JP2010153963A - Cooling camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling camera capable of evaporating water drops in the inside of the camera in a short time and preventing dew condensation of an image pickup element. <P>SOLUTION: The cooling camera has: the image pickup element 5, a casing 6 for hermetically housing the image pickup element 5, an electronic cooling element 2 arranged in the casing 6 and cooling the image pickup element 5, and a dehumidifying element 4 provided on the wall of the casing 6 and using a solid polymer electrolytic film. A first surface 2a of the electronic cooling element 2 contacts the image pickup element 5 and a second surface 2b contacts the wall surface of the casing 6, and the cooling camera executes a first action for allowing the first surface 2a of the electronic cooling element 2 to act as a cooling surface and the second surface 2b to act as a heat radiation surface, and a second action for allowing the first surface 2a of the electronic cooling element 2 to act as a heat radiation surface, allowing the second surface 2b to act as a cooling surface, and dehumidifying the inside of the casing 6 by the dehumidifying element 4 while switching the actions. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a cooling camera incorporating an electronic cooling element.

Conventionally, a cooling camera with a built-in Peltier element is known as an electronic cooling element. In recent years, an electrolysis cell has been used to prevent condensation on the image sensor, and the Peltier element is activated when the internal humidity of the camera is high. There has been proposed a configuration in which only the electrolysis cell is operated and the Peltier element is operated when the humidity is sufficiently lowered (see, for example, Patent Document 1). There has also been proposed a cooling camera having a water absorbing sheet for absorbing moisture condensed near the Peltier element (see, for example, Patent Document 2).
JP 2003-143449 A JP 2006-14248 A

  However, the conventional cooling camera using the electrolysis cell is very long in order to evaporate the water droplets by the electrolysis cell when water droplets are generated inside the camera due to use in a high humidity environment or for a long time. There was a problem of taking time. In addition, a conventional cooling camera using a water absorbing sheet can absorb water droplets by the water absorbing sheet, but when the water absorbing amount of the water absorbing sheet reaches a saturated state, the humidity inside the camera rises and condensation occurs on the image sensor. There was a problem of incurring problems such as blurring.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a cooling camera capable of evaporating water droplets generated inside the camera in a short time and preventing condensation of the image sensor. .

In order to solve the above problems, the present invention
An image sensor;
A housing for airtightly storing the image sensor;
An electronic cooling element that is disposed in the housing and cools the imaging element;
A dehumidifying element using a solid polymer electrolyte membrane, provided on the wall of the housing;
The first surface of the electronic cooling element is in contact with the imaging element, and the second surface is in contact with the wall surface of the housing;
A first operation in which the first surface of the electronic cooling element acts as a cooling surface, and the second surface acts as a heat dissipation surface; and the first surface of the electronic cooling element acts as a heat dissipation surface; There is provided a cooling camera characterized in that the surface is caused to act as a cooling surface and the second operation of dehumidifying the inside of the housing by the dehumidifying element is switched.

  According to the present invention, it is possible to provide a cooling camera capable of evaporating water droplets generated in the camera in a short time and preventing condensation of the image sensor.

Hereinafter, a cooling camera according to each embodiment of the present invention will be described with reference to the accompanying drawings.
(First embodiment)
FIG. 1 is a cross-sectional view showing the configuration of the cooling camera according to the first embodiment of the present invention.
As shown in FIG. 1, the cooling camera 1 according to this embodiment includes a Peltier element 2, a substrate 3, an electrolysis cell 4, an imaging element (CCD) 5, and the like described in detail below in a housing 6. .

The housing 6 includes a front housing 7 and a heat radiating housing 8, which are fixed at a plurality of positions with screws 10 on a flange portion 7 a on the outer periphery of the front housing 7 through an O-ring 9 while maintaining an airtight state. Yes.
An opening 7 b is formed in the front casing 7 at a position facing the CCD 5, and a glass plate 11 is fixed to the opening 7 b through an O-ring 12 while maintaining an airtight state. In the front housing 7, a mount portion 7 c for attaching the main cooling camera 1 to a lens barrel such as a microscope is provided at the outer peripheral position of the glass plate 11.

The heat radiating housing 8 is formed with a through-hole 13 adjacent to the projection 8a formed in the heat radiating housing 8, that is, in the vicinity of the Peltier element 2, and the front housing 7 side of the through-hole 13 is A large diameter portion 13a is provided at the position. The electrolytic cell 4 whose outer periphery is covered with an insulator 14 such as a resin is fixed to the large diameter portion 13a with an adhesive while maintaining an airtight state. The insulator 14 is formed with an opening for exposing the anode 4a of the electrolysