DE2306606A1 - DEVICE FOR CONTROLLING THE CONCENTRATION OF IONS IN A PRESSURIZED GAS, IN PARTICULAR PRINT HEAD FOR ELECTRO-IONIC PRINTING - Google Patents

Description

Applicant's file number: EN 972 012

Device for controlling the concentration of ions in a gas under pressure, in particular a print head for electro-ionic printing

The invention relates to a device for controlling the concentration of ions in a pressurized gas, particularly for electro-ionic printing and for creating an image by a gas jet directed onto a dielectric surface, the concentration of which can be controlled by ions carried along according to patent ... (patent application P 22 23 628.8). The device described in the main patent is intended as a print head for electro-ionic Printing processes are improved.

Probably the most important prior art publication is US Pat. No. 3,594,162, which discloses a latent image is generated as a result of corona discharge through a gap at which control electrodes are provided. It won't do either a pressurized ionized gas is used, nor can low control voltages be used in the known printhead .

According to the present invention, in a further embodiment the in the main patent ... (patent application P 22 23 628.8) described print head an improved print head for electro-ionic

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2306608

Printing created in which a number of electrodes arranged in pairs lie on opposite sides of a common gap through which an ionized gas flow moves ₃ , the electrodes provided in pairs being excitable by relatively low voltages to produce an image on the dielectric surface.

The control of the ion concentration in a moving gas stream specified in the main patent should preferably be improved, in particular significantly simplified. At the same time, electrostatic images of high quality and resolution should be achieved on a dielectric surface. This is achieved according to the invention in that a number of pairs of electrodes lie on the walls of a gap common to all channels, which gap is connected to a source of a gas of high ionic concentration, and that the individual pairs of electrodes are connected to means for selective excitation ₃ and that furthermore the Electrode pairs are arranged on opposite sides of the gap and are isolated from one another by insulating spacers. The arrangement is preferably such that the electrodes consist of a number of electrically conductive plates which are insulated from one another by insulating plates and that the narrow sides of the electrode plates are opposite one another on the inside of the gap.

The invention will now be described in more detail using an exemplary embodiment in conjunction with the accompanying drawings. It shows

Fig. 1 shows the new print head for electro-ionic printing

according to the invention;

Fig. 2 is a schematic representation of the invention

three channels in the printhead connecting between a DC power source and a character pulse generator lie;

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Pig. 3 is a schematic representation of a printer

using a print head according to FIG. 1;

Fig. 4 A, B and C schematically the seven channels of a print head

and the impulse images for producing the images of the letters E and H.

In Figure 1, a print head is shown with an ion chamber 1, which is similar to that in the main patent ... (patent application P 22 23 628.8) is described. A gas, for example air, is pressurized into the ion chamber 1 through the inlet port 2 is introduced and the ions are generated in this ion chamber. The gas emerging from the chamber 1 has a very high ion concentration. The ion chamber 1 is connected to a gap in the print head 4. This gap is electrical divided into a number of ion channels. Je-Ί -, anal consists of a pair of electrically conductive electrodes, such as 5al and 5bl, those of adjacent electrodes through insulating spacers 63a and 63b are separated. The print head 4 is by suitable, Means not shown are connected to the ion chamber 1 and are also held together by means also not shown. The printhead 4 consists of a number of parallel ion channels which, although physically connected, are electrically connected to each other are isolated and thus deliver a number of individual ion currents, each of which has a very high ion concentration having. The cross-section of each channel can be arbitrary per se, for example rectangular, square, or any other have desired cross-section. There are electrical leads 15a to 15g and 16a to 16g on the upper and lower electrodes connected. The lines l6a to l6g are connected to a common direct current source, while the lines 15a to 15g through pulses occurring at different times are controlled, which are supplied by a character pulse generator.

As the gas flows pass through their respective channels, the ion concentration increases through recombination and neutralization

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-ΜDuct walls off. The ion losses occurring through the conductive walls can be increased quite significantly by the fact that one on opposite channel walls, for example on the Top and bottom of the channels to which an electric field is applied. If you put a sufficiently strong electrical Field on, the ion concentration in the gas flow of the channel in question is suppressed almost 100%. If you oppose it If the strength of the electric field is reduced, then this also reduces the extent of recombination and neutralization. If ^ one then the electric field on essentially If the value is reduced to 0, a maximum concentration of the ions to be transmitted through the individual channels is obtained. The concentration the ions and thus the electrical charge transferred through each of the channels is thus transversely to through a suitable shape electric field applied in the direction of current flow. This electric field is created by applying an electric Potential induced via lines 15a to 15g, which are applied to opposite electrodes of the channels, as shown in FIG. are connected. The write status of a channel is achieved when a very weak electrical transverse field or an electrical transverse field with the value 0 is applied, while the blocking state is applied by applying an increased bias field is achieved, by which more ions are removed from the gas flow. The change in the electrical potentials on the individual channels and their electrode pairs for generating the individual letters by a Character pulse generator controlled.

The application of the necessary electrical fields to a print head according to FIG. 1 is shown schematically in FIG. In this schematic representation, the print head is shown schematically by " three capacitors are shown, which are intended to represent three of the seven channels shown in FIG. The plates 5al, 5a2, 5a7, 5bl, 5b2 and 5b7 of the capacitors correspond to the lower and upper electrodes of the individual channels, respectively. Each capacitor is on top of that Lines 15a to 15g between the character pulse generator and

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a direct current source switched on, which is set to a desired potential V of, for example, 15 volts, so that the desired ion concentration results. The character pulse generator delivers pulses of suitable polarity and amplitude, substantially equal to the potential V of the power supply. While of a time interval of a write process, the field over the capacitors (the channels) is reduced to such an extent that that the ion concentration in the gas stream reaches its maximum value and against the image recording surface to generate the desired Figure is directed.

