DE1773227A1 - Method and device for measuring light transmittance - Google Patents

Description

Patent attorney

Dipl.-Ing. E. Edor

Munich 15, EHsabethsfr. 34 1773227

Attorney File No. 6219

GOlJLTKR ELECTRONICS Ltd., Dunstable, Beda. / England

Method and device for measuring light transmittance

The invention relates generally to a light transmittance measuring method and apparatus for carrying out this method, and more particularly to a method and apparatus for determining hemoglobin content by measuring the difference in optical transmittance between a reference medium and a sample by storing an electrical signal representing the reference medium , and then comparing this signal with a signal representing the sample, with simultaneously

209809/1320 bad original

the stored signal is reduced until the two signals are the same. The amount of time the stored signal was reduced gives a measure of the hemoglobin content of the sample.

Conventional ones are used for the device for carrying out the method Storage, receiving, control and circuit elements included in the arrangements according to the invention are used. In a circuit arrangement, both the reference medium and the sample signals are also fed to the memory circuit, which also carries out the comparison. With a second circuit arrangement the memory circuit only accepts the signal of higher voltage. In a circuit arrangement of the latter Art becomes a biasable switch for the comparison process used. Preferably a voltage follower is from high accuracy coupled to the input of the biasable switch.

As is well known, hemoglobin is an iron-containing protein pigment that is found in the red blood cells of humans and many others Forms of animal life is found. The relative amount of hemoglobin in a blood sample is one of the important parameters which is used for the diagnosis and treatment of various diseases and conditions, such as anemia.

2093Q9 / 1328

SAD

known methods for determining the hernioglobin content exist in hemolyzing the Bjut to break up the red blood cells and releasing the hemoglobin from inside the same, and then releasing the resulting suspension with an appropriate reagent to treat. Has an international hematology committee Standard values established. The standard for measuring hemoglobin using a particular wavelength of light is defined by the formula

(1) HGB - 36.77D = 36.77 log _1Q 100 / T

in which:

HGB is the hemoglobin in grams per 100 ml,

D is the optical density or absorbance of a 540 manometer light 1.00 cm long and T is the percent light transmission.

D is reported above as being equal to the logarithm to the base 10 of 100 divided by the percent transmittance of light. The chosen wavelength can be obtained by using certain filters, the length of the beam can be through a factor can be set in the results and the function is logarithmic.

BUILDING

209809/1328

In the applicant's application of April 17, 1968, there is a device described in which a number of the parameters of the blood are measured and automatically derived from blood samples. The heart of the device is the particle analyzer, which is located under the Trademark "Coulter Counter" known lot. One of the important parameters welcJ> r obtained using the "Coulter Counter" is the white blood count. With this automatically working Device a dilution of the blood sample is formed, treated and analyzed and measured as part of such an analysis of the hemoglobin content. The object of the invention is to create a method and a device for performing such a hemoglobin measurement.

Those skilled in the art of particle counting and analysis will no doubt be aware of the substantial advantages that can be achieved by the numerous devices in use are obtained which are marketed under the trademark "Coulter Counter" and based on U.S. Patents 2,656,508, 2,869,078, and 3,259,842.

Although the invention is described in connection with particle analysis and is particularly advantageous for determining the hemoglobin content, the invention comprises the comparison of the light transmittance bipknit a sample and a reference medium for measurement

209809 /! 328 bad

the light transmission of the sample. The particular sample and the parameter of the sample that affects its light transmission, are part of the application of the broader features of the invention consider.

The preferred embodiments of the invention are described below for example in connection with the accompanying drawings, namely show:

1 shows a block diagram of the device according to an embodiment of the invention;

FIG. 2 shows a simplified electrical circuit diagram of that in FIG. 1 illustrated embodiment;

FIG. 3A shows waveforms for the memory circuit according to FIG. 2, and 3 B

drove to two slightly different "Jodi;

PL; ·. Figure 4 is an elevational view of a preferred form of fluid- ^ electro-optical container and transducer, which can be used in conjunction with the electrical device of the invention;

Fi; r, '3 is a block diagram of an apparatus according to a second Execute un ^ jforin of the invention;

Fi, ^r . 6 a veru Lnfach tey eiülctriuchea circuit diagram dor AurjführungfDrin riatUi FLf. ';, and

209809/1328

Pig. 7 is a diagram showing the voltage at different points in the device according to FIG. 6 in succession Points in time.

Referring first to Figure 1, an electro-optical transducer 10 is shown in block form. This Transducers can be of various shapes and sizes Process types of inputs to achieve its goal, viz the supply of two consecutive electrical outputs, one of which is the transparency of a reference medium while the other represents the transmittance of the diluted blood sample. In a simple form can be a photoelectric source or photocell and an illumination source be fixedly arranged on opposite sides of a narrow channel, in which successive one Reference cell R and then a sample cell S containing the diluted blood sample enters. The reference cell can have a volume of a Contain diluent, which in turn, the conventional saline, preservative acting hemoglobin reagent and a Contains hemolyzing material. A diluent of one Such a composition would have a certain optical density by which a relative amount of that would pass through the photocell Lighting is absorbed. By using a volume of the diluent as a reference and by

209809/1328 _BA d cwssnal

using a common source of diluent for both the reference cell and sample cell B would result in changes the optical density of the diluent as a result of its composition, temperature, etc., no congenital deviations in the comparative color monitoring.

In a simple form of the transducer 10, either a reference filter simulating a dilution, air, clear water or another reference medium or substance can be used in place of the fluid volume of the diluent. A more complex form of transducer works according to the principle of a flow rate and enables an automatically running treatment or processing of successive Blood samples. Such a more complicated shape is shown in Fig. 4 and will be described below. In the following Describing the invention, the signal representing the reference medium will be deemed to be of higher voltage than that of the sample described and first supplied to the memory circuit. This is the case when the reference medium has higher light transmission than the sample medium has. However, the invention will also work when the relative optical density levels are reversed and first converting the measured value of the sample.

As FIG. 1 shows, a memory circuit 12 with the measured value converter 10 is rekcnpelt by an I-erUm ^ 14, ¹ IIe de: 'ioi'Uv' ⁷ ■. '! ■■

209809/1328 bas ^ ^il3li * ^AU

len R and S is common. The memory circuit is provided so that first the output from the reference cell R is received and stored. As the reference medium coloring density relatively is low, there is little absorption so that a signal is converted from a relatively high V / ert and supplied to the memory circuit.

With the memory circuit 12, a receiving circuit 16 is through an output line 18 coupled. The receiving circuit is ineffective during the supply of the signal from the reference cell R to the memory circuit 12, but during the supply of the Sample in the signal representing cell S the receiving circuit unlocked so that they can be used as a derivative for that in the memory circuit 12 stored reference signal is effective. This control will made possible by a control device 20 via its output line 22, which serves as a control input via the receiving circuit 16. The control device is in reality an automatic one Programming center that regulates the various punctures in the fully automated system described in the aforementioned patent application is described. Through a switching line 24, the control device also regulates which of the cells R or S through the Converter circuitry within transducer 10 is actuated will.

209809/1328

The output 22 of the control device is common to the input of a control circuit 26, so that both the receiving circuit and the control circuit 26 are triggered simultaneously during the conversion of the measured values of the content of the sample cell S. The control circuit 26 has an output 28 which is connected to the Ent-3perrurbrseingang a fine bistable device; 30 coupled iat »Furthermore, the S _t > e Loh circuit 12 is coupled to a blocking input D of the bistable device; 0 via a line 32. In response, the bistable device is switched to the on-state when -the signal from the sample cell of the Speieherachal tiuu ·; augefäur I; becomes, and after a Zaitdauyr, give way to the difference 3w.ii-j.chen of the duty of the Beau ^ umediumo and that of the r ro berifliedi. Hau propor * ι on al. i: it, in the or / ui'r ^ uu tand shelled. .

, / eria; ewatiaoiii., can d '; r h'iüHi.iuit.l ~ iah his Duiuif gon tdiier te Auag-üi.: · from the bin ta.bi It-ui' / urriohtung .H) niwic ληαίοιτ,?;) Τΐ & üinea I ¹ FJ ₁ ",.! ..; tr j ο render- i.-t. ^f . ', /; orH i.dij H Kugefiiiirb become,: \ n4effii" ^! ills or, j -. / i-ur,.: t.Hi ^; riri £ 3ch it'll i oil k-am der aei t; slope; j ^ o ^ u.> _t , ιϊΐ. _: · "From the bi ■ wtfibi. L'jii Vorric'li tu ng eLuou pulse generator '?> H oiiif obbitidf) t and then -J. · .; .IiiipuLj ro ino in ivLnen printer;> ü odor Ln ei.ao iindar «ti« -. r'te Aui-jj-j'-üii ^ jvorrifiii l; uüg üi.niitjio-i tet been.

