. Specifically, it has been found that, by using a

the
Light intensity level G is the resistance value of the photoconductive

Materials 22 versus that of the receiver sheet would decrease, a value much higher than that of the photoconductor reactance at 100

Mega Hertz was achieved, and specifically a value of 1% so that the series equivalent impedances of the photoconductive layer and the receiver sheet, Z and Z, were substantially matched, respectively. A

ph r
The maximum amount of energy was emitted here over the photoconductive layer in areas that were hit by the light intensity G.

In FIG. 7, curve 36 transfers the change in the energy output the series equivalent impedance of the photoconductive layer according to Fig. 5 again with the change in photoconductor impedance caused by changes in R. caused by the intensity of the light. the Curve 37 gives the change in the energy output over the constant recording sheet impedance with changes in the impedance of the photoconductive layer again. You can see that in agreement with known physical laws a maximum of energy is given off over the photoconductive layer if its impedance is the of the recording sheet is adapted. This is the condition indicated by the intersection between curve 35 and line 38 in FIG. 6 and the intersection between curves 36 and 37 and the line is displayed in FIG. The energy output in the form of heat

909045/1432. ^BATH

_{acts in such a} way that the resistance value of the photoconductive material changes inversely with the temperature, a a ß the resistance value of the photoconductor is brought below its reactance value with the result that the series equivalent impedance Z of the photoconductor

^S ph ter-RC element drops rapidly to a negligible value, which is shown by the series equivalent impedance curve 35 to the left of the line kl in FIG. As a result, almost all of the voltage V appears across the recording sheet impedance Z and has

a size E ₁ which is sufficient to heat the recording sheet to a recording temperature in a time t in areas which are in contact with the areas of the photoconductive plate which have been struck by the light intensity G. Thus, negatives as in Fig. 2 are produced.

As noted above in connection with FIG. 3, exactly the same can good positives of the incident light pattern can be received. The unexpected effect that light of relatively low intensity G a Impedance matching between the photoconductive layer and the receiving sheet causes heating in the photoconductive layer and consequently a decrease in its resistance value (and impedance value) to a negligible value. In this way, as mentioned above, both negatives and positives can be generated.

When the on the photoconductor, i.e. the photoconductive material of the Layer 22, GM falling light intensity. to such a value reduces that Z is smaller than Z (dotted line 38 »Fig.6)

ph r

is, (Ui. that a mismatch occurs, or to such a

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BATH ORIGINAL

Value (to the left of the line 39> Fig. 7) »that there is insufficient energy in the photoconductive layer to noticeably heat it up and thus reduce its resistance value R, (and Z) and for

ph s, ph

Sufficiently large voltage delivered at the recording impedance Z.

r will; thus no marking would occur in areas where

High intensity light G is incident on the photoconductive layer.

CmI

In particular, in order to obtain a positive of the document 26, the photoconductive layer 22 is exposed to ambient light or a Vorbeieuchtungs- or background light, which from lamps 32 of the Marking intensity G referred to above is generated. This leads to an impedance matching between the parameters of the photoconductive layer and the receiving sheet, so that a marking is effected at the points indicated above. However, the photoconductive plate becomes light of high intensity at the same time G exposed, which of areas 28, as shown in Fig. 3, is reflected by controlling the lamps 29. This is intended to result in a mismatch between the impedances of the photoconductive Layer and the receiving sheet are effected. Under these conditions, as mentioned above, there is insufficient voltage across the receiving sheet, which is attached to areas of the photoconductive layer that were struck by light of intensity Gi thereby its dielectric heating is prevented, thereby forming a positive as shown in FIG. 3 to the original 26 of FIG.

