JP4626474B2 - Electronic camera and microscope with cooling control function - Google Patents

Description

  The present invention relates to an electronic camera with a cooling control function and a microscope.

For example, an image sensor such as a CCD type or a MOS type is used for the electronic camera. These image sensors generate fixed pattern noise (hereinafter abbreviated as FPN) due to dark current in response to self-heating during use or an increase in environmental temperature. FPN deteriorates the signal-to-noise ratio between the image signal and noise and causes the image signal quality to deteriorate.
As a technique for reducing the FPN, conventionally, a cooling means such as a Peltier element is provided in an image pickup device, and the image pickup device is cooled to suppress an increase in dark current.

FIG. 4 shows a normalized luminance output (vertical axis) with respect to the temperature (horizontal axis) of the image sensor. As seen from this, the FPN determines the image quality when the charge accumulation time is long or when the temperature of the image sensor is high. Therefore, cooling the image sensor has a great effect in reducing the FPN and improving the image quality of the image signal.
The adjustment of the cooling temperature of the image sensor using the cooling means is performed by adjusting the power supplied to the cooling means. Specifically, the variable resistance (variable resistor (device for electrically changing the resistance) is defined in a broad sense. And the like, and the like, and the like (hereinafter referred to as DC drive). For example, when a transistor is used as a variable resistor in direct current drive, the power supplied to the cooling means is adjusted by adjusting the base current of the transistor.

However, the power adjustment by direct current drive has a disadvantage that a large amount of heat is generated in a variable resistor in a broad sense such as a variable resistor and a transistor, which reduces the cooling effect and consumes useless power.
Therefore, as described in Patent Document 1, the power supplied to the cooling means is turned on / off using a switching element, and the power supplied to the cooling means is controlled by PWM control (hereinafter referred to as a pulse) at a ratio of the on time to the off time. (Referred to as driving) has been proposed. In this pulse drive, even if the power supplied to the cooling means changes, its efficiency can always be kept high, so that the circuit portion generates very little heat and wasteful power consumption can be suppressed.
JP-A-7-295659

However, adjustment of the cooling temperature of the image sensor based on pulse driving has the following problems.
That is, on / off control (PWM control) of the power supplied to the cooling means causes regular ripples in the power supply voltage of the electronic camera. As a result, there is a problem that noise is generated in the captured image and the image quality is deteriorated.
The present invention has been made paying attention to such problems of the prior art, and provides an electronic camera with a cooling control function and a microscope that can obtain high-quality images with low power consumption. Objective.

Cooling control function-equipped electronic camera of the present invention includes an imaging means for generating image signals by imaging an object, in the electronic camera cooling control function and a cooling means for cooling said imaging means, before Symbol imaging means A controller that sets whether the operation mode is a mode that prioritizes image quality or a mode that prioritizes image quality, and whether the set operation mode of the imaging means is a mode that prioritizes an image or a mode that prioritizes image quality When it is determined that the operation mode determination means for determining and the determined operation mode is an operation mode that prioritizes image quality, the adjustment of the power supplied to the cooling means is DC drive, and the determined operation mode is And a cooling control unit that performs pulse driving to adjust the power supplied to the cooling unit when it is determined that the operation mode is one in which image quality is not prioritized. To.

Further, the operation mode of the non-primary pre Symbol image quality is characterized by an image monitoring mode or focus mode or exposure control mode.
Also, priority operation mode image quality is characterized by an image recording mode.

The cooling control means includes a variable resistor for adjusting power supplied to the cooling means, a variable resistance value setting D / A converter for controlling the variable resistance, and an optimum pulse for controlling the variable resistance. has a pulse driving pulse generator for generating a pulse having a width, the time of pre-Symbol DC driving, the cooling means is driven by said variable resistance controlled by the variable resistance value setting D / a converter In the pulse driving, the cooling means is driven by the variable resistance controlled by the output from the pulse driving pulse generator.

Further, the microscope of the present invention is characterized by having an electronic camera mounting serial to any described above.

  According to the present invention, it is possible to provide an electronic camera with a cooling control function and a microscope that can obtain a high-quality image with low power consumption.

Hereinafter, embodiments of the present invention will be described.
(First embodiment)
FIG. 1 is a block diagram showing a first embodiment when the present invention is applied to an electronic camera.
In FIG. 1, an image pickup means 1 is an image pickup element such as a CCD type image sensor or a MOS type image sensor. Light from the subject enters the imaging means 1 via an optical system (not shown) such as a lens and a diaphragm. The incident light is photoelectrically converted in the imaging means 1. That is, the imaging unit 1 controls the exposure time in accordance with a charge accumulation control signal (not shown) input from the image processing unit 2, and further outputs a readout signal (not shown) input from the image processing unit 2. In response, image signals are sequentially output in units of pixels.

