JP2011002732A - Microscope camera - Google Patents

Abstract

A microscope camera capable of performing optimum photographing by changing an illumination light amount / exposure time / camera gain in accordance with a blur amount of a subject image.
A control unit (microcontroller 4) of a microscope camera 1 controls a gain control unit 14 as a preliminary operation before taking a digital image of a sample O and is set to a predetermined camera gain. The optical image blur detection unit 16 detects the blur amount of the image of the sample O, the exposure time adjustment unit 13 shortens the exposure time in the imaging unit 3, and the illumination dimming unit 7 emits illumination from the illumination unit 6 A first mode is provided for performing exposure with an increased amount of light.
[Selection] Figure 1

Description

  The present invention relates to a microscope camera.

  2. Description of the Related Art Digital cameras that take a subject image using an image sensor, display the resulting image on a monitor, and record it in a built-in flash memory are widely used. In these digital cameras, various blur correction methods have been proposed in order to reduce image blur that occurs when a subject with relatively low illuminance is imaged. For example, the longest exposure time is calculated from the focal length and the pixel pitch, and a method of shooting with an appropriate exposure amount calculated based on the longest exposure time based on the aperture / camera gain / exposure time (see, for example, Patent Document 1) And a method of selecting either camera gain priority (see, for example, Patent Document 2) has been proposed. In addition, in the case of a microscope digital camera or a microscope system that takes a dark subject using an optical system with a relatively high magnification, an apparatus with a large anti-vibration mechanism in consideration of vibration is essential.

JP 2004-140793 A Japanese Patent No. 4174552

  However, in the method described in Patent Document 1, since the actual amount of blur cannot be reflected, if the preset maximum exposure time is exceeded, the camera gain is increased because the image blur is warned, and more than necessary. The amount of noise may increase, and if an optical blur correction device is provided as in the method described in Patent Document 2, a drive unit for operating the optical system and the image sensor is required, and the device becomes expensive. Also, there was a problem of increasing the size. In particular, when a large vibration isolating mechanism is provided, it is necessary to provide a large stationary stage, and it is impossible to construct a small microscope camera that enables handheld shooting, battery driving, and the like.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a microscope camera that can perform optimum photographing according to the amount of blur of an image of a subject.

  In order to solve the above problems, a microscope camera according to the present invention includes an illumination unit that irradiates illumination light to a subject, an illumination dimming unit that changes the amount of illumination light emitted from the illumination unit, and light from the subject. An imaging unit that focuses the light and forms an image of the subject, an imaging unit that detects the subject image and outputs it as a video signal, and controls an exposure time when the imaging unit detects the subject image An exposure time adjustment unit; a gain control unit that adjusts a video signal output from the imaging unit to a signal amplitude corresponding to a camera gain; an optical image blur detection unit that detects a blur amount of an image of a subject; and illumination dimming A control unit that controls the operation of the exposure unit, the exposure time adjustment unit, and the gain control unit to capture a digital image of the subject. Then, as a preliminary operation before taking a digital image, the control unit detects the blur amount by the optical image blur detection unit in a state where the gain control unit is controlled and set to a predetermined camera gain, and the blur amount is detected. Is larger than the predetermined value, the exposure time adjustment unit shortens the exposure time, and the illumination dimming unit has a first mode in which exposure is performed with the amount of illumination light increased.

  In such a microscope camera, when the amount of blur is larger than a predetermined value, the exposure time adjustment unit shortens the exposure time, and the gain control unit further increases the camera gain in the second mode. It is preferable that the first and second modes can be switched.

  Further, such a microscope camera has a photometric unit that detects the luminance of the image of the subject, and the control unit detects the luminance by the photometric unit before the preliminary operation, and the exposure time so as to maintain the luminance. Accordingly, it is preferable that the digital image of the subject is acquired by controlling the light amount and the camera gain.

  In such a microscope camera, the control unit is configured to shorten the exposure time until the amount of blur detected by the optical image blur detection unit is smaller than a predetermined value in the first and second modes. It is preferable.

  Furthermore, in such a microscope camera, it is preferable that the optical image blur detection unit is configured to detect the blur amount from the contrast of the digital image obtained in the preliminary operation.