In Fig. 8 there is shown an embodiment which has been referred to as a two-wire arrangement. A pair of spaced apart wire electrodes k2 and 43 with a diameter on the order of

909845/1432

- 27 -

Order of about 0.63 cm (0.250 inch) extend across the Width of a suitably held photoconductive plate-shaped Elektro.de with a photoconductive, normally insulating layer 44, which is self-supporting or impregnated in silk fabric or can be applied to silk fabric} but it can also be a coating on glass or mica. In one embodiment the photoconductive plate was made of Sylvania P-l4 photoconductive material, mixed in a proportion voi. 2.5! 1 with Union Carbide LKSA-OlOO resin and impregnated in silk fabric. The photoconductive plate 44 is suitably in contact with the electrodes 42 and 43 held. A recording sheet 15 can with its heat-sensitive Overlay 17 can be held against and in close contact with photoconductive plate 44. When a high frequency alternating voltage E is applied from a source 45 to the spaced electrodes 42 and 43 for a time t determined by a electronic timer, 25 is set, an electric field is built up, which is spread through the layers of photoconductive Plate 44 and the receiving sheet 15 extends. In this embodiment For example, the function of the photoconductive plate 44 can be regarded as that of an electrode, i.e. as a continuation of the Lead electrodes 42, 431 as they increase the density of the electrical Field as a function of its conductivity. In the dark Areas or in those areas exposed to ambient lighting, which may be the case, as in the description the parallel plate arrangement was mentioned, the density of the field is not large enough in the recording material to accommodate it Uptake, i.e. marking temperature in a predetermined time t to warm up.

9098U / U3 ,:

BATH ORIGINAL

As shown in Fig. 8, the image to be reproduced may be a photographic negative 46 which is transparent, i.e. translucent The rich 47 and dark, i.e. not translucent Areas 48 be. A lamp 49 directs light through the negative 46 through the collimating lens 51 and the light passing through the transparent area 47 penetrates through a lens 52 mapped onto the photoconductive plate 44. On the other hand, light can be caused by reflection from white areas 28 of an original document 26 to be reproduced, as shown in Fig. 1, through a lens 52 onto the photoconductive plate be judged.

The two-wire arrangement differs from the parallel plate arrangement in that the field established between electrodes 16 and 43 extends through the planes of photoconductive layer 44 and the plane of receiving sheet 15 with the result that the source voltage E is normally , ie with uniform light distribution, drops evenly over each elementary height section between the electrodes. Assuming three sections a, b and c and a source voltage E, there is a voltage - over each section in the dark or with ambient lighting, which may be the case. If light is directed onto one of the sections, e.g. section b, which reduces the resistance of the photoconductive plate, the magnitude of its impedance would also decrease in accordance with curve 35 in FIG. 6, with the result that the voltage drops across the Increase in sections a and c accordingly. If this is large enough to bring in the greater part of the field, would

9 0 9 8 U 5 / ι k 3 2 ^w '

SAD

as a result, the adjacent sections of the recording sheet are dielectrically heated in a certain time t. The naturally expected mode of operation of the two-wire arrangement is therefore the generation of positives; that is, no marking occurs in areas of the receiving sheet which adjoin areas of the photoconductive layer kk which have been struck by light.

As mentioned above, no photoconductive material has yet been found whose resistance value can be brought below its reactance value at the frequencies used. A sufficient reduction in the resistance value of the photoconductive plate in the direction of its reactance value on the right-hand side of the line kl in FIG adjacent areas

t of the recording sheet are marked.

It should be noted here that when the resistance value is the photoconductive layer could be brought below its reactance value, which affects the impedance of the photoconductive material hit by light, e.g. in section b, would result in a negligible value, the voltage at each of the sections a and c would be substantially equal to half the source voltage and marking would occur such that positives in shorter time intervals !! disfigure.

If in Figs. 8 and 9 the light from the lamp ^ 9 has a high intensity G, the marking on the recording sheet is

9 0 9 8 k b / U 3 2 " ⁷ "

BATH ORIGINAL

... 30 -

surfaces, which adjoin the areas struck by the light intensity G _Q , are prevented in accordance with the transparent areas 47; however, it occurs in areas of the recording sheet where no light of intensity G _{r) is} incident. In this way, a positive (FIG. 9) of the photographic negative 46 is produced.

However, when the light of the intensity G of the lamp 49 as below in _β is applied with lower intensity, so W marker enters the recording sheet in areas on adjoining areas of the photoconductive layer, which have been hit by the light intensity G, corresponding to the light-transmissive Areas 47 · In this way, a negative of the photographic negative 46 as in Fig. 10 is produced.

