U.S. patent number 4,362,386 [Application Number 06/208,076] was granted by the patent office on 1982-12-07 for method and apparatus for recognizing smears.
This patent grant is currently assigned to Hitachi, Ltd.. Invention is credited to Hajime Matsushita, Yoshimasa Shimura.
United States Patent |
4,362,386 |
Matsushita , et al. |
December 7, 1982 |
Method and apparatus for recognizing smears
Abstract
After a slide glass having blood smeared thereon has been
mounted on a movable stage of a microscope, the stage is moved to
position a view field of the microscope to the center of the slide
glass. Then, the stage is moved in one direction along the length
of the slide glass. The view field of the microscope moves as the
stage is moved so that red blood corpuscle densities on the smear
are measured sequentially along the length of the slide glass.
Based on the measurement a computer determines an optimum test area
on the smear for the recognition of white blood corpuscles and the
stage is moved to a start position of the optimum test area by an
instruction from the computer. Thereafter, a normal stage scan
operation for detecting the white blood corpuscles is carried out
and the detected white blood corpuscles are automatically
classified.
Inventors: |
Matsushita; Hajime (Katsuta,
JP), Shimura; Yoshimasa (Katsuta, JP) |
Assignee: |
Hitachi, Ltd. (Tokyo,
JP)
|
Family
ID: |
15463430 |
Appl.
No.: |
06/208,076 |
Filed: |
November 18, 1980 |
Foreign Application Priority Data
|
|
|
|
|
Nov 19, 1979 [JP] |
|
|
54-148912 |
|
Current U.S.
Class: |
377/10 |
Current CPC
Class: |
G01N
21/5911 (20130101); G06M 11/04 (20130101); G06K
9/00127 (20130101); G02B 21/00 (20130101) |
Current International
Class: |
G01N
21/59 (20060101); G02B 21/00 (20060101); G06M
11/00 (20060101); G06M 11/04 (20060101); G06K
9/00 (20060101); G01N 033/48 () |
Field of
Search: |
;356/39,71
;235/92PC,146.3CA |
References Cited
[Referenced By]
U.S. Patent Documents
|
|
|
3827804 |
August 1974 |
Miller et al. |
4175859 |
November 1979 |
Hashizume et al. |
|
Other References
"Leukocyte Pattern Recognition", Bacus et al., IEEE Transactions of
Systems, Man, & Cybernetics, vol. SMC 2, No. 4, Sep. 1972, pp.
513-526..
|
Primary Examiner: McGraw; Vincent P.
Attorney, Agent or Firm: Antonelli, Terry & Wands
Claims
We claim:
1. A method for recognizing a smear comprising the steps of;
(a) positioning a slide held on a movable stage of a microscope to
a predetermined position such that the test smear on said slide is
positioned within a view field of said microscope,
(b) moving said stage along said smear in response to an
instruction from a control unit such that different areas of said
test smear along the length of said smear are sequentially
positioned within the view field of said microscope,
(c) sequentially detecting by a detector objects to be counted in
test samples at respective measuring points appearing in the view
field of said microscope as said stage is moved, to determine
distribution densities of the objects to be counted at the
respective measuring points,
(d) comparing the distribution densities at the respective
measuring points with a preset distribution density to determine an
optimum test area on the test smear, and
(e) moving said stage in response to an instruction from said
control unit such that the view field of said microscope is
positioned to said optimum test area.
2. A method for recognizing a smear according to claim 1 wherein in
said step (b) a high object distribution density area of said smear
is first positioned to the view field of said microscope and the
measuring point is sequentially moved toward a low object
distribution density area.
3. A method for recognizing a smear according to claim 1 or 2
wherein said test sample is blood smeared on said slide along a
longer side of said slide.
4. A method for recognizing a smear according to claim 3 wherein
said objects to be counted are red blood corpuscles and said
objects to be recognized are white blood corpuscles.
5. A method for recognizing a smear according to claim 1 or 2
wherein in said step (c) pulses corresponding in number to the
member of objects detected are counted.
6. A method for recognizing a smear comprising the steps of;
(a) positioning a slide held on a movable stage of a microscope to
a predetermined position such that the test smear on said slide is
positioned within a view field of said microscope;
(b) moving said stage in a predetermined direction in response to
an instruction from a control unit such that different areas of
said test smear along the length of said smear are sequentially
positioned within the view field of said microscope;
(c) sequentially detecting by a detector object to be counted in
test samples at respective measuring points appearing in the view
field of said microscope as said stage is moved to determine
distribution densities of the objects to be counted at the
respective measuring points;
(d) comparing the distribution densities at the respective
measuring points with a preset distribution density to determine an
optimum test area on the test smear;
(e) moving said stage in response to an instruction from said
control unit such that said optimum test area is positioned within
the view field of said microscope;
(f) moving said stage such that the view field of said microscope
scans transversely to the length of said smear in said optimum test
area on said test smear; and
(g) detecting said objects as the viewfield of said microscope
scans and classifying the detected objects.
7. An apparatus for recognizing a smear comprising;
an optical microscope having a movable stage for holding a slide on
which a test sample to be recognized is smeared in a predetermined
direction;
means for moving said stage;
means for detecting object to be counted in measuring areas
positioned within a view field of said microscope and counting said
objects in the respective measuring areas;
means for storing the counts for the respective measuring areas in
accordance with the moving direction of said slide; and
control means for instructing said moving means to move said stage
such that said slide is moved along the length of said test smear
and selecting a desired one of said counts stored in said storing
means to control the movement of said stage such that a start
position for the recognition determined by said selected count is
positioned within the view field of said microscope.
8. An apparatus for recognizing a smear according to claim 7
wherein said detecting and counting means includes a photo-electric
converter of a semiconductor linear array.
9. An apparatus for recognizing a smear according to claim 7 or 8
wherein said moving means includes a motor for moving said stage in
the direction of the length of said smear and in the direction
transverse thereto.
10. An apparatus for recognizing a smear comprising;
an optical microscope having a movable stage for holding a slide on
which a test sample to be recognized is smeared in a predetermined
direction;
means for moving said stage;
means operable in a pre-scan mode for detecting objects to be
counted in measuring areas positioned within a view field of said
microscope and operable in a recognition mode for detecting objects
to be recognized;
means for counting the objects in the respective measuring
areas;
means for storing the counts for the respective measuring areas in
accordance with the moving direction of said slide;
control means for instructing said moving means to move said stage
such that said slide is moved along the length of said test smear
and selecting a desired one of said counts stored in said storing
means to control the movement of said stage such that a start
position for the recognition determined by said selected count is
positioned within the view field of said microscope, said control
means further operable in the recognition mode to stop the movement
of said stage in response to a detection signal for the object to
be recognized;
means for recognizing a pattern of said object to be recognized
while said stage is stopped in the recognition mode; and
means for classifying the recognized objects.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for
recognizing a smear, and more particularly to a method and an
apparatus for automatically recognizing an object smeared in test
samples on a slide.
In a prior art method for examining blood cells, it has been common
that a skilled examiner visually observes a blood sample smeared on
a slide glass by an optical microscope to discover white blood
corpuscles and classify them by pattern recognition technique in
accordance with shapes and colors of the white blood corpuscles.
However, since such a visual method accompanies with the fatigue of
the examiner, a long time work is difficult to do and only a small
number of samples can be processed. In order to resolve such a
problem, an automatic classifying apparatus for white blood
corpuscles has been developed. Apparatus for classifying the blood
smeared on a slide and observed by a microscope in accordance with
the configuration of the blood cells are shown in the U.S. Pat. No.
4,175,859 to A. Hashizume et al, U.S. Pat. No. 3,827,804 to M. N.
Miller et al and an article entitled "Leubocyte Pattern
Recognition" by J. W. Bacus et al, IEEE Transactions on Systems,
Man and Cybernetics, Vol. SMC-2, No. 4, page 513, 1972.
Blood smears to be tested usually have various blood cell
distribution densities and conditions on a slide gears depending on
the smear condition and it is difficult to prepare samples of a
uniform blood cell distribution.
Particularly when the samples are prepared by hand application or
an automatic wedge type smear apparatus, the configuration of the
blood cell changes from position to position on the slide glass.
Accordingly, when such a sample is to be tested, an examiner views
each sample through a microscope to find out an area of less change
in configuration before the blood cells are automatically
classified by the apparatus.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method and an
apparatus for automatically determining an area of a smear of test
objects which is appropriate for recognition.
It is another object of the present invention to enhance the
accuracy of the recognition of the test objects and enhance the
number of test objects processed.
It is still another object of the present invention to a method and
an apparatus for allowing the observation of an area of the same
object distribution density for respective samples when different
samples are sequentially processed.
In accordance with the present invention, a sample having objects
smeared on a slide along a predetermined direction is observed
through a microscope. In such a sample, a distribution density or a
concentration of the objects, e.g. blood cells in the test sample
gradually decreases from the starting point of the smear on the
slide to the end point. Let us assume a case where test blood is
smeared on the slide to observe the white blood corpuscles. Most of
the blood cells of the blood smeared on the slide are red blood
corpuscles, and the white blood corpuscles which are objects to be
observed exist at a rate of only one per approximately one thousand
red blood corpuscles. For a blood sample for blood cell
classification, it is ideal that the smear includes the red blood
corpuscles dispersed at an appropriate interval. In actual case,
however, the first half area from the beginning of smear has a high
distribution density and the red blood corpuscles therein are
overlapped to each other or closely disposed while the latter half
area has a preferable distribution density. The area of preferable
distribution density depends on the conditions under which the
samples are prepared and the properties of the blood, and it
differs from sample to sample. What is important in the
classification of blood is that the configuration of the white
blood corpuscles is correctly maintained. Where the distribution
density of the red blood corpuscles is high, the white blood
corpuscles are collapsed by the red blood corpuscles and the
configuration changes. Depending on a drying condition when the
blood is smeared, the white blood corpuscles shrink in a high blood
cell density area while the white blood corpuscles tend to expand
or be collapsed in the area of the end of smear where the blood
cell density is low.
Accordingly, it is desirable to automatically preselect an area
which is best for the observation while taking the above blood cell
distribution in the blood sample into consideration. This applies
not only to the blood cell samples but also to cell samples such as
cancer cell samples or other samples.
The present invention is based on the consideration described
above, and it provides a method and apparatus for allowing the test
of the test object at an optimum test area of the sample by
predetermining the optimum test area of the sample when the sample
such as blood cell sample is to be tested.
In accordance with the present invention, a predetermined area of a
test smear on a slide is positioned within a view field of a
microscope and the slide is moved from that position along the
smear line on the slide, from a high density area toward a low
density area, for example. As the slide is moved, the area of the
smear which appears in the view field of the microscope changes.
The objects to be counted, e.g. the red blood corpuscles in each
area are detected by a detector to determine the densities of the
objects along the movement areas on the view field of the
microscope. Based on the density information, the optimum test area
on the smear is determined and that area is positioned to the view
field of the microscope. This completes a pre-scan mode.
In accordance with the present invention, the pre-scan mode may be
followed by a recognition mode. In the recognition mode, the slide
is moved regularly in X and Y directions and the test objects in
the optimum test area are detected. When a test objects, e.g. a
white blood corpuscle is detected, the slide is stopped at that
position and a pattern of the test object is recognized and
classified.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a block diagram for illustrating one embodiment in
accordance with the present invention.
FIG. 2 shows a schematic perspective view of a stage drive
mechanism shown in FIG. 1.
FIG. 3 shows a plan view of a slide for illustrating a smear in a
pre-scan mode.
FIGS. 4A, 4B, 4C and 4D show signal status of red blood corpuscle
signals detected at various points.
FIG. 5A shows an example of pulse distribution of the number of
pulses produced in response to the X-direction movement of a blood
sample.
FIG. 5B shows an example of red blood corpuscle density in the
X-direction of the blood sample.
FIG. 6 shows another embodiment in accordance with the present
invention.
FIG. 7 shows a flow chart for illustrating the operation of the
embodiment of FIG. 6.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows an embodiment of an apparatus for recognizing a blood
sample. In FIG. 1, an optical microscope 1 has a movable stage 2
which is movable in X and Y directions. The movable stage 2 is
moved by a stage drive mechanism 20 as required to determine a
particular area of the stage to be positioned to a view field of
the microscope 1. Retained on the movable stage 2 is a blood sample
3 which includes, as shown in FIG. 3, a slide glass 14 and a smear
15 of test blood smeared thereon. A longer side of the rectangular
slide glass 14 is referred to as an X-axis while a shorter side is
referred to as a Y-axis. The slide glass 14 is held in position on
the movable stage 2 such that the longer side and the shorter side
of the slide glass 14 coincide with the X and Y directions,
respectively, along which the movable stage 2 is moved. That is,
the movable stage 2 is movable in the directions of the longer side
and the shorter side of the slide glass 14.
FIG. 2 shows a perspective view of the stage drive mechanism 20.