Here, the imaging unit 1 receives a command from the system controller 6 via the image processing unit 2, and, for example, an image monitoring mode, a focus mode, an exposure control mode, an image recording mode, etc. according to the command from the system controller 6. It is set to each operation mode.
Here, the image monitoring mode is a mode for monitoring an image on a composition confirmation screen (LCD or the like) of the electronic camera. The focus mode is a mode for focusing on the subject. The exposure control mode is a mode for obtaining an appropriate exposure. The image recording mode is a mode for storing a captured image in a recording medium (not shown) such as a memory card.

The image signal output from the imaging unit 1 is input to the image processing unit 2. The image processing means 2 adjusts the amplitude of the input image signal via an amplifier (not shown), then converts the analog value into a digital value (A / D conversion), and outputs it as a digital value image signal.
The imaging unit 1 is provided with a cooling unit 5 made of, for example, a Peltier element in close contact. The imaging unit 1 is provided with a temperature sensor 3 for detecting the temperature. The analog output of the temperature sensor 3 is converted into a digital value by the temperature measurement A / D converter 41 of the cooling control means 4. The system controller 6 detects the temperature of the imaging means 1 by reading the digital value output from the temperature measurement A / D converter 41.

The system controller 6 selects the driving mode (DC driving or pulse driving) of the cooling control unit 4 according to the operation mode of the imaging unit 1.
That is, the system controller 6 selects that the cooling control unit 4 is operated by DC driving when the imaging unit 1 is operating in the image recording mode (image quality priority). In this case, the variable resistance value setting D / A converter 43 is operated in consideration of the cooling temperature of the imaging means 1 obtained from the temperature sensor 3, and the variable resistance 44 is controlled to an appropriate value. Thereby, the power supplied to the cooling means 5 is adjusted appropriately. Note that since the image recording mode is normally set only during image recording, the problem of “wasteful power consumption” caused by operating by direct current drive can be almost ignored.

  On the contrary, the system controller 6 operates the cooling control means 4 by pulse driving when the imaging means 1 is operating in a state where image quality is not prioritized as in the image monitoring mode, the focus mode and the exposure control mode. select. At this time, the system controller 6 operates the pulse generator for pulse drive 42 in consideration of the cooling temperature of the imaging means 1 obtained from the temperature sensor 3. The pulse generator 42 for pulse driving outputs a pulse having an optimum pulse width to the variable resistor 44, whereby the power supplied to the cooling means 5 is appropriately adjusted. In the image monitoring mode, the focus mode, and the exposure control mode, high image quality is not required. Therefore, “regular ripple generation in the power supply voltage” and “noise in the captured image” caused by operating by pulse driving. "Deterioration of image quality" is hardly a problem.

FIG. 2 is a circuit diagram showing an example of the variable resistor 44 and the cooling means 5. In FIG. 2, the transistor Tr is used as the variable resistor 44, but the present invention is not limited to this, and other switching elements such as an electrical variable resistance device or FET may be used. A Peltier element 51 is used as the cooling means 5. In the figure, Vt is a reference voltage.
In the above description, the system controller 6 is configured to automatically switch the cooling system. However, the present invention is not limited to this, and the system controller 6 is configured to be manually switched by a changeover switch or the like. Is also possible.

  According to the first embodiment, when the electronic camera is operating in a state where image quality is not prioritized as in the image monitoring mode, the focus mode, and the exposure control mode, the imaging unit 1 is cooled by pulse driving with low power consumption. To do. Further, when the electronic camera is operating in a state in which image quality is prioritized as in the image recording mode, the imaging unit 1 is cooled by direct current drive with less noise. Therefore, the user of the electronic camera can always hold the imaging unit 1 in a cooled state by a driving method suitable for the set mode, so that a favorite image can be taken with high quality at a desired timing.

In addition, selection between pulse driving and DC driving may be performed in conjunction with camera mode switching, and a suitable driving means may be automatically selected, or the user may be switched by selecting means such as a switch.
In the first embodiment, the electronic camera has been described as an example. However, the present invention is not limited to this, and can be widely applied to an imaging apparatus using a general solid-state imaging element.
(Second Embodiment)
FIG. 3 is a block diagram showing a second embodiment in which the electronic camera of the present invention is attached to a microscope.

In FIG. 3, the same parts as those of the first embodiment shown in FIG. The second embodiment shown in FIG. 3 is different from the first embodiment shown in FIG. 1 in that the electronic camera 100 is attached to the microscope 200.
In FIG. 3, 21 is an imaging lens, 22 is a mirror, 23 is an objective lens, 24 is a sample, 25 is a stage, 26 is a transmission illumination unit, and 27 is an epi-illumination unit (optical that guides light from the epi-illumination unit to the sample). 28 is a microscope control unit.

