CN116723396A

CN116723396A - Camera focusing method, cell analysis instrument and blood detection equipment

Info

Publication number: CN116723396A
Application number: CN202310461121.5A
Authority: CN
Inventors: 杜捷; 夏才
Original assignee: Hunan Ehome Health Technology Co ltd
Current assignee: Hunan Ehome Health Technology Co ltd
Priority date: 2023-04-25
Filing date: 2023-04-25
Publication date: 2023-09-08

Abstract

The invention provides a camera focusing method, a cell analysis instrument and blood detection equipment, and relates to the technical field of blood cell detection, wherein the camera focusing method comprises the following steps: setting a plurality of preset points on a movement path of a camera; controlling the camera to move along the movement path of the camera, and controlling the camera to acquire an image once when the camera reaches one of preset points; selecting an image which accords with a preset standard from a plurality of images, and taking a preset point corresponding to the image which accords with the preset standard as a focus; by arranging the driving piece, the driving piece drives the camera to move on the moving path, and the control module controls the camera to acquire an image once every time the camera reaches a preset point, namely, before focusing is completed, the camera is in a continuous moving state in the whole course of the moving path without any pause. Therefore, the time for the camera to complete the moving path is short, the focusing speed of the cell analysis instrument is high, and the detection efficiency of the blood detection device is high.

Description

Camera focusing method, cell analysis instrument and blood detection equipment

Technical Field

The invention relates to the technical field of blood cell detection, in particular to a camera focusing method, a cell analysis instrument and a camera photographing method.

Background

In blood testing devices, a blood sample is typically photographed using a cell analyzer. In order to improve the definition of the photographed image, focusing is required before photographing.

The cell analysis instrument comprises a closed-loop stepping motor and a camera, wherein the camera moves along a movement path with a plurality of preset points under the drive of the closed-loop stepping motor. The camera stops moving each time it reaches a preset point, and photographs the blood sample. After photographing is completed, the moving path is continued. This is repeated until the camera reaches the end of the path of motion. And finally, selecting a preset point of the clearest image from all the images as a focus.

However, in this process, it takes a lot of time for the camera to stop and restart at a preset point, resulting in a long time for the camera to finish the moving path, and slow focusing speed of the cell analysis instrument. Especially, the pre-focusing distance is longer, the focusing area is larger, the focusing time is greatly prolonged, and the detection efficiency of the blood detection equipment is greatly influenced.

In view of this, a new solution is needed to solve the above technical problems.

Disclosure of Invention

The invention aims to solve the technical problems that the camera has long moving path, and the focusing speed of a cell analysis instrument is low.

In order to achieve the above purpose, the invention adopts the following technical means:

the first aspect of the invention discloses a camera focusing method, comprising the following steps:

setting a plurality of preset points on a movement path of a camera;

controlling the camera to move along the movement path of the camera, and controlling the camera to acquire an image once when the camera reaches one of preset points;

selecting an image which accords with a preset standard from a plurality of images, and taking a preset point corresponding to the image which accords with the preset standard as a focus.

In particular, the movement path is a straight line perpendicular to the camera and the blood sample carrier, the depth of field of the camera lens ranging between a start point and an end point.

Specifically, the preset points are distributed at equal intervals or unequal intervals on the motion path.

Specifically, the controlling the camera to move along the movement path of the camera comprises the following steps:

transmitting a first signal to a driver;

the driving piece responds to the first signal and drives the camera to move to the pre-focusing position;

judging whether the camera moves to a pre-focusing position;

if yes, a second signal is sent to the driving piece, and the driving piece responds to the second signal to drive the camera to move along the movement path.

the driving piece responds to the second signal and drives the camera to move along the movement path, and then the method further comprises the following steps:

judging whether the camera reaches the end point of the motion path;

if so, a third signal is sent to the driving piece, and the driving piece responds to the third signal, so that the camera stops moving.

Specifically, each time the camera reaches one of the preset points, the step of controlling the camera to acquire an image once comprises the following steps:

acquiring the position of a camera;

judging whether the position of the camera is coincident with the position of the preset point;

if yes, a fourth signal is sent to the camera, and the camera responds to the fourth signal to acquire an image.

Specifically, the selecting the image meeting the preset standard from the plurality of images includes the following steps:

numbering the images and preset points, wherein the numbers of the images correspond to the numbers of the preset points;

performing definition calculation on the image, comparing the calculation result with a preset standard, and selecting a qualified image;

and acquiring the number of the qualified image, and taking a preset point corresponding to the number of the image as a focus.