Movable member 22 is mounted on a base 21 to allow slide movement
in the Y-direction while a movable member 23 is mounted on the
movable member 22 to allow slide movement in the X-direction and a
movable member 24 is mounted on the movable member 23 to allow
slide movement in the Y-direction. A slider 29 is fixed to the
movable member 22 and a slider 30 is fixed to the movable member
24. Lead screws 27 and 28 are meshed with the sliders 29 and 30,
respectively. The movable member 23 has an arm 31 on which the
blood sample is held. The movable members 22, 23 and 24 and the arm
31 form the stage 2.
A Y-axis pulse motor 25 rotates the lead screw 27 to move the stage
2 in Y-direction while an X-axis pulse motor 26 rotates the lead
screw 28 to move the stage 2 in X-direction.
The optical microscope 1 shown in FIG. 1 is provided with a blood
cell detector 4 comprising a semiconductor linear array, which is
driven by pulse signals from a pulse generator 7. Respective
channels of the semiconductor linear array comprise a plurality of
semiconductor photo-electric conversion devices arranged in series.
The blood cell detector 4 detects dyed objects to be counted (e.g.
red blood corpuscles in the present embodiment) in the blood sample
3.
The blood cell detector 4 is connected to a pulse amplifier 5 for
amplifying a red blood corpuscle detection signal from the blood
cell detector 4, thence to a discriminator 6 for producing a gate
signal in response to the amplified red blood corpuscle detection
signal, and thence to a gate circuit 8 which receives the gate
signal.
The pulse generator 7 is connected to the gate circuit 8, which
sends out the pulses only for the time duration of the red blood
corpuscle detection signal. The pulses are counted by a pulse
counter 9 which is connected to a memory 10 which in turn stores
the total member of pulses counted by the pulse counter 9 at an
address corresponding to an X-axis address on the sample 3.
A stage position control 11 controls the operation of the stage
drive mechanism 20 in accordance with an instruction from a
micro-computer 13. An address counter 12 specifies an address of
the memory 10 in correspondence to the scanned area on the smear.
The micro-computer 13 presets an optimum red blood corpuscle
distribution density range and it also averages the detection
results stored in the memory 10 and compares the average value with
the optimum red blood corpuscle distribution density range to
determine the optimum test area on the blood sample 3.
A pre-scan mode in the embodiment of FIG. 1 is now explained.
When the blood sample 3 has been mounted on the movable stage 2 by
an automatic loading apparatus not shown, the movable stage 2 is
moved to a predetermined position. When the view field of the
microscope 1 is positioned to the center of the slide glass 14 as
shown in FIG. 3, the movement of the stage 2 is stopped. Then, an
object lens of the microscope is moved up and down to automatically
focus the lens. Then, the slide glass 14 is moved linearly along
the direction of the smear of the test blood. That is, the view
field of the microscope sequentially scans the blood sample from
the high red blood corpuscle concentration area to the low
concentration area. In the blood samples, particularly those
prepared by hard application or a wedge type automatic smear
apparatus frequently used in hospitals, the blood cell distribution
density, that is, the blood cell concentration gradually decreases
from the beginning point of the smear on the slide glass to the end
point of the smear. Most of the blood cells are red blood
corpuscles, and the white blood corpuscles exist at a rate of only
one per approximately one thousand red blood corpuscles. For the
blood sample for the blood cell classification, it is ideal that
the red blood corpuscles disperse at an appropriate interval, but
in actual case the first half from the beginning of the smear
includes overlapped or too closely disposed red blood corpuscles
and hence has a high distribution density while the latter half
area has a preferable distribution density. The preferable
distribution density area depends on the conditions under which the
samples are prepared and the properties of the blood and it changes
from sample to sample. What is important in the blood cell
classification is that the configuration of the blood cells,
particularly of the white blood corpuscles is correctly maintained.
Where the red blood corpuscle distribution density is high, the
white blood corpuscles are collapsed by the red blood corpuscles
and the configuration changes.
The movement of the stage is effected by the X-axis pulse motor 26.
The stage 2 is incrementarily moved at a constant pitch of 50-500
microns. Each time the view field of the microscope is positioned
at a new area on the smear, the red blood corpuscles in the view
field are detected by the blood cell detector 4. The detection
signal for the red blood corpuscles is applied to the amplifier 5,
thence to the discriminator 6 and thence to the gate circuit 8 as
the gate signal.
