DE2130365A1 - Electrophotographic photosensitive element - Google Patents

Description

Patent attorney 18, J (JMi 1971

Dipl.-ff> g- A. Qrünecket Dr.-Ing. H. Kinkeldey

Dr -ing. W. Stockmak £. IOUODO

Dr.rer. not. W. Fischer 8 Munich 22. Maximilians *. 49

CANON KABUSHIKI KAISHA 30-2, 3-chome Shimomaruko, Ohta-ku, Tokyo , Japan

"Electrophotographic Photosensitive Element"

The invention relates to an electrophotographic, photosensitive Element and in particular the improvement of an electrophotographic photosensitive element made from a Base layer, a photoresist layer and an insulating layer.

There are already various electrophotographic photosensitive ones Elements with such a three-layer structure as well as Inventions relating to an improvement in such photosensitive elements have become known, the latter mostly related to an improvement of the photosensitive elements a stable! retention of an electrical charge or charge.

A useful means of being able to inject sufficient photocurrent carriers, on the other hand, has not yet been known or disclosed.

The invention is therefore based on the object of providing an improved photosensitive element having three layers of the layers specified at the outset Art to create that is able to stably receive or hold back a charge, in which photo current carriers are sufficiently injected and capable of forming excellent electrostatic images, and a method for making such photosensitive elements available.

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The subject of the invention is an electrophotogranhiseh.es, Photosensitive element having a base layer, a photoconductor layer and one overlying the photoconductor layer Insulating layer, as well as a barrier layer lying between the base layer and the photoconductor layer.

The attached drawing shows:

Figure 1 is an enlarged cross-sectional view of an inventive electrophotographic photosensitive member;

Figure 2 is a diagram showing the charging and discharging characteristics a photoconductor layer according to the invention or the Photoconductor layer of a light-sensitive according to the invention Element reproduces;

Figure 3 is a diagram showing the charging and discharging characteristics a barrier layer according to the invention or a barrier layer characterizing the photosensitive elements according to the invention reproduces;

Figure 4 is a graph showing the charging and discharging characteristics reproduces a photosensitive element according to the invention;

FIG. 5 shows a diagram in which the decrease in charge of a photosensitive element according to the invention and that of a photosensitive element according to the prior art are shown in a comparison in each case for the case of exposure and the case of dark discharge;
and

FIG. 6 (A) and (B) the state of charge of a photosensitive element according to the prior art or one according to the invention photosensitive element.

Examples of electrophotographic processes in which a photosensitive element composed of a base layer serving as a base, a photoconductor layer and an insulating layer is used are, for example, processes which include primary charging, secondary charging with simultaneous imagewise exposure and total exposure, for example in the USA.-patent applications ITr. 563 899 from b. July 1966 and No. 571 53ö of August 10, 1966 described electrophoto-

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graphic process.

.N & ch .... electrophotographic processes of this type can Electrostatic images are created by holding a certain charge Applying polarity to the insulating layer, at the same time a charge of opposite polarity from the Base side or the base layer is injected in order to bring the charge close to the interface between the photoconductor layer and the insulating layer and in the photoconductor layer, then a DC corona discharge with the opposite of the primary charge Polarity or an alternating current corona discharge with simultaneous image-wise exposure to the photosensitive Allowing the element to act, whereby the charge attached to the points of adhesion does not appear in the bright or exposed areas the dark areas is released, and finally one Apply iotal exposure to increase contrast and create an electrostatic image.

An essential meaning comes in or with the light-sensitive Three-layer elements correspond to the state of charge of the Primary charging at traps to fixed charges. It it is extremely desirable that the cargo is held securely, the sensitivity of the photoconductor layer is increased and injected from the base or conductive layer lightly and in sufficient quantity photocurrent carrier into the light-sensitive layer will.

