DE3507670A1 - METHOD FOR CONTROLLING AND IMPROVING THE WRITTEN QUALITY OF A PRINTER - Google Patents

Abstract

1. A method of controlling and improving the printing quality of a printer, in particular an ink jet printer, wherein at least one ink jet (6) is produced by means of the voltage and frequency applied to an oscillator (5) through at least one nozzle (2) of a perforated plate (1) and, after a certain distance from the perforated plate (1), charged droplets (7) are released from the ink jet (6), the droplet breakaway distance (Sa ) from the perforated plate (1) being optimally adjusted by regulation of the oscillator voltage, and the flight time of a droplet (7) from the droplet break-away point (8) to a charge detector (27) is measured, characterised in that the viscosity of the ink is regulated by observing the oscillator voltage and the droplet break-away distance (Sa ).

Description

DR RER. NAT PETER H. WEISS T \ "D T7 [7" EiTC2O

PATENT LAWYER LJ XV. VV.Lji.C5l3 - '- ■ -0- / 7.OUbINQEN

SCHLACHTHAUSSTRASSEI: '——' .. ' TELLPHON (077 3T, 6 77

D-7700 SINGEN "TELEGRAM: HEGAU PATENT

_{PATENT ADVERTISER} ^TELE ^ iB Ψ & 7

EUROPEAN PATENT ATTORNEY 07731-68215, group 2 *)

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society

for Automationstechnik mbH

Alois Mutz Str. 8

7768 Stockach 1 J

Method for controlling and improving the quality of the font in a printer

The invention relates to a method for controlling and improving the quality of the characters in a printer, in particular an ink jet printer, wherein at least one ink jet is applied to a vibrator by means of Voltage and frequency through at least one. Nozzle of a nozzle plate is generated and charged drops after a certain distance from the nozzle plate, remove it from the ink jet, remove the droplet removal is set by the nozzle plate via a regulation of the oscillator voltage.

■ 2-: ''.: - ■ '.: ■ ^: ■ - ■

Ink jet printers as a form of matrix printers are found today as peripheral devices for electronic devices Computing systems for outputting data application. Similar to the principle of a dot matrix printer the print head of the inkjet printer has a row of nozzles arranged vertically one below the other and next to one another, v / ground by jets of liquid ink under high pressure onto the material to be written on. Depending on which nozzles are open or closed, on the labeling material from Dots of color the image of the desired letters and numbers. When writing, nozzles and control devices wander (For example, for closing or for electrostatic or magnetic deflection of the undesired ones Rays of paint) line by line past the labeling material and spray one character after the other.

In addition, so-called continuous color jet printers (continuous jet system) are known, for example from DE-PS 24 46 740. With him, an ink jet is through a nozzle and then equally spaced Ink droplets of the same size generated, which a charging electrode and a constant generated by baffles electric field, whereby the drops are deflected in one direction depending on their charge experienced while the droplet is deflected in the other direction by another suitable measure, for example, the object to be labeled is moved.

There are essentially two interference parameters that affect the quality of the font in such a continuous inkjet printer, namely

the ambient temperature of the system, which changes the viscosity of the ink (especially with alcohol

soluble inks such as MEK (methyl ethyl ketone) and ethanol) and

Ink pressure fluctuations in the hydraulic system.

The above-mentioned interference parameters always lead to a reduction in the quality of the writing. However, they can be in one certain defined area can be compensated by for the current operating state of the system the optimal tear-off distance is set. This compensation has so far been done optically-manually. The behavior of the drop formation is monitored with a magnifying glass over a stroboscopic diode attached to the write head observed and readjusted by changing an oscillator amplitude by means of a potentiometer This procedure is quite insecure, since it depends on the subjective feeling of the observer and demands it a high level of system knowledge and practice on the part of the user. This effort leads to a limitation in the range of applications and in the marketability of an ink jet printer.

The inventor has set himself the goal of developing an automatic process and incorporating it into existing ones or to integrate new process units, which on the one hand regulates the optimal tear-off removal on-line, in order to guarantee the highest possible quality of writing and, on the other hand, an increase in the above-mentioned interference parameters display and / or prevent beyond a certain area. The procedure is intended to take into account respective characteristics of the transducer and nozzle used in an ink jet printer configure so as not to require very tight manufacturing tolerances.

A printer of the type mentioned above leads to the solution of this task, in which the flight time of a drop from

The tear-off point measured up to a charge detector and the tear-off distance over this flight time is determined.