On the other hand, in order to drive the semiconductor linear array
used in the blood cell detector 4, the pulses from the pulse
generator 7 are supplied to the blood cell detector 4. The pulses
from the pulse generator 7 are also supplied to the gate circuit 8
so that the pulses are counted by the pulse counter 9 only for the
duration of the red blood corpuscle detection signal. Since the
number of red blood corpuscles is approximately proportional to the
duration of the signal detected by the blood cell detector 4, the
total number of pulses counted by the pulse counter 9 corresponds
to the number of red blood corpuscles detected, that is, the red
blood corpuscle distribution densities in the respective view
fields. The total number of pulses is stored in the memory 10 at
the address corresponding to the X-axis address. In this manner, by
sequentially controlling the stage position control 11, the numbers
of pulses corresponding to the numbers of red blood corpuscles in
the respective view fields of the microscope spaced at a constant
interval on the X-axis are stored at the memory addresses specified
by the address counter 12. In this manner, the stage 2 is linearly
moved in the X-axis direction until the red blood corpuscle
concentration in the view field of the microscope in the blood
smear falls below a predetermined value, and the red blood
corpuscles are detected and the counts are stored at the addresses
corresponding to the respective view field addresses.
The detection results stored in the memory 10 are averaged by the
micro-computer 13 and the average value is compared with an optimum
red blood corpuscle distribution density (red blood corpuscle
concentration) which was previously stored in the micro-computer
13. Based on the comparison, the most appropriate view field
position in the measured sample is selected to determine the
optimum test area by the micro-computer 13. The micro-computer 13
then specifies a start position for observation, and the stage
position control 11 and the stage drive-mechanism 20 function to
move the stage 2 such that the start position is positioned to the
view area of the microscope.
The pre-scan mode is thus completed. Thereafter, a recognition mode
starts to automatically classify the white blood corpuscles. In the
present embodiment, the white blood corpuscles are recognized in
the recognition mode, although the red blood corpuscles may be
recognized.
FIG. 3 shows a plan view of a blood sample. The distribution of the
red blood corpuscles of the blood smear 15 on the slide glass 14 is
essentially uniform in the Y-axis direction except the opposite
ends, but the distribution density in the X-axis direction is not
uniform, that is, it gradually decreases from the beginning 33 of
the smear to the end 34 of the smear. The measurement of the red
blood corpuscles is effected by scanning the center area of the
blood smear 15 as viewed in the Y-direction, along the X-direction.
A broken line area 35 shown in FIG. 3 indicates the area of
pre-scan and the start point 36 of scan is located at the center of
the slide 14. The end point 37 of scan is in the low concentration
area of the smear 15.
The semiconductor linear array of the blood cell detector 4
comprises a number of photo-electric devices arranged in series in
the direction transverse to the direction of the smear, that is, in
the Y-direction. For example, when the red blood corpuscles are to
be detected by a 256-channel linear array and a microscope having
an object lense of a magnification factor of 100, the number of red
blood corpuscles detected in one time is sixteen assuming that the
red blood corpuscle size is approximately eight microns. In the
high red blood corpuscle distribution density area, the red blood
corpuscles overlap or contact to each other and the correspondence
between the red blood corpuscle detection signal from the blood
cell detector 4 and the number of red blood corpuscles is lost.
FIG. 4A diagramatically shows the correspondence between a
semiconductor linear array 41 and red blood corpuscles 16. Let us
assume that the patterns of the red blood corpuscles 16 shown in
FIG. 4A corresponds to the number of red blood corpuscles
detectable in one view field of the microscope. Photo-electric
devices 42 which face the red blood corpuscles 16 produce detection
signals. As a result, a signal produced by the blood cell detector
4 can be represented as a light absorption signal shown in FIG. 4B.
A level line 43 in FIG. 4B shows a slice level of the discriminator
6. A reshaped signal as shown in FIG. 4C is applied to the gate
circuit 8. FIG. 4D shows an input signal to the pulse counter
9.
Assuming that the width of the detection signal for each red blood
corpuscle is approximately the same, a signal of double pulse width
is produced when two red blood corpuscles contact to each other.
Accordingly, it may be considered that the accumulation of the
widths of the signals corresponds to the number of red blood
corpuscles detected. This theory cannot be applied to the area
where the red blood corpuscles overlap but it may be practically
applied to the optimum test area where no substantial overlap of
the red blood corpuscles exists. FIGS. 4C and 4D illustrate a
method for converting the signal duration to a digital signal. The
sum of the respective durations corresponds to the sum
(.SIGMA.n.sub.i) of the respective numbers of pulses n.sub.1,
n.sub.2, . . . .
