EP0601658B1 - Kalibrierungsverfahren für Heizelemente eines thermischen Kopfes in einem Thermodrucksystem - Google Patents

Kalibrierungsverfahren für Heizelemente eines thermischen Kopfes in einem Thermodrucksystem Download PDF

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Publication number
EP0601658B1
EP0601658B1 EP19930203404 EP93203404A EP0601658B1 EP 0601658 B1 EP0601658 B1 EP 0601658B1 EP 19930203404 EP19930203404 EP 19930203404 EP 93203404 A EP93203404 A EP 93203404A EP 0601658 B1 EP0601658 B1 EP 0601658B1
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Prior art keywords
heating element
heating elements
power
heating
thermal head
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French (fr)
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EP0601658A1 (de
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Dirk C/O Agfa-Gevaert N.V. Meeusen
Henri C/O Agfa-Gevaert N.V. Tack
Erik C/O Agfa-Gevaert N.V. Kaerts
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Agfa Gevaert NV
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Agfa Gevaert NV
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/315—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material
    • B41J2/32—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material using thermal heads
    • B41J2/35—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material using thermal heads providing current or voltage to the thermal head
    • B41J2/355—Control circuits for heating-element selection
    • B41J2/36—Print density control

Definitions

  • the present invention relates to thermal sublimation printing and more particularly to a method for calibrating the heating elements in a thermal head of said thermal printing system
  • Thermal sublimation printing uses a dye transfer process, in which a carrier containing a dye is disposed between a receiver, such as paper, and a print head formed of a plurality of individual thermal heat producing elements which will be referred to as heating elements.
  • the receiver is mounted on a rotatable drum.
  • the receiver and carrier are generally moved relative to the print head which is fixed.
  • a particular heating element is energised, it is heated and causes dye to transfer, e.g. by sublimation, from the carrier to an image pixel in the receiver.
  • the density of the printed dye is a function of the temperature of the heating element and the time the carrier is heated. In other words, the heat delivered from the heating element to the carrier causes dye to transfer to an image related to the amount of heat transferred to the carrier.
  • Thermal dye transfer printer apparatus offer the advantage of true "continuous tone" dye density transfer. By varying the heat applied by each heating element to the carrier, a variable dye density image pixel is formed in the receiver.
  • the printing density is not uniform across the page, but that lines, streaks, and bands are visible. This uneveness can arise from several causes, including variations in the resistance of different heating elements, variations in the mechanical or thermal contact between the thermal head and the dye layer, and variations in the thermal contact between the ceramic base of the head assembly and the heatsink.
  • JP-A-63 209 954 discloses density correction for a thermal transfer recorder by providing means for detecting resistance of individual heating element, means for storing the detected resistance of individual heating element, and means for controlling energy to be applied onto individual heating element corresponding to the stored resistance.
  • US 4,827,279 discloses a method for measuring the uneveness in the image. According to this method, first a flat field is printed on a transparent receiver, then a microdensitometer measures the transmittance values of the receiver, then the digitised values are stored and finally these are used to adjust the number of heating pulses that are supplied to the heating elements.
  • a disadvantage of said method is the fact that this method requires the printing of a test-image which has to be measured by special equipment and the values need then to be brought in the printer. Therefor such calibration method can only be carried out by a service-technician. It would be more convenient if the customer himself could carry out a calibration of the printer by a calibration built in the printer or even more preferred where the printer would be able to periodically automatically calibrate itself.
  • FIG 1 there is shown a global rempli-scheme of a thermal printing apparatus that can be used in accordance with the present invention and which is capable to print a line of pixels at a time on a receiver or acceptor member (11) from dyes transferred from a carrier or dye-donor member (12).
  • the receiver (11) is in the form of a sheet; the carrier (12) is in the form of a web and is driven from a supply roller (13) onto a take-up roller (14).
  • the receiver (11) is secured to a rotatable drum or platen (15), driven by a drive mechanism (not shown) which continuously advances the drum (15) and the receiver sheet (11) past a stationary thermal head (16).
  • the thermal head (16) presses the carrier (12) against the receiver (11) and receives the output of the driver circuits.
  • the thermal head (16) normally includes a plurality of heating elements equal in number to the number of pixels in the data present in a line memory.
  • the image-wise heating of the dye donor element is performed on a line-by-line basis, with the heating resistors geometrically juxtaposed each along another and with gradual construction of the output density.
