Device of measuring a blood coagulating time

A device of measuring a blood coagulating time, the device being constructed such that when the specimen is placed in a detecting section in which it is maintained at a desired temperature, the measuring initiation time is set, followed by the transmission of a series of measuring data to a memory through an arithmetic circuit until a saturation is reached in response to which the measuring operation is stopped. On presumption that the saturating value is 100%, arithmetic operation is conducted, the results of which are stored in the remaining space of the memory. The device includes a keyboard switch whereby a time corresponding to particular percentages, such as 20%, 50%, and 80%, is previously set so as to enable the time to be easily recognized and accurately reproduced.

BACKGROUND OF THE INVENTION 
The present invention relates to a device of measuring a period of time 
during which blood coagulates, and more particularly, to a device of 
measuring a period of time required for a blood sample to coagulate, the 
device securing reproducibility and operational ease. Hereinafter, this 
period of time will be referred to as a blood coagulating time. 
In general, there are many items under which ailments of animals as well as 
human beings are diagnosed by measuring a blood coagulating time; that is, 
a prothrombin time (PT), a partial thromboplastein time (PTT), a 
figrinogen quantity (Fbg), a deficient factor quantity, an activated 
partial thromboplastein time (APTT), and a Ca reapplication time. These 
items are decided on in accordance with the kind of a reagent to be added, 
and the part of the blood with which the reagent is caused to react. Take 
an example of a prothrombin time (PT), a systematic thromboplastein and 
calcium are adequately added to the plasma which was collected through 
centrifugal separation of blood. Subsequently, the period of time is 
measured until the production of whitish net-like fibrin lumps results. 
Let us take another example of the activated partial thromboplastein time 
(APTT). First, blood plasma is collected after the blood was subjected to 
centrifugal separation, and then acting is added thereto. In addition, 
calcium chloride is added. The period of time is measured until 
coagulation is formed More in detail, the blood plasma is stored in a 
refrigerator after it was obtained through centrifugal separation of 
blood. Acting of 0.1 ml, which was warmed in a water having a temperature 
of 37.degree. C. for a minute, is poured into a test tube containing 0.1 
ml of the plasma The mixture is allowed to stay in a water of 37.degree. 
C. for two minutes. Then to this mixture, 0.1 ml of CaCl.sub.2 of 0.02 M, 
which had been placed in a water having a temperature of 37.degree. C., is 
added under pressure. At this moment a stop watch is switched on. The test 
tube is heated in the water of 37.degree. C. for 25 seconds. The test tube 
is taken out, and if coagulation is observed, the stop watch is turned 
off. In this way the blood coagulating time is measured. 
The above described practice is a hand operated direct method, which is 
commonly called a manual method. This manual method requires a lot of 
skill and experience in carrying it out. Disadvantageously, it is 
difficult for inexperienced persons. 
To overcome this difficulty of the manual method, an automatic measuring 
method has been proposed An optical method is a typical example, in which 
blood coagulations are optically detected However, under this method the 
coagulations are only locally detected, which is likely to result in an 
inaccurate measuring of a coagulating time In addition, the 
reproducibility is reduced. Furthermore, under the automatic methods it is 
a difficult problem how to define the blood coagulating time In an optical 
method a particular optical level is set, and when the level is crossed, 
it is accepted as the blood coagulating time being completed or when a 
point of change (the peak value obtained by differentiating the curve of 
changes with time) is observed, it is recognized as the blood coagulating 
time. 
In the level detection it is likely to happen that the previously set level 
is not reached when the blood sample is abnormal. In such cases it is 
recorded as "measuring is impossible". Referring to FIGS. 1 and 2, the 
level L.sub.3 is set. FIG. 2 shows that the curve fails to reach the level 
L.sub.3, thereby causing the test to continue perpetually. 
Referring to FIGS. 3 and 4, in which a point of change is to be detected, 
if the blood sample is abnormal, the detection will be difficult. It is 
likely that any change is mistaken as an expected point of change though 
it is actually not. This is shown in FIG. 4. The data obtained by the 
automatic methods of the above-mentioned kinds are not necessarily in 
accord with those obtained by the manual direct method, and for a 
diagnosis purpose it is necessary to adjust the measured values by 
comparison with those under the conventional method. 
OBJECTS AND SUMMARY OF THE INVENTION 
The present invention aims at overcoming the problems and difficulties 
pointed out above, and has for its object to provide an improved device of 
measuring a blood coagulating time with high reproducibility and at ease 
whether the blood sample may be normal or abnormal. 