Difj .: '- nc-iiü ti,; cht; Dun-i'm.- 1 1 an ·., The Pig, 2 uit; ij; 11.oht «ih ins ;, lii rizeLrie- ..- v'-iheiMlei-: Vux ^ j ί, ίΜκίη ι .; ^Λ d-; u "'^ rb'-jLtiSv / oij'! Un

2 O 9 Ö O 9/1 3 2 Ö

- ίο -

effects of the transducer 10, the memory circuit 12, the receiving circuit 16 and the control circuit 26, which elements are indicated by dashed rectangles. In this context it should be noted that this electrical circuitry is greatly simplified, but should be sufficient to the expert a reasonable statement to - ^r even, after an equivalent circuit that can be brought to market easily be built icann ₀

The primary electrical components within the Meßwertumwandlern 10 are ei: ie photoelectric line 40 and a :: 'rom LU annungsumformör- ^r IILF sschal ~ ung 42. En is only a Phntozelüe errorderlich if the reference and u Lf: sample cell or R .S or their equivalents are mechanically transferred to the Phobo cell arrangement; Your oinr i exercise 20 cinn alternate excitation of the photocell 40 'by the cells R and ö bev / irkb. Nafcürlioli can have two Pho t: o. '. B1 lan and the assigned. · ■■ t; _: ; ; Sf .: ri - .. ltu.n ^: uanordnunr wüchaelwöise the Aus.-r-mgsleitung 14 bolieiOrn, jrdoc}. ·. can iiierby an untio tii-er Aiu-js-mgs-foal inIj .U-- ■ before. ; ^; ; heroin brings about changes between the two monitors; will.

The 8 no ir; he restitution 12 umt'aJSt, an ochalbtrann i ytor 44, who with the L «! - ^r ; ung 14 connected iat, an Auü ^ ungiilu i. Iwn ' ' ^ '', a

2 0 9 Ö 0 9/1 3 2 8 bad original

positive voltage source + V and a conventional RC element with a grounded capacitor 46 and a resistor 48, which enables access to the output line 18 «The initial Charging of the capacitor takes place when the photocell 40 through energizing the illumination passing through the reference cell and applying a controlling base current to line 14 lays. This has the consequence that the transistor 44 becomes conductive, where- (| is coupled to the capacitor by + V. Since the inputs of the ■ bistable devices sensitive to the leading or trailing edge may be, the fact that the transistor 44 is now conductive does not mean that from its output 32 a blocking signal is transmitted. The transducer 10 responds to each subsequent representation of the reference cell for a brief period of time at. In this way the capacitor is charged to the relative value which is proportional to the permeability i.e. the absorption of the reference media. Although the resistance is 48 forms a discharge path, discharge is prevented because the receiving circuit 16 including a transistor 50 closes this point in time is prevented from becoming conductive, since a triggering input on line 22 from the control device 20 is missing.

At this junction, the. Control device 20 their Continue programming and use the switching line 24 to do this

2Ö3809 / 132

Responding the converter 10 to the contents of the sample cell S. Because the hemoglobin in this cell makes the cell fluid a distinctive Gives color, the light passing through the photocell is absorbed to an extent which is proportional to the hemoglobin content. The voltage applied to the output line 14 is therefore inversely proportional to the hemoglobin content. As mentioned, the outputs 22 of the control device are unlocked at the same moment at which the Voltage representing hemoglobin is applied across line 14. The capacitor 46 therefore becomes discharged at the same time unlocked via resistor 48 and transistor 50 · Furthermore, bistable device 30 is simultaneously activated by the control circuit 26, which is then a suitably biased transistor 32.

Care should be taken to note that although lead 14 carries a voltage representative of the hemoglobin in the sample, that Transistor 44 not driven second time has been. This is due to the fact that the charge placed on the capacitor 46 as a result of the conversion the content of the reference cell is greater than the voltage which is now fed to the line 14, so that the transistor 44 is blocked will. However, since the capacitor continues to discharge through resistor 48, the difference in the emitter voltage

209809/1328

Äung to the base is voltage of the transistor 44 until the The voltage at the emitter is sufficiently low that the Hemoglobin caused base voltage can unlock the transistor in the conduction state. The duration of the capacitor discharge is therefore proportional to the base voltage, which is inversely proportional to the hemoglobin content of the blood sample.

fgnii the transistor 44 is brought back into the conduction state, fgr ^ changes the level of the output 32 of the memory circuit 12, pp is blocked by dijs bistable device 30. The hemoglobinder Sample therefore became a measurable duration of an Ausypisch in the form of a square wave, from the pre-30 converted. This pulse duration can easily be converted into registered analog and / or digital outputs through conventional | iitt.el; for example of the type shown in Fig. 1, convert. Although not shown in Figs. 1 and 2, this can

the bistable device 30 or even the second Entdee Trigger transistor 44 through suitable feedback lines control device to start a new duty cycle

to initiate ^ to the reference cell contents and a further again to monitor and convert successively. Of course, during the renewed duty cycle, the capacitor becomes brought into the same state of discharge as it was initially

