DE1652426A1 - Device for applying liquid to a surface - Google Patents

Description

HCA 57 6 $ 7 ■ "'■ ■
US Ser. No. 593 ** 9 *
Piled: November 10, 1966

Radio Corporation at America, New York, N. Y ,, V, St.A ₄

Device for applying liquid to a surface.

The invention relates to a device for applying Liquid on a surface. In particular, it relates to an improved applicator head for latent electrostatic development Charge images on the surface of a recording medium. With the help of such a head, a developer liquid, the electrically charged toner or Contains dye particles, distributed.

In so-called electrophotography or electrostatic Printing is known (USA patents 3,196,832 and JS 176 655), developer applicators with liquid distribution heads to use, by means of which the developer liquid is distributed over the surface of a charged sheet of paper will. Such distributor heads can be very closely spaced arranged from the paper surface and passed over this to apply a thin developer film.

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When asked. · From developer liquid to electrostatic Charge image, the liquid must be stirred during application in order to distribute the charged dye particles in such a way that that a flawless. Pressure arises. This stirring is quite a critical process. If the particles don't are stirred sufficiently, there is a high concentration of particles in the more strongly charged areas of the image, while in those areas that are weak charged areas the particle concentration is insufficient. On the other hand, if the agitation is too vigorous, they have resulting prints have a blistered appearance, and the image is unclear and somewhat distorted due to the lack of sharpness in detail.

The invention is based on the object of an improved To create an application head for the electrostatic printing process, by means of which the developer liquid or a rinsing liquid can be applied evenly to a surface, the for an optimal distribution of the dye particles over the charged paper surface required stirring action is generated. The liquid supply is achieved by means of the application head according to the invention controlled so that there is no leakage or uncontrolled loss of fluid. The application head according to the invention is also for the simultaneous or consecutive up ^ carry various fluids such as those used for making of multicolor printing according to the electrostatic printing process are required.

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According to one embodiment of the invention is an apparatus for applying liquid to a surface with an application head with a closely spaced from the surface End face and three penetrating the head, each opening onto this end face with an elongated opening Lines, the elongated openings at a distance from one another run parallel over the end face, characterized in that the middle of the three openings over the connected Line is connected to a source of pressurized gas that one ■ the other two openings via the connected line is connected to a source of the liquid to be applied, and that the third opening via the connected line to a Vacuum source is connected in such a way that the gas from the central opening over the surface to this third opening flows, with the head in relation to the surface essentially parallel to this and at right angles to the openings, and indeed in the direction from the second to the third opening the central opening is movable such that the liquid from the second opening above the surface in the gas flow between the central opening and the third opening.

This design of the application head ensures that the liquid flowing onto the surface to be coated is introduced into the gas stream, which sweeps over the surface at high speed. This is what makes the liquid like this stirred or mixed, that an optimal distribution

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of the dye particles results. Furthermore, excess developer liquid removed so that the film of liquid applied to the surface has the correct thickness. The applicator has the further advantage that after each application of developer a Dry rinsing liquid can be sprayed on, so that successively different developers for the production of multi-color prints can be applied.

The invention is explained below using an exemplary embodiment explained with reference to the drawings. Show it:

Fig. 1 is a perspective view of an embodiment the device according to the invention;

Fig. 2 is a bottom view of the Jodenflache of the device according to Fig. 1;

3 is an enlarged section taken along line 3-3 in FIG Fig. 1; and

. Fig. 4 is a front view of the liquid supply device the device according to FIG. 1.

The invention is illustrated, for example, with the aid of a device for applying developer liquids with various pigments particles on charge images on an insulating surface in the course of the production of color prints after the electrostatic Printing process explained.

Fig. 1 shows a device 10 for applying one or several liquids on a surface 12, for example the

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Surface of a recording medium sheet 24, as it is generally used in both electrophotography and photography. A latent electrostatic charge image can be located on the surface 12, for example, which is to be developed ⁷ with the aid of a liquid developer.