For a more detailed explanation after the accepted one Theory to explain the positive and negative labeling effects observed in the two wire arrangement, reference is made to Fig. 11 ^ which is an electrical equivalent circuit diagram 8, and FIG. 12 which shows a series equivalent circuit of the parallel RC circuits of FIG reproduces. The dotted lines 50 in Figs. 11 and 12 indicate the interface between photoconductive plate 44 and receiving sheet 15 from Fig. 8 onwards.

In the two-wire arrangement, the resistance is Ii of the receiver sheet greater than its reactance value X and the dark (or ambient

r
lightJ photoconductive layer resistance value R is greater than yours

Reactant value X. With this arrangement, one takes a leash.

^ph 90984 5 / ι 43 2 -V-

BATH ORIGINAL

tar range of about Ο, θ63 cm (0.01 square inches) in the plane of the photoconductive plate, the reactance value of the photoconductive plate is higher than the reactance value of the parallel plate arrangement just as the value of the capacitance, if the field runs in the planes of a plate, is determined by a region A, which defines the Product of the thickness of the photoconductive plate and a unit width of the photoconductor and a thickness d in the field direction. Typical fourths are, ηimini one assumes that a region of the photoconductive layer, struck by light, about 0.063 cm (0.01 square inches) as in Fiel has:

H ₁ /. . , χ = 10 ^C ohms
ph (dark)

R = 1.6 10 ' 0hm

X = 0, o χ 10 ⁶ 0hm

X a 0, u x 10 0hm.

c
r

Assuming elementary sections a, b and c including the photoconductive plate kk and the receiving sheet 15 between the electrodes, each section is distinguished by a first parallel RC element 53 connected in series, which has a path in the surface of the photoconductive plate reproduces, provided with a second parallel connected RC element <jk as a shunt, which reproduces a rfo.c through the thickness of the photoconductive plate and is connected in series with a parallel RC element 55, which represents the recording sheet parameters. Sections b and c have a similar structure. FIG. 12 shows the series equivalents of the members 53, 5'l and 55 of FIG. 11. The series equivalent impedance of the member 53 is denoted by Z (series), that of the member 5k

9 ü 9 8 ι '■ : ·'. 3 i

BATH ORIGINAL

rait Z (parallel) and the link 55 with Z

^s ph ^S r

The generation of positives is discussed below. With a source voltage E on the electrodes 42 and ky , each section has the voltage -r on its series-connected photoconductor RC element 53 or Z (series) and a voltage -r on the parallel-connected-

^s _P h 3

th series combination of the RC elements 5k and 55 of the photoconductive

the

Plate and recording sheet. Referring to Figure 12, V is voltage drop at the recording sheet impedance Z, represented by the

E ^r

Member 55 of FIG. 11, less than ~ by the amount of the voltage drop across the member <jk or Z (parallel). When light from high

Intensity G is directed to the section b, which is shown e.g. in Fig. 9 is shown, this will noticeably reduce the value of Z (series)

^S ph ring (and Z parallel to a lesser extent than the resistance

⁸ ph ^is

ability in the thickness direction of the photoconductive layer (much higher than the resistance in the plane direction). As a result, the tension on the remaining sections a and c is increased sufficiently so that an increase in the tension drop on the receiving sheet Z is brought about in these areas and marking is

r
correct time t, as mentioned above, occurs.