This means that an observer is not required to determine the tear-off point. Furthermore, the change in the Droplet break-off point no longer depends on the observer's subjective ability to observe, but becomes automatically determined very precisely. Depending on the fine-tuning of the system, there may be a change in the oscillator voltage and thus a displacement of the tear-off point takes place very quickly, so that suddenly occurring Pressure fluctuations in the hydraulic line can be taken into account very quickly. While so far the The distance between the nozzle plate and the tear-off point was determined, the distance is now determined between the tear-off point and a charge detector, this distance always being inversely proportional to the teardrop distance is changed.

An essential element of the present invention is the synchronization between droplet breakup and droplet charging. First of all, it is determined whether a charged drop is even displayed on the charge detector will. If this is not the case, a phase jump is made in the charging pulse frequency. this happens until the detector shows a charge.

Then the pulse width of the detected signal is compared with the pulse width of a stored signal. If deviations are found here again, a further phase shift of the charging pulse frequency takes place .

The Time of flight of the drop measured. This flight time is then based on, for example, a stored flight time

Compare the measurement of the previous flight time. If the actual flight time deviates from the saved one Plug time, the oscillator voltage is changed until the current flight time is the same or less than the stored value and thereby the range of the optimal teardrop removal has been reached.

In practice it has proven to be beneficial not to use the value from the memory for every single flight time compare, but add up a large number of flight times and use them to form an average value, which one is compared with an average value from the memory.

A further improvement of the method according to the invention is preferred, in which after the regulation of the optimal tear-off removal, a constant comparison of the vibration voltage values with reference values takes place from another memory. These reference values are values of an oscillation voltage for a optimal tear-off removal depending on the transducer used and a valid operating viscosity the color. If deviations of the oscillation voltage values from this reference value are found, so the viscosity of the paint can be changed according to the invention. It is known that increasing paint viscosity requires a steady increase in the oscillation voltage, so that with a certain color viscosity the Control range of the optimal tear-off removal is left. This is done by influencing the Color viscosity itself avoided.

The procedure is not tied to any particular form of implementation, i.e. it can be used as a hardware solution and / or integrated into the system as a software solution will. To measure the controlled variable, i.e. the droplet separation, it only needs the existing ones Components and measuring devices, which are used for sytfnchro-

nization of the drop charge to its demolition in the Are integrated into the system. It will have good font quality over a relatively wide range of viscosities Color guaranteed. Measurements have shown that systems with a defined operating viscosity of approx. 3.1 mPa χ see with a viscosity increase above 7 mPa χ see still have a high quality of writing.

In a device according to the invention for controlling and Improving the quality of the writing of a printer, in particular an ink jet printer, with a transducer for Generating at least one ink jet through at least one nozzle of a nozzle plate, the ink jet charging electrodes are assigned and after a certain distance from the nozzle plate drops from the Solve the ink jet and remove this tear-off from the nozzle plate by regulating the oscillator voltage should be adjustable, is a device for determining the flight time of a drop from the tear-off point provided to a detector. This device for determining the flight time of a drop consists preferably from the charging electrode for applying a charging voltage to the drop, a charging detector for detection the load and a flight time counter. Both the transducer and the charging electrode are except for one Pulse generator or pulse converter is preceded by a frequency divider, which both together with a System clock feed are connected.

A start signal is used to set a DAC counter (DAC = digital-to-analog converter) stimulated, which in turn is connected to a DAC initial value memory. Of the DAC counter is connected to an amplifier via a digital / analog converter, which is connected between the Schwinger and its pulse converter is switched on. In this way the oscillation voltage can be changed. Here the digital / analog converter and the DAC-2 counter that is used to automatically track the setting

EAD ORIGINAL

size (oscillator voltage) potentiometer used so far. However, there are also other suitable actuators conceivable.

Switching elements for synchronizing the charging voltage or a charging pulse are activated via a second start signal switched on with the tear-off. These switching elements consist of a pulse counter, the above-mentioned frequency divider for the charging electrode and a pulse width comparator. via the latter can be obtained from the frequency divider output charge pulse frequency are phase-shifted, the pulse width comparator with both the Charge detector as well as with the flight time counter is in connection and controls the latter. The pulse width comparator is also assigned a pulse width memory, which has a value for comparing the current Contains the value of the pulse width comparator. This value should preferably be changeable in the pulse width memory, i.e. current values can be adjusted.

The time-of-flight counter is followed by a time-of-flight comparator, which compares the time-of-flight values with values from a time-of-flight memory compares and controls the DAC counter. These values in the flight time memory can also be entered by entering can be changed by current values.