The liquid is applied to the surface 12 by means of an application head 30, which is driven by a drive a Bortel chain driven by a motor (not shown) at a predetermined distance from the surface 12 over the latter is moved. The sheet 24 lies on the surface 26 of a support plate 28 and is kept smooth thereon by suction, through a frame-shaped slot 29 in the base plate 28 attacks in a known manner.

The liquid to be applied to the surface 12 can either a single phase liquid such as water or a multiphase liquid, for example a developing liquid with finely divided, charged, dispersed in a carrier liquid Pigment particles used in electrostatic printing.

As liquid celestones, which can be used one after the other, at the same time or in to be applied to the surface 12 in a desired sequence are, for example, cyan, magenta, yellow and black developers (Toner) in question. These fluids are of appropriate Sources, for example, through gravity conveying in pipes or pipes 14, 16, 18 and 20 are fed. As the source of the

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Cyan developer 19 is used, for example, in a ventilated container 21 Containers (partly indicated by dash-dotted lines) are provided for the other liquids. A washing or rinsing liquid, for example the liquid "Freon TF" (goods oak) is fed into the pipe from a suitable ventilated source 22 fed in. The various fluids are selectively fed into the tubes 14-22 by controlling valves such as the valve 23, in the lines between the liquid storage tanks and the tubes 14-22 inserted.

According to one embodiment of the invention, the application head 30 with a liquid supply line 32 and a liquid discharge line 34 arranged in such a way that it can be moved over the surface 12, namely always at a predetermined distance therefrom. The application head 30 consists of an elongated, cuboidal configuration having a bottom surface 36 spaced approximately 0.38 mm (15 mils) from the surface 26 of the Backing plate 28, i.e., about 0.25 mm (10 mils) from surface 12 for sheet 24 thickness of approximately 0.13 mm (5 mils) can be placed. The surface 36, which is shown here as flat, can be any the shape adapted to the surface 12 if the surface 12 is not flat.

At the ends 42 and 44 of the head 30 there are guide devices in the form of a plate 38 or 40, for example, fastened adjustable by means of slots and screws. On the plates 38

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and 40, a respective front vertical spacer roller 46 or 48 is attached so that it rests on the surface 26 of the base plate 28. Rear vertical spacer rollers (not shown) also attached to plates 38 and 40, along with front rollers 46 and 48, maintain head 30 a predetermined distance from the latter as it moves across surface 12. Furthermore, horizontal guide rollers 50 and 52 are attached to the plates 38 and 40 and run over the one vertical surface 54 of the support plate 28 in order to guide the head 30 over the surface 12 as it moves. On the plate 28 is a corresponding set of horizontal guide rollers. (not shown) provided. The Bortel chain 56 is connected to the plate 40 and coupled to suitable drive means (not shown) to move the head J> 0 back and forth across the surface 12. The base plate 28 can also be movable with respect to the head 30. In any case, the drive device causes a relative movement between the head 30 and the surface 12 such that the surface 36 and the surface 12 move in parallel planes.

Details of the head 30 will now be explained with reference to FIGS. 2, 3 and 4. The liquid drainage line 34 has a central longitudinal slot 60 which passes through the head and extends from an elongated opening in the lower surface 36 to an opening in the surface 62. The opening of the slot 60 in the lower surface 36 runs across the surface 12.