  When the microscope camera according to the present invention is configured as described above, optimum photographing can be performed by changing the amount of illumination light in accordance with the amount of blur of the subject image.

It is a block diagram which shows the structure of a microscope camera. It is a flowchart which shows a process when imaging | photography of a to-be-photographed object in the said microscope camera.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. First, the configuration of the microscope camera according to the present embodiment will be described with reference to FIG. The microscope camera 1 has a microscope optical system including an objective lens, an imaging lens, and the like, and an imaging unit 2 that focuses light from the sample O as a subject to form an image of the sample O. An imaging unit 3 that is composed of a solid-state imaging device such as a CCD image sensor or a MOS type image sensor, detects an image of the sample O imaged by the imaging unit 2, and outputs it as a video signal (electrical signal); A microcontroller 4 that is a control unit that controls the operation of the microscope camera 1 and an image of the sample O acquired by the imaging unit 3 based on control by a program stored in the microcontroller 4 and output as a video signal, The image sensor control unit 5 that processes the video signal and outputs a digital image of the sample O, the illumination unit 6 that irradiates the sample O with illumination light, and the amount of illumination light emitted from the illumination unit 6 are controlled. An instruction from an illumination dimmer 7, a photometric unit 8 that detects the luminance of the image of the sample O from a digital image output from the image sensor control unit 5, and an operator who operates the microscope camera 1 are input. The operation unit 9, the display unit 10 for displaying the digital image of the sample O, the image memory 11 for storing the digital image of the sample O, the microcontroller 4, the display unit 10 and the image memory 11 are connected to each other. The system bus 12 transmits and receives signals between them. The image sensor control unit 5 further adjusts the exposure time adjustment unit 13 that adjusts the exposure time in the imaging unit 3 and the video signal output from the imaging unit 3 to a predetermined signal amplitude (value for this adjustment). Is called a “camera gain”) and an A / D converter 15 that converts the video signal (analog signal) adjusted by the gain controller 14 into a digital signal and outputs the digital signal. . Further, an optical image blur detection unit 16 that detects a blur of the optical image based on the digital image output from the image sensor control unit 5 is provided as a program executed by the microcontroller 4.

  Here, the solid-state imaging device constituting the imaging unit 3 receives an image formed by the imaging unit 2 with a light receiving element, and outputs a video signal by taking out the electric charge accumulated in the light receiving element. However, the intensity of the signal (the brightness of the image) changes depending on the time for accumulating charges. For this reason, in the present embodiment, the time for accumulating charges in order to acquire an image (video signal) in this solid-state imaging device is referred to as “exposure time”.

  In the microscope camera 1 according to this embodiment, the illumination unit 6 includes at least two light sources, and these light sources are arranged so as to surround the imaging unit 3 in an annular shape. Therefore, since illumination light can be irradiated to the sample O from a plurality of directions surrounding the sample O, a portion that is shaded by the unevenness of the sample O can be reduced, and uniform illumination can be performed. . In addition, by using a light source that emits visible light for the illumination unit 6, it is possible to observe the sample O by epi-illumination. Further, by using, for example, a light source that emits near-ultraviolet light as the illumination unit 6, observation by fluorescence generated in the sample O (epi-fluorescence observation) becomes possible. Furthermore, oblique illumination is possible by turning on a part of the light source of the illumination unit 6 and turning off a part thereof.

  Further, the operation unit 9 selects a switch (release button) for instructing the timing for acquiring the digital image of the sample O, and a mode for adjusting the exposure time in the preliminary operation as will be described later. These switches (mode selection buttons) are provided at least.

  In such a microscope camera 1, the video signal obtained by the imaging unit 3 is adjusted to a signal amplitude corresponding to the camera gain by the gain control unit 14, and then converted to a digital value by the A / D conversion unit 15. This is a video signal. As will be described later, the combination of the exposure time and the camera gain is determined by the microcontroller 4 so that the luminance detected by the photometry unit 8 becomes an appropriate value for this video signal, and the exposure time adjustment unit 13 and the gain control unit are determined. 14, the imaging unit 3 and the gain control unit 14 are controlled according to the set value. In particular, it is necessary to eliminate the effects of image noise as much as possible for still images for printing and enlargement display compared to the live view operation where image data is constantly updated. It is preferable to shorten the exposure time so that image blurring does not occur.