  • Each of these resistors is capable of being energised by heating pulses, the energy of which is controlled in accordance with the required density of the corresponding picture element.
  • the output energy increases and so the optical density of the hard-copy image (17) on the receiving sheet.
  • lower density image data cause the heating energy to be shortened, giving a lighter picture (17).
  • a digital signal representation is obtained in an image acquisition apparatus (21). Then, the image signal is applied via a digital interface (22) and a first storing means (indicated as "memory" in fig. 2) to a recording unit (23), namely a thermal sublimation printer. In the recording unit (23) the digital image signal is processed (24). Next the recording head (16 in fig. 1) is controlled so as to produce in each pixel the density value corresponding with the processed digital image signal value (24). After processing (24) and parallel to serial conversion (25) of the digital image signals, a stream of serial data of bits is shifted into another storing means, e.g. a shift register (26), representing the next line of data that is to be printed.
  • a shift register 26
  • these bits are supplied in parallel to the associated inputs of a latch register (27).
  • a latch register Once the bits of data from the shift register (26) are stored in the latch register (27), another line of bits can be sequentially clocked into said shift register (26).
  • the heating elements (28) the upper terminals are connected to a positive voltage source (indicated as V th in fig. 2), while the lower terminals of the elements are respectively connected to the collectors of the driver transistors (29), whose emitters are grounded.
  • These transistors (29) are selectively turned on by a high state signal (indicated as "strobe” in fig. 2) applied to their bases and allow current to flow through their associated heating elements (28).
  • FIG. 3 is a detailed cross-section of a thermal head, indicated as part 16 in figure 1.
  • a heatsink 31
  • a temperature sensor 32
  • a bonding layer 33
  • a ceramic substrate 34
  • a glazen bulb 35
  • a heating element 36 in fig. 3, being equivalent to 28 in fig. 2
  • a wear-resistant layer 37
  • the resistance value (R e ) of a heating element decreases depending on the number of the electrical pulses applied, typically -15% after some 10 8 pulses. So the more frequently an element is used, the faster its resistance value will decrease. In order to keep the print quality constant, these changes should be compensated.
  • Fig. 6 shows a typical plot of percent (%) change in resistance of a representative one of the printhead elements or ⁇ Re/Re % drift, versus the number of times that the heating element has been pulsed. Note that as the number of pulses increases the thermal printhead resistance can decrease in value by about 15% and then start to rapidly increase.
  • the resistance for each element within the print head may change in a unique, independent manner, so that the initial Gaussian distribution of resistance of individual elements is not maintained throughout the operating life of the print head.
  • the resistance value R e (e.g. nominally 2600 ⁇ ) of every resistor element can be different: between several thermal heads there can be an initial "between-variation" of about ⁇ 15% regarding the nominal resistance value (e.g. between 2210 ⁇ and 2990 ⁇ ); within one thermal head there can be an initial "within-variation", e.g. assymetric differences of - 5% to + 10% regarding same said nominal resistance value; later on, due to aging, the resistance value of the individual heating elements can vary up to minus 15% .
  • a method for calibrating the heating elements in a thermal head of a thermal printing system containing initial configuration settings at least for the highest value of the resistance (R max ) or the largest value of the time-averaged power that can be dissipated by all heating elements (hereinafter referred to as P min ) and comprising the steps of activating each heating element under simulated operational conditions taking into account said initial settings, measuring the current through each heating element and calculating the resistance or the dissipated power of each heating element, to obtain new values for R max or P min .
  • the mathematical minimum power -being the largest power that can be generated by all the heating elements of the thermal head- thus occurs at the highest values of the resistances, symbolicaly abbreviated as R max , and amounts for P min ( V 2 ) : R max
  • the activating power of all the heating elements has to be equal. This can preferably be attained by restricting the power of each heating element down to the power (P min ) as dissipated in the heating element with the highest resistance value (R max ), which itself may be determined by measurement of the current through each heating element.
  • the activation of the heating elements is executed pulse-wisely, in a special manner as indicated in Fig. 7, which shows the current pulses applied to a single heating element (ref 28 in Fig. 2).
  • the repetition strobe period (t s ) consists of one heating cycle (t son ) and one cooling cycle (t s - t son ) as indicated in the same fig. 7.
  • the strobe-pulse width (t son ) is the time an enable strobe-signal (ref "strobe" in fig. 2) is on.
  • the duty-cycle of a heating element is the ratio of the pulse width (t son ) to the repetition strobe period (t s ).
  • the strobe period (t s ) preferably is a constant, but the pulse-width (t son ) may be adjustable, according to a precise rule which will be explained later on; so the duty-cycle may be varied accordingly.