FIG. 5A shows a graph of the total number .SIGMA.n.sub.i of pulses
as the number of red blood corpuscles in the Y-axis versus the
address of sample in the X-address. The measures at the respective
measurement points 1, 2, 3, . . . have a large variation.
Accordingly, those values are smoothened with respect to the X-axis
as shown in FIG. 5B and then an optimum range (x.sub.i -x.sub.j) on
the X-axis is determined by a preset optimum red blood corpuscle
density area for the blood cell classification, that is, a range
extending from an upper limit 51 to a lower limit 52. At the start
of the recognition mode, the X-axis position of the slide 14
corresponding to the upper limit 51 is positioned to the view field
of the microscope. Reference values corresponding to one thousand
red blood corpuscles for the upper limit of the optimum area and
fifty red blood corpuscles for the lower limit, assuming that the
diameter of the view field of the microscope is 200 microns, are
preset in the memory of the computer 13.
FIG. 6 shows another embodiment of the present invention, which
carries out the pre-scan mode and the recognition mode
automatically. FIG. 7 shows a flow chart for the operation of FIG.
6. A chain line block 70 shown in FIG. 7 corresponds to the
pre-scan mode. In FIG. 6, the elements having the same functions as
those shown in the embodiment of FIG. 1 are designated by the same
reference numerals.
Referring to FIG. 6, an object lens drive mechanism 60 of the
microscope 1 is driven by a focus control 61 which is connected to
the micro-computer 13, to move a lens cylinder upward and downward.
As shown in FIG. 7, in the pre-scan mode 70, the sample 3 is
mounted on the stage 2 and the stage 2 is positioned at a step 71
such that the center of the slide 3 is positioned to the view field
of the microscope. Then, the focus at the center is automatically
adjusted at a step 72. The stage 2 is stepped 50 microns at a time
along the direction of the test smear at a step 73 and each time
the stage 2 is stopped at a new view field the red blood corpuscles
are counted at a step 74. So long as the count N of the red blood
corpuscles is no less than ten per view field which is a stop level
for the stage preset in the computer 13, the stepping operation is
continued at a step 75. As the counting operation continues, the
respective counts are stored in the memory 10. When the count N
falls below ten which is the stage stop level below the lower limit
shown in FIG. 5B, the computer determines that the specified area
has been scanned and the movement of the stage in one direction is
interrupted. Then, the stage 2 is moved at a step 76 such that the
view field is positioned to the start point of the selected optimum
test area. The pre-scan mode is thus completed and it is now ready
for the recognition mode.
Referring to FIGS. 6 and 7, the operation of the recognition mode
is now explained.
After the pre-scan mode has been completed, the signal from the
blood cell detector 4 is sliced at a level which permits the output
of only the signals corresponding to the white blood corpuscles,
and the output signal is applied to the computer 13. The slice
operation is carried out by a discriminator not shown. In the
recognition mode, the white blood corpuscles are searched while the
slide 2 is moved in the X-direction and the Y-direction alternately
from the upper limit point of the optimum area on the sample to the
lower limit point. At a measurement start step 77, the movement of
the stage 2 is controlled at a step 78. In the course of the
movement, if a white blood corpuscle is detected at a step 79, a
signal from the blood cell detector 4 causes the micro-computer 13
to instruct to the stage position control 11 to move the stage 2
such that the white blood corpuscle is positioned at the center of
the view field. Then, the stage 2 is stopped. The focus control 61
instantly drives the pulse motor of the drive mechanism 60 in
response to the instruction from the microcomputer 13 to adjust the
focus at a step 80. An image signal from a television camera 62 is
processed by a feature extraction circuit 63 as shown in U.S. Pat.
No. 4,175,859 to extract data necessary for blood cell
classification, such as nucleus area, nucleus periphery length,
nucleus concentration and cell area. When a white blood corpuscle
is determined at a step 82, it is classified to one of blood cell
species based on an identification algorithm stored in a
micro-computer 65 at a step 83. When it is not a white blood
corpuscle, the stage 2 starts to move to search a white blood
corpuscle. The white blood corpuscle detection operation continues
until a predetermined number of, e.g. two hundreds white blood
corpuscles are detected, when the operation completes at a step 84
and the classified results are displayed on a CRT display 68 at a
step 85 and also printed out on a print sheet of a printer 69 at a
step 86. An I/O interface 66 of the microcomputer 65 is connected
to a control panel 67 for setting measurement conditions, the CRT
display 68 and the printer 69.
* * * * *