FI59885C - ANORDINATION FOR THE CONDITIONING OF ENCLOSURE WITHIN FAIRGSTRAOLETRYCKANORDNING - Google Patents

Description

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Patent- och ragictaratyralsan v 'amMcm utltgd och utUkrtft · »pubiicarad 30.06.81 (32) (33) (31) Requested« tuofkau * —Baglrd priority 11.12.72 USA (US) 313913 "(71) International Business Machines Corporation, Armonk , Eg IO50U, USA (72) John Ghougasian, Mahopac, NY, Jon Hart, Cambridge, Mass., Hans Yohanan Juliusburger, Putnam Valley, NY, Paul Lowy, Peekskill, NY, USA (US) ( 7 ^) Oy Kolster Ab (5 * 0 Device for sensing droplet charging in a toner jet printing machine -

The present invention relates generally to toner jet weight-4 devices and more specifically to a droplet with a Taraase drop, which detects the charges of the droplets in the toner jet.

The need for parenpil printing equipment with low bulk and high speed has increased over the years. There is a serious bottleneck in the overall computer system, where the information produced by the aystene often has to be temporarily stored on a magnetic stripe. on the beach, etc. for several hours before a particular printing equipment may produce the required result. The most commonly used printing arrangements in this general area are currently of the striker type, in which the part of the weight is applied with a certain force, the marking o may be required to produce a visible letter or mark. In recent years, toner jet printing has always developed, in which case the ink is fed under pressure to a suitable mouthpiece. This color is affected so that it disintegrates into individual droplets. Droplet formation is controlled according to a number of different methods available in the art, including physical vibration of the mouthpiece, pressure disturbances to supply ink to the mouthpiece, etc. The purpose of developing such external disturbances in the toner beam apparatus is to dissipate or dissipate to separate into homogeneous droplets at a predetermined number of cycles and at certain varying distances from the tip of the mouthpiece. However, it is necessary that this droplet formation and the placement of video reservation marks in this toner flow be synchronized with each other. The rate of droplet formation in such a system is determined by a particular signal that is fed to devices for physical noise generation, e.g., mouthpiece vibrators. Certain apparatus for providing electrostatic charge to each individual droplet provided in the mouthpiece exists in such systems in connection with the point at which dye flow begins to form such droplets, normally this apparatus consists of a hollow tube, duct, plates, etc. surrounding the outlet and connected to a suitable charge supply source. Video signals are introduced between the mouthpiece and the charge electrode, whereby a particular droplet receives a charge determined by the amplitude of the particular video signal element that the waxing electrode has at that time when the droplet separates from the toner flow.

The droplet then passes through a particular fixed electric field and the extent of the deflection support is determined by the amplitude of the charge in that droplet at the time it passes through that deflection field. A suitable marking surface is arranged further in the direction of this flow from this deflection device, as a result of which the drop hits the reproduction surface and forms a certain stain on it. It should be obvious that the point of the drop on the writing surface is determined by the deflection to which the drop falls, which in turn is determined by the charge of this drop. By appropriately modifying this amount of reserve, the place where the drop hits the marking surface can thus be controlled. As a result, by introducing suitable video markers into this system, the production of visible, human-readable printed text on the marking surface can be achieved. U.S. Patent 3 * 596,275, entitled "Fluid Droplet Reoorder", describes such a marking or printing system.

From the above, it should be seen that the time at which a droplet 5 59885 separates from the fluid flow from the mouthpiece is highly critical because the charge that the droplet receives to carry is normally formed by electrostatic induction. The field formed by the video mark is retained as the droplet separates. This droplet has to carry a charge determined by this video signal and proportional to its magnitude. However, if at a given point in time the video signal is either undergoing an ascending or descending phase or is not present at all at that time when the droplet separates, the exact charge of that droplet must be a certain time function of the largest video sign and not proportional to that sign. . In order to accurately place the predetermined charges in the individual droplets according to the successive video tokens, it is thus necessary to know exactly the time for the droplet separation compared to the time of the video token. In other words, the moment of separation of the drop and the moment of switching the video signal must be very precisely synchronized with each other. If proper synchronization does not occur between the droplet shape support and the video mark, the result will be very inaccurate control of the printing process, resulting in a serious deterioration in uniformity, clarity, and overall quality of the final print.