Specifically, the step of performing sharpness calculation on the image, and comparing the calculation result with a preset standard to find an image meeting the preset standard, and the step of selecting a qualified image includes the following steps:

calculating MTF parameters of each image;

judging whether the MTF parameter of each image reaches a preset MTF threshold value or not;

if so, the image is qualified.

The second aspect of the present invention discloses a cell analysis apparatus for implementing any one of the above camera focusing methods, comprising:

a camera for acquiring an image;

a driving member for driving the camera to move along a movement path of the camera;

a position detecting member for acquiring a position of the camera on a movement path of the camera; and

The control module is used for setting a plurality of preset points on the movement path of the camera; controlling the camera to move along the movement path of the camera, and controlling the camera to acquire an image once when the camera reaches one of preset points; the preset point of the sharpest image is selected from the plurality of images as the focal point.

A third aspect of the present invention discloses a blood testing device comprising the above-described cell analysis apparatus for implementing any one of the camera focusing methods described above.

Compared with the prior art, the invention has the following technical effects:

according to the camera focusing method, the driving piece is arranged and drives the camera to move on the moving path, the control module receives the signal feedback of the position detection piece every time the camera reaches a preset point and controls the camera to acquire an image once, namely, before focusing is completed, the camera is in a continuous moving state in the whole course of the moving path without any pause, so that the time of the camera walking through the moving path is short, the focusing speed of a cell analysis instrument is high, and the detection efficiency of blood detection equipment is high.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic view showing an internal structure of a blood test apparatus according to an embodiment of the present invention;

FIG. 2 shows a schematic view of the interior of a blood testing device at another angle;

FIG. 3 is a schematic diagram showing the operation of a cell analyzer according to an embodiment of the present invention;

FIG. 4 shows a schematic diagram of the electrical signal transmission principle of the cell analyzer of FIG. 3;

FIG. 5 is a flow chart of a camera focusing method according to an embodiment of the invention;

fig. 6 shows a schematic flow chart of step S20 in fig. 5;

fig. 7 shows a schematic flow chart of step S21 in fig. 6;

fig. 8 shows a schematic flow chart of step S22 in fig. 6;

fig. 9 shows a schematic flow chart of step S30 in fig. 5;

fig. 10 shows a schematic flow chart of step S32 in fig. 9.

Description of main reference numerals:

10-cell analysis instrument; 11-a closed loop stepper motor; 12-a camera; 13-a control module; 20 trays; 30-a frame; 40-guide; 100-consumable support; 110-counting plate.

Detailed Description

The following description of the embodiments of the present invention will be made apparent and fully in view of the accompanying drawings, in which some, but not all embodiments of the invention are shown. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

In addition, the technical features of the different embodiments of the present invention described below may be combined with each other as long as they do not collide with each other. Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout.

The invention discloses blood detection equipment, such as a blood cell analyzer. Referring to fig. 1 and 2, fig. 1 is a schematic view illustrating an internal structure of a blood test apparatus, and fig. 2 is a schematic view illustrating an internal structure of a blood test apparatus at another angle.

The blood detection device includes: the cell analysis instrument 10 and the tray 20, the tray 20 is provided with a consumable support 100, and the consumable support 100 is fixed with a counting plate 110. In testing the blood sample on the counter plate 110, the cell analysis instrument 10 is positioned directly above the counter plate 110.

Wherein the consumable support 100 is used as a carrier for the counter plate 110. And, a plurality of sample cells are formed on the consumable support 100, and a hemolytic agent, a detergent, and a diluent are placed in the sample cells. And, form the TIP head standing groove on the consumable support 100, TIP head standing groove is used for placing the TIP head, TIP head can avoid the blood sample to directly contact with the application of sample ware, thereby reduced the probability that blood sample was polluted.

The counting plate 110 is used as a carrier of a blood sample, and specifically, the counting plate 110 is divided into three counting cells for respectively counting red blood cells, platelets and white blood cells.

The blood test apparatus further includes a frame 30, and the cell analyzer is mounted through the frame 30. The cell analyzer is kept at a distance from the counter plate 110 in the height direction that gives the cell analyzer 10 room to move sufficiently in focus. And, the cell analysis instrument 10 can be moved toward or away from the counter plate 110 to find a suitable focal position. Thus, the cell analysis instrument 10 can realize shooting and cell identification of a blood sample, classify and display the shot cells to a user, and has the advantages of rich functions and high automation degree.