2C98Ö9 / 132Ö

iiliä *, '·,.:. . ■

-H-

In Pig. Typical capacitor waveforms V _{RC are} shown in FIGS. 3A and 3B. 3A shows the operation already described, in which the capacitor was initially charged to a value V ₁ (voltage due to the reference cell) and then _{discharged to a value V g} (voltage applied due to the blood sample). This quantity of discharge required a duration of t. - t _Q = t, which led to a similar builder of the output signals from the bistable device 30. Using the common discharge formulas it results that:

so that

When using formulas (1) and (2) and taking into account, that the absorption of the reference medium is a constant while to equate the grams per 100 ml of the sample with

(3) 15.95t ;

Similarly, if a digitized staircase is in use
/ a pulse generator of the type shown in Fig. 1 ber

209ÖOÖ / 1328

- Ϊ5 -

is used, the hemoglobin content can be calculated as follows:

(4) k χ fp χ t

in which k is a precalculated constant that depends on the standard values used, fp is the frequency of the pulse generator and t is the output duration. In this way, the pulse frequency can be adjusted so that there is a simple relationship for hemoglobin concentration, «For example, one hundred pulses can represent 1 g of hemoglobin per 100 ml of sample.

FIG. 5B differs from FIG. 3A in this respect; is used as a two-step reference sample procedure. Initially, the transducer monitors a completely clear or bare medium, such as air or water. This has the consequence that the capacitor is charged to the value of V _B , which is higher than the value V ". The reference cell is then monitored optically and the receiving circuit 16 is triggered. Since V "is lower than V ^, the capacitor begins to discharge at t, which is earlier than t _Q. However, the control circuit is only triggered after the voltage V _{RG has} dropped to the value V _R.

The only electrical changes that are necessary to those in Pig. To achieve the operation shown in FIG. 3B, the previously common output 22 from the control device is unlocked separately and a third monitoring position

209809/1328

(blank) is provided for the switching line 24. Suppose that the dashed rectangle R in Fig. 1 contains both mechanical parts of this modified reference cell. It is also assumed that that the transducer 10 has the necessary mechanical and optical equipment included to enable the required monitoring and relative placement of reference and sample media As mentioned, the transducer 10 may have two monitors (or even a third one for providing V-g) so that the monitoring need not be consecutive, even if the different voltages are applied to the line 14 should be consecutive.

Fig. 4 shows a preferred embodiment of the transducer 10, which is suitable for the rapid, sequential analysis of numerous samples in an electronic particle analyzer. A tubular bath 60 is provided with a plurality of openings Tubes 62, each of which has its own opening 64, a first electrode 66 and a manometric suction tube 68 owns. Furthermore, the bath is preferably provided with a common second electrode 70, a medium inlet 72 and an outlet 74 of rectangular cross-section. On opposite sides of the drain 74 are an illumination source 78 and a Photocell 76, the latter of which is equivalent to photocell 40 in FIG is arranged. The photocell 76 is with one, for example

209809/1328

wise green filter 80, which is used to select that part of the spectrum that is used for testing the red-colored sample suitable is.

With this form of the transducer, a hemoglobin determination can easily be combined with a leukocyte count in the following manner. After a diluted blood sample has been introduced into the bath through inlet 72, the red and white cells are separated and the white cells counted and the solution is drained and flushed with an amount of fresh diluent which enters through drain 74. At this point in time, the reference voltage V _{R is} converted and coupled to the memory circuit 12. A fresh sample in diluent is then introduced via inlet 72 and the value of V _g obtained. While the leukocyte count is collected and the bath is drained off and rinsed again, the device according to the invention carries out the treatment and the hemoglobin content of the sample is recorded in the manner already described in connection with FIGS. 1 to 3.

It follows that the preferred use of the diluent as a reference medium and through the preferred use of a single photo-optical transducer as well through the direct supply of both the converted reference and

2ÖÖÖÖS / 1328

the sample signals to the same capacitor to determine the The amount of charge and the extent of the relative discharge, variables such as temperature, aging of the components, Coloring of the reference medium, etc., all are prevented from affecting the accuracy of this hemoglobinometer. Additionally is the desired one because both the absorption and discharge characteristics of the memory circuit are exponential Output linear.

In Pig. 5 shows a second arrangement according to the invention. For the sake of simplicity, it is assumed that the transducer 110 the same as the transducer previously described 10 is. With the output of the transducer 110, a computation or Puncture amplifier 112 coupled via a line 114. The arithmetic or puncture amplifier is designed in its construction so that it operates according to a voltage sequence mode, so that its output voltage on line 16 closely follows the input on line 114. The computation or puncture amplifier is like all in Pig. 5 shown block elements in connection with Pig. 6 described in more detail.