In the photosensitive element shown in Figure 1 is between a highly sensitive photoconductor layer 2 and a base layer 4 a locking rail 3 is provided to easily Inject photocurrent carriers and a charge with that of the primary charge in an insulating layer 1 at traps fixed charge of reverse polarity at the level of the interface between the photoconductor layer 2 and the insulating bar 1 hold or hold back.

The sensitivity of a light sensitive element with a on a conductor (base not 4) by vapor deposition or flattening applied rail made of a Se-Te alloy (photoconductor layer 2) varies depending on the tellurium content. The higher

109882/1680 ORIGINAL BATHROOM

The higher the tellurium content, the higher the rjupfinalicukeit * The sensitivity reaches a maximum at a tellurium content of about 20 percent by weight, whereby the resistance decreases, while the crystallization is accelerated and ~ the life of the photosensitive member is shortened.

According to the present invention, it has been found that crystallization can be suppressed without lowering sensitivity by adding 0.01 to 8 percent by weight of germanium, silicon or Ge-Si to the photoconductor layer. If the material obtained in this way is used as a photoconductor layer, the selenium contains 6 to 45 percent by weight tellurium and, if desired, additionally 0.01 to 8 percent by weight Ge, Si or Ge-Si. The photoconductor material can be vapor-deposited onto an aluminum plate as a photoconductor layer. The photosensitive element obtained in this way is positively or negatively charged by means of a Kofona discharge device in the dark for a certain period of time "t". The resulting charge potential, as can be measured by means of an electrometer, is shown in FIG. 2, from which it can be seen that the charge applied at the charging time f gradually falls or sinks regardless of the polarity of the charge due to dark discharge. In FIG. 2, "a" denotes a positive charge curve (charging and discharging curve) and "b) a negative charge curve.

When the tellurium content reproduced in a to produce a photosensitive member on an aluminum plate vapor-deposited selenium layer and more specifically, selenium-tellurium layer is reduced to less than about $ 5>, so resulting in a negative or positive charge of this photosensitive member in FIG 3 Charge curves (charge and discharge curves). Compared to the charge curves with a high tellurium content, the surface potential in the case of the negative charge or charge shown in FIG. 3 is considerably lower. In other words, this curve is to be interpreted in such a way that it is easy to inject positive holes (photoconductor) from the base layer (base or carrier).

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When the above-mentioned selenium or tellurium .enthaltende different amounts of selenium alloys used in combination, and a positive or negative charge · dial ¹ end of a time interval "f" is applied, ao is obtained reproduced in Figure 4. charge state.

The negative charge curve (charge and discharge curve) is almost the same as that shown in Figure 3 of the barrier layer with a lellurium content of less than 6 ^c , O _t while the positive charge curve (charge and discharge curve) is almost that of a photoconductor layer shown in Figure 2 equates to a relatively high or heavy waste.

In figure j ^{l is} the change in measured by means of an electrometer surface potential is reproduced, which one finds when f is a negative charge during a period of time on the one hand to a photosensitive member having a photoconductive layer having the shown in figure 2 Aufladungsund dark discharge characteristics, and also lying insulating layer, and on a photosensitive element with a photosensitive layer with blocking or rectifying effect and the charging and dark discharge characteristics shown in Figures 3 and 4, as well as an overlying insulating layer and discharging the photosensitive elements in the dark or under exposure.

The charge drop curves or discharge curves for selenium alloy containing Se or more than 6 ^a Jo tellurium are denoted in FIG caused by dark discharge

from
vividly. The fall curves / Se or selenium alloys with a tellurium content of less than 6 ^c / o are denoted by ß and ß ¹ , with the curve denoted by ß the potential drop during exposure and the ^{curve denoted by ß 1} the potential drop due to dark discharge. There is hardly any difference between the curves marked β and β ^1.