A number of different arrangements have been used in this technique to detect the time of droplet formation in such toner jet printing equipment. Two of these arrangements are described in U.S.A. in patents 3 * 465 * 350 and 3 * 465 * 351. However, both of these arrangements require that a drop of toner actually hit a particular receiving portion, e.g., a toner trough or the like. In virtually all of these toner jet printing equipment, where droplet formation occurs rapidly, extremely precise control of system synchronization is mandatory. Detector arrangements such as those described in both of the above patents present problems due to the accumulation of color in the receiver portion, which then degrades the sensitivity of this system. This entails the loss of control over the synchronization of the system when the system is operating at a very high speed. Accumulation of color also causes maintenance problems because this color must be removed from time to time.

It has also been shown that such toner jet printing devices have improved detection to detect the exact times at which droplets form, using a portion to feel the inductive charge, this portion consisting of a rod-shaped conductor placed close to the toner flow but in a 4 59885 position so that the toner jets do not hit this part. This, however, allows charging from inductive electrostatic forces in essentially the same way as the color droplet initially charged.

The main object of the present invention is thus to provide an improved part for detecting the instillation moments of dye droplets using this in dye-spraying systems.

Another object of the present invention is to provide such a part which uses the charge carried by the individual droplets to detect the separation areas of such droplets.

Yet another object of the present invention is to provide a coupling part in which the charge of the droplets is detected by electrostatic induction ·

Another object of the present invention is to provide such a part which eliminates the problem of color accumulation in the part itself.

Yet another object of the present invention is to provide a portion that allows for an improved signal-to-noise ratio in the portion of the sensing circuit. The further features of the present invention are set out in the following claims.

The foregoing and other objects, features and advantages of the present invention will become apparent from the following more detailed description of the preferred embodiments illustrated in the accompanying drawings.

Fig. 1A, which is a combination of a block diagram and a simplified perspective view, shows the main mechanical and electrical parts in a dye beam detector arrangement using the droplet charge detecting portion according to the present invention.

Figure 1B shows a series of curves illustrating certain critical time dependencies in the arrangement of Figure 1A *

Figure 2 comprises a series of curves illustrating a preferred method for charging color silicon during the experimental phase of the operating cycle of this system *

Figure 5 shows a set of curves illustrating another embodiment for placing a test mark on different color droplets during the testing phase of the operating cycle.

Figures 4A and 4B illustrate the location of a particular drop of color relative to the tip of the recognition probe at times t1 and tg.

Fig. 5 is a graphical representation of the charge formed in the identification section as a result of the charged drop bypassing this section.

Figures 6A to 6D are curves representing a series of individual Induced Charges in the detection section and no cumulative charge effect generated induced in that section.

Fig. 7 is a graph showing the currents that should be induced in the detection circuit as a result of the induced charge shown in Fig. 6D.

Figure 8 is a perspective view of a preferred embodiment of the present invention that includes identification elements as a matrix and illustrates the application of the present invention to control the synchronization of a plurality of individual dye streams.

Fig. 9 is a partial fragmentary view of Fig. 8 showing a single detection member of the type used as well as the mouthpiece, charging equipment and deflection system as they would be arranged in a corresponding system.

The object of the present invention is generally realized with a detection part for use in a toner spray printing system in which individual droplets of color are charged to electrostatic and then deflected to electrostatic. This part includes a conductive part located forward in the direction of flow from the charging station and connected in close but not "closed" contact until droplet flow. A pair of shading plates are each arranged on their respective sides of said detector part at a substantially right angle against said color flows, each plate being provided with a small hole through which the flow of color droplets is intended to pass.

The detector is connected to a suitable current amplifier which generates an output pulse according to the inductive charges detected in the part. According to a preferred embodiment, the present invention uses a test cycle in which a specific test charge or charge is applied to these color droplets and a plurality of successive droplets are used which then cumulatively accumulate a certain charge in the recognition part, substantially improving its signal-to-noise ratio and thus accuracy.

Figure 1A shows more or less a typical dye-jet marking system using electrostatic deflection of color droplets using the inductive detector of the present invention! so gets in place between the charging station and the deflection station. The mechanical part of this system includes a container 10 in which the paint is stored under pressure. From here, the color flows through the conduit 12 to the mouthpiece 14. The toner jet stream 16 exits the nozzle 14 under pressure and later forms droplets 18. The details of the droplet separation flow are most clearly shown in Figure 9. However, it should be noted that droplet formation is not immediate. it occurs at a certain point later in the direction of flow from the mouthpiece And inside the charging station 20. As will become clear later, this is necessary because - In order for a charge to be placed in these droplets inductively - there must be a current path through this color while it is affected by the electrical charging fields Just before these droplets 18 are formed. This situation is clearly illustrated in Figure 9 as mentioned above.

After the droplets have left the charging station, they pass through the shading plates 24, which have suitable holes, and further close to the droplet charge sensor 22, which in the actual embodiment includes an elongate metal rod. Details regarding the placement of this rod relative to the droplet flow are shown more clearly in these figures,

Which will be described later below. The droplets achieve this Deflection plates 26, wherein the deflection of individual droplets occurs as a result of charging in each droplet according to the magnitude of the charge in the deflection plates, Controlled by Voltage Source 39. In a more commonly used system, illustrated in the charge in individual droplets is changed. It should be understood, however, that the detector in question would work just as well with results in a system where the charge should be constant And the plates use a variable field. The color droplets hit the detector surface 2Θ after passing across the deflection field, whereby their specific position is determined by the video mark which is fitted in the charging section 20.

It should be noted that the droplet forming transformer 30 is shown attached to the side member 14 * In conventional apparatus, as referenced above, this transformer is a piezoelectric crystal that mechanically vibrates the mouthpiece so as to provide droplets 18. The number of oscillations of this crystal is determined by the droplet formation. Thus, the step in the vibration of the crystal determines the exact moment, especially with respect to the input source of the video signal, at which these droplets are formed. If the time for droplet formation is not properly synchronized with the matched characters from the video signal source 32, as mentioned earlier, these droplets will either be completely uncharged or incorrectly charged, resulting in very poor printing. The actual system uses a synchronous signal input source 34, which both uses a transformer 30 and acts as a base time adapter source for the video signal input source 32. Such an input would normally be a conventional oscillator with Bouri stability that provides the desired period number for droplet formation. They sync tokens that go to video token source 3? pass through a phase conversion network 36, where it is possible to provide a phase change according to the signal received from the amplifier 38 when it is connected to the detector part 22.

Thus, if the droplets separate too early or too late compared to the development of the charge token, a phase change can be introduced into the network 36 so as to correct this situation in a manner known per se in the art.

The three curves shown in Fig. 1B illustrate what happens when a droplet deviates from the color flow at the correct stage or at the completely wrong stage compared to the charge mark. In this curve, curve A represents the character input to the droplet formation transformer 30. Both arrows in this curve represent the exact moments at which the droplet separates from the current. Curve B illustrates the charge signal obtained in the charge section 20 from the video source 32 essentially in the same lie as the separation, and curve C represents the charge mark obtained when the droplet separation has already taken place. When the situation according to curve C occurs, of course, practically no charge is formed in the droplet, which leads to a malfunction of the system.

Thus, accurate and reliable means of synchronization are required in such dye beam marking diets in order to guarantee optimal operation of this system. As already mentioned, previously known systems require direct contact with dye droplets in order to provide such time matching measurements. It should be obvious that as color accumulates in such contact parts, different types of problems are inevitable. One problem is the lack of sensitivity as the color accumulates and dries on top of the part. This may also interfere with parts close to this. In order to avoid such accumulation and, accordingly, to minimize its effects, periodically renewed maintenance disassembly and cleaning of this machine in the detection section has proved necessary. However, in accordance with the principles of the present invention, this charge indicator never comes into contact with individual droplets of color, but receives a charge inductively when this mark is subsequently amplified in a suitable amplifier.

In a preferred embodiment, it has been shown that the best results are obtained if a special 8 59885 test periods are used periodically for this system, so that the current droplet synchronization and charging is tested.