In this embodiment, an image of the specimen 24 is formed on the imaging surface of the imaging means 1 by the objective lens 23 and the imaging lens 21, and photographing is performed on this specimen image.
According to this embodiment, since the electronic camera is always cooled by pulse driving, the sample image obtained from the microscope 200 can be taken with high image quality at any time by switching to DC driving. This embodiment is useful because it can record an image with a significantly reduced FPN, particularly in dark field / fluorescence photography, nighttime astronomical imaging, and the like.

In the second embodiment, the electronic camera has been described as an example. However, the present invention is not limited to this, and can be widely applied to an imaging apparatus using a general imaging element.
In the first and second embodiments described above, the A / D converter 41 for temperature measurement, the pulse generator 42 for driving pulses, and the D / A converter 43 for setting variable resistance value are a one-chip microcontroller. This can be realized by using an A / D converter, a D / A converter, and a pulse generator incorporated in the circuit. Similarly, the temperature measuring A / D converter 41, the pulse driving pulse generator 42, and the variable resistance value setting D / A converter 43 may be provided inside the system controller 6.

In the first and second embodiments described above, in calculating the amount of power supplied to the cooling means 5, in addition to the temperature information output from the temperature sensor 3, the exposure time, the remaining battery power, etc. are supplied with power. It is good also as a parameter of quantity calculation. That is, the exposure time affects the generation of FPN, and the battery remaining amount is useful for determining the upper limit of the amount of power supplied to the cooling means 5.
In addition, when used for microscopic observation, it is particularly effective for fluorescent observation in which weak light is acquired continuously over a long period of time.

  The present invention can be greatly utilized industrially in the fields of electronic cameras, imaging devices, microscopes, and the like.

It is a block diagram which shows the 1st Embodiment of this invention. It is a circuit diagram which shows an example of the variable resistance and cooling means shown in FIG. It is a block diagram which shows the 2nd Embodiment of this invention. The horizontal axis shows the temperature of the image sensor, and the vertical axis shows the normalized output of luminance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Imaging means, 2 ... Image processing means, 3 ... Temperature sensor, 4 ... Cooling control means, 5 ... Cooling means, 6 ... System controller, 21 ... Imaging lens, 22 ... Mirror, 23 ... Objective lens, 24 ... Sample , 25 ... stage, 26 ... transmitted illumination unit, 27 ... epi-illumination unit, 28 ... microscope control unit, 29 ... operation unit, 41 ... A / D converter for temperature measurement, 42 ... pulse generator for pulse drive, 43 variable Resistance value setting D / A converter 44... Variable resistance 51. Peltier element 100. Electronic camera 200 200 Microscope Tr Tr transistor

Claims (5)

In an electronic camera with a cooling control function, comprising: an imaging unit that images a subject to generate an image signal; and a cooling unit that cools the imaging unit.
A controller that sets whether the operation mode of the imaging means is a mode that prioritizes image quality or a mode that prioritizes image quality;
An operation mode determination unit for determining whether the set operation mode of the imaging unit is a mode in which image quality is prioritized or a mode in which image quality is not prioritized;
When it is determined that the determined operation mode is an operation mode that prioritizes image quality, the adjustment of the power supplied to the cooling means is DC drive, and the determined operation mode is an operation mode that prioritizes image quality Cooling control means for adjusting the supply power to the cooling means to be pulse-driven when it is determined that
An electronic camera with a cooling control function. In the electronic camera with a cooling control function according to claim 1,
  The electronic camera with a cooling control function, wherein the operation mode in which the image quality is not prioritized is an image monitoring mode, a focus mode, or an exposure control mode. In the electronic camera with a cooling control function according to claim 1,
  An electronic camera with a cooling control function, wherein the operation mode giving priority to the image quality is an image recording mode. In the electronic camera with a cooling control function according to claim 1,
  The cooling control means includes a variable resistor for adjusting power supplied to the cooling means, a variable resistance value setting D / A converter for controlling the variable resistance, and an optimum pulse width for controlling the variable resistance. Having a pulse generator for driving a pulse to generate a pulse having,
  During the DC driving, the cooling means is driven by the variable resistance controlled by the variable resistance value setting D / A converter, and during the pulse driving, an output from the pulse generator for pulse driving. An electronic camera with a cooling control function, wherein the cooling means is driven by the variable resistance controlled in step (a). A microscope comprising the electronic camera according to any one of claims 1 to 4.

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