However, it is preferable not to compare each individual flight time with a value from the flight time memory. To record a plurality of values or their mean value, the flight time counter is a measured value counter and possibly assigned a control device for a certain number of measured values, with flight time counters between and a time-of-flight comparator is interposed with a time-of-flight adder for forming a mean value.

The time-of-flight comparator increments or decrements the DAC counter depending on the existing deviations in the flight time and via the DAC counter or the digital / analog

BATH ORIGINAL

iff

log converter and amplifier becomes the oscillation voltage changes.

Furthermore, a flip-flop, to which a DAC comparator is connected, can be controlled via the first start signal. In this DAC comparator, the values of the DAC counter are in turn stored with values from a DAC reference memory compared. The reference value in the DAC reference memory represents the oscillator voltage for an optimal one Droplet separation depending on the used Schwingers and a valid operating viscosity of the paint. It can also be changed if necessary. If the DAC comparator provides a difference between the reference value from the DAC reference memory and the value of the DAC counter, it controls a device for regulating the viscosity of the paint. depending on The difference between the two values is either a valve of a tank for the paint or a valve of a Solvent tanks open and paint or solvent poured into a main tank.

Overall, the device works fully automatically and is completely independent of the subjective feelings of an observer. The disturbance parameters, such as ambient temperature of the system and color pressure fluctuations in the hydraulic system are automatically compensated. the Operability of the system within a reaction time for the viscosity to be replenished guaranteed by adjusting the optimal tear-off distance for the current ink viscosity will. In addition, the response time of the replenishment is relatively short, even with long hydraulic lines.

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Further advantages, features and details of the invention emerge from the following description a preferred embodiment, as well as based on the drawing; this shows in

FIG. 1 shows an enlarged schematic illustration of the mode of operation of a color jet printer;

FIG. 2 shows an enlarged detail from FIG. 1;

FIG. 3 shows a graphic representation of the dependence of the tear-off distance on the one Vibrator applied voltage;

FIG. 4 shows a graphical representation of the dependence of an oscillation voltage level on the paint viscosity;

FIG. 5 shows a graphic representation of the dependence of a satellite-free area on the ink viscosity;

FIG. 6 shows a block diagram of a circuit for carrying out the method according to the invention for controlling the tear-off distance.

According to Figure 1, a nozzle 2 is arranged in a nozzle plate 1, through which ink color from a nozzle antechamber 4 is pressed. With 3 a supply line with ink is indicated. In this nozzle antechamber 4 an oscillator 5 is arranged. The ink color forms after the nozzle 2 an ink jet 6 with a Diameter d ^, (see Fig. 2) and a flow rate ν. After a certain distance from the nozzle plate 1, the ink jet 6 forms Drops 7 out, then soft off the ink jet 6 at a tear-off point 8 and become with one drop distance IV further.

Crack distance from tear-off point 8 to nozzle plate 1

is denoted by s, a

The drop break-off point lies between two charging electrodes 25, each drop being different (corresponding to the shape of the character or die) is electrostatically charged. A downstream charge detector 27 checks whether the drops 7 are charged. Afterward the drop 7 flies through an electric field of two deflection plates 71 and 72, to which high voltage is created. According to its charge, the drop 7 is deflected in one direction (here vertical). The droplet is deflected in the other direction (here horizontal) by the movement of a object to be written on 73. If no writing process is triggered, the drop is not removed from the deflector plates 71, 72 deflected, but flies into a catch pipe 74 or the like. and is, not shown in detail, with conveyed back into a main tank 64 by a suction pump.

The tear-off distance s is now considerable

Dimensions depend on a voltage U applied to the oscillator 5, as shown in FIG.

If the oscillating voltage U is continuously increased, starting with U, the tear-off distance s increases

gradually decreasing. As soon as the oscillating voltage has reached level ü, the tear-off removal s begins to start again. Between two levels above and below

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The hatched so-called satellite-free oscillator voltage arises Area 9 of the drop formation. An optimal font quality of the system is only possible in guaranteed in this area.

The oscillation voltage level U lies between the two Values U and U and is for the shortest teardrop distance representative.

An increase in ink viscosity with the system configuration unchanged (Transducer / nozzle) and at constant

Ink print would create a family of curves with different values for the vibration voltage level U, ü
and U in Figure 2 result. The dependence of the oscillation voltage level U, which is representative for setting the shortest droplet separation distance and thus the satellite-free area, on the ink viscosity * 2 ^ is represented in FIG.

