DE2042592A1 - Light-sensitive layer structure for electrophotography - Google Patents

Description

DIPL.-ING. A. GRÜNECKER

DR.-ING. H. KINKELDEY

DR.-ING. W. STOCKMAIR, Ae. E. _t o * L '... nst.

PATENT LAWYERS

8OOO MDNOHEN 22 MaxlnWonttrae 43 T * l * fon 29 7100/296744 ! • (• pious · Mon nap at M5ftdi.il Τ · Ι · χ OJ-MMO

August 27, 1970 PH 34-67-39 / HÖ.

CANON KABUSHIKI KAISHA 5-30-2, Shimomaruko, Ohta-ku, Tokyo / JAPAN

Light-sensitive layer structure for electrophotography

The invention relates to a photosensitive layer structure for electrophotography.

So far it is used for photosensitive material in electrophotography amorphous selenium is often used. Amorphous selenium has advantageous properties in terms of resistance, high sensitivity and low fatigue. In photosensitive layers mainly made therefrom, however, the amorphous selenium tends to be present above room temperature to crystallize. The crystallization

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is also caused by environmental influences such as temperature fluctuations and adversely accelerates light rays to which the material is exposed. Crystallization reduces the Dark resistance of selenium and thus destroys the light-sensitive material. Strong crystallization thus has a shortening effect affects the life of the photosensitive layer. For example, the volume resistivity is amorphous

12th
Selenium in the dark is greater than 10 ohm cm, whereas that of crystalline selenium is only 10 ohm cm. As a result, crystalline selenium is not suitable as a light-sensitive material. In the production of photosensitive material from amorphous photosensitive substances, for example amorphous selenium, the temperature of a substrate on which the selenium is vapor-deposited must be kept at a constant value. For this purpose, the substrate is in contact with a bath kept at a constant temperature, so that a rise in temperature of the substrate is avoided during vapor deposition, since this would trigger the start of crystal formation. In addition, it is also necessary to monitor the vapor deposition temperature, so that a great deal of technical effort is required, particularly when vapor deposition is carried out on a circumferential drum-shaped base. Accordingly, the manufacturing cost is high.

Photosensitive layers mainly containing selenium are generally poor in sensitivity to red Light, so they do not have the panchromatic properties that are indispensable for the reproduction of color images. So far this has been The disadvantage was compensated for by the addition of tellurium, resulting in an amorphous selenium-tellurium mixture that is sensitive in the red range. The greater the share of tellurium, the more panchromatic

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was the alloy because it was sensitive to red Light rose. On the other hand, a high addition of tellurium causes a considerable reduction in the life of the photosensitive Layer. The tellurium content is therefore limited to less than 10% by weight in terms of service life. These are the reasons photosensitive layers with an alloy of selenium and tellurium are not advantageous.

In another known improvement of selenium bases for panchromatic photosensitive layers, a selenium layer is used applied to an electrically conductive base and placed over this a red-sensitive selenium-tellurium layer. The thin red-sensitive layer is also covered with a thin selenium-arsenic protective layer. Such multi-layered however, the photosensitive material is difficult to manufacture, which makes the manufacturing cost high.

When two photosensitive layers with different sensitivity ranges are stacked on top of one another, the one is used for widening The most effective arrangement of the sensitivity range is one in which one compared to short-wave, i.e. blue Light-sensitive layer is superimposed on a layer that is sensitive to long-wave, i.e. red light. In contrast, the opposite is true With the arrangement of the layers, an expansion of the sensitivity range cannot be achieved, since the entire light radiation is absorbed in the upper layer.

If a stable selenium layer that does not tend to crystallize is required as the charge carrier layer on the substrate the reverse stratification in spite of the above mentioned

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share, however, inevitable. The so formed photosensitive Layer structure is therefore less sensitive to blue and therefore not panchromatic. There is also a reduction in sensitivity not entirely resolved due to crystal formation.