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As can be seen from Figure 5, the Gberfluchenpotei-vtial drops of the selenium or a selenium alloy with a tellurium ^ ehalt of at least ^l G ß> (corresponding to the Kurvenforu of Fi _o ur 2) after charging from. The above-mentioned photosensitive member, when charged, has a charge distribution. The charge is injected from the conductive layer 11 to neutralize the charge on the insulating bar 13 over time, and then drops. For comparison, an inventive electrophotographic photosensitive member of the type shown in Figure 6b is provided with a barrier layer 14 having a uniform moderate electrostatic charge on the Isolierschicht'13 and in the liähe the interface between the insulating layer and the Phοtoiexterschicht 12, wherein hardly any Ladungsab- ψ event occurs . This indicates that positive holes are injected in sufficient I ^ ass.

In the above-mentioned electrophotographic process, the wear in the area of the interface between the photoconductor layer and the insulating layer attached to traps to higher sensitivity, high resolution, high Contrast and good image quality.

According to a preferred embodiment of the invention, as Base layer a conductor, such as aluminum, copper, brass and the like in any thickness and in the desired shape, e.g. in the form of sheets, webs, plates, drums and cylinders,). On the base layer are known according to Layer production methods such as spraying, co-evaporation or Vacuum evaporation of a barrier layer and a photoconductor layer upset.

The barrier layer can be formed by vapor deposition of the base layer with a chalcogen mass containing 0 to 6 percent by weight tellurium, e.g. Se, Se-Te, Se-Ge, Se-Si, Se-Ge-Si, Se-Te-Ge, Se-Te-Si, be applied Se-Te-Ge-Si, and the like ^, eluting with a stepped Basisechicht- or Subs temperature of about 65 to etv / a 8O ⁰ G works and an approximately 1 to 60 applied to thick layer.

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The photoconductor layer can be created by adding one more as 6 and preferably "containing up to about 45 percent by weight of tellurium" ^ Chalcogenin mass, such as Se-Te, Se-Te-Ge, Se-Te-Si, Se-Te-Ge-Si and the like, in a thickness of about 1 to 80 µm. applies.

As the insulating layer overlying the photoconductor layer, any insulating material which is excellent can be used Has the ability to retain or hold charges and rays to which the material of the photoconductor layer is sensitive. Representative examples of suitable insulation materials are organic insulating layers, such as synthetic resin films, e.g. polypropylene and polyester films, inorganic insulating materials, such as alumina, mica and the like, and composite materials of inorganic and organic insulating materials.

The examples illustrate the invention, which, however, is not restricted to the examples.

example 1

A mixture of selenium and iellur powder with a purity of more than 99 _t 99 5 »in a weight ratio of 9 ϊ 1 is poured into a quartz ampoule evacuated to about 10 Torr, whereupon the ampoule is melted shut and lasted for about 7 hours 550 C is heated to melt the contents. "The melt is preferably sufficiently stirred by shaking or rolling. The ampoule is then quenched in water. In this way, a glassy or amorphous Se-Te alloy is obtained." The glassy alloy thus obtained is under a pressure of

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10 to 10 mm Hg at a base layer or substrate temperature of 65 to 70 ° C and a steam source temperature of about 250 C on an aluminum base layer to form an approx 40 µm thick light-sensitive layer or photoconductor layer vaporized. Then, a 25 ^ in thick layer is applied to the surface of the photosensitive layer using an epoxy resin Glued on polyethylene fcerephthalate film, whereby one is a light-sensitive Element with a layer structure is retained. This light-sensitive element is referred to as "light-sensitive

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Liches standard element ", continues to be in a

-3
About 10 Torr evacuated quartz ampoule filled with selenium powder, whereupon the ampoule is ^{heated to about 500 °} C. for 6 hours in order to melt its contents and then quenched in water. Glassy or amorphous selenium is obtained. This glassy 'Seieulegie-

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tion is vapor-deposited onto an aluminum base layer at a pressure of 10 to 10 mm Hg, a base layer or substrate temperature of 65 to 75 ° C. and a steam source temperature of about 250 ° C. to form a barrier layer about 20 μm thick. On this barrier layer is then pressed at a pressure of 10 to 10 mm Hg, a substrate temperature of 85 to 80 ^0C and a vapor source temperature of about 250 C, the above-mentioned glassy or amorphous Se-Te alloy to form an about 30 "^ to Then a 25 μm thick polyethylene terephthalate film is stuck onto the light-sensitive layer with an epoxy resin, whereby a light-sensitive Είδ element with a four-layer structure is obtained.