An application of this type of ion concentration control can be seen in FIG. 3, which shows, purely schematically, a printer according to an embodiment of the invention, by means of which a latent electrostatic image is to be generated on a dielectric medium 20 moving from right to left under a charging station 21. The charging station 21 is intended to charge the medium 20 with a desired potential and a polarity which is opposite to the ion polarity. The charged dielectric now moves under a print head 4 ″, as described above. The print head is connected to an ion generator 1 ^? To which a gas, for example air, is supplied via the inlet port 2. By controlling the individual channels of the With suitable voltage pulses, latent images of letters or numbers can be imaged on the charged dielectric surface of the medium 20. The medium 20 with its latent images runs through a development station 22 and then through a fixing station of a known type the latent image is fully developed and fixed and represents the visible image of two letters E and H. The character pulse generator can send any desired combination of electrical pulses to the individual channels of the writing head with their electrodes to generate the desired latent images on the dielectric surface of the Med iums 20.

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The ion transmission is effected to take place by applying a pulse of the same polarity and amplitude as the bias voltage to the electrode on the other side of the slot in the region ₃ in the ion transmission. So if you want to write a straight line parallel to the longitudinal direction of the slot, all seven electrodes are excited simultaneously with pulses, so that for a short period of time an ion transfer takes place over the entire cross-section of the slot. To write a perpendicular line, a long pulse is applied to only one electrode and while the medium 20 is moving on, a line is written, the length of the line depending on the speed of the medium or recording medium and the duration of the write pulse. The two lines mentioned above will be perpendicular to each other if the longitudinal direction of the slot forms an angle of exactly 90 ° with the direction of the relative movement of the medium. If this is not the case, letters or numbers are inclined in one direction or the other. The generation of letters with the aid of the printing arrangement according to FIG. 3 will now be described in connection with FIGS. 4a, 4b and 4c.

In the schematic representation of FIG. 4a is a number of seven capacitors to represent the seven channels of a printhead are shown. The left plates, 5al to 5a7 the Capacitors are connected to a direct current source of -15 volts, while the right plates 5b 1 to 5b7 of the capacitors are connected to a character pulse generator, which is not shown in the drawing. This delivers selectively Voltage pulses to the right sides of these capacitors and thus causes the desired latent charge image on the dielectric medium 20. It can be clearly seen from FIG. 4b that in the Generation of the image of the letter E the vertical section of the letter E is generated during the time interval ΔΤ, while there is no electric field across the channels of the printhead, while at the same time the character pulse generator a pulse potential of -15 volts to the corresponding

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Apply electrodes to all channels. It can also be seen from Figure 4b that the lower, upper and the middle horizontal line of the letter E by supplying a potential of -15 volts to the electrodes-5al, 5bl, 5a4, 5b4 or 5a7 _s 5b7 for about five time intervals, as shown in Figure 4a. At the end of the first time interval ΔΤ, the character pulse generator supplies the voltage 0 volts to the electrodes 5b2, 5b3a, 5b5 and 5b6. These electrodes are kept at zero potential for the duration of the character generation. The -15 volt potential at electrode 5b4 is maintained for four periods of time. Of course, it will be understood that the latent image is formed on dielectric medium 20 as it moves from right to left under the corresponding channels of the printhead.

From a consideration of FIG. 4c, m ^ ~ -: ■ "· .h recognizes the pulse diagrams for the channels 4a1 to 4a7 for the generation of the letter H. The block-like representation of the letters is achieved when adjacent electrodes are at the same electrical potential or are close to the same potential as the opposing electrodes so that ions are transferred once through the channel between the electrodes and also through the region of the gap between the electrodes, provided that the dimensions are appropriately chosen.

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Claims (7)

PATENT CLAIMS 1. Device for controlling the concentration of ions in a pressurized gas, in particular a print head for electro-ionic printing and for generating an image by a gas jet directed onto a dielectric surface, the concentration of which is entrained Ions can be controlled according to patent .... (patent application P 22 23 628.8), characterized in that a number Electrode pairs (5al to 5a7, 5bl to 5b7) on the walls of a gap common to all channels, the one with a source (1) of a gas of high ion concentration is connected, 'and that the individual pairs of electrodes with Means associated with selective arousal. 2. Apparatus according to claim 1, characterized in that the gap merges into a rectangular channel with a source (1) of a pressurized gas with high ion concentration is connected. 3. Apparatus according to claim 1 and 2, characterized in that the electrode pairs on opposite sides Sides of the gap are arranged and isolated from one another by insulating spacers (63a, 63b). 4. Apparatus according to claim 1 to 3, characterized 'that the electrodes (5al to 5a7, 561 to 5b7) consist of a number of electrically conductive plates which are insulated from one another by insulating plates (63a, 63b) and that the narrow sides of the Electrode plates face each other on the inside of the gap. 5. Apparatus according to claim "4, characterized in that the electrodes, which are isolated from one another, extend over the entire depth of the gap. en 972 012 3 0 9 8 3 8/0845 6. Apparatus according to claim 5 ₃ characterized _} that the electrodes on one side of the gap are all connected together via lines (16a to 16g) with a direct current source. 7. Apparatus according to claim 6 _S, characterized in that the electrodes (5al to 5a7) on the other side of the
Spaltes are connected to a character pulse generator via control lines (15a to 15g) for selective excitation. en 972 012 30 98 38/08