Therefore, the previously known photosensitive image carriers could not satisfy P and the development of photosensitive ones Layers with high sensitivity, panchromatic properties and long life is desirable in view of the recent development of multicolor electrophotographic processes,

An essential object of the invention is to provide a light-sensitive layer structure for electrophotography specify, with which the disadvantages of known layers of this type are avoided. The light-sensitive layer structure should be easy to manufacture from amorphous photosensitive raw materials and be suitable for multicolored electrophotography. k Depending on the electrophotographic used in each case In particular, the sensitivity, the panchromatic properties and the service life should be variable over a wide range.

This object is achieved according to the invention in that a first layer containing selenium, tellurium and germanium and / or silicon as an additive and a second layer, selenium and germanium and / or Silicon as an additive containing photoresistive layer is provided.

According to the present invention, the photosensitive material is formed by being layered one on top of the other multiple layers to improve panchromatic properties, sensitivity and elongation

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the life of a selenium-based photosensitive material.

In general, light-sensitive material is designed according to the invention in such a way that that a layer I sensitive to long-wave light lies on the substrate and one to short-wave light sensitive layer II is applied to layer I. Thus, the arrangement of the layers is opposite to known photosensitive Layers opposite. With such a construction of the photosensitive layer according to the invention there is no protective layer necessary.

An alloy of selenium and tellurium shows in the range of the long-wave, So the red, light has good sensitivity, but with the addition of germanium and / or silicon it gets through easily Crystal formation destroyed, so it is unstable. Therefore, an alloy of selenium and tellurium is not used as a charge storage layer of the base can be used. In contrast, the addition of germanium and / or silicon results in an alloy of selenium and tellurium according to the invention a stable ternary or quaternary alloy produced, which can be used as a charge storage layer on the base is.

The layer to be applied to the above-mentioned layer consists of an alloy of selenium, germanium and / or silicon, the sensitivity of which is in the short-wave, i.e. blue, range of light and thus the sensitivity range of the said alloy containing selenium, tellurium, germanium and / or silicon supplements, so that a panchromatic and highly sensitive layer

arises. The alloy layer is stable and the crystallization in the surface is much reduced, so that this layer can simultaneously form the protective layer. As a result, no special protective layer is necessary, so that a permanent photosensitive material with fewer layers than known material can be produced. As a result, the panchromatic properties, the life and the sensitivity of a selenium-based photosensitive material according to the present invention can be improved are improved so that only two layers are applied. The photosensitive layer based on selenium which has been improved in this way is particularly suitable for multicolor electrophotography, and can be produced easily and at low cost, since only two layers are to be raised.

Further advantages and features of the invention emerge from the The following description of exemplary embodiments with reference to the drawing, which is an enlarged schematic representation Figure 10 shows a sectional view of an embodiment of the photosensitive layer according to the invention.

An electrically conductive base 1 is made of brass, aluminum, Copper or the like in the form of a sheet, a good track, a plate, a cylinder, a drum or any other shape with any thickness. Likewise is metallized paper and glass provided with a metallic coating, for example aluminum, copper iodide or the like. In a special one Execution, the surface of the base can be covered with a thin insulating layer. In another version can the document can also be omitted.

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An essentially glassy alloy layer 2 is composed of selenium, tellurium, germanium and / or silicon. The glassy one Layer 2 can have a thickness between about 10 and 300 µm. For economic reasons, the thickness is preferably in the range from 20 to 80 µm. Basically has a relatively thick layer of more than 300 .mu.m less adhesive strength compared to the base, so that from this point of view, too, a thickness of 20 to 80 .mu.m is appropriate.

The ratio of the additives to the alloy can be varied over a wide range. For example, tellurium can be contained in a ratio of 5% by weight to 25% by weight. With a salary of less. Less than 5% the sensitivity to red light decreases somewhat, while at a content of more than 25% a disadvantageously high dark discharge occurs. Only small additions of germanium and / or silicon are necessary for adequate stabilization. A larger addition of these substances brings about a reduction in sensitivity, so that the content should not be more than 5%. The content of these substances is preferably in the range from 0.001 to 1% by weight, so that production is simplified.