Optionally, a guide 40 is provided on the frame 30, and the guide 40 is sleeved outside the cell analysis instrument 10. The guide 40 is annular in shape, and the inner diameter of the guide 40 is slightly larger than the outer diameter of the cell analysis instrument 10.

By providing the guide 40, the guide 40 can guide the movement of the cell analysis instrument 10 to improve the stability of the operation of the cell analysis instrument 10.

Referring to fig. 1 to 4, fig. 3 is a schematic diagram illustrating the operation of the cell analyzer 10, and the arrow in fig. 3 is the direction in which the camera 12 moves along the movement path during focusing. FIG. 4 is a schematic diagram of the electrical signal principle of the cell analyzer of FIG. 3.

In one embodiment of the invention, a cell analyzer for use in the blood testing apparatus described above is disclosed. The cell analysis instrument 10 includes:

a camera 12 for acquiring an image;

a driving member for driving the camera 12 to move along a movement path of the camera 12;

a position detecting member for acquiring a position of the camera 12 on a movement path of the camera 12; and

A control module 13 for setting a plurality of preset points on the movement path of the camera 12; controlling the camera 12 to move along the movement path of the camera 12, and controlling the camera 12 to acquire an image once when the camera 12 reaches one of preset points; the preset point of the sharpest image is selected from the plurality of images as the focal point.

The control module 13 is electrically connected to the camera 12, the driving element, and the position detecting element, respectively. Based on this, the control module 13 can send signals to the camera 12, the driving element, and can receive signals fed back from the position detecting element. The control module 13 is a CPU, which is used as an operation and control core for information processing and program operation, and is capable of making a motion path, setting a plurality of preset points on the motion path, and calculating and judging an image meeting a preset standard.

The description is as follows: in addition to the camera 12, an electronic device with an image capturing function such as a video camera may be employed.

The image acquired by the camera 12 includes a counter 110.

As an alternative embodiment, the carrier of the blood sample is a smear. The smear comprises a slide and a blood sample on the slide.

Illustratively, a closed-loop stepping motor 11 is used in the present embodiment, and the closed-loop stepping motor 11 is a motor with a position detection function, which is capable of detecting the real-time position of the camera 12.

Wherein, the closed loop stepping motor 11 is connected through a GPIO (General-purpose input/output), and the closed loop stepping motor 11 sends an interrupt signal through the GPIO.

Specifically, the closed-loop stepping motor 11 includes: a drive motor for providing power for movement of the camera 12 and a closed loop encoder; the closed loop encoder is used to detect the position of the acquisition camera 12 in the path of motion of the camera 12. That is, the driving motor corresponds to the driving element, the closed-loop encoder corresponds to the position detecting element, and the closed-loop stepping motor 11 realizes functions of both the driving element and the position detecting element.

Of course, the closed loop stepper motor 11 of the present embodiment is only one of the options of the driving member and the position detecting member. The driving piece can also adopt a cylinder with high output precision and other types of stepping motors. The position detecting member may employ a position sensor.

Referring to fig. 5 to 10, an embodiment of the invention discloses a camera focusing method, which is implemented by the above-mentioned cell analysis instrument.

Referring to fig. 5, the camera focusing method includes the following steps:

step S10: setting a plurality of preset points on a movement path of a camera;

step S20: controlling the camera to move along the movement path of the camera, and controlling the camera to acquire an image once when the camera reaches one of preset points;

step S30: selecting an image which accords with a preset standard from a plurality of images, and taking a preset point corresponding to the image which accords with the preset standard as a focus.

The preset standard is a preset MTF threshold of the camera lens. The MTF (Modulation Transfer Function ) is a quantitative description of the sharpness of imaging of a camera lens. Can provide visual and reliable basis for the definition of the image.

The focus is a position of the camera, which is suitable for photographing the counting plate on the motion path. When the camera is in focus, the focal point of the camera is on the counter plate, and the whole counter plate is positioned in the depth of field of the camera lens.

The description is as follows: the depth of field is the clear range before and after the focus of the camera is completed. The picture elements in the depth of field range can be clearly seen, and the effect of gradual blurring can be realized outside the depth of field range. Generally, we need to make the object within the depth of field and the background outside the depth of field, so that the object can be highlighted.