It can be clearly seen that an increase in the ink viscosity * 2 ^ an increase in the vibration stress level U required to achieve optimal teardrop separation s. In doing so, the tear-off distance increases

s, based on the nozzle plate 1, from.

Typical values for U. at * 2 ■ = 2.5 mPa χ sec: 35 - 60 V.

Typical values for ü _w at h = 5 mPa χ sec: 80 - 120 V.

The spread of the limit values for U, and U
are due to the different oscillator characteristics.

FIG. 5 shows the satellite-free area as a function of the ink viscosity, delimited by the Vibration voltage level U and U. This satellite-free area becomes with increasing ink viscosity smaller. The course of the oscillation voltage level ü

for an optimal tear-off distance S is

marked with dashed lines. An optical / manual readjustment of this level with increasing ink viscosity is only possible with great difficulty, since the observer can only express his subjective opinion about the satellite status of the ink jet and does not have the appropriate teardrop separation.

A circuit for implementing the invention

BATH ORIGINAL

According to FIG. 6, the method consists of three main blocks: a phase control 20, a droplet break-off control 40 and a viscosity control 60. Phase control 20 and droplet separation control 40 are via a system clock connection 15 coupled to one another, with a frequency divider 22 on the one hand and a frequency divider 43 on the other is excited, which have the same frequency.

A first control signal 10 = "start control" applies Droplet break control 40. With it 10a, a DAC counter 41 (DAC = digital / analog converter) is excited in such a way that that it charges itself with an initial DAC value of 42. This initial value should be such that at the output of an amplifier 45 after a pulse generator 44, for example, a sinusoidal voltage of 20 Vpp with a frequency of for example 64 kHz is present, generated by the frequency divider oscillator 43. The output of the amplifier 45 supplies the oscillator 5 and is the manipulated variable of the entire droplet break-off control 40. Desired voltage changes for the oscillator 5, the amplifier 45 is input via a digital / analog converter 54 via 55, which is connected to the DAC counter 41.

With a second control signal 11 = "start synchronization" the phase control 20 is initiated. A pulse counter 21 is started via 11a and for δ Clock periods of 64 kHz of the frequency divider 22, which like the frequency divider oscillator 43 with the system clock 15 is connected, charging voltages alternating between 8 V and 0 V via a charging pulse generator 23 and optionally an amplifier 24 is applied to the charging electrode 25 and the ink droplets are charged. With the Control signal 11b starts a flight time counter 46 at the same time, which increments synchronously with system clock 15 will. The flight time counter 46 can be stopped by the output 16 of a pulse width comparator 26, provided the drops 7 are loaded with a charge BAD ORIGINAL

been. Otherwise, the flight time counter 46 reaches a maximum count and causes the charge pulse frequency experiences a phase jump 17 of approx. + 12 ° compared to the oscillator frequency. This phase jump is achieved in that the division factor of the frequency divider 22 before the charging pulse generator 23 for one Clock period is changed.

The phase control is repeated until drops with charges are detected by the charge detector 27 and these values via a charge amplifier 28, optionally with pulse processing at the input of the Pulse width comparator 26 are applied as a square pulse. The pulse width comparator 26 then compares the current pulse width of the signal with the last maximum pulse width from a pulse width memory 29, which was originally input from the pulse width comparator 26 to the pulse width memory 29 via 30. At the same time the flight time counter 46 is stopped via the output 16 and a measured value counter 47 is decremented via 16a. If the current pulse width is larger, the old value and the new value in memory 29 will exceed 30 overwritten and the phase of the charging pulse generator 23 in the same direction as the last measuring process by 6 ° opposite shifted the oscillator frequency. If the current pulse width is smaller, the phase is + 6 °, and are both values shifted equally by -6 °. The connections 18, 19 between the pulse width comparator are for these phase jumps 26 and frequency divider 22.

This phase control 20 ensures an optimal synchronization between the charging of the drops 7 causes a certain charge and its demolition. Furthermore, the electrical properties of the measuring device (Charging electrode 25, charge detector 27 and amplifier 28) by the adaptive method of pulse width evaluation automatically adjusted.