A substantially glassy alloy layer 3 mainly settles composed of selenium and an additive, germanium and / or silicon, and is applied to layer 2. The thickness of the Layer 3 usually ranges between 0.1 and 3 pn · together with the lower layer 2, the layer 3 imparts panchromatic properties to the photosensitive material, i.e. one sufficient sensitivity in the visible light range up to a wavelength of 4 · 000 1. The content of germanium and / or silicon is preferably somewhat higher in layer 3 than in layer 2

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and usually ranges between 0.1 and 5 weight percent to be sufficient to obtain stable alloy.

In the preferred embodiment, it is photosensitive according to the invention Layer composed of a base and a photoresist layer formed from two layers and applied thereon.

An insulating layer 4 is not always necessary, but it provides effective protection of the surface of the photosensitive layer and increases their service life. The layer 4 is formed, for example, from a polyester layer material.

The photosensitive layer thus constructed with an insulating layer 4- is for electrophotographic processes according to the Example 1 in Japanese Patent Laid-Open No. 23910/1967 can be used advantageously.

The light-sensitive one having an insulating layer of the type mentioned Layer can be exposed to an image, provided that the substrate or the insulating layer is exposed to radiation the photoresistive layer responds, can be passed through. Accordingly, the insulating layer is preferably transparent.

To create a new use of the photosensitive In a further embodiment according to the invention, the material can have a converter layer in which a Radiation image can be stored in the form of a resistance pattern.

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The photosensitive layer of the present invention is according to various Process producible. A vapor deposition process is particularly suitable, some examples of which are given below are.

In one method, one containing selenium, tellurium, germanium and / or silicon and one containing selenium, germanium and / or silicon

Alloy containing -7 -5 "is vapor-deposited one after the other in a vacuum of 10 'to 10 ^y mm Hg on a base. It is also possible to arrange the two alloys at different feed points in a common vacuum vessel and to apply them one after the other without interrupting the vacuum.

In another process, the individual components of the alloy are brought separately into a common vacuum and the Temperature of the individual components monitored in such a way that a coating with one of the different. Ingredients in the desired Alloy containing ratio takes place.

Another suitable method is one in which a mixture made of selenium, tellurium, germanium and / or silicon in powder form in appropriate amounts in a vessel at around 400 - 600 ° C is introduced and evaporated for application on a base.

The substrate is kept at a temperature of about 50 to 80.degree. C. in the specified processes. A cooling device, for example a water-cooled plate, is provided to maintain this constant temperature. During vapor deposition at about 280 ° 0 in a vacuum of about 5 * 10 "^ mm Hg for about one hour, an alloy of selenium, tellurium Qer-

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manium and / or silicon existing layer with a thickness of about 60 µm.

Some examples to illustrate the invention are given below, however, which do not constitute a limitation of the invention.

Example 1: -.

An aluminum plate. 1 mm thick and 200 χ 200 mm in size was polished with a chamois leather and cleaned with trichlorethylene vapor and serves as a base for light-sensitive items Material.

The aluminum plate was brought into close contact with a copper plate in a vacuum vessel to maintain its temperature at about 60-70 ° C. At a distance of about 250 mm below the aluminum plate was a vessel with a lid containing numerous small holes. An alloy of 85% by weight selenium, 15% by weight tellurium, and 0.1 % by weight germanium is placed in the vessel. A shut-off device was arranged between the base and the vessel.

Gas was first evacuated for 30 minutes at 180 ° C., then the vessel containing the alloy was brought to a temperature of 250 ° C. and the shut-off device was opened. After steaming for 30 minutes, the shut-off device was closed again. A layer with a thickness of approximately 40 μm is thereby formed. This is followed by a further vaporization for 4 minutes

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an alloy containing 95% by weight selenium and 5% by weight germanium made at about 400 ° C, a layer of about 0.5 µm thick. In the two mentioned steaming

5 4

-5 -4-the pressure was kept at 10 Ms 10 mm Hg. To after closing the shut-off device, the pad was quenched to room temperature. The manufacture of the photosensitive Material was made by applying Epojcydharz solidifiable at room temperature to produce a 12.5 pn thick Polyester layer completed.