The size of the depth of field refers to the size of the clear range in the picture. Jing Shenjian, the clear range is small, and other picture elements are in the depth of field range except the shot object, so that the background is blurred, and the background is simpler and more concise, so that the shot subject is highlighted. The shallower the depth of field, the better the background blurring effect. On the contrary, the depth of field is large, the clear range is large, and the shooting subject and other picture elements are in the depth of field range, so the whole picture is clear. The larger the depth of field, the more clear the background.

In this embodiment, the counter is used as the shooting object, and the camera is driven to move until the focusing point of the lens of the camera falls on the counter, and the counter is located in the depth of field. In addition, the camera lens needs to be provided with a smaller depth of field to highlight the counting plate, and the background around the counting plate is blurred. Depth of field and depth of field size are common sense in the art and will not be described in detail herein.

By arranging the driving piece, the driving piece drives the camera to move on the moving path, and the control module receives signal feedback of the position detection piece every time the camera reaches a preset point and controls the camera to acquire an image. I.e. the camera is in motion all the way through the motion path before focusing is completed. I.e. the camera does not make any pauses in the path of motion. Therefore, the time for the camera to finish the moving path is short, the focusing speed of the cell analysis instrument is high, and the detection efficiency of the blood detection device is high.

For example, the preset path is 200um, 41 preset points are set, and the interval between adjacent preset points is 5um. Where 5um is the depth of field setting according to the camera lens. The number of preset points, the distance between preset points, and the distribution of preset points on the motion path can be configured by the user according to the own requirements, and the method is not limited by the embodiment.

When the camera moves from the starting point of the path to 5um, the position detection part sends a signal to the controller, the control module sends a signal to the camera according to the signal fed back by the position detection part, and the camera receives the signal and then shoots the 1 st image. When the camera continues to move to 10um, the position detection part sends a signal to the controller again, the control module sends a signal to the camera according to the signal fed back by the position detection part, and the camera receives the signal and then shoots the 2 nd image. This is repeated until the motion reaches the end of the motion path at 200 um. At this time, the camera has taken 40 images.

An image whose MTF parameter is greater than a preset MTF threshold is selected from 40 images, for example, a motion path is set to 200um, and a preset point is set every 5um. The MTF parameter threshold is a, the MTF parameters of the 10 th and 11 th sheets and the MTF parameters of the 12 th sheets are b, c and d respectively, and b, c and d are all larger than a. Then, any preset point of 45um, 50um,55um on the motion path can be used as the focal point of the camera.

The image is stored in a storage module of a storage medium, and the storage module is internally provided with data of codes for realizing a camera focusing method. In step S30, the control module invokes and analyzes the code and data in the storage module to analyze the image. Specifically, the storage medium is a usb disk, an optical disk, and a removable hard disk.

Alternatively, the largest image of the MTF parameters may be taken from among the plurality of images. And taking a preset point corresponding to the image as a focus.

For example, the motion path is set to 200um, and a preset point is set every 5um. The MTF parameter threshold is a, the MTF parameters of the 10 th image and the 11 th image are b, c, d, b, c and d respectively, and b is larger than a and b is larger than c and larger than d, and the 45um on the motion path is selected as a focus.

Compared with the preset standard defined as the MTF threshold value, the camera lens can select the most suitable preset point as a focus, and the most reasonable depth of field range can be obtained.

In a specific embodiment, the movement path is a straight line perpendicular to the camera and the blood sample carrier, and the depth of field of the camera lens ranges between the start point and the end point.

The motion path is a virtual axis set by the control module, and the virtual axis coincides with the actual motion track of the camera.

The movement path is configured as a straight line perpendicular to the camera and the blood sample carrier, i.e. the camera can be moved towards or away from the blood sample under the driving action of the driving element, so that a focusing point is found on the movement path of the camera.

The camera under the scene belongs to a precise instrument, and the distance between the starting point and the end point of the motion path is larger than the depth of field of the lens of the camera, so that the motion path has a longer distance, and thus the installation error of the counting plate on the structure can be contained, clear pictures cannot be found due to the fine structural error, the focusing is failed, and each measurement can be ensured to be focused correctly.