Figures 2 and 3 show two possible ways to provide a test mark on these droplets. In both figures, the curves 1 represent the transformer mark, with the arrow indicating the moment of droplet separation and the curves B representing the mark being introduced into the charge plates. In Fig. 2, the test mark shows a series of pulses which are short-lived and which are successively located in the region of the transformer cycle. Thus, the test cycle in Figure 2 requires a series of test pulses, arranged in a predetermined number of color droplets, to be filled with a certain number of phase shifts in each series. When a predetermined sign size is detected in the detector and the amplifier, it becomes apparent that the droplet has separated at a certain predetermined time point relative to the transformer phase. The phase reservation network 36 can be actively caused to center the charge video signal with respect to the correctly detected time of separation.

By means of known arrangements, e.g. the trough 27 in Fig. 1, a way is provided for handling uncharged or only partially charged Koepi ears so that they do not interfere with the detection activity. · If required, the test drops are reserved in contrast to those used for normal marking.

Figure 3 illustrates an analogous system in which a sawtooth wave is placed in a series of drops during a test phase and in which a time adjustment of the separation of color droplets relative to the phase of the transformer mark can be easily determined based on the amount of charge indicated. In this illustrated case, the droplet separation thus occurs at a relatively low eagle wave voltage. However, if the droplet were to be separated later at this stage, a larger sawtooth or reserve mark would be placed on these droplets, so that the resulting higher charge would be detected in the detector. The correction mark would then be input to the phase correction network as described in connection with the open embodiment of Figure 2.

It is now required that electronics known per se in the art be used to build the necessary phase correction networks for controlling the time at which the video signal is applied to the charging electrode. Even if the ila part is described in this connection in a particular application, it should be obvious that it can also be used in conjunction with a number of different control circuits and mechanisms without having to be modified for this purpose.

Referring to Figures 4-7, the operation or charge effect 9 59885 itself will now be described. Figures 41 and 4® show only the location for each individual drop of color compared to time t1 and t1. Looking at Figures 5, 41 and 4® simultaneously, it appears that at time t ^ the maximum induced charge is generated when the color droplet reaches the leading edge is expressed so that its full charging effect is indicated here. It can be seen from Figure 5 that at time t ^ the beginning is formed for the flat part of the characteristic curve, i.e. the Plato region.

This effect of the maximum charge is observed up to time t ^, after which time the charge starts to decrease when the droplet leaves the detector. As for the leading edge, the charge accumulates in the same way, slowly rising as the droplet approaches the detector unit.

Figures 61-6D illustrate the manner in which a series of droplets used during the test phase is available so as to maximize the total amount of induced charge shown in Figure 6D, "thereby increasing the sensitivity of the system or the signal-to-noise ratio. 6B and 6C are copies of curve 5 and serve to illustrate the charge effect in a successive series of droplets passing the detection section.

Fig. 6B shows the total scaling of the charge amount to the detection unit during the series of charged drops detected. The accumulation of the most sensitive or charge in the detection unit and thus in the detection circuit of the detection element, such as most preferably an amplifier with a very high input resistance, has essentially the waveform shown in Fig. 6D. When this is fed to the amplifier, the waveform of the charge signal forms a signal current amplifier non-input circuit as illustrated by the curve in Fig. 7.

Depending on the circuit used in each case, the character present at time ^ or tg may be used to control the phase shift circuit.

It should be noted that the particular preferred embodiment of the present invention, shown in cross-section in Figures 4A and 4B, is simply an elongate rod-like part made of a highly conductive material, e.g. copper or possibly aluminum. It should be understood that the charge detector may also have a different shape and consist of, for example, a plate, an annular part or a U-channel surrounding the path of the color jet and suitably connected to the detector circuit.

The cladding plates may be made of any thin metal, eg aluminum, brass, copper, etc. The opening must be large enough so that there is no risk of the passage of color droplets passing through them. The thickness of the plates and the distance between them are not any particularly critical factors. These plates may, for example, be placed at a distance of about 1.5 am to even a pnolollo detector part.