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The liquid inlet line 32 is removably arranged within the liquid drain line 34 so that it can be removed for cleaning purposes if necessary. The liquid supply line 32 has an elongated rectangular plate 64 (FIG. 4) made of electrically insulating material such as "Plexiglas" (trademark). Two tabs 66 and 68 are secured in recesses on the two edges of the surface 70 of the plate 64, for example by means of screws, so that they protrude laterally from the plate 64. A metallic manifold 74 having a lower surface 72 is attached to the lower surface of the plate 64. The tabs 66 and 68 are used to position and hold the liquid supply line 32 within the slot 60 so that the lower surface 72 of the manifold 74 is a predetermined distance above the surface 12, for example a distance of about 0.38 mm (15 mils) to open carry the liquid is arranged. When the liquid feed pipe inserted into the slot 60 32, the lower surfaces store the sideways ψ projecting tabs 66 and 68 on the surface 62 of the liquid outlet conduit 34. Between the surface 62 and the tabs 66 and 68 washers may be used to the bottom surface 72 of the distributor piece 74 to be adjusted with respect to the surface 12, if desired.

The tubes 14-22 of the liquid supply line 32 are over separate bores I4a-22a in the plate 64 to the manifold 74 connected. The lower surface 72 of the manifold

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has a longitudinal slot 76 (Fig. 5). The slot 76 is approximate 0.15 mm (5 mils) wide and runs down the center of slot 60 over almost its entire length and essentially parallel to its side walls. The sectional area of the slot 76 is relatively small, approximately equal to the cross-sectional area of one of the tubes 14-22, so that the liquid in the correct Inflow amount emerges and is evenly distributed. The liquid entering one of the tubes 14-22 flows through the corresponding one of the bores I4a-22a in the hollow manifold and exits through slot 76. As a result, the liquid comes into contact with the surface 12. Because of the relatively is the small width of the slot 76 and because of the gravity conveying of the liquid, the flow impinging on the surface 12 essentially laminar and undisturbed or undisturbed.

In electrostatic printing, it is often desirable to keep the dye applicator in relation to the conductive base, on which the recording medium is arranged to be biased with a voltage of suitable polarity in a known manner. For this purpose, one or more metal screws 78 (FIG. 4) are in contact with the metal of the manifold through the insulating plate 64 74 led. A wire 80 for supplying the preload is connected to the screw 78. Such a bias Is possible with the application head J5Q according to the invention, since the distributor piece 74 is separated from the rest of the device 10 is electrically isolated by the insulating plate 64.

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As especially in Pig. 2 and 3, the fluid discharge line has J4 two elongated discharge channels 82 and 84 on both sides of the slot 60. The channels or passages 82 and 84 open into openings at the lower surface J> 6 and communicate with the space 86 between the surface 12 and the lower surface 36 in connection. The channel 82 is enlarged at 83 at one end 44 of the head JO, while the channel 84 is enlarged at 85 at the other end 42 of the head 30 and communicates with a source of reduced gas pressure, ie with a suction device. For this purpose, the liquid drainage line 34 has openings 90 and 92 which are in communication with the widened parts 83 and 85 of the outlet channels 82 and 84 and receive flexible outlet tubes 94 and 96, respectively. The hoses 94 and 96 are connected to a common hose 98 (FIG. 1), which in turn is connected to a suction device, for example a vacuum pump (not shown).

A feature of the applicator head 30 according to the invention is its relatively wide slot 60 which is open at the embodiment of the vorliegen- * outwardly to produce 82 and 84 a substantially constant pressure at the openings of the channels. In the present embodiment, this constant pressure corresponds to atmospheric pressure, since the two major surfaces 93 and 95 of the plate 64 are spaced from the two major surfaces 97 and 99 that form the slot 60, so that the plate 64 is only about half or less Volume of the slot 60 occupies. It thus forms the plate 64 with the side walls

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of the slot 60, the two channels or openings 100 and 102 (Pig. 3), which are open to the surrounding atmosphere, so that the openings of the channels 100 and 102 in the surface 36 of the Block are acted upon with gas of essentially constant atmospheric pressure. These openings are located between the Surface 72 of the manifold and the side edges of slot 60 in surface 36.

An electrical heater I03 in the form of a "heating rod is attached to the application head 30, for example by bracket 105, in order to to heat it electrically if necessary. The heater 103 prevents excessive condensation of moisture during the operation of the head JO due to the cooling effect by the negative gas pressure within the channels 82 and 84.