  Therefore, in the microscope camera 1 according to the present embodiment, in order to obtain a blur-free digital image while maintaining the brightness of the image of the sample O obtained by the photometry unit 8, the following processing is performed for exposure. Configured to adjust time. Hereinafter, this process will be described with reference to FIG.

  As described above, the operation of the microscope camera 1 is controlled based on the program stored in the microcontroller 4. When the power of the microscope camera 1 is turned on, the microcontroller 4 takes out the luminance of the image of the sample O detected by the photometry unit 8 (step S100), and sets the optimal camera gain and exposure time according to this luminance. After the determination and the exposure time adjustment unit 13 and the gain control unit 14 are controlled, a digital image of the sample O is acquired and displayed on the display unit 10 (step S101). The digital image is used for confirming the image of the sample O acquired by the operator with the imaging unit 3 by displaying the digital image on the display unit 10, and the sample is more than the noise superimposed on the digital image. Since priority is given to the fact that O can be clearly confirmed, the exposure time is set to be shorter than the frame rate of image display such as 30 frames per second, and the camera gain is set to be high (so that a bright image is obtained). Further, the light amount of the illumination light applied to the sample O from the illumination unit 6 is automatically set by the microcontroller 4 based on the luminance detected by the photometry unit 8, or the operation unit 9 by the operator is used. It is configured to be adjustable by operation.

  Then, the microcontroller 4 reads the state of the operation unit 9 (step S102), determines whether or not the release button for image capturing has been operated, and when the release button has not been operated, returns to step S100. The above process is repeated (step S103). That is, until the release button of the operation unit 9 is operated, an image (digital image) of the sample O is acquired and displayed on the display unit 10 at a predetermined time interval. The state in which step S103 is being executed is referred to as “live view operation”. On the other hand, when it is determined in step S103 that the release button has been operated, the following preliminary operation is performed to obtain a digital image that is not affected by blurring.

  First, the microcontroller 4 refers to the setting state of the mode selection button among the states of the operation unit 9 read in step S102 (step S104). In the microscope camera 1 according to the present embodiment, as a method of shifting the exposure time in order to obtain a blur-free image, a method of adjusting the amount of illumination light (hereinafter referred to as “first mode”) and a camera gain are used. Two modes comprising adjustment methods (hereinafter referred to as “second mode”) are provided, and these modes can be selected by a mode selection button of the operation unit 9.

[First mode]
If it is determined in step S104 that the first mode is selected by the mode selection button of the operation unit 9, the microcontroller 4 sets the camera gain of the gain control unit 14 to a predetermined value (step S104). S105). As described above, the camera gain is set high so that the image of the sample O is clearly displayed on the display unit 10 in the live view operation. Therefore, in a normal state, in step S105, the camera gain is set. The gain is set to be lower than that in the live view operation. Next, the illumination light quantity is changed in accordance with the camera gain set in step S105 so that the luminance of the image of the sample O becomes the value measured in step S100, and the illumination dimming unit 7 It sets (step S106). As described above, since the camera gain is set low in step S105, the illumination light quantity is set to increase in step S106.

  In this state, the microcontroller 4 shortens the current exposure time by a predetermined time width and sets it in the exposure time adjustment unit 13 (step S107). When the exposure time is shortened, the luminance of the image of the sample O is reduced accordingly, so that the microcontroller 4 increases the amount of illumination light and sets it in the illumination dimming unit 7 so as to obtain the luminance measured in step S100. (Step S108). In this state, the optical image blur detection unit 16 determines whether the digital image output from the image sensor control unit 5 is affected by the blur (step S109). When the digital image is affected by blurring, the image of the edge portion spreads (blurs), and the change in luminance becomes gradual. Therefore, when the contrast is calculated in such a state, a low value is obtained. On the other hand, if there is no influence of blurring, the image of the edge portion becomes sharp and the change in luminance becomes large, so that the contrast becomes a high value. Therefore, when the optical image blur detection unit 16 determines that the contrast is equal to or less than the predetermined value, that is, the microcontroller 4 returns to step S107 and repeats the above processing. On the other hand, when it is determined that the contrast is larger than the specified value, i.e., there is no influence of the shake, the microcontroller 4 finishes the above preliminary operation and acquires the digital image of the sample O at that time from the image sensor control unit 5. (Taken) and stored in the image memory 11 (step S115), and returns to step S100 (live view operation).

