DE2239292C3

DE2239292C3 - Densitometer

Info

Publication number: DE2239292C3
Application number: DE19722239292
Authority: DE
Inventors: Karlheinz Dipl.-Phys. 6071 Götzenhain Fürst
Original assignee: Du Pont de Nemours (Deutschland) GmbH, 4000 Düsseldorf
Filing date: 1972-08-10
Publication date: 1976-10-21

Description

3 43 4

Zur Veranschaulichung des Linearisierungsvor- Untersetzers U_F 1:100, so ist beim variablen Unterganges sell F i g. 2 dienen. Dort ist die zu linearisie- setzer U_v das Untersetzungsverhältnis
rende Kurve durch drei geradlinige Xurvenstücke angenähert. Die dort voll ausgezeichnete Kurvp niht \
den nichtlinearen Verlauf der Signalgröße y als Funk- 5 ^Mw ⁼ _„ ·
tion der Meßgröße χ wieder. Der /vbstand der voll '
ausgezogenen Kurve y von der gestrichelten GeradenTo illustrate the linearization pre-scaler U _F 1: 100, in the case of the variable sinking, sell F i g. 2 serve. There the U _v to be linearized is the reduction ratio
The curve is approximated by three straight pieces of the curve. The full there excellent Kurvp niht \
the non-linear course of the signal quantity y as func- 5 ^M w ⁼ _ "·
tion of the measurand χ again. The distance of the full '
solid curve y from the dashed line

ist damit der Fehler der Signalgröße y gegenüber der F i g. 3 zeigt ein Beispiel für eine Schaltung zur Meßgröße Jt, der durch die Linearisierung eliminiert digitalen Linearisierung für fünf frei wählbare Meßwerden soll. Dies erfolgt dadurch, daß in Meßgrö- χα größen und Intervalle. Sie wurde mit integrierten ßenintervallen die Kurve durch je eine Gerade Digitalschaltkreisen realisiert. Verschiedene NAND-y_; = C₁X angenähert wird. Dabei ist c,· der jeweilige Verknüpfungen wurden mit DTL-Inverter und vor-Proportionalitäts.aktor zwischen der Meßgröße .rund geschalteten Dioden gebildet.is thus the error of the signal variable y compared to the F i g. 3 shows an example of a circuit for the measured variable Jt, which is to be eliminated by the linearization, digital linearization for five freely selectable measurements. This takes place in that in measured variables χα sizes and intervals. It was realized with integrated ßenintervallen the curve by a straight line digital circuits. Various NAND-y _; = C ₁ X is approximated. Here c, · the respective links were formed with DTL inverters and pre-proportionality.actuator between the measured variable .Round-connected diodes.

der Signalgröße y und äußert sich in der Darstellung Zu Beginn eines Meßvorgangs werden durch einthe signal variable y and is expressed in the representation. At the beginning of a measurement process, a

der Fig. 2 als Steigung der jeweiligen, strichpunk- 15 L-Signal die vier Dekaden des Anzeigezählers sowie2 shows the four decades of the display counter as well as the slope of the respective dash-dot 15 L signal

tiert dargestellten Annnäherungsgeraden y,·. die Flip-Flop-SchaltungenFFl bis FF 4 zurückge-approximation straight line y, ·. the flip-flop circuits FFl to FF 4 back

Bei dem in Fig. 2 gezeigten Beispiel gelten dann setzt. Die Flip-Flop-Schaltungen FFO und FF5 wer-In the example shown in FIG. 2, sets then apply. The flip-flop circuits FFO and FF5 are

die Gleichungen: den gesetzt. Die Flip-Flop-Schaltung FF5 gibt dannthe equations: the set. The flip-flop circuit FF 5 then gives

ein Löschsignal für die drei Dekaden des Unterset-a clear signal for the three decades of the subset

V₁ = C₁ χ = 2 χ für 0 < χ < 1 *<> zers U_v. V ₁ = C ₁ χ = 2 χ for 0 < χ < 1 * <> dec U _v .