The generation of negatives is discussed below. It is believed that the same mechanism for matching the impedance of adjoining portions of the photoconductive plate and the recording sheet as that of the negative-parallel-plate operation for negative recording in the two-wire arrangement, i.e. for the marking effect where light can be assumed. If in a certain section the impedance Z (parallel) and Z - / -

909845 / U32 ^ph bad original

the photoconductive plate and the receiving sheet are matched, maximum energy becomes in this section of the photoconductive layer dissipated and the heat generated therein reduces its resistance value below its reactance value. Therefore, if according to FIG. 12 of the Illumination level or the intensity of the light from the lamp is reduced to an intensity G so that Z (series) becomes

^S ph does not change significantly to get positive at a time t

promote, as mentioned above, the voltage drop across the limb 53 for Z (parallel) and the series-connected impedance Z as

ph r

constant voltage source appear. The change in Z

³ Ph (parallel) with light of low intensity G, however, becomes Z

^{1 3} Ph

(parallel) in the direction of matching with the recording sheet impedance If you move Z, do this as described in connection with FIG.

r
Cleans, occurs, the energy output in the associated photoconductive plate section will generate heat and lead its resistance value below that of its reactance value and at the same time the

Impedance Z (parallel) to a negligible value, with ^S.

p _E

The result is that the entire voltage - at Z (series) at the

^{3 8}

Recording sheet impedance Z appears and is sufficient to

r
to produce the effect in a time t. This happens in areas where light of intensity G in the light pattern hits the photoconductive plate, as in FLg. 10 shown.

Referring to Fig. 13, positive recording can be promoted, that is, accelerated, if the entire photoconductive element, including the portions a and c which are not exposed to the high intensity light G from the lamp k ⁽ ) , are simultaneously exposed to background light , ie a pre-exposure of marking intensity

909845 / U32 ^{- /} ~

BATH ORIGINAL

G exposed to pre-exposure sources such as lamps 56

is explained, in order to promote a marking "as in the case of the negative recording".

According to the energy required to generate a mark or Recording is required, the effect requires about 2000 V per millimeter at time intervals on the order of 5 milliseconds (50 volts / mil). Larger distance between the electrodes in the fc two-wire arrangement requires higher input voltages, since C (Equation 3) decreases with increasing distance. From a practical standpoint, the distance between the electrodes is in the two-wire arrangement limited to about 0.63 cm (250 mils). So is the size of the image that can be reproduced on typed letters which have areas on the order of about 0.063 cm (0.01 square inches).

In the case of the parallel plate arrangement, however, the thickness of the receiving sheet material is between the plate-shaped electrodes 18 and 23 ″ constant with changes in the area of the images, so that each any plate size can be used with the same size of the input voltage.

The above features can be typed in a similar manner arrangement can be installed, in the keyboard operation by selecting and inserting negatives 46 (Fig. 8) light the window G generated the letter area 47 and on the photoconductive Plate of Fig. 1 or Fig. 8 for marking, i.e. Admission, right. The features are suitable for use in copier

909845/1432 - / -

& m ORfGfNAL

maschinenι where the incident light hits the photoconductive plate may be reflected from an original being copied. Further Applications include, for example, strip chart recorders when the recording sheet is moved to form a time base, and facsimile pens, the moving pen being in the shape of a adopts information-modulated light source. In the broadest sense This process can then be used to produce continuous recordings of any desired Light patterns are used, either in the form of visible markings on a recording sheet or as latent changes, which can be developed in the following.

The photoconductor plate assemblies described herein preferably use resins to make them relatively smooth, strong, abrasion resistant Surfaces to form, and the term "photoconductive element" or "electrode" is used to refer to in their scope also layer arrangements of such resin photoconductive material mixtures to include. It should be mentioned here, however, that photoconductor materials are placed directly on a carrier plate can be, e.g. by melting or vapor deposition. Thus the expressions "photoconductive element", "electrode" and "plate" used generically.

90S845 / U32

BATH ORIGINAL

Claims (26)