The phase control 20 and droplet break-off control 40 are inter alia via the pulse width comparator 26 connected. This stops / as stated above, the flight time counter 46 and decrements the measured value counter 47 only if the maximum pulse width was detected by the phase control 20. The meter reading on The output of the time-of-flight counter 46 is directly proportional to the time of flight of the droplets 7, namely from their break 8 to a charge detector 27, i.e. inversely proportional to the droplet separation distance S to the nozzle plate

el

1. The current count is then added to a mean value formation in a time-of-flight adder 48. If a number of the required measured values 56 is reached, an output 33 of the measured value counter 47 activates one Time-of-flight comparator 49, so that the current mean value of the drop flight time with the last mean value a time-of-flight memory 50 is compared. Then the last mean value is compared with the current mean value overwritten in flight time memory 50 via 34. If the current mean value of the drop flight time is greater than the last mean value, i.e. the tear-off distance S_

in relation to the nozzle plate 1 has become smaller, so the DAC counter 41 is incremented via the connection 35 and the oscillator voltage is increased by approx. 2 V. This control process is repeated until the current mean value of the drop flight time has become equal to or smaller than the last mean value and thereby the range of optimal drop removal has been reached.

If this state is reached, the DAC counter 41 is decremented via the connection 36. A flip-flop 51, which by the signal 10 "start control" via 10b was reset, is set again, so that a DAC comparator 52 is activated via 37 and an output 38 of the DAC counter 41 with an output 39 of a DAC reference memory 53 is continuously compared for all further control processes.

When the system is switched on for the first time (commissioning), the value at output 38 of DAC counter 41 loaded with the setting of the flip-flop 51 in the DAC reference memory 53, as indicated by arrow 12. This The value serves as a reference for the oscillator voltage for optimal tear-off removal depending on the used oscillator 5 and the valid operating viscosity of the ink.

In order to regulate the optimal tear-off removal, the DAC counter 41 is used during the next regulating operations as long as it is decremented as long as the tear-off distance S is to the right of the turning point U or in the area 9 (see Fig. 3), i.e. the current measured drop flight time is greater than that of the last Measurement or at least the same.

If the current measured drop flight time is less than that of the last measurement, then the tear-off distance S is greater and is therefore to the left of the area a

of the turning point U (see Fig. 3). The DAC counter 41 is incremented until the droplet separation is reached S again to the right of the area of the turning

el

point U is located. Through this regulation of the tear-off distance ink pressure fluctuations in hydraulic systems can be compensated for on their own v / earth.

An increasing ink viscosity requires a constant increase in the oscillation voltage u in order to remain in the control range of the optimal tear-off distance S (see FIG. 4). 6 shows a simple method and arrangement for viscosity control. 60 shown. The DAC comparator 52 continuously compares the output 38 of the DAC counter 41 with the value of the output 39 of DAC reference memory 53. The reference value is representative of the oscillator voltage U, the tfernung to achieve the optimum droplet break _en S

is required. If the value at the output 38 of the DAC counter 41 is lower when the operating viscosity is valid or the same as that from reference memory 53, output 61 from DAC comparator 52 activates a valve 62 of an ink tank 63 / so that a main tank 64 is refilled with ink up to a maximum filling level will. If, on the other hand, the value at the output 38 of the DAC counter 41 is greater than the reference value, the Output 61 of the DAC comparator 52 activated a solvent valve 65 of a solvent tank 66 and the Main tank 64 refilled with solvent to the maximum level. This increases the viscosity of the ink in the main tank 64 again.

Furthermore, a fill level monitor 67 is arranged in the main tank 64, the signals of which are sent to a fill level monitor 68 are given. Level monitoring 68, valves 62 and 65 and output 61 of 52 are through appropriate suitable switching elements, such as AND gate 69 and amplifier 70, are connected to one another.

Claims (28)