_ für 1 < ϊ < 2 Sobald das Tor T für Zählimpulse freigegeben_ for 1 <ϊ <2 As soon as gate T is enabled for counting pulses

3*2 — ^C2 ^x — wird löscht die positive Flanke des ersten Impulses3 * 2 - ^C 2 ^x - will delete the positive edge of the first pulse

y₃ = C₃ χ = \x für 2 < .υ < 4 die Flip-Flop-Stufe FFS, und mit der Rückfianke y ₃ = C ₃ χ = \ x for 2 <.υ <4 the flip-flop stage FFS, and with the backfianke

des ersten Impulses beginnt die Zählung im Unter-Ziel der Linearisierung ist es, zwischen Meßgröße χ 25 setzet. Erreicht dieser die durch die Dioden vorge- und Anzeige ζ eine über den ganzen Meßwertbereich wählte Zahl U₀, so wird erneut die Flip-Flop-Stufe geltende lineare Beziehung zu schaffen, die im Bei- FF5 gesetzt und damit der Untersetzer auf Null zuspiel der F i g. 2 Gleichheit zwischen Meßgröße χ und rückgesetzt. Andererseits gelangt in den Anzeige-Anzeige ζ bedeutet, aber in anderen Fällen auch nur zähler ein Zählimpuls. Die Vorderflanke des folgen-Proportionalität zu sein braucht. Hierzu muß man — 30 den Generatorimpulses löscht wieder die Flip-Flopwie Fig. 2 zeigt — innerhalb der einzelnen Meß- Stufe FF5, und der ganze Zyklus wird erneut durchgrößenintervalle zwischen Signalgröße y, und An- laufen. Sobald der Anzeigezähler die durch die Di-,. „ ... 1 „„ p.- · . ■ öden vorgewählte Zahl A1 erreicht, wird die Flipzeige s die Funktion ζ = -y, erzeugen. Dies wird im _Flop__Stu£_{FF0 gdöscht und die Fli}p-_Fi_Op-Stufeof the first impulse the counting begins in the sub-goal of the linearization is to set between the measurand χ 25. _{If this reaches the number U 0} selected over the entire measured value range by the diodes and display ζ , then the flip-flop stage will again create the linear relationship that applies, which is set in the case of FF5 and thus the coaster to zero F i g. 2 Equality between measured variable χ and reset. On the other hand, the display shows ζ means, but in other cases only counter, a counting pulse. The leading edge of the follow-proportionality needs to be. For this purpose, it is necessary to - 30 again clears the pulse generator, the flip-Flopwie Figure 2 shows -. Within each measuring stage FF 5, and the whole cycle again by size intervals between signal y size, and run arrival. As soon as the display counter shows the values indicated by the Di- ,. "... 1""p.- ·. ■ If the preselected number A 1 is reached, the flip display s will generate the function ζ = -y. This is _{canceled in the Flop} _ _Stu £ _{FF0 and the Fli} p- _F i _O p level

vorliegenden Fall dadurch erreicht, daß bis zur Meß- 35 FF1 gesetzt. Damit bestimmt für die folgenden Zy-The present case is achieved by setting FF 1 up to measurement 35. Thus determined for the following cycle

giöße.v=! der variable Untersetzer V_v mit dem klen die Vorwahl t/l das Untersetzungsverhältr.is,giße.v =! the variable coaster V _v with the small the preselection t / l the reduction ratio,

Üntersetzungsverhältnis Uc₁ =1:2 arbeitet. Ent- bis der Anzeigezähler die Vorwahl A 1 erreicht. Die-Reduction ratio Uc ₁ = 1: 2 works. Until the display counter reaches the preselection A 1 . The-

sprechend muß für das Intervall x> 1 bis χ Z. 2 das ser Vorgang wiederholt sich bis zur Vorwahl A 4. DieSpeaking must for the interval x> 1 to χ Z. 2 this process is repeated up to the preselection A 4. The

Untersetzungsverhältnis Uc₂ == 1:1 und für .v>2 Anzahl der Vorwahlen kann praktisch beliebig er-Reduction ratio Uc ₂ == 1: 1 and for .v> 2 the number of preselections can be set in practically any

bis χ Z. 4 gleich Hc₃ = 1: \ = 2 :1 sein. Wählt man 40 weitert werden. Dadurch läßt sich jede gewünschteup to χ line 4 be equal to Hc ₃ = 1: \ = 2: 1. If you choose 40 you will continue. This can be any desired

beispielsweise als festes Untersetzungverhältnis des Genauigkeit der Linearisierung erreichen.For example, as a fixed reduction ratio, the accuracy of the linearization can be achieved.