Claims 1.ι method for printing, marking, copying, recording or the like, characterized in that visible patterns are generated on thermally variable dielectric material (15) by means of selective application of a high-frequency alternating electric field on those areas of the material (15) which correspond to the pattern, the high-frequency alternating electric field having sufficient intensity to generate thermal changes by means of molecular friction through dielectrically generated heat, which leads to a change in the appearance of the areas that correspond to the pattern by creating a light pattern that corresponds to the desired pattern, is applied to a photoconductive element (22, kk) and the high-frequency alternating electric field is guided into the material (15) on the way via the photoconductive element (22, kk). 2. Method according to claim 1, characterized in that it is marked hn e t that the material (15) is a polar dielectric material. 3. Method according to claims 1 or 2, characterized in that the photoconductive element (22, kk) forms a high-frequency alternating electric field with discontinuities in the field intensity at points which correspond to the desired pattern on the way of the conductivity pattern which is created therein by applying the Light pattern formed 9 9 8 Ü U b / h 1 3 1 - / - BAD ORIG / NAL and that the material (15) was exposed to the field for a time which is sufficient to change the appearance of those areas of the material which are exposed to high field intensities are without significantly changing those areas that are exposed to low field intensities. 4. Method according to claims 1 to 3 ι thereby geken nzeich, that in places of the extensive surface area of the photoconductive element the areas of high conductivity of the photoconductive element (22, 44) have relatively high field intensities in the material (15) in such places where the dielectric material (15) is to be changed to make markings on it to form that correspond to the desired pattern, while having relatively low field intensities in areas low conductivity of the photoconductive element (22, 44) are provided in the remaining part of the extended surface area. 5. Method according to claims 3 or 4, characterized by geken, that the high-frequency alternating electrical field between an electrode, which the photoconductive element (22) οLnloses, and another electrode (23) is formed, the impedance conditions for the field are adapted so that places with relatively high impedance and relatively low impedance for the field by projecting an image of the desired pattern onto the photoconductive element, and that the material (15) between the photoconductive element (22) and 9 0 9 o'clock : ■> / ι 4 3 Ί BATH ORIGINAL the other electrode (23), whereby the material (15) is exposed to the field. 6. The method according to claim 5i characterized by the use of two parallel, substantially flat electrodes (Io, 23)> one of which (liJ) is the photoconductive element (22) includes in the form of a photoconductive layer, which on projection of the image has areas, the paths with relatively low impedance form for the field, and other areas that form relatively high impedance paths for the field, the areas corresponding to the desired pattern, through at least one layer of the thermally alterable dielectric Material (15) between the electrodes (l8, 23) and in that the field is formed between the electrodes, whereby a field distribution is generated, those from areas of relatively high field intensity and other areas is composed of relatively low field intensity. 7. Hethode according to claims '} or 4, characterized ς ekc η η-characterized in that the high-frequency electrical alternating field is designed to run over the photoconductive element (44), the Impedanzb ed Lngunßen for the field are set so that places be generated with relatively holier impedance and relatively low impedance for the field by projecting an image of the desired pattern onto the photoconductive element (44), and that the material (15) is applied to your phot οίο 1 toad en element (44). 9 0 9 8 4 ä / 1 4 3 ORIGINAL " ⁷ " 8. The method according to claim 71, characterized in that the guidance of the electric field is achieved by applying alternating potentials between a pair of elongated electrodes ( ^l i2 _t k '}) which are set up in a plane which is adjacent to the plane of the photoconductive element (4'i) and the material (15) adjoins. ^c ). Method according to claims 1 to ο, characterized in that maximum light levels of the licit pattern, which axif the photoconductive element (22) are applied, are selected so that they lie in the range G at which marking occurs, whereby a Negative of the light pattern is generated (Fig. 2). 10. The method according to claims 1 to 0, d a d u r c h g e k e π nzeich, that minimum light intensities of the light pattern, which are applied to the photoconductive element (22) are selected so that they lie in the region G in which Marking occurs, creating a positive of the light pattern (Fig. 3) 11. The method according to claims 9 or 10, characterized in that the overall lighting level which is incident on the photoconductive element (22, kk) is regulated in such a way that light of a predetermined intensity G is an impedance match between adjacent areas of the photoconductive element (22 , kk) and the material (15) 90984S / U32 BATH ORIGINAL - 4ο - The field is effective when this corresponds to the electrical or predetermined frequency are exposed, thereby dielectrically heating the photoconductive element (22t 44) and reducing its impedance is caused to a negligible amount. 