Other objects and advantages of the present invention will become apparent 
from the detailed description given hereinafter; it should be understood, 
however, that the detailed description and specific embodiment are given 
by way of illustration only, since various changes and modifications 
within the spirit and scope of the invention will become apparent to those 
skilled in the art from this detailed description. 
According to the present invention, there is provided a device of measuring 
a blood coagulating time, the device comprising: 
a detecting section comprising an accommodater including a container 
containing a specimen, a cover for covering the accommodater against 
light, an optical unit including a source of light and a light receiver 
located beside the container, and a thermal controller whereby the 
specimen in the container is maintained at a desired temperature; 
a pipette including a switch whereby the measuring of the blood coagulating 
time is started, wherein the switch is turned on when the specimen is 
placed in the container; 
a detector circuit for detecting signals transmitted from the detecting 
section 
a keyboard switch by which the items to be measured and the desired 
conditions are input; 
an arithmetic circuit connected to the pipette, the keyboard switch, the 
detector circuit, and the thermal controller; 
a memory circuit connected to the arithmetic circuit; 
a display connected to the arithmetic circuit; and 
a recording section connected to the arithmetic circuit, thereby ensuring 
that the values obtained at the detecting section are stored in the memory 
through the detector circuit and the arithmetic circuit until the 
saturation is reached with the varying values becoming constant where the 
arithmetic circuit transmits a signal to the detector circuit so as to 
stop the measuring, and conducts an arithmetic operation on presumption 
that the saturating value is 100%, so as to measure the blood coagulating 
time by comparison with the value predetermined by the keyboard switch.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 5, there is provided a detecting section 1, which 
includes an accommodator 3 for accommodating a container 2 in which the 
specimen is stored, a cover 4 for covering the accommodator 3 against 
light, an optical unit including a source of light 5 and a light receiver 
6, and a thermal controlling element 7 whereby the specimen in the 
container 2 is maintained at a desired temperature The reference numeral 8 
denotes a pipette equipped with a switch which is turned on when the 
specimen previously warmed to a desired temperature is poured into the 
container 2 through the pipette 8, thereby generating a signal with which 
the measuring is initiated. The light receiver 6 is connected to a 
detector circuit 10 which is to detect signals from the detecting section 
1. 
There is provided a keyboard switch 11 which is to input the items to be 
measured and the desired conditions. The reference numeral 12 denotes an 
arithmetic circuit connected to the keyboard switch 11, the pipette 8, the 
detector circuit 10 and the thermal controlling element 7. The reference 
numerals 13, 14 and 15 denote a memory, a display and a recorder, 
respectively, all of which are connected to the arithmetic circuit 12. The 
reference numerals 16 and 17 denote a thermal controlling circuit and a 
container for containing a reagent, respectively. 
The pipette 8 is provided with an upper button 18 which, when pressed down, 
causes a predetermined amount of liquid to drop through a lower tip 19. At 
the same time a switch 20 is closed, thereby transmitting a contact signal 
to the arithmetic circuit 12. The pipette 8 is a type available in the 
market. 
Under the system described above a specimen previously warmed to a desired 
temperature and a reagent equally warmed are poured into the container 2 
through the pipette 8. At this moment the switch attached to the pipette 8 
is turned on so as to set a starting time for measuring the blood 
coagulating time at the arithmetic circuit 12. When the cover 4 is closed, 
the measuring is started. The measured values are transmitted in series to 
the detector circuit 10, to the arithmetic circuit 12, and stored in the 
memory 13. The measured values can be monitored through the display 14. 
The curves continue for some time, and then become flat, which means that 
a saturation is reached with the varying values becoming constant. At this 
stage, the arithmetic circuit 12 instructs the detector circuit 10 so as 
to stop the measuring, which is displayed through the display 14. The 
final measured value, i.e. the saturating value, is presumed to be 100% on 
the basis of which arithmetic operation is carried out at the arithmetic 
circuit 12. The results of the arithmetic operation are stored in the 
remaining space in the memory 13. If a time corresponding to 20%, 50% and 
80% is previously set by the keyboard switch 11 such that it is printed or 
displayed as a final value, the time is calculated by the arithmetic 
circuit 12. 
Under the system of the present invention it is easy to calculate the time, 
whether the specimen may be normal (in the case of FIG. 6) or abnormal (in 
the case of FIG. 7). As shown in FIGS. 6 and 7, the time corresponding to 
20%, 50% and 80% can be calculated at ease. The value set in the 
neighborhood of 80% is found to be best in accord with the blood 
coagulating time which is measured by the conventional manual method. 
The calculation based on percentage exhibits a constant value irrespective 
of mechanical malfunction, such as degeneration of the lamp or the light 
receiver, or an inadequate adjustment of the device, thereby ensuring that 
a constant value is always output.