Hierzu 3 Blatt ZeichnungenFor this purpose 3 sheets of drawings

Claims

accordingly the programming changing control signals

In this way, the facilities for

Densitometer with an analog-digital wall acquisition, a measurement that is linearly combined with the blackening for digitizing an analogue display that is hanging in the digital part of the circuit and characterizes a film sample. There, however, with the switching elements, signals and a circuit for generating a stand such as diodes and the like, only the respective counter with the blackening is linearly connected, switching operations are to be carried out in order to change the display from the nonlinear blackening measurement to the reduction ratio. There is no signal characteristic, which is characterized by a critical behavior of the circuit and the fact that the sounding has a subset switching elements against temperature changes zer (U _v ) with a controllable reduction ratio and thus any reproducible display with the Output of the digital analog aggravating drift

log converter (K, G, T, Z, AID) is connected that An embodiment of the invention is in

a programmable counter (Za, S) provided 15 explained in more detail below with reference to the drawing; it is whose input points to the output of the sub-

setter (U _v ) is connected and the one with the F i g. 1 is a block diagram for the circuit for

Control input of the reducer (U _v ) coupled production of an output that is linearly combined with the blackening for the output of the display relating to the reducers,

ratio according to the programming 20 F i g. 2 a diagrammatic representation for the eyelids Has control signals. nearization of a curve and

F i g. 3 is a circuit diagram for the practical implementation of the circuit for obtaining a display that is linearly related to the blackening.
25 to one input of a comparator K is the

Voltage U applied that is to be digitized.

The other input of the comparator K is with the

Output voltage of a digital-to-analog converter AD

connected, the digital input of which is controlled by a counter

30 ler Z is controlled. If the input voltage U

The invention relates to a densitometer at the comparator K greater than the output voltage with an analog-to-digital converter for digitizing the digital-to-analog converter AD, which is like an analog, the blackening of a film sample of a NAND gate trained gate T for pulses characterizing measurement signal and a circuit open. It then pass pulses from Impulsgenezur obtaining a, with the linear density to-35 rator G through the gate T and a coaster U _F sammenhängende display from the non-linear with fixed reduction ratio employed in the blackening measurement signal characteristic. Counter Z until the voltage of the digital-analog

There are known densitometers of this type (DT-OS converter AD with the input voltage U -17 97 236), which is one in the analog part of the arrangement. The counter Z then shows the voltage fun ctionsgenerator with switching elements included, 40 value U digitally.

by means of which the comparison voltage controlled variable- The reducer U _F is provided in this example.

Characteristic of the function generator on the measuring units so that a pulse generator G can be used. Although this basically delivers a unit, on the other hand the counter Z does not have to have an excessively large counting capacity, which is linearly related to the blackening. The display from the non-linear density measurement use of a high number of pulses per unit of time is achieved as a signal characteristic. Due to the arrangement for the devices below, in particular in connection with these devices in the analog section, these devices have FIG. 3 explained linearization parts of the arrangements, however, a critical behavior, in particular order to achieve increased accuracy of the front with regard to temperature changes, so that 50 part.

in practice a drift is unavoidable, which is strong to linearization - as shown in fig. 1 indicates -

makes it more difficult to obtain a reproducible display in black and white of the exit of the gate T not only over the sub-units. setter U _F with a fixed reduction ratio of the

In contrast to this, the invention is connected with the task of Zer Z, but also a display counting basis, to create a densitometer of the above-described 55 Za via a coaster U _v with variable Un-type, in which these difficulties reduction ratio. The linearization takes place and a strictly proportional and above all reproducible display in blackening detail is obtained exclusively in the digital part of the arrangement. The linearization process can be obtained for all digits. use talization circuits in which the voltage

This object is achieved according to the invention in that the circuit has a reducer with control (sawtooth encoder, dual-slope method, achievable reduction ratio, the voltage-frequency converter, tracking method), the The output of the digital-to-analog converter basically consists in the fact that the number of pulses that is required for a programmable counter to get into the display counter Za is through the variahcn, the input of which is connected to the output of the display counter Coaster U _v is affected, of which the jeweilisetzcrs connected and a ges with the control Un is ¹ · controlled ietzungsverhältnis in turn coupled by the jeeingang of the reducer output to weih version of the display counter Za a Ahoabc of the reduction ratio correspond stent '1 S .