A biasable circuit 118 is on its input side with the output of the arithmetic or puncture amplifier via a line 116 coupled. Therefore, the inputs of both the

209809/1328

Amplifier 112 as well as the ijcjialtkreises 118 in a voltage sequence relationship, The output side of the circuit is through line 120 to a first side of a controlled switch 122 and coupled by a line 124 to a receiving circuit 126. A latch circuit 128 has a second side of the controlled switch 122 is connected through a line 130. The arrowheads for lines 120 and 130 represent the fact shows that the memory circuit 128 is charged via the switch 122 and can subsequently be discharged through the same switch to receiving circuit 126.

An output converter 132 is connected to the output by line 134 of amplifier 112 is coupled. A controller 136 provides a control input to the output converter via line 138. A switching line 140 optionally regulates which of the cells R or S is operated by the transducer 110. The control device also regulates the status of the controlled switch, as symbolized by a control line 142.

The operation of the device shown in Fig. 5 is very simple brief summary as follows. Initially, the controller chooses 136 the reference medium to be converted R and closes the switch 122, so that a voltage proportional to the Lioht permeability of the reference medium across the amplifier 112, the

2Ö9809 / 1328

Circuit 118 and the switch 122 of the memory circuit 128 is supplied. The control device then opens the switch 122 and selects sample S for measurement conversion. The sample has a lower light transmission than the reference medium R, see above that the voltage supplied through the amplifier 112 and the biasable circuit 118 is lower than that in the memory circuit 128 is stored. The controller then closes switch 122 and enables discharge from the Memory circuit via the controlled switch to the receiving circuit 126. The discharge continues to matter until the memory circuit is at the same lower potential than that which is converted with respect to the sample S.

During the discharge period, the biasable circuit 118 is biased off. As a result of the state of discharge and via line 134, amplifier 112 triggers output converter 132. Once the charge is on both sides of the circuit is balanced again, the triggering input for the converter is removed. The converter 132 measures the duration while which it was unlocked, and this measurement is proportional to the difference in light transmission between the reference medium and the sample, which of course is a directly proportional one Measurement of the hemoglobin content of the sample is when it is blood.

209809/1328 ^ßAD

The details of the device according to the invention are illustrated by the schematic representation in FIG. 6 in connection with the voltage schart in Pig. 7 more recognizable. It should be mentioned here that the circuit combinations in Pig. 6 of a preferred Embodiment correspond and are not to be regarded as limiting the circuit blocks which they represent.

The primary electrical components within the transducer 110 are a photocell 144 and a current-to-voltage converter 146. The output line 14 contains an insulating and substituting resistor 148 and a node A. The node A and other nodes, which are identified in more detail below , serve to compare the voltages of different points in the schematic representation and are related to similarly marked waveforms in FIG. It is assumed, for example, that a positive 10 V signal is generated by the conversion of the measured value of the reference medium R and that the conversion of the measured value of the sample S results in a positive signal of only 5 V. Therefore, at t ₁ in Pig. 7, a voltage of +10 V is shown for the waveform at node A, which represents that the transmittance of the reference medium is then measured by the photocell 144.

The node A is in the positive (+) input of the radio fcionrerstärkers 112 coupled. This amplifier is shown symbolically

209009 / 132Θ

instead of more detailed circuit details, there are numerous Shapes of circuitry can be used as long as they are operated in a voltage follower mode so that the voltage at node B in the amplifier output line 116 follows the voltage at node A very precisely. Voltage Follower Puncture Amplifier correspond to this criterion in that they have an almost infinite input impedance (in the order of magnitude of 100 megohms) at the lowest load, a particularly low output impedance (of the order of 1 ohm) and a high one Have gain factor · The illustrated amplifier 112 is a balanced differential amplifier and has a negative input (-) in negative feedback from a node C. Even a change of a few millivolts between the two inputs has the consequence that the output is stable from full negative to full positive saturation oscillates. In this form the amplifier has negligible attenuation and is well suited for its task, maintaining tension at the nodes Keep A, B and C at the same level. This is at t «at waveforms A, B and G.

Although different and simpler forms for the voltage follower circuit An arrangement could be used that would be required and the precision achieved by the invention suffer. It is even possible to connect nodes A and B directly to one another.

208809/1328

to join or unite with each other, but stability and accuracy would be less than desirable «

The biasable circuit 118 has a diode so coupled is that it by the voltage at node B in the forward direction and aure the voltage at node C in the reverse direction is operated. The feedback from node G to the negative input of amplifier 112 is via a line 150. Line 124 couples both node G and the line 120 to the receiving circuit 126, the one to ground has lying resistance.