Claims 1. A method for controlling and improving the quality of the writing of a printer, in particular an ink jet printer, wherein at least one color beam by means of voltage applied to a transducer and Frequency is generated by at least one nozzle of a nozzle plate and charged drops after a certain distance from the nozzle plate, remove it from the ink jet, remove the droplet removal is set by the nozzle plate via a regulation of the oscillator voltage, characterized, that the flight time of a drop from the tear-off point to a charge detector is measured and the tear-off distance is determined via this flight time. 2. The method according to claim 1, characterized in that the droplet breakup and the droplet charging are synchronized v / earth. 3. The method according to claim 1 or 2, characterized in that the charging by regular charging pulses he follows. 4. The method according to claim 3, characterized in that upon detection of the non-charge of the drops on Charge detector the charge pulse frequency a phase jump until a charge is detected by the charge detector. 5. The method according to claim 4, characterized in that the pulse width of the detected signal with the Pulse width of a stored signal compared will. 6. The method according to claim 5, characterized / that in the event of a deviation in the current pulse width shifted from the stored the charge phases of the charge pulse with respect to the oscillator frequency will. 7. The method according to claim 6, characterized in / that the new pulse width is saved as the current pulse width after the phase shift. 8. The method according to any one of claims 2-7, characterized / that the determination of the flight time of the Droplet is only made after the synchronization between droplet break-off and droplet charging. 9. The method according to at least one of claims 1 8, characterized / that the current flight time is compared with a stored flight time and then, if necessary, the new flight time is saved. 10. The method according to claim 9, characterized / that when the current flight time deviates from stored flight time the oscillator voltage is changed until the current flight time equals or is smaller than the stored value and therefore the range of the optimal tear-off removal is achieved. 11. The method according to claim 9 or 10, characterized in that that a large number of flight times are measured and added up to form an average value. 12. The method according to at least one of claims 1 11, characterized in that according to the scheme the optimal tear-off removal a constant Comparison of the vibration voltage values with reference values from another memory takes place, which as a reference of the oscillating voltage for an optimal tear-off removal depending on the used and a valid operating viscosity of the paint. 13. The method according to claim 12, characterized in that that if the vibration voltage values deviate from the reference value, the viscosity of the paint changes will. 14. Device for controlling and improving the font quality of a printer, in particular an ink jet printer, with an oscillator for generating at least one color beam through at least one Nozzle of a nozzle plate, charging electrodes being assigned to the ink jet and according to a specific one Distance from the nozzle plate, drops are released from the ink jet and this tear-off removal can be adjusted from the nozzle plate by regulating the oscillator voltage, characterized in that that a device for determining the flight time of a drop (7) from the tear-off point (8) is provided to a detector (27). 15. The device according to claim 14, characterized in that the means for determining the flight time a drop (7) from the charging electrode (25) for applying a charging voltage to the drop (7), a Load detector (27) for detecting the load and a flight time counter (46) consists. 16. Apparatus according to claim 14 or 15, characterized in that a start signal (10) DAC counter (41) can be excited, which is connected to a DAC initial value memory (42) and Via which a certain sinusoidal voltage with a certain frequency at the output of an amplifier (45), generated by a frequency divider (43) to which the oscillator (5) is applied. 17. The device according to claim 16, characterized in that a second start signal (11) Switching elements for synchronizing the charging voltage or a charging pulse with the tear-off can be activated are. 18. The device according to claim 17, characterized in that the switching elements consist of a pulse counter (21), a frequency divider (22) and a pulse width comparator (26), over which the from the frequency divider (22) via a charging pulse generator (23) to the charging electrode (25) Charge pulse frequencies are phase shiftable, the pulse width comparator (26) also with the Charge detector (27) is in communication and controls the flight time counter (46). 19. The device according to claim 18, characterized in that the pulse width comparator (26) has a pulse width memory (29) is assigned which changeable values for comparing the current values of the pulse width comparator (26). 20. Apparatus according to claim 18 or 19, characterized in that the frequency divider (22) over a system clock (15) with the frequency divider (43) of the oscillator (5) and the flight time counter (46) in Connection. 21. Device according to at least one of claims 16 to 20, characterized / that the flight time counter (46) is followed by a flight time comparator (49) is / which is the time-of-flight values with possibly changeable values from a time-of-flight memory (50) compares and controls the DAC counter (41). 22. The device according to claim 21, characterized in that that the flight time counter (46) with a measured value counter (47) and possibly with a control device (56) is connected for a number of the measured values, with between flight time counter (46) and Time-of-flight comparator (49), a time-of-flight adder (48) is arranged for forming an average value. 23. The device according to claim 22, characterized in that that the time-of-flight comparator (49) also via a flip-flop (51) controlled by the start signal (10) a DAC comparator (52) is connected, in which the values of the DAC counter (41) with values from a DAC reference memory (53) are comparable. 24. The device according to claim 23, characterized in that this reference value is the oscillator voltage for optimal tear-off removal (S) in egg Dependence of the transducer used and a valid operating viscosity of the paint. 25. Apparatus according to claim 22 or 23, characterized in that that the DAC comparator (52) with a device (60) for regulating the viscosity of the Color is connected. 26. The device according to claim 25, characterized in that the device consists of a main tank (64) for the color, which is with a paint tank (63) and a solvent tank (66) is in communication. 27. The device according to claim 26, characterized in that that the level in the main tank (64) is monitored. 28. Device according to claim 26 or 27, characterized in that that on the paint tank (63) and on the solvent tank (66) valves (62, 65) for controlling the Addition are arranged.