The standard photosensitive element will be that of Japanese Patent Publication No. 24748/1968 electrophotographic process using an amount of exposure light of about 10 lux. Seconds, taking an image with an electrostatic contrast of about 400 V receives.

For comparison, the above-described according to the invention photosensitive element using the same conditions subjected to the same electrophotographic process as the standard photosensitive member, with one Exposure light amount of 5 lux. Seconds an electrostatic Contrast of about 600 V is achieved and the photosensitive member of the present invention is also excellent in resolving power and panchromasia shows.

Example 2

Se, Te and Ge powders, each with a purity of more than 99.99 '/ °, are mixed in an atomic ratio of 1: 1: 1, ground in a ball mill for about 20 hours and then on

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about 10 Torr evacuated quartz ampoule melted, whereupon the ampoule is ^{heated to about 800 °} C. for 50 hours in order to melt its contents. The melt is preferably mixed in the ampoule by shaking or rolling. The ampoule is then quenched in water to give a glassy Se-Ie-Ge alloy. Furthermore, a Se-Te alloy with a weight ratio of selenium to tellurium of 100: 7 is produced analogously to the procedure described in Example 1. Then, a selenium barrier layer applied to an aluminum plate according to Example 1 is applied using the Se-Te . Ge alloy or the Se-Te alloy is approximately 30 pr applied by Gobedampfen a strong light-sensitive layer or photoconductor layer the photosensitive layer thus obtained selenium, tellurium, and germanium in a weight ratio of about 90:. 10: 0,4 '. During the vapor deposition of the photoconductor layer, the following conditions are used: pressure 10 "" * to 1G ~ ^P mm Hg; substrate temperature 65 to 82 ⁰ C; and steam source temperature about 55O ⁰ C in the case of the Se-Te-Ge alloy and about 250 ⁰ C in the case of Se-Te Iegierung. Then, it is bonded to the surface of the photosensitive layer with an epoxy resin are each a 25 p thick polyethylene terephthalate film, to obtain a light-sensitive element with four-layer structure.

This photosensitive element is analogous to Example 1 and under the same conditions as in Example 1 an electrophotographic Subject to proceedings. An exposure light amount of 5 IjUX is obtained. Seconds an electrostatic Contrast of about 550 * volts, and also the resolution, the panchroiaasia and the durability of the tested photosensitive elements prove to be excellent.

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Claims (1)

Patent claims fly electrophotographic, photosensitive element with a base cMc: it (4), a photoconductor layer (2) and an insulating layer (1) lying on the photoconductor layer (2), as well as a barrier layer lying between the base layer (4) and the photoconductor layer (2) ( 3). 2. Photosensitive element according to claim 1, characterized in that that the photoconductor ^ sends (2) more than 6 ', p Contains te. 5. Photosensitive element according to claim 1 or 2, characterized in that the barrier layer (3) contains less than 6 fi Te . 4. Photosensitive element according to claim 2 and 3, characterized in that the photoconductor layer (2) contains up to 45 ^c ß> Te. 5. Photosensitive element according to at least one of the claims 1 to 4, characterized in that the photoconductor layer (2) 6 to 45 # Te and 0.01 to 8 56 Ge, Si and / or Contains Ge-Si. 6. A method for producing an electrophotographic, photosensitive element, in particular according to at least one of claims 1 to 5, characterized in that a selenium or selenium alloy layer (barrier layer) containing less than 6 # tellurium is applied to this barrier layer on a base layer 6 $ έ and preferably less than 45 $> tellurium-containing photoconductor layer and applies an insulating layer to the photoconductor layer. 109 882/16 80 BATH ORIGINAL A4 Blank page