[Second mode]
On the other hand, when it is determined that the second mode is selected with the mode selection button of the operation unit 9, the microcontroller 4 sets the camera gain of the gain control unit 14 to a predetermined value (step S110). ). As in step S105 described above, the camera gain is set to be lower than that in the live view operation. Next, the exposure time is changed in accordance with the change in the camera gain set in step S110 so that the luminance of the image of the sample O becomes the value measured in step S100, and the exposure time adjustment unit 13 is set (step S111). Also in this case, since the camera gain is set low in step S110, the exposure time is set longer in step S111.

  In this state, the microcontroller 4 shortens the current exposure time by a predetermined time width and sets it in the exposure time adjustment unit 13 (step S112). When the exposure time is shortened, the brightness of the image of the sample O is reduced accordingly, so that the microcontroller 4 increases the gamer gain and sets it in the exposure time adjusting unit 13 so as to obtain the brightness measured in step S100. (Step S113). In this state, the microcontroller 4 analyzes the digital image output from the image sensor control unit 5 by the optical image blur detection unit 16, detects an edge included in the digital image, and further contrasts the edge. Is calculated and it is determined whether or not the contrast is within a specified value (step S114). The blur detection method (contrast calculation method) in step S114 is the same as that in the first mode described above, and details thereof will be described later. In step S114, when the microcontroller 4 determines that the contrast is less than or equal to the specified value by the optical image blur detection unit 16, that is, there is an influence of blur, the microcontroller 4 returns to step S112 and repeats the above processing. On the other hand, when it is determined that the contrast is larger than the specified value, i.e., there is no influence of shaking, the microcontroller 4 ends the preliminary operation and acquires a digital image of the sample O at that time from the image sensor control unit 5. (Taken) is stored in the image memory 11 (step S115), and the process returns to step S100.

  By the way, a method for determining the presence or absence of the influence of blur (detecting the blur amount) from the contrast of the digital image captured by the image sensor control unit 5 in the optical image blur detection unit 16 will be described. The microscope camera 1 is configured so that an operator wants to preliminarily designate a region where the operator wants to determine blurring in the digital image of the sample O displayed on the display unit 10 by the live view operation by operating the operation unit 9. ing. Then, the optical image blur detection unit 16 extracts the edge portion of the image in the designated region of the digital image acquired by the image sensor control unit 5 and calculates the contrast of the edge portion. As a method for calculating the contrast, for example, when the maximum value of the luminance at the edge portion is Imax and the minimum value is Imin, the contrast can be calculated by (Imax−Imin) / (Imax + Imin). As described above, it can be determined that the lower the edge contrast, the greater the blur amount. When the microcontroller 4 detects a plurality of edges in the area designated by the operator, the microcontroller 4 determines that there is no influence of the shake when all the contrasts at the respective edges are within the specified value. (Proceed to step S115).

  As described above, the microscope camera 1 according to the present embodiment is provided with the first mode in which the processing for shortening the exposure time by adjusting the amount of illumination light is performed. As a result, when the exposure time is shortened and the camera gain is increased in order to prevent blurring, an image in which blurring is prevented can be obtained even in the case where the ratio of the noise component to the luminance increases and the image quality deteriorates. It has become. On the other hand, shortening the exposure time to prevent blurring and increasing the amount of illumination light may not be desirable in view of increased power consumption and damage to the subject. In such a case, the microscope camera 1 is configured to shorten the exposure time in order to acquire a digital image with reduced influence of blur. However, the exposure time is shortened by adjusting the camera gain. And a process (first mode) that adjusts the amount of illumination light to shorten the exposure time. When the second mode for adjusting the camera gain is selected, the exposure time can be shortened while maintaining the illumination light amount in the current state, and therefore, for example, heat generation and power consumption of the microscope camera 1 can be suppressed. Therefore, this microscope camera 1 can be driven by a battery, and can be adapted to hand-held shooting. Further, in this second mode, since the illumination light quantity is not increased, damage to the sample O due to the increase in the illumination light quantity can be reduced when the sample O is a living cell or the like. However, since the camera gain is increased as the exposure time decreases, the noise superimposed on the digital image is also amplified, and the influence of this noise increases. On the other hand, when the first mode for adjusting the illumination light amount is selected, the illumination light amount applied to the sample O increases as the exposure time is shortened, so that the influence of noise superimposed on the digital image can be reduced. However, as described above, heat generation and power consumption in the microscope camera 1 increase, and the possibility of damaging the sample O increases. In any mode, the exposure time is shortened to reduce the blurring of the image of the sample O. Therefore, a mechanism for operating the imaging unit 2 and the imaging unit 3 to correct the blurring becomes unnecessary, and this microscope is not necessary. The camera 1 can be lightweight.