To explain the operation of the device 10, it is assumed that by some known method on the Surface 12 an electrostatic charge image has been produced and that, in order to make this charge image visible, the cyan developer 19 is to be applied to the surface 12. A suction device such as a vacuum pump is attached to the hose 98 connected to create a strong suction in the hose, so that a gas flow at a speed of about 3500 feet per minute over the surface 12 of the Openings of the channels 100 and 102 to the openings of the channels 82 and 84 flows. The cyan developer 19, hereinafter referred to as "liquid" is indicated by opening the valve 23 through the pipe

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l4 and the bore l4a let into the distributor piece 74. the Liquid exits manifold 74 through slot 76 into space 104 between surface 12 and the lower surface of the distributor piece 74. The liquid emerges slowly in a laminar flow under the aforementioned conditions.

While the liquid flows out onto the surface 12,)) the head JO is moved over the surface in the manner described moved in a direction perpendicular to the elongated, parallel openings of the channels 52, 100, 102, 82 and 84. The that Flow of the liquid through the manifold 74 causing Pressure is provided by gravity of the liquid above the slot 76. During operation, the surrounding gas is on both sides of the outflow channels 82 and 84 continuously into the space between the end face 56 of the block and the surface 12 as well as into the Channels 82 and 84 sucked in the directions indicated by dashed arrows 82a and 84a. Through this rapid flow of gas the excess liquid is removed from the surface 12. The surrounding gas flowing from the outside of the head 30 into the Channels 82 and 84 is sucked, prevents liquid from draining or leaking under the head 30, so that the dispensed liquid always limited to the area below the head 30 remain. This controlled flow of liquid occurs even when the head stops, as it does at the end of its stroke can be done via the surface 12. Those in channels 82 and

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The liquid that has been sucked in can, if necessary, be built in an interceptor can be recovered into the hose 98 in a known manner.

The size, shape and arrangement of the openings connected to the gas supply channels 100, 102 and the vacuum channels 82 and 84 in the head surface 36 were empirically determined so that the desired Gas flow rate of 3500 feet per minute. It was found that this air flow rate results in an optimal stirring or distribution of the dye particles in the developer liquid. The outflow channels Ö2, 84 with their enlarged parts 83 * 85 essentially form a single vacuum channel that surrounds the other openings in the head, so that the gas and liquid flow substantially from the slot 76 of the manifold 74 to the outside against the periphery of the Surface 56 of the application head takes place. Since the liquid in the Line 32 is also under the ambient atmospheric pressure, it flows in the direction of the vacuum openings connected to the outflow channels 82, 84. It was found that the speed the flow of gas through space 86 is critical for obtaining optimal results. This is not necessary However, maintaining a critical close spacing of the block surface 36 from the surface 12, so that the possibility a contact of these two surfaces with contamination or destruction of the electrostatic pressure is reduced accordingly .

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When several different developer liquids are applied to the surface 12 in succession, after each Developer application of detergent by moving the head back applied over the surface 12. The detergent is conveyed in the same way through the space 86 and in the outflow channels 82, 84 intercepted. By applying the detergent, the previously applied developer film is dried very quickly; so that the next time the head passes over the surface 12, a second and different developer liquid will be applied to the substantially dry surface can be applied. Furthermore, between the individual developer applications When the flushing process is switched on, the supply line 32 and the distributor piece 74 are cleaned, so that no undesired mixing the different developer liquids can be done.

If in operation of the application head 30 there is a risk of excessive There is moisture condensation around channels 82 and 84, the electrical heater 103 can be connected to a suitable voltage source in order to heat the head 30 and thereby eliminating the condensation. The extent of moisture condensation on the head 30 depends on the Volatility of the liquid applied to the surface 12 from.

The invention thus provides an improved apparatus for applying liquid to a surface and for removing it excess fluid is created from the surface.