  • the line time (t l ) is divided in a number (N) of strobe pulses each with repetition strobe periods t s as indicated on fig. 7.
  • N the number of strobe pulses each with repetition strobe periods t s as indicated on fig. 7.
  • the maximal diffusion time would be reached after 1024 sequential strobe periods.
  • Said initial settings for which the printer is configured may further include:
  • the pulse-wisely activation of the heating elements is used discontinuously, as already indicated in fig. 7.
  • P ave the time-averaged electric power
  • P min [( V 2 ) : R max ].
  • time-averaged power measurements as described in the present invention, still brings a further advantage, namely in that possible uneveness in density due to inherent differences in switching characteristics (e.g. time delay, exponential rise-time, etc) are automatically weighted out. Experiencing that said differences may result in differences in pulse profile and thus in differences in strobe-on time, practically up to about e.g. 90 nanosecondes, these time-differences in the prior art of pulse-number modulation may cause differences in density and even may accumulate.
  • the method of the present invention measures the time-averaged power, said differences are immediately corrected, no accumulation takes place and no unwanted differences in density are created.
  • said simulated operational conditions which are very close to the printing operational conditions, especially regarding the temperature in the heating elements may further include predetermined values of the voltage applied to the thermal head (V th ) and predetermined values of the temperature of the thermal head (T th ) and of the temperature of the ambient (T a ).
  • T e,max [(k 1 ) x (T th )] + [(k 2 ) x (T a )] + + ⁇ (k 3 ) x [(V th - V ls ) 2 /R e ] x (t son /t s ) ⁇
  • the above-mentioned pulse-wisely activation of the heating elements preferably will be executed with a measurement duty-cycle, defined in a preparatory step, and calculated from a mathematical model.
  • R max represents the highest resistance value of the heating elements as contained in the initial settings.
  • the really applied thermal head voltage (V th ) is measured, the real ambient temperature (T a ) is measured (e.g. by the temperature of the drum) and the real thermal head temperature (T th ) is measured.
  • T a real ambient temperature
  • T th real thermal head temperature
  • a specific measuring duty-cycle (t son /t s ) can be defined by adapting the strobe pulse width (t son ), knowing the fixed value for the strobe period (t s ) which can be contained in the initial settings of the printing system.
  • the activation of the heating elements while measuring may restrict the available power in each element to P min , as contained in the initial settings, to obtain the same operational temperature (T e,max ).
  • each heating element is effected in accordance with a special electrical test-image pattern, which allows every heating member to be tested.
  • This pattern (symbollically illustrated in fig. 8) preferably includes lines of dots, wherein each dot represents a heating element: on each line one pixel is activated, while said activated dot of each line is sequentially moved across the pattern.
  • the thermal head consists of e.g. 2880 heating elements and the test-image pattern is basically a white page with 2880 lines, wherein every line contains exactly one heated pixel, further indicated as "test-dot".
  • the position of said pixel in every line is equal to its line number (e.g. 0 to 2879), so that the resultant measurement path runs diagonaly across the test-page (see fig. 8).
  • Figure 10 is a chart of an electrical test-image pattern signal during the measurements of the heating elements, according to the present invention, and thus allocates one test-dot pro line from the top-left to the right-bottom of the (soft) page.
  • each test-dot is preferably energised with a digital value corresponding to the density-value for which the human eye has the highest sensitivity for visual perception in the output print on the receiving material of density differences around this density-value .
  • said highest sensitivity appears at an optical density of about 1.
  • one of the preferred embodiments further completes the generating of said test-image pattern by the following signals: pro said test-dot and in the same line a number of neighbouring dots on the left and on the right of the generated central dot are switched on and off.
  • a diagonal test-line (fig. 8)
  • fig. 9 a diagonal test-band
  • figure 11 is a chart of an electrical test-image pattern signal of a preferred embodiment as it is practically applied to each central test-dot, which thus is surrounded at its left side and at its right side by e.g.
  • the measurement method of the present invention thus simulates the flat field conditions which were also used in the factory-calibration.
  • the measurement can be carried out without the need for any consumable, which is a great advantage of the present invention for the customer.
  • Further advantages lie in the facts that the calibration can be carried out fully automatically, without the need for a service-technician and in the fact that new settings for the resistance or the dissipated power of each heating element are automatically brought into the system.
  • the thermal head When no contact between the thermal head and the drum is made during the measurement, the thermal head is not thermally loaded by the carrier nor by the receiver and per consequence the temperature T e,max will be somewhat higher then during printing.