A node D and the node C are on opposite sides Sides of the controlled switch 122 and are connected to this by lines 130 and 120. The hub D indicates the voltage across memory circuit 128, which has a capacitor connected to ground. As can be seen the memory circuit and the receiving circuit constitute a conventional one RC element.

Although switch 122 is shown as normally open, it is closed by controller 136 at time Xq so that the +10 V voltage at nodes A, B and C is also applied to the charging circuit and therefore also applied to node D voltage of +10 V exists, for the purposes of the

BAD orviSi 209809/1328

Description was the typical voltage drop across the prestressable Diode 118 left out of account for the sake of simplicity, however, as can be seen, at time t the voltage at node B is higher than +10 and is, for example, +10.6 V.

First, the content of the output converter 132 will not be described and only mentioned that at its input a diode 152 is normally caused by the positive voltage at node B. is operated in the reverse direction, which voltage is higher than that which is applied to the diode by the positive voltage source, which is symbolized in the output converter Therefore, at the point in time tβ, during the measured value conversion of the reference medium R the output converter locked. As can be seen from the below, the output converter 132 is only unlocked when a negative potential at node B, i.e. between the times t 1 and t.

At time t ₁ , the control device 136 supplies a signal to the line 142, so that the switch 122 opens and the memory circuit 128 is isolated from the rest of the circuit arrangement. As shown in Figure 7, the voltages at each of the nodes remain constant. At the point in time t _g , the switching line 140 of the control device is brought into the position relative to the sample S and, furthermore, a blocking signal is sent to the output transducer via the line

209809/1323

given to switching surges in the event of an undesired triggering of the output converter to prevent.

Since the sample S allows a smaller amount of light to pass through, follows a lower voltage, for example +5 V, than at node A at node B, so that the diode of the circuit 118 is operated in the forward direction, which also brings node C to +5 volts.

It is recalled that switch 122 was opened at time t ₁ and remains open at time to. At time t., Switch 122 is closed again by the control device, which results in significant reactions. The nodes G and D, at which different voltages exist, are coupled to one another. Node G continues to receive the +5 volts from transducer 110, amplifier 112, and circuit 118, except when circuit 118 is reversed, as will be described below. The node D can only draw the voltage stored in the memory circuit 128. At time t, the memory circuit therefore discharges via nodes D and C into the resistance of receiving circuit 126 and to ground. As a result, the voltage at node C jumps to +10 V and then drops to ground at the same time as the voltage at node D.

209809/1328

As soon as the voltage at node G jumps to +10 V, the biasable circuit 118 is operated in the reverse direction, whereby a direct connection from node B to node C is prevented. At the same time brings the feedback line a substantially different voltage than that applied to the line 114 is placed, to amplifier 112. The function amplifier is therefore driven to saturation and its output voltage at Node B drops to -5V. As a result, the diode 152 in the output converter 132 is operated in the forward direction, thereby unlocking the converter.

During the time between t ~ and t, the voltages are as in 7 shown. At time t, the voltage at node C has dropped to +5 V, which is also the value of the negative input of the amplifier 112 via the feedback line 150 is, and the same amount of voltage is fed via the input line 114 to the positive input of the functional amplifier. As a result, the inputs of the functional amplifier are adjusted so that it goes out of saturation, its output voltage at Node B jumps back to +5 V and the diode 152 in the output converter is operated again in the reverse direction, which prevents further operation of the converter. Way, a measurement of the exact point in time of the voltage discharge from the reference level to the sample level is obtained, which is converted into a

209609/1328

equivalent hemoglobin calculation for the sample can.

As for the circuit arrangement of the output converter and its operation, so if the diode 152 is in the forward direction is operated, current is drawn from the base of a transistor 154 so that it does not conduct and its collector voltage goes into the positive. The positive collector voltage is fed to the base of a unijunction transistor 156, see above that this becomes conductive and provides an output to an integrator 158. The integrator is for the duration of (Ί / - ^) effective and supplies an analog value of the hemoglobin content at its output 160 for further processing by a suitable one facility not shown. A transistor 162 has its base connected to the inhibit signal line 138 to prevent an undesired To prevent the unijunction transistor from switching on during the time tp.

So early after time t. than can be carried out mechanically, the reference medium R can again be controlled by the control device for the start of a further work cycle from t to t . to get voted. The same or different samples can be analyzed during each cycle or on a periodic or alternating basis depending on the programming of the controller and the needs of the user.