The surface of the photosensitive material was "corona discharge of about 7000 V with a negative charge of 2000 V provided and then with simultaneous exposure to a radiation image of a corona discharge with the above exposed to opposite polarity. Eventually the entire area was used to produce a latent electrostatic Image exposed to uniform radiation.

The photosensitive layer was found to be sensitive over the entire range of visible light, the sensitivity being up to 1 lux sec. ₍ . This means that the sensitivity is »more than ten times that of the known so-called xerographic plates based on selenium.

By developing the latent images with positively charged color toners, clear images with good resolving power become clear obtain. When using liquid toners, the power increased.

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The photosensitive according to the invention was used to determine the shelf life Material up to violent destruction to 50, 60, Heated 70 ° C and so on and compared the results with conventional selenium-based plates. It was found that the photosensitive material according to the invention is just as stable and durable as conventional selenium plates even if none insulating surface layer is provided thereon. On the other hand, when an insulating surface layer was applied, was the photosensitive material of the present invention was hardly attacked. The light-sensitive one provided with an insulating layer as a surface In addition, the material was mechanically strong and its properties remained almost unchanged.

A comparison of the properties of the different materials is shown in the following table:

Sensitivity Lux.see.

spectral

sens-

opportunity

Lifetime (conventional layers = 1)

According to the invention it is "photosensitive Material with an insulating surface layer

Panchromatic

Higher than

Material according to the invention without an insulating layer

Panchromatic

Higher than 3

Conventional material
based on selenium

20th

Low sensitivity in the red area

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Example 2;

A powdery mixture of selenium, teelur and germanium with a degree of purity of more than 99 »99% was made in a vacuum of about 10 "" * mm Hg enclosed in a quartz vial. To the Melting the contents of the vial was done at 500 ° C for 5 hours heated. The vial was rotated while heating to obtain a homogeneous melt. The vial was then placed in Immersed in water to quench the resulting glassy alloy of selenium, tellurium and germanium. There were ten in this process Vitreous alloys No. 1 to 10 produced with different compositions. The change in composition was made through change the mixture ratio of the powdery raw materials selenium, Tellurium and germanium.

Glassy alloy content (wt.%)

Selenium tellurium germanium

No. 1 Ho. 2 Fo, 3 Ho. 4 Ho. 5 Ho. 6 Ho 7 Ho 8 Ho. 9 Ho 10

99.9 0 -, 0.1 97.9 2 0.1 94.9 5 0.1 89.9 10 0.1 84.9 15th 0.1 79.9 20th 0.1 74.9 25th 0.1 69.9 30th 0.1 59.9 40 0.1 49.9 50 0.1

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The vitreous alloys listed above were applied to an aluminum base in a layer thickness of 60 μm by vacuum vapor deposition. During vapor deposition, the vacuum was 10 to 10 'mm Hg, the temperature of the aluminum base concerning
held.

position was 60 to 80 C and the vapor deposition temperature was 350 C.

Using the method of Example 1, a 97 wt.% Selenium and 3 wt.% Germanium was applied to these coatings Alloy evaporated in vacuo to form a layer approximately 1 µm thick. Thus, with the alloys 1 to 10 photosensitive plates 1 to 10 were prepared. The photosensitivity and the darkness value of these plates was measured under the following conditions.

The photosensitivity was measured by the photosensitive Plate was placed on a rotating electrometer and positively charged. Then the plate was covered with a 60 watt tungsten Filament lamp is illuminated and the amount of light required to lower the potential to 1/10 of the initial value (lux> see) is measured. The measured value was expressed as a sensitivity value. The irradiation was started at an initial value of 500 V in each case.

The dark fading value was determined by: Charging the surface of the plates to about +800 V by means of a corona discharge of + 6KV with subsequent rest in a dark place and measuring the reduction of the charge to half the initial value, i.e. to 400 V ₁

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"required time is determined. The reciprocal value of this time is taken as the dark fade value to facilitate comparison with the sensitivity value. The value of the photosensitive Plate 1 was used as a basis for comparison.