  • the strobe pulse width is decreased according to a constant amount in temperature, preferably between 30 and 50 degrees (°C), or according to an amount in power, preferably about 30 percent (%). This correction is integrated in the mathematical model further taking into account the actual types of consumables.
  • the current through each heating element is measured, this in order to obtain the power dissipation and the resistance values and the heating elements.
  • I ave P ave / (V th - V ls )
  • the activation of the heating elements preferably according to the electrical test-image pattern is followed by measuring pro central dot the instantaneous current (I e ) and the corresponding time-averaged current (I ave ), calculating pro central dot the time-averaged power (P ave ) and by calculating pro central dot the resistance of the corresponding heating element (R e ).
  • FIG. 13 there is shown a functional circuit diagram describing a preferred embodiment for measuring the required values.
  • a heating element indicated as R 1 and R 2 in fig 13, or as ref 131 in fig. 13, equivalent to ref 28 in fig. 2, or ref 36 in fig. 3
  • the power wires can be disconnected by means of a power relays (134a).
  • the capacitors (135) parallel on the power supply (132), which itself is adjustable but stabilised by an electronic regulator (136), can be disconnected by means of a relays (134b).
  • the minus-wire (133c) of the thermal head is connected to the virtual ground (137) of an operational amplifier (138).
  • the two measurements, I e and I ave are preferably done at the same time. Therefore these values are preferably kept in a sample and hold device (141a, 141b) at the moment the central test-dot (e.g. strobe pulse 1023) is applied. Then said measured values are converted from analog to digital values by an analog to digital convertor (140) and stored in a memory means.
  • an analog to digital convertor 140
  • low pass filters may be used.
  • fig. 13 indicates a low pass filter (142b) for the measurement of I ave and a switchable low pass filter (142a) for the measurement of I e .
  • the printed density is a function of the applied power.
  • the available time-averaged power for every heating element may be made equal and preferably equal to the power of the heating element actually producing the lowest time-averaged power (P min ) and was determined in the foregoing measurement procedure.
  • P min time-averaged power
  • the eventually increased power of the actual reference element may be kept constant by reducing the pulse duration of the strobe pulses and thus reducing the duty-cycle accordingly (cf. fig. 7).
  • all heating elements may be activated with a reduced, but common duty-cycle.
  • the further and individual reduction of the power of said other elements may preferably be done by skipping a number of heating pulses (see fig. 12).
  • skipping a number of heating cycles of those heating elements that generate too much instantaneous power the time-averaged power of all heating elements becomes equal and so the temperatures of the elements do.
  • the calibration method further comprises the sequential steps of first limiting the printing power of each heating element by commonly reducing the strobe duty-cycle of all heating elements, and secondly of skipping for each heating element an individual-apt number of strobe-pulses.
  • the individually compensated energy (E ic ) of a heating element should be equal to a reference energy (E ref ).
  • N ref - N c The number of energy quanta (N ref - N c ) is not applied to the resistor element with index i, but skipped, as illustrated by the timing diagram of fig 12.
  • This figure 12 is a chart illustrating practically the activating strobe-pulses of a heating element (with an exemplary duty-cycle and exemplary skipping) according to the present invention.
  • a pulse-train is drawn as activating the reference heating element (with R max or P min ), thus generating the restricted power as it is available in the actual printing cycle, after reducing the common duty-cycle as it was necessary to compensate the power for decrease of the resistance during the lifetime.
  • a corrected pulse-train is drawn as activating another heating element with e.g.
  • R e 0.75 R max and which in the abscence of the present invention, would dissipate e.g. 25 percent of energy above said reference (thus 125% E ref ).
  • every fourth strobe pulse may be skipped.
  • the available time-averaged power for every heating element may be made equal and preferably equal to the power of the heating element actually having the lowest time-averaged power (P min ) or the highest resistance (R max ).
  • the measurement of the resistance of each heating resistor may occur at the power up of the system, after a number (e.g. 300) of prints, after a change of consumable, etc.
  • the calibration method described in the present invention accounts for deviations in the resistance or the dissipated power of each heating element as prescribed in the initial configuration settings, within the same scope, also compensations may be made in order to reach good printed eveness regarding other parameters, such as voltage drop of the power supplied to the heating elements, evolution of the ambient temperature during the calibration, etc.
  • This invention may be used as well for grey-scale thermal sublimation printing as well as for colour thermal sublimation printing. Further, the printing may be applied in graphic representations, in medical imaging, in facsimile transmission of documents etc.