Figures 8 and 9 show an embodiment of the present cocaine, which is specially adapted for use in conjunction with individual toner nozzle bodies of the type used in the technique of an atrium-type printing platform known per se. Here, in practice, there is a separate sensor in Aries for each of the dye beams that make up the atrium. Only one ilial part is shown in Fig. Θ, because the overall structure largely resembles the case of Fig. 1A. However, it should be noted that there are numerous mouthpieces, complete electronics, etc. connected.

Fig. Θ shows a number of individual rod-shaped portions 22 positioned electrically conductive in the opening body 40. The shading plates 42 are exaggerated in one way or another by attaching the body 40 and the openings 44 in these ways to the path through which the flow of toner droplets may pass through the sensor arrangement. A number of individual color droplet streams are shown in the drawing and are asr-separated by a reference difference 46. As can be seen from this drawing, each color stream in time and a point to be determined at a predetermined location on the celebration screen.

Further, as shown in these drawings, an amplifier 48 connected to each of these lallin units 22 is a suitable impedance portion. through resistor 50. Alternatively, the sensor may be connected from the current to the voltage at the input of the amplifier, as described, for example, in "Operational Amplifiers" Design and Application, Toby, Graeap and Huelea, McGrav Hill, New York, 1971 · The output signal from each amplifier is phase changing or · controlling circuits so as to control the phase in the charge sheet at the associated nozzle or charge selectode.

The relative structure for the entire system is shown in Figure 9, which illustrates the nozzle, droplets breaking from the color flow, the charge plate, the glow nozzle including the sensor, and finally the deflection plates. This figure clearly shows the droplets that form in the region of the charge electrode 20. As already mentioned, this is necessary because if the charge voltage is to have the desired effect on a particular droplet, the droplet must be completely under the influence of the charge field just before it diverges so that electrons can escape from the affected U 59885 droplet through the toner flow and ground. The placement of the charge electrodes follows the normal standard and the point for droplet formation is relatively constant because the primary physical variables of the system are its viscosity, temperature, and the like. The variable which causes the problem solved by the present invention is the precise synchronization of the droplet separation with the development of the charge sign in the charge electrode. As can be seen from these figures, in particular from curve C in Figure IB, a drop occurs if there is no charge in the electrode at the time when the drop separates either to remain except for the full charge or to receive a very small charge due to the effects of the previous charge.

Figure 9 clearly shows the shape and location of the recognizable word 22 relative to the shading plates 42 with the apertures 44 "As shown. there is no risk of the color droplets hitting the air! sine part.The size of the mark is less significantly affected by the width of this detector because only the incoming and outgoing charged drops participate in the output mark of this detector.In practice, there is a detector with a width of 5 to 10 times The distance difference between the droplets must be between 3 and 10 times the diameter of the droplet. itat is in accordance with the above.

In describing the preferred embodiment of the present invention, it is mentioned to use a number of drops during the assembly period, although this is not absolutely necessary. By way of example, only a single droplet may be used, but the dependency between signal and noise for a detector-amplifier is likely to be more important. A test mark with an increased size compared to the print mark is also available using one or more sets of test drops to provide a phase-indicated mark.

Having now described the operation of the detector unit according to the present invention, it is again stated that the most essential parts are the conductive charge detector and the series of shade plates. The conductive part is arranged to have an inductive charge dependence on the dye flow but is at a sufficient distance from it to ensure that the dye flow cannot hit the part. During operation, this part thus detects the presence of the charge i2 59885 in the droplet ·· »inductively and · further detects the amount of charge in the droplet * which can be used to provide a positive indication of the efficiency of this charge signal. In the latter case, the amplitude can be used to time-synchronize the charge token by checking the exact moment of the color droplet separating from this current. It is possible to easily increase the overall accuracy in this system by collecting energy from successive charged droplets one after the other so as to provide higher output signals and a better signal-to-noise ratio. It is also possible to use high impedance in the detector circuit * which also improves the signal-to-noise ratio. Finally, this part can be used in corresponding systems * which actively monitor parameters other than special charge synchronization, e.g. in speed measurements *, whereby a number of such parts are placed at precisely known intervals in the color flow direction.