The photosensitivity values and dark shrinkage values of plates 1 ( up to 10 according to the above measurement methods are given in the following table)

Dark fading

1.0 1.2 1.28 1.8 2.3 2.8 4.6 7.8

10.5 13.0

Photosensitive * j • "i f * \\ Ή f * vn t \ * P Sample plate LL L-UL U Ciup J. No. 1 30th No. 2 25th No. 3 21st No. 4th 18th No. 5 18th No. 6th 15th No. 7th 13th No. 8th 12th No. 9 - 10 No.10 7th

The above results show that the photosensitive plates No. 3 to 7, i.e. the plates with contents of 2 - 25% Tellurium, excellent electrophotographic elements.

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Example 3:

In the same way as in Example 2, the following 13 vitreous alloys were produced using selenium, tellurium and germanium in powder form.

Glassy alloys Content of metal components (% by weight )

Selenium tellurium germanium

No. 1 No. 2 No. 3 No. 4 No. 5 No. 6 No. 7 No. 8 No. 9 No. 10 No.11

* No.12 No.13

85 15th O 84,0009 15th 0.0001 84.009 15th 0.001. 84.09 15th 0.01 84.9 15th 0.1 84 15th 1 83.5 15th 1.5 83 15th 2 82 15th 3 80 15 · '. 5 78 15 '. 7th 75 15 ' 10 70 15th 15th

The above-identified glassy alloys were applied under the conditions given in Example 2 by vacuum vapor deposition in a 60 by sinterized layer on an aluminum base. On this layer a further layer has been applied appropriately when the game. 2 In this way they became photosensitive

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Plates 1 to 13 are made. The photosensitivity and durability the plates were measured. The same procedure as in Example 2 was used to measure the photosensitivity. The procedure for measuring the durability is explained below.

The light-sensitive plate was uniformly charged positively by a corona discharge of + 6KV and then exposed to exposure by means of a 10 V tungsten lamp at a distance of 30 cm for 2 seconds through a positive transmitted light image. The resulting latent image was developed into a visible image using the magnetic brush process and this was transferred to paper. After the transfer, the photosensitive plate was cleaned and subjected to a corona discharge to remove residual electrical charge. The copying process was repeated in the manner described. The durability was determined by the number of copies that can be made with a clear image. A copy with a clear picture was based on the requirement that nothing more was visible to the naked eye
copy are recognizable.

to the naked eye not more than 30 scattering points per 100 cm of the paper

The values determined for panels 1 to 13 are as follows Given in the table.

Photosensitive Lightly sensitive- Haitharkfiit Sample plate worth 1 15th 5700 2 16 7900 3 16 31100 4th 17th 38200

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5 19 52 * 00

6 29 56 000

7 34 57 900

8 40 61500

9 43 62 700

10 50 66 100

11 71 74 400

12 85 76 800

13 104 80 100

The above results show that the Flatten 3-10 are particularly high, so that a germanium content of 0 _t oo1 particularly good properties to 5% for electrophotography yields. Repeating the same procedure with silicon instead of germanium gave good results.

Venn, for example, silicon in each half of the The amount of germanium used, the values for photosensitivity and durability were 80% of those determined for the addition of germanium.

Example 4;

In the same procedure as in Example 2, 84.9% selenium, Tellurium and 0.1% germanium for the production of a glassy alloy used. The alloy was uniformly evaporated in a method according to Example 1 to a thickness of 40 µm on an aluminum backing plate.

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For the second layer of glaze to be applied to this layer, were the following 14 different vitreous alloys were produced in a method according to Example 2.