  In the above description, the case where the first and second modes are switched by the operation of the mode selection button provided in the operation unit 9 has been described. However, the control unit corresponds to the shooting environment. It is also possible to configure the microcontroller 4 to select.

  Further, although the optical image blur detection unit 16 has been described so as to determine the presence or absence (blurring amount) of the blurring effect on the digital image based on the contrast of the edge detected in the predetermined region, step S107 is described. To S109 or steps S112 to S114, the digital image acquired in step S109 or step S114 is temporarily stored, and the digital image acquired in the previous process and the digital image acquired in the current process are temporarily stored. It is also possible to memorize the contrast of the edges, and to determine that there is no influence of blurring when the difference between these contrasts becomes smaller than a predetermined value. This is because when the digital image is affected by blurring, the contrast value changes for each repeated process. Alternatively, the microscope camera 1 may be provided with a gyro or the like to mechanically detect blurring of the image of the sample O.

  In the above description, the case where the program stored in the microcontroller 4 is configured to control the photographing of the digital image of the sample O has been described. However, all or part of these processes is performed by a dedicated IC. You may comprise as a chip | tip. For example, since the optical image blur detection unit 16 that detects the presence or absence of the blur effect on the digital image is required to be processed at high speed, the effect is exhibited by using a dedicated IC chip.

DESCRIPTION OF SYMBOLS 1 Microscope camera 2 Imaging part 3 Imaging part 4 Microcontroller (control part) 6 Illumination part 7 Illumination light control part 8 Photometry part 13 Exposure time adjustment part 14 Gain control part 16 Optical image blur detection part O Sample (subject)

Claims (5)

An illumination unit that illuminates the subject with illumination light;
An illumination dimming unit that changes the amount of the illumination light emitted from the illumination unit;
An imaging unit that focuses light from the subject to form an image of the subject;
An imaging unit that detects an image of the subject and outputs it as a video signal;
An exposure time adjustment unit that controls an exposure time when the image of the subject is detected in the imaging unit;
A gain control unit that adjusts the video signal output from the imaging unit to a signal amplitude corresponding to a camera gain;
An optical image blur detection unit for detecting the blur amount of the image of the subject;
A control unit that controls the operation of the illumination dimming unit, the exposure time adjustment unit, and the gain control unit to capture a digital image of the subject,
As a preliminary operation before taking the digital image, the control unit,
The optical image blur detection unit detects the blur amount in a state in which the gain control unit is controlled and set to a predetermined camera gain. When the blur amount is larger than a predetermined value, the exposure time adjustment unit A microscope camera having a first mode in which the exposure time is shortened and exposure is performed with the illumination dimming unit increasing the amount of illumination light.   A second mode in which when the amount of blur is greater than a predetermined value, the exposure time adjustment unit shortens the exposure time and the gain control unit performs exposure with the camera gain increased; The microscope camera according to claim 1, wherein the microscope camera is configured to be switchable between the first and second modes. A photometric unit for detecting the luminance of the image of the subject;
The control unit detects the luminance by the photometry unit before the preliminary operation, and controls the light amount and the camera gain according to the exposure time so as to maintain the luminance. The microscope camera according to claim 1, wherein the microscope camera is configured to acquire a digital image.   The said control part is comprised so that the said exposure time may be shortened until the said blur amount detected by the said optical image blur detection part becomes smaller than predetermined value in the said 1st and 2nd mode. 3. The microscope camera according to 3.   5. The microscope camera according to claim 1, wherein the optical image blur detection unit is configured to detect the blur amount from a contrast of the digital image obtained in the preliminary operation.

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