12. The method according to claim 11, characterized by the use of at least one pre-exposure Light source (32, 56) for controlling the overall lighting level. 13. Method according to claim 12, characterized in that the total level of light intensity G supplied by the additional light source or sources provides illumination of the photoconductive element (22, 44) in the range of intensities at which marking occurs, so that Areas of high intensity of the applied light pattern increase to a total illumination level G ₀ in areas of impedance mismatch between the photoconductive element (22, 44) and the material (15), thereby preventing marking of the material (15) in areas of high intensity of the light pattern to create a positive of the light pattern. l4. Method according to claims 1 to 13, characterized by using a plate-shaped photoconductive Elements (22, 44). ^ß 4D ORIGINAL 9Ü984b / U32 15. Method according to claims 1 to l4, characterized by using conventional thermosensitive dielectric Materials (l5) 16. Method according to claims 1 to l4, characterized in that that the material (15) is paper and the thermal mixed change by dielectrically applied heat consists in a blackening, corresponding at least partially occurring charring. 17 · Device for producing visible markings or patterns of markings on dielectric material which penetrates The appearance of heat changes, like paper, heat sensitive material or similar dielectric material, in particular for printing, marking, recording and / or copying, characterized in that that a high-frequency alternating electric field is built up in it, which discontinuities in the field intensity in places whose shape corresponds to that of the pattern, correspond to which is to be generated, Vthat a device is provided is to expose the dielectric material (15) to the field, resulting in a permanent change in appearance due to dielectrically generated heat in sole lie η areas of the material (15) is caused, which are exposed to the high field intensity that on a photoconductive element (22, 44) the desired Image is projected, creating the conductivity pattern is formed in the photoconductive element (22, 44) which the 5909846/1432 BATH ORIGINAL Discontinuities created in the field intensity of the pattern. l8. Apparatus according to Claim 17 »characterized by a plate-shaped photoconductive element (22, 44). 19 · Device according to claim 10, characterized in that the photoconductive element forms part of an electrode (18) ψ , which consists of a layer of conductive transparent material (21) between a layer of insulating transparent material (19) and a layer of photoconductive, normally insulating Materials (22) is composed. 20. Apparatus according to claim 19, characterized in that that the high-frequency alternating electrical field between the conductive transparent layer (21) and another Electrode (23) is formed, wherein the recording material (15) is placed therebetween (Fig. L). 21. Apparatus according to claims 17 or l8, characterized by a pair of electrodes (42, 43) »separated from each other spaced along the photomagnetic element (44) are to the flow of the high frequency alternating electric field focus on the photoconductive element (44}, with at least a sheet of thermally alterable dielectric material such as paper or thermosensitive recording material (15) 1 which is applied to the photoconductive element (44) ! Fig. 8.) V- 9098A5 / 1432 BATH ORIGINAL 22. Apparatus according to claims 17 to 21, characterized by a normally resting oscillator (24, 45), which can be initiated for short periods of time that are sufficient in order to cause thermal changes in the appearance of the dielectric material (15) only in places which Exposed to high intensity fields 23 · Device according to claim 22, characterized in that the frequency of the oscillator (2k, k ^) corresponds essentially to the frequency at which the loss factor of the material (15) has a maximum. 24. Apparatus according to claims 17 to 22, characterized by arrangements for projecting an image of the desired pattern onto the photoconductive element (22 4 44). 25 · Device according to claims 17 to 24, characterized by means for holding sheets of receiving material (15) in contact with the photoconductive element (22, 44). 26. Apparatus according to claims 17 to 25, characterized by a lighting arrangement (32, 56), which a pre-exposing light intensity on the photoconductive element in addition to the image of the light pattern. 27 · Device according to claim 26, characterized in that the pre-exposing light intensity is regulated or 90984b / Hi 32 _{BAD 0RIG} , _NAL Can be adjusted to light intensities of a size 6 to produce a change in the impedance of the photoconductive element (22, 44) towards matching with the impedance of the recording material (15) is caused to generate heat to form in the photoconductive element (22, 44) and thus reduce its impedance to a negligible value, thereby increasing the tension. adjacent spacing ^ Sections of the recording material (15) dielectrically heated and thermally changed ♦. . 9 U 9 8 L,:; , > 3 2 Blank page