Alloy Alloy ratio (wt.%)

Selenium germanium

Uo. 1 99.99 0

No. 2 99-9 0.01 '

No. 3 99.5

No. 4 -99 '0.5'

No. 5 98 2

No. 6 95 5

No. 7 93 7

No. 8 90 10

No. 9 88 12

No.10 85 15

No.11 80 -. 20th

No.12 75. '- ² 5

No. 13 65 -35

No.14 50 50

The above-mentioned vitreous alloys were under the conditions given in Example 1 to the first mentioned Layer is vaporized and thus a layer cover of 0.4 µm is achieved. The light-sensitive ones listed in the table below were thereby determined Plates 1 to 14, the second layer of which corresponds to the listed alloys 1 to 14, are obtained. The sensitivity to light and shelf life of the panels was determined according to the procedures given in Examples 2 and 3.

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The following table shows the results obtained:

Photosensitive 14-cht sensitive TTq ι ^ ~ ι ** ω v * I ^ ^ i ^ * r Sample plate worth fi ^ fl j ^ u g ^ X Jx ^? JL w 1 15th 5600 2 17th 10100 3 19th 20700 4th 22nd 28800 5 23 37400 6th 26th 45500 7th 29 49200 8th 32 52700 9 40 53000 10 41 54100 11 48 56800 12th 56 57300 13th 61 59400 14th 80 60800

From the above results, it was concluded with respect to the second layer that as the germanium content of the alloy increases, the durability increases while the photosensitivity decreases. With regard to the course of this increase or decrease , it can be seen that the photosensitive flats No. 3-11, in particular 3-6, are excellent, that is, that a germainium content in the range from 0.1 to 20%, preferably between 0 , 1 and 5% provides excellent electrophotographic properties. It can also be seen that the plate 1 without germanium has poor durability.

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Using the same proportions of germanium and silicon, but without further changing the mixing ratios of the above For example, an alloy was made for the second layer. For example, 0.05% germanium and silicon were used in alloy 3 in the table above, so that their total was still 0.1%. In the case of alloy 8, the proportions were 5% each, which together is one Germanium / silicon content of 10% resulted. Using these alloys as a second coating, the photosensitive plates 1-14 of the table below. The determined sensitivity to light and durability of these photosensitive plates are shown in the following table.

Photosensitive sample plate

Light sensitivity value

durability

1 17th 5600 2 19th 12900 3 20th 25500 4th 22nd - 30100 5 26th - 41200 6th 35 50500 7th 40 52200 8th 48 55600 9 55 59700 10 67 60700 11 89 61100 12th 102 63100 13th 135 63800 14th 143 64000

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Claims (12)

Claims Light-sensitive layer structure for electrophotography, characterized in that one of a first layer (2) containing selenium, tellurium and germanium and / or silicon as an additive and a second layer (2), selenium and a photoresistive layer formed as a layer (3) containing germanium and / or silicon is provided. 2. Layer structure according to claim 1, characterized in that the thickness of the first layer (2) "Is 20 to 80 pm. 3. Layer structure according to claim 1 or 2, characterized in that the tellurium content in the first Layer (2) is between 5 and 25% by weight. 4. Layer structure at least according to claim 1, characterized characterized in that the content of the additive in the first layer (2) is not higher than 5% by weight. 5. Layer structure according to claim 4, characterized in that the content of the additive in the range of 0.001 to 1% by weight. 6. Layer structure at least according to claim 1, characterized characterized in that the second layer (3) has a thickness of 0.1 to 3 pi. 7. Layer structure at least according to claim 1, characterized in that the content of the additive in of the second layer (3) in the range between 0.1 and 5% by weight lies. 10 9 8 12/1507 20A2592 8. Layer structure at least according to claim 1, characterized characterized in that the content in wt .-% of the additives in the second layer (3) is greater than the one in the first layer (2). 9. Layer structure according to at least one of claims 1 to 8, characterized in that a base is provided on which the first layer (2) is applied is, and that the second layer (5) is applied to the first layer (2). 10. Layer structure at least according to claim 9t thereby characterized in that the base (1) is electrically conductive. 11. Layer structure at least according to claim 9 »thereby characterized in that the base (1) has an electrically insulating effect. 12. Layer structure according to at least one of claims 1 to 9 » characterized in that on the second layer (3) an insulating layer permeable to radiation to which the photoresist layer is sensitive is upset. 109812/1507 it Blank page