By setting the depth of field range of the camera lens between the starting point and the end point, the plane where the counting plate can clearly image is positioned between the starting point and the end point of the motion path, and the images at the positions of a plurality of preset points necessarily contain pictures meeting preset standards. The focus position can be found correctly in each focusing, and the focusing reliability is high.

In a specific embodiment, the plurality of preset points are equally or unequally spaced on the path of motion.

The preset point is a virtual point position set on the virtual axis by the control module.

Illustratively, the equidistant distribution is such that every 5um of the preset points are distributed on the 200um path of motion. And will not be described in detail herein.

The non-equidistant distribution may be such that the closer to the focus, the denser the distribution of preset points.

Illustratively, the focusing point is 45um, and a preset point is still distributed every 5um in 0-40um and 50um-200um of the motion path, and the preset point is distributed every 1um in 40um-50 um. In this way, more focal points meeting the preset criteria can be obtained.

The focus obtained by the preset points is only an actual value, and compared with a theoretical value, a difference between the actual value and the theoretical value can be reduced by setting more preset points more densely in a section close to the focus. The definition of the image shot by the camera is improved, and the method is suitable for scenes with high requirements on the definition of the image.

Of course, the non-uniform distribution may be a random distribution, and is not limited to the specific limitation of the present embodiment.

Referring to fig. 6, in order to further describe the process of the camera on the motion path, step S20 is split into:

step S21: controlling the camera to move along a movement path of the camera;

step S22: the camera is controlled to acquire an image once every time the camera reaches one of the preset points.

Referring to fig. 7, further, step S21 includes the following steps:

step S211: transmitting a first signal to a driver;

step S212: the driving piece responds to the first signal and drives the camera to move to the pre-focusing position;

step S213: judging whether the camera moves to a pre-focusing position;

step S214: if yes, a second signal is sent to the driving piece, and the driving piece responds to the second signal to drive the camera to move along the movement path.

The first signal is a reset signal of the camera. The camera will reach the end of the motion path after focusing is completed. Then the control module needs to control the camera to return to the start of the motion path again for the next focus by the camera. The starting point of the motion path is a pre-focusing position.

When the camera is positioned at the pre-focusing position, at least one position of the counting plate is within the depth of field of the camera lens. Resetting the camera to the pre-focus position can reduce the time of focus compared to other positions.

The second signal is a motion signal driving the camera to move along a motion path of the camera. Under the control of the second signal, the camera starts to move from the pre-focus position.

Further, step S21 further includes the steps of:

step S213: judging whether the camera moves to a pre-focusing position;

step S215: if not, step S213 is performed again until the camera moves to the pre-focus position.

In the process of moving the camera to the starting point of the movement path, multiple judgments are usually needed to avoid that the camera has reached the pre-focusing position and is stopped due to untimely detection. By setting step S215, the time interval between the camera and the camera moving along the moving path after the camera is reset to the pre-focusing position can be reduced, and the focusing efficiency of the camera can be further improved.

Further, after step S214, the method further includes the following steps:

step S216: judging whether the camera reaches the end point of the motion path;

step S217: if so, a third signal is sent to the driving piece, and the driving piece responds to the third signal, so that the camera stops moving.

Step S218: if not, judging whether the camera reaches the end point of the motion path again.

Wherein the third signal is a stop signal of the driving member. That is, when the end point of the motion path is detected, the position detecting element generates a feedback signal, the feedback signal includes the position of the camera, and the control module receives the feedback signal to determine whether the camera reaches the end point of the motion path.

The control module sends a third signal to the driving piece, so that the camera can stop moving at the end point of the moving path of the camera, and the image acquisition phase of focusing of the camera is ended.

Illustratively, the movement path is 200um, and when the camera moves to 200um, the control module sends a third signal to stop the driving member, so that the camera stops moving.

Referring to fig. 8, step S22 includes the following steps:

step S221: acquiring the position of a camera;

step S222: judging whether the position of the camera is coincident with the position of the preset point;

step S223: if yes, a fourth signal is sent to the camera, and the camera responds to the fourth signal to acquire an image.

Step S224: if not, the step S222 is repeatedly executed until the position of the machine coincides with the position of the preset point.

The fourth signal is a photographing signal that the camera reaches a preset point. The position acquisition of the camera is realized through a closed-loop encoder of a closed-loop stepping motor, and when the closed-loop encoder detects that the camera reaches a preset point, a feedback signal is sent to the control module, wherein the feedback signal comprises the position of the camera. The control module receives the feedback signal and judges whether the position of the camera is coincident with the position of the preset point.