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Claims (10)

  1. Kalibrierverfahren für Heizelemente (28) eines Thermodrucksystems, das einen thermischen Kopf (16) mit einer Vielzahl von Heizelementen (28), einen einen Farbstoff enthaltenden Träger (12), einen auf einer drehbaren Trommel (15) montierten Empfänger (11) umfaßt sowie anfängliche Konfigurationseinstellungen wenigstens für den höchsten Wert des Widerstandes aller Heizelemente (Rmax) bzw. des größten Wertes der Leistung, die in allen Heizelementen verbraucht werden kann (Pmin), enthält, wobei das Verfahren die folgenden Schritte aufweist: das Aktivieren jedes Heizelements unter simulierten Betriebsbedingungen, wobei die Anfangseinstellungen berücksichtigt werden, das Messen des Stroms durch jedes Heizelement und das Berechnen des Widerstandes oder der verbrauchten Leistung jedes Heizelements, um neue Werte für Rmax oder Pmin zu erhalten.
  2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Aktivierung der Heizelemente impulsweise ausgeführt wird.
  3. Verfahren nach Anspruch 2, dadurch gekennzeichnet, daß die Aktivierung der Heizelemente einem elektrischen Testbildmuster entspricht.
  4. Verfahren nach Anspruch 2, dadurch gekennzeichnet, daß die simulierten Betriebsbedingungen den größten Wert der zeitlich gemittelten Leistung umfassen, der in jedem Heizelement verbraucht werden kann (Pmin).
  5. Verfahren nach Anspruch 4, dadurch gekennzeichnet, daß die simulierten Betriebsbedingungen außerdem vorbestimmte Werte der an den thermischen Kopf angelegten Spannung sowie Werte der Temperatur des thermischen Kopfs und der Temperatur der Umgebung oder der Temperatur einer drehbaren Trommel (15) umfassen.
  6. Verfahren nach Anspruch 2, dadurch gekennzeichnet, daß die impulsweise Aktivierung der Heizelemente während des Messens mit einem Tastverhältnis (tson:ts) durchgeführt wird, das aus einem mathematischen Modell für eine in einem Heizelement verbrauchte zeitlich gemittelte Leistung berechnet wird, wobei ein Wert für die an den thermischen Kopf angelegte Spannung (Vth, Vth -Vls) berücksichtigt wird, der durch eine tatsächliche Messung bestimmt wird, mit einem Widerstandswert (Rmax), der durch eine vorhergehende Messung bestimmt wird, mit einem festen Wert für eine Tastimpuls-Periodendauer (ts), die in den anfänglichen Konfigurationseinstellungen enthalten ist, mit einer Temperatur des thermischen Kopfs (Tth) und einer Temperatur der Umgebung (Ta), die gemessen werden, wobei das mathematische Modell [(V th - V ls ) 2 : R max ]. {t son :t s ) = c 1 .T th + c 2 .T a + c 3 .(V th ) 2
    Figure imgb0019
     aufweist, wobei C1, C2 und C3 Konstanten sind.
  7. Verfahren nach Anspruch 3, wobei das Erzeugen eines elektrischen Testbildmusters das Festlegen eines zentralen Testpunkts für jede Zeile von links oben auf der Seite nach rechts unten auf der Seite oder umgekehrt umfaßt und wobei für jeden Testpunkt auch eine Anzahl von benachbarten Punkten links und rechts von dem zentralen Testpunkt in derselben Zeile ein- und ausschaltet werden.
  8. Thermodrucker, der einen thermischen Kopf mit einer Anzahl von Heizelementen und Mittel zum gezielten Aktivieren jedes Heizelements umfaßt und der folgendes aufweist: Mittel zum Speichern anfänglicher Konfigurationseinstellungen für den höchsten Widerstandswert aller Heizelemente (Rmax) oder den größten Wert der Leistung, die in allen Heizelementen verbraucht werden kann (Pmin), Mittel zum Aktivieren jedes Heizelements unter simulierten Betriebsbedingungen, wobei die anfänglichen Konfigurationseinstellungen berücksichtigt werden, Mittel zum Messen eines Stroms durch jedes Heizelement und zum Berechnen des Widerstandes bzw. der verbrauchten Leistung jedes Heizelements sowie Mittel zum Erhalten neuer Werte für Rmax oder Pmin.
  9. Thermodrucker nach Anspruch 8, wobei die Aktivierung der Heizelemente impulsweise mit einem einstellbaren Tastverhältnis ausgeführt wird, der außerdem folgendes aufweist: Mittel zum Angleichen der verfügbaren Leistung jedes Heizelements während des Druckens durch, erstens, ein Begrenzen der Druckleistung jedes Heizelements durch gemeinsames Vermindern des Tastimpuls-Tastverhältnisses aller Heizelemente und, zweitens, durch Überspringen einer individuell geeigneten Anzahl von Tastimpulsen bei jedem Heizelement.
  10. Thermodrucker nach Anspruch 9, wobei das Überspringen einer individuell geeigneten Anzahl von Tastimpulsen bei jedem Heizelement ein zeitlich äquidistantes Überspringen ist.
EP19930203404 1992-12-09 1993-12-03 Kalibrierungsverfahren für Heizelemente eines thermischen Kopfes in einem Thermodrucksystem Expired - Lifetime EP0601658B1 (de)