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One or more liquids can be applied either one after the other or at the same time, and the feed device for the liquid can be connected to the distributor piece with as many tubes as is desired in each case. Since the cross-sectional area of the slot in the distributor piece is comparatively small, namely essentially equal to the cross-sectional area of each of the lines leading into the supply line device, no liquid enters a line when the valve between the storage container and the relevant pipe is closed. The application head JO is therefore largely leak-proof and economical in terms of liquid consumption. Further, since the application head never touches the surface to which the liquid is to be applied, and since the liquid is applied to the surface in a laminar flow, the developed images on the surface are not smeared.

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Claims (1)

Claims 1.) Device for applying liquid to a surface with an application head with a close distance from the Surface arranged end face and three the head penetrating, on this end face each with an elongated opening opening lines, the elongated openings running parallel over the end face at a distance from one another, thereby characterized in that the middle of the three openings via the connected line (100) with a Pressurized gas source is connected; that one (76) of the other two openings is connected to a source via the connected line (32) to be applied liquid (21) is connected, and that the third opening via the connected line (82) to a vacuum source (98) is connected in such a way that the gas flows from the central opening via the surface (12) to this third opening flows with the head in relation to the surface essentially parallel to this and at right angles to the openings, and although it can be moved in the direction from the second to the third opening via the central opening, in such a way that the liquid from the second opening above the surface into the gas flow between the Central opening and the third opening is entered. 2.) Device according to claim 1, characterized in that the head has two additional lines (84, 102), each with an additional elongated 109847/0305 opening in the end face (j56) at a parallel distance from the three openings on the one of the middle and the first opening the opposite side of the second opening (76) open out, the one of the two additional openings located first of the second opening openings via the connected line (102) with the Pressurized gas source and the second additional opening via the connected Line (84) are connected to the vacuum source (98). j5.) Device according to claim 1 or 2, characterized in that that the line (52) connected to the second opening (76) is removably mounted in the head. 4.) Device according to one of claims 1-5, characterized in that the head has a slot (60) which extends from the end face (j56) to the opposite surface (62), and that the one connected to the second opening Line (52) is arranged within the slot. 5.) Device according to claim 4, characterized in that the slot is attached to the central opening connected line (lOO) forms. 6.) Device according to claim 4 and 5, characterized in that the slot (60) is elongated and the line (32) connected to the second opening an elongated plate (64) which is arranged in the center of the slot and with the side walls (97, 99) 1U9847 /. ·. 3J-: those connected to the middle and to the first additional opening Lines (100, 102) forms. 7.) Device according to claim 6, characterized in that that the elongated plate (64) on the face of the head in a liquid inlet manifold (74) ends, which has a second opening for the discharge of the liquid to the surface forming slot (76). "8.) Device according to claim 7, characterized in that that the distributor (74) via several lines (14-22) to different liquid sources for simultaneous or successive discharge of different liquids onto the surface. 9.) Device according to claim 7 or 8, characterized in that the distributor (74) is formed as insulated electrical conductors and connected to a bias voltage source (80) to dye particles in a discharged through the f manifold developer liquid to be electrically charged. 10.) Device according to one of claims 7-9 * characterized in that the manifold (74) together with the slot (60) on the end face (36) of the head die middle and the first additional opening forms. 11.) Device according to one of claims 2-10, characterized characterized in that the third opening and the 1Ü9847 / 0305 second additional opening via your connected lines
(82, 84) are connected to one another and together form a negative pressure channel which essentially surrounds the other openings in such a way that the gas and liquid flow from the second opening (76) to the negative pressure channel. 12.) Device according to one of claims 4-11, characterized
characterized in that the slot (60) on the other surface (62) of the head against the surrounding atmosphere
is open. 15.) Device according to claim 11 or 12, characterized in that the vacuum channel is located near the peripheral edge of the end face (36) of the head, such
that the ambient air flows into the channel from the edge of the end face. 109847/0305