The camera takes a picture under the control of the fourth signal to obtain a plurality of images to provide the basis for the control module to provide the analysis at step S30.

In the prior art, besides sending a photographing signal to a motor, a control module needs to send a motor stop signal and a motor restart signal to a driving piece, and signal control is complex. In the embodiment, the control module only sends the third signal to the camera to realize fixed-point photographing of the camera reaching the preset point, so that the signal control is simple and the practicability is high.

Referring to fig. 9, in a specific embodiment, step S30 includes the following steps:

step S31, numbering the images and preset points, wherein the numbers of the images correspond to the numbers of the preset points;

step S32, performing definition calculation on the image, comparing the calculation result with a preset standard, and selecting a qualified image;

step S33, acquiring the number of the qualified image, and taking a preset point corresponding to the number of the image as a focus.

By means of numbering, the image can be associated with preset points, and the calculation operability of the control module is improved.

The sharpness calculation is to calculate the MTF parameter of the image. The MTF (Modulation Transfer Function ) is a quantitative description of the sharpness of imaging of a camera lens.

The preset criteria is a preset MTF threshold. The following are to be explained again: the preset criterion is a preset MTF threshold for the camera lens.

For example, the motion path is 200um, a preset point is arranged every 5um, the starting point number of the motion path is 0, the preset point number at the 5um is 1, the preset point number at the 10um is 2, and the preset point number at the end point of the motion path is 40. Then, the number of the image acquired by the camera at 5um is 1, the number of the image acquired at 10um is 2, and so on, and the number of the image acquired at the end of the moving path is 40. And when the image No. 17 meets the preset standard, taking the preset point No. 17 as the focus of the camera on the motion path.

Referring to fig. 10, in a specific embodiment, step S32 includes the following steps:

step S321: calculating MTF parameters of each image;

step S322: judging whether the MTF parameter of each image reaches a preset MTF threshold value or not;

step S323: if so, the image is qualified.

Step S324: if not, storing or deleting the image.

When the MTF parameter of the image calculated by the control module is larger than or equal to the preset MTF threshold value, the focusing point of the camera lens falls on the counting plate, and the whole counting plate is positioned in the depth of field of the camera lens. I.e. the counting plate can be clearly presented in the image.

When the MTF parameter of the image calculated by the control module is smaller than the preset MTF threshold, the definition of the image can not meet the use requirement, and the photo can be stored in the storage module of the storage medium or can be directly deleted from the storage module according to whether the use is possible or not in the future.

It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications of the invention are intended to fall within the scope of the invention.

Claims

1. A camera focusing method, comprising the steps of:

setting a plurality of preset points on a movement path of a camera;

2. The camera focusing method of claim 1, wherein the motion path is a straight line perpendicular to the camera and the blood sample carrier, a distance between a start point and an end point of the motion path is greater than a depth of field of a lens of the camera, and a depth of field of the lens of the camera ranges between the start point and the end point.

3. The camera focusing method according to claim 1, wherein a plurality of the preset points are distributed at equal intervals or non-equal intervals on the movement path.

4. The camera focusing method according to claim 1, wherein the controlling the movement of the camera along the movement path of the camera comprises the steps of:

transmitting a first signal to a driver;

judging whether the camera moves to a pre-focusing position;

5. The method of focusing a camera according to claim 4, wherein the driving member is responsive to the second signal to drive the camera to move along the movement path, and further comprising the steps of:

judging whether the camera reaches the end point of the motion path;

6. The camera focusing method according to claim 1, wherein the controlling the camera to acquire the image once every time the camera reaches one of the preset points comprises the steps of:

acquiring the position of a camera;

7. The camera focusing method according to claim 1, wherein the selecting an image satisfying a preset criterion from among the plurality of images includes the steps of:

8. The method of focusing a camera according to claim 7, wherein the step of performing sharpness calculation on the image and comparing the calculation result with a predetermined criterion to find an image meeting the predetermined criterion, and selecting a qualified image comprises the steps of:

calculating MTF parameters of each image;

if so, the image is qualified.

9. A cell analysis instrument for implementing the camera focusing method according to any one of claims 1 to 8, characterized by comprising:

a camera for acquiring an image;

10. A blood testing device, comprising: the cell analysis instrument of claim 9 for implementing the camera focusing method of any one of claims 1 to 8.