JPS6232768B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a blood cell detection device that detects blood cells for automatically examining blood images.

Conventionally, the microscope used in this type of equipment has the following features:
An image sensor, a blood cell (for example, white blood cell) detection element, and a focus detection element are provided. Usually, a three-tube color camera is used, and sometimes a CCD (charge coupled camera) is used.
device) line sensor is used. in this case,
Since both the detection element and the imaging element are arranged so as to be located relatively at the center of the field of view of the microscope, it is necessary to move the captured blood cell image accurately to the center of the field of view. Therefore, the movement operation and the return operation to the original traveling line take a considerable amount of time, which is a major obstacle to high-speed processing.

Further, although the imaging light is divided by a half mirror for blood cell detection and focus detection, there is a problem in that the amount of light entering the image sensor is reduced because of this.
That is, when a color camera using a CCD as an image sensor is used, there is a problem in that the color reproducibility deteriorates as the amount of light decreases because the color sense of blue is low.

In view of these points, it is an object of the present invention to provide a blood cell detection device that can shorten the stage movement time by moving the blood cell image to the field of view using the deceleration period of stage movement.

Another object of the present invention is to provide a blood cell detection device that can prevent a decrease in the light intensity of an imaging camera.

The present invention will be explained in detail below with reference to the drawings. FIG. 1 is a configuration diagram of main parts showing an embodiment of a blood cell detection device according to the present invention. In Figure 1, 1
0 represents a biological microscope, 20 represents a blood specimen, 30 represents a line sensor, and 40 represents an area sensor. The biological microscope 10 has a stage 11 movable in the XY plane and an objective lens 12 movable in the Z direction. A blood specimen 20 is placed on a stage 11, and its microscopic image is provided to a line sensor 30 and an area sensor 40, which is an imaging device. The line sensor 30 is a light receiving element formed by arranging a plurality of photodiodes, for example. In the optical system shown in FIG. 2, two line sensors 31 and 32 are used. Use it properly. That is, the first line sensor 31 in relation to the scanning direction
and the second line sensor 32 to detect a blood cell image. The output signal of this line sensor 31 or 32 is used to control the operation of the stage 11. Note that the drive circuit system in this case is well known and is not directly related to the present invention, so a description thereof will be omitted. The area sensor 40 captures an image in the center of the field of view of the microscope, and can use, for example, a CCD color camera.

FIG. 2 shows an optical system in which a beam of light emitted from an objective lens 12 is bent by a prism, and then a portion of the beam is bent by a dichroic mirror 14. Note that the prism 13 may be a reflective mirror.

The dichroic mirror 14 here is a half mirror configured to reflect only a portion of green light, and the reflected light (green light) is guided to a line sensor 30 disposed on the imaging plane, while the transmitted light is The light is guided to an area sensor 40 placed on the imaging plane. The relative positional relationship between the line sensors 31 and 32, the area sensor 40, and the field of view of the microscope is as shown in FIG. That is, the area sensor 40 is located at the center of the microscope field of view 15, while the line sensors 31 and 32, whose longitudinal directions are perpendicular to the scanning direction, are arranged in parallel on both sides of the area sensor 40 with a distance d from the center of the area sensor 40. It is located at Note that the scanning width W is the width of the line sensors 31 and 32.
Letting the length of the area sensor 40 be l, and the width of the area sensor 40 be w, then W=(l+w)/2. The input area 41 defines an area to be taken in as image data, and in the case of white blood cells, about 20 μm square is sufficient, which is considerably smaller than the field of view of the area sensor 40. The position of the input area 41 is set by a control unit (not shown) using a computer or the like so that the movement is the smallest. Figure 4 shows the movement of the stage, in other words, the field of view 1 for blood specimen 20.
5 shows the scanning mode of No. 5. In the case of white blood cell detection, since white blood cells are scattered at an average rate of 1 per 200 μm square on a blood specimen, the scanning width W should be set to 170 μm, for example.
As shown in FIG. 4A, scanning is performed in a rectangular waveform with a width of 200 μm. A microscopic view of this scanning is shown in FIG. That is, when a white blood cell image is detected at the end of the vertical scanning, a horizontal movement is also applied so that the blood cell image completely falls within the field of view of the area sensor 40. Note that the distances w ₁ and w ₂ are the moving distances of the area 41. FIG. 5 shows the speed of movement of the stage 11 from detection of blood cells to detection of new blood cells. That is, it starts from a low speed _V1 , returns to the scanning progress line, and accelerates to a speed _V2 . Linear scanning is performed in the vertical direction at this speed V ₂ , and when the line sensor 31 (or 32) detects a white blood cell image, it is decelerated again to the speed V ₁ , and at the same time, the line sensor 31 (or 32) scans horizontally until the blood cell image enters the area sensor 40 in the center of the field of view of the microscope. move in the direction and then stop.