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US11237502B2 (en) 2018-05-11 2022-02-01 Hewlett-Packard Development Company, L.P. Calibration of a temperature sensor of a printing device

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US5608442A (en) * 1994-08-31 1997-03-04 Lasermaster Corporation Heating control for thermal printers
US5786837A (en) 1994-11-29 1998-07-28 Agfa-Gevaert N.V. Method and apparatus for thermal printing with voltage-drop compensation
US5724084A (en) * 1995-12-05 1998-03-03 Gerber Scientific Products, Inc. Apparatus for making graphic products having a calibrated print head, and method of calibrating same
US5825394A (en) * 1996-02-20 1998-10-20 Lasermaster Corporation Thermal print head calibration and operation method for fixed imaging elements
EP0835760A1 (de) * 1996-10-09 1998-04-15 Agfa-Gevaert N.V. Korrektur der streifenförmigen Druckunregelmässigkeiten in einem thermischen Drucksystem
US6249299B1 (en) 1998-03-06 2001-06-19 Codonics, Inc. System for printhead pixel heat compensation

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US5087923A (en) * 1990-05-25 1992-02-11 Hewlett-Packard Company Method of adjusting a strobe pulse for a thermal line array printer

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Publication number Priority date Publication date Assignee Title
US11237502B2 (en) 2018-05-11 2022-02-01 Hewlett-Packard Development Company, L.P. Calibration of a temperature sensor of a printing device

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