2 Ö 9 8 0 ^9/1 3 1 8 ßAD

The preceding description has focused on the determination of the hemoglobin content parameter directed to a blood sample. Furthermore, both a method and an apparatus for simultaneous measurement conversion have been developed a blood sample in two different ways to determine more than one parameter, especially the white one Blood count (erythrocyte count) and the hemoglobin content. In this context it should be mentioned that the described Method and device for converting measured values of sample and reference media and for comparing their light transmittance are not limited to the determination of blood parameters.

Patent attorney

Dipl.-Ing. E. Fdct

Munich 13, Elisabeths. 34

Patent claims:

209809/1328

Claims (1)

ipUncv. ϊ, r _; :? r .: Munich 13, ι?;. 'r «. IA - 29 claims 1. A method for determining at least one parameter of a sample medium, characterized in that a parameter of the sample medium as well as a reference medium is converted into two discrete electrical signals, at least the signal representing one of the media mentioned is fed to a memory, since the stored signal is compared with the signal representing the other medium, the memory is emptied until the two signals are equal, and
the duration of this emptying is measured. 2. The method according to claim 1, characterized in that _Ä daa mentioned supply occurs for both media and the larger of the supplied signals is supplied first. 3. The method according to claim 1 or 2, characterized in that that the memory is enabled to use the lower signal level at the same time as the measured value conversion of the other medium to search. 209809/1328 4. The method according to claim 1, characterized in that the signal representing the other of the media mentioned before Comparing a comparison device is supplied. 5. The method according to claim 4t, characterized in that W gel the other of the converted signals is tracked during its supply at one leading to the comparing means of the point and Signalpe- the signal then located in the memory is fed back to the mentioned point during the mentioned emptying. 6. The method according to claim 5, characterized in that the tracking takes place in the form of a voltage, the mentioned measurement is triggered by a conflict resulting from an attempted tracking of a signal which fe differs significantly from the feedback signal. 7. Process according to claims 1 to 6, characterized in that the reference medium is introduced in the form of a diluent, the sample medium in the form of a hemolyzed and reacted, blood solution entrained in the diluent is introduced, and 209809/1328 the discrete conversion of measured values of each medium is carried out photo-optically will. 8. The method according to claims 1 to 6, characterized in that that introduced the reference medium in the form of a transparent substance which is followed by a substance that has the density of a Ver ™ has thinner, the sample medium in the form of a hemolyzed and reacted, blood solution entrained in the diluent is introduced, and the discrete conversion of measured values of each medium is carried out photo-optically will. 9. The method according to claims 1 to 6, in which the sample medium is blood, characterized in that m the sample medium is hemolyzed, the aforementioned measurement gives a 7 / ert, from which the hemoglobin content of the sample medium can be calculated. 10. The method according to claims 1 to 9, characterized in that that the memory is prevented from being emptied before the mentioned comparison. 209809/1328 11. The method according to claims 11 to 10, characterized in that that the sample medium is converted in such a way that data are obtained which at least relate to a second parameter of the sample medium
belong, and this second conversion is carried out simultaneously and in a common location with the aforementioned sample medium conversion. 12. The method according to claims 1 to 11, characterized in that that the aforementioned conversion into discrete electrical signals in the manner is carried out that the light transmission of the media mentioned is maintained. 13. The method according to claim 11 or 12, characterized in that that the mentioned further implementation by recognizing individual microscopic Particles happens within the sample medium. 14 · Device for determining at least one parameter of a
Sample medium, characterized by a transducer (10; 110), which is based on a parameter of a Responds to the reference medium and a sample medium and generates discrete signals representing these parameters, 209809/1328 a latch circuit (12,128) connected to the transducer is coupled to receive and store at least one of the media representing signal, a receiving circuit (16,126) which, if necessary, communicates with the memory circuit is coupled and can then record at least part of the mentioned one stored signal, a control device (20,136) for actuating the receiving circuit after the storage of said one signal and to one Point in time related to the generation of a signal representing the other medium, and a switchable circuit (30,118), which with the memory circuit is coupled and is characteristically responsive to the duration during which the receiving circuit receives the portion of the signal for the one medium receives, which duration is proportional to the mentioned one parameter of the sample medium. 15 · Device according to claim 14, characterized in that the memory circuit comprises a signal comparison device (44) for receiving both discrete signals and for comparing the Value of the stored signal with that of the signal representing the other medium, which signal comparison device reacts when the discrete signals mentioned have a relative value with respect to each other. 209Ö09 / 1328 16. Apparatus according to claim 14 or 15, characterized in that the control device is coupled (22) to both the receiving circuit and the switchable circuit in order to both To operate circuits at the same time as the measured value conversion of the other medium. 17. Apparatus according to claim 16, characterized in that the switchable circuit has a bistable device (30) whose Blocking input is coupled to an output of the memory circuit (32). 18. Apparatus according to claim 17, characterized by a pulse generator (36) and a coincidence gate (UNI)), which bistable device and which pulse generator outputs which are coupled to the coincidence gate during the reception period in a coincident manner in order to pass through the coincidence gate to enable a series of pulses, the frequency of which is proportional to a measure of the one parameter of the sample medium. 19 «Apparatus according to claims 14 to 18, characterized in that _T, the receiving circuit comprises an electronic switch (50) having an input connected to a reference potential output. 209809/1328 20. Device according to claims 14 "to 19» characterized in that that the memory circuit comprises a biasable switch (44) »which has an input (14), which is connected to the transducer, furthermore a second input which is connected to a fixed potential source (+ V) is, and two outputs (18,32), and an RC element, the capacitor (46) of which with one output of the biasable switch is connected and its resistor (48) at one end to the aforementioned one output of the biasable Switch and is connected to the capacitor, while the other end of the resistor is connected to the receiving circuit connected is, while the other of the mentioned outputs is connected to the switchable circuit. 21. Apparatus according to claim 20, characterized in that the switchable switch is a normally non-conductive transistor (44), which is switched so that it can first be driven into the conduction state by a signal which the mentioned represents a medium, and subsequently by a signal which represents the mentioned other medium, the last-mentioned line condition is prevented until the Has discharged capacitor across the resistor to a value which is below that of the then supplied reference signal 8 of the one Medium lies. 209809/1328 22. Apparatus according to claim 14 »characterized in that the switchable circuit is formed by a biasable circuit (118) which is connected between the transducer and the Storage circuit is arranged, and the control device keeps the receiving circuit unlocked during the generation of the signal representing the other medium. 23. Apparatus according to claims H or 22, characterized by an output converter (132) which is coupled to a node (B) which is located between the transducer and a Input to the switchable circuit is located, which output converter to a characteristic response of the switchable circuit can respond. 24. Apparatus according to claim 23 »characterized in that the biasable circuit comprises a first diode (118) and the mentioned characteristic responses to the bias condition depends on the first diode, a second diode (152) an input stage for the aforementioned output converter forms, and the mentioned diodes are opposite with respect to the mentioned node are polarized. 209809/1328 25. Apparatus according to claim 24 »characterized in that the The memory circuit and the receiving circuit in combination form an RC element and the output converter has an analog structure, which is actuated by the second diode during its response time. 2 £ · device according to claims 14 or 22 to 25 »M gekennzeich- net by a voltage amplifier (112) connected between the transducer and the input of the switchable circuit is arranged. 27 · Device according to claim 26, characterized by a feedback path (152) for the voltage amplifier, which feedback path is coupled between the output of the switchable circuit and an input of the voltage amplifier. 28. Apparatus according to claim 27, characterized in that the voltage amplifier is a symmetrical differential amplifier built operational amplifier and the feedback path and the transducer with two separate Inputs (+, -) of the amplifier mentioned are coupled. 2f. Device according to claims H or 22 to 28, characterized in that 209809/1328 the control means comprises a controlled switch (122) arranged between the receiving circuit and the memory circuit is. 30. Device according to claims 14 to 29, characterized in that that the transducer is a flow cell. 31. Device according to claims 14 to 30, characterized in that that the transducer has a photoelectric, color-sensitive scanning device (40; 144; 76,80) and
a current-voltage conversion circuit (42; H6),
which scanner is responsive to the absorption of light passing through said media. 32. Apparatus according to claims 14 to 31, characterized in that the sample medium is blood in a diluent,
the reference medium is of the optical character of the diluent, and the transducer is coupled to the control device (24; 140) to selectively scan and translate the reference medium and the sample medium to thereby obtain an output which is only related to the color of the blood. 209809/1328 33. Apparatus according to claim 32, characterized in that the reference medium has a portion that is substantially colorless, and the control means sequentially scanning the colorless Part of the remainder of the reference medium and blood sample colored by the diluent. 34. Apparatus according to claim 31 or 32, characterized in that the diluent hemolyzing agent and reagents for action on the red blood cells and the hemoglobin they contain and the transducer has a source of illumination (78) and is particularly responsive to the absorption by the red color of the blood sample so that the device takes a measurement of the hemoglobin provides in the sample which one of the parameters mentioned is " 35. Apparatus according to claims 30 to 34 »characterized in that the aforementioned flow cell elements (62.64 »66.68.70) for implementation which has individual microscopic particles carried along by the sample medium, which particle conversion supplies data which belong to at least one second parameter of the sample medium. 209804 / 1-32 » Patent attorney EdQT Munich 13 / W * bethstr. 34 Lee rs e ite