The operation of the blood cell detection device of the present invention in such a configuration will be described below. As shown in FIG. 5, the microscope stage 11 is moved from a speed of 0 to V ₁ and V ₂ , and rectangular wave scanning shown in FIG. 4A is started. When white blood cells are detected by the line sensor 31 in the scanning width W of the microscope field 15 as shown in FIG. 3, the stage 11 decelerates and stops. At this time, if the detected white blood cells are at the end of the detection width W, the stage is moved in the lateral direction and the stage is decelerated and stopped so that the white blood cell image falls within the field of view of the area sensor 40. In this case, the separation distance d in FIG. 3 is selected to be substantially equal to the amount of vertical movement of the stage 11 moving during this deceleration period, so that when the stage 11 stops, the white sphere image is within the field of view of the area sensor. It will be located in Among the images captured by the area sensor 40, an input area 41 (the white blood cell image in question is contained in this area) is positioned based on the amount of movement during the deceleration period. Only this image is extracted and a pattern recognition circuit (not shown) Enter. When the image input is completed, the stage 11 starts scanning again while returning to the original scanning progress line. If there is lateral movement at this time, unevenness a and b as shown in FIG. 6 will occur in the scanning area, but in order to avoid irregular scanning, the detection data of the protrusion a is discarded.

When the scanning direction is reversed, the second line sensor 32 detects white blood cells.

White blood cells are detected at high speed by the scanning described above, and the optical system is as follows. Although a dichroic mirror 14 guides a microscopic image using only green light to the line sensors 31 and 32, green light alone is sufficient for white blood cell detection and focus adjustment. Since a part of the green light is branched for the line sensor, part of the green light is reduced in the imaging light to the area sensor 40.
When a CCD color camera is used as the area sensor 40, the sensitivity of this camera is low in blue sensitivity and quite high in green sensitivity.
It is necessary to use an ND filter, etc. but,
In the present invention, since the dichroic mirror 14 reflects a portion of the green light, imaging light suitable for the sensitivity of the CCD color camera is provided to the camera 40 without using an ND filter. In addition, in a color camera, input light is converted into R, R, etc. using a dichroic prism, etc.
Since it is branched into G and B rays, the branched G
A part of the light beam may be extracted by a half mirror and used for a line sensor.

Through such an operation, the blood cell image is moved into the field of view 15 of the image sensor using the deceleration period of the stage 11, and the dichroic mirror 14 is moved.
Since only a portion of the green light is used for the line sensor, a decrease in the amount of light to the color camera 40 can be prevented.

Note that the CCD line sensors 31 and 32 are also used as sensors for focus adjustment. In this case, the focus signal F is obtained by differentiating the line sensor output, taking the absolute value, and integrating this. This focal signal F is transmitted from the objective lens 12 to the blood sample 20.
It changes as shown in A or B in FIG. 7 with respect to the distance x to the upper blood cell. Therefore, automatic focusing can be accomplished by stepping the objective lens 12 a small distance in the direction in which F increases, and then stepping back one step and stopping when F begins to decrease. Note that focusing is not limited to this, and for example, two line sensors 31 and 32 may be used.
Compared to the area sensor 40, one of the optical path lengths is longer and the other shorter, and the respective focal positions are set to be shifted by Δx as shown in A and B of FIG. 7, and the objective lens 12 is moved. It is also possible to stop and focus when one of the moving signals F increases and the other decreases. In this case, a one-step return operation is not required.

As explained above, according to the present invention, the relative separation distance between the line sensor and the area sensor is made to match the movement distance of the stage during the deceleration period, and the input area is considerably smaller than that of the area sensor. Since it can be positioned at any position within the sensor, there is no need for micro-movement of the white blood cell image to the center of the field of view, which was required in conventional devices. Therefore, at least the moving operation time can be shortened, and the speed of the apparatus can be increased.

In addition, in the optical system, a dichroic mirror is used to give part of the green light in the imaging light to the line sensor, so that the CCD color camera is guided to the CCD color camera with proper input light with a partially reduced amount of green light. It will be destroyed. Therefore, there is no need for an ND filter or the like, and it is possible to easily provide a sufficient amount of light to the camera.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of main parts showing one embodiment of a blood cell detection device according to the present invention, Fig. 2 is a block diagram of main parts of the optical system shown in Fig. 1, and Fig. 3 is a relative diagram of a line sensor and an area sensor. Figures 4 and 6 are diagrams showing the positional relationship, Figures 4 and 6 are diagrams explaining how the stage moves, Figure 5 is a diagram showing changes in the moving speed of the stage, and Figure 7 is a diagram explaining focusing. . 10... Biological microscope, 11... Stage, 12
...Objective lens, 15...Microscope field of view, 20...
Blood specimen, 30...line sensor, 40...area sensor.

Claims (1)

[Claims] 1. In a blood cell detection device that places a blood specimen on a microscope stage and captures a blood cell image by moving and scanning the stage, a CCD color camera is used to capture an image in the center of the field of view of the microscope image. The area sensor and the photodiode are arranged in a line to detect blood cell images. two sets of line sensors arranged in parallel at positions separated from the center of the area sensor by a distance substantially equal to the amount of movement of the rear stage until it stops moving; and one set of line sensors for green light only. and is placed in an optical system between the objective lens of the microscope and the area sensor, and arranged so that the transmitted light is applied to the area sensor and the reflected light is applied to the two sets of line sensors. A blood cell detection device characterized in that it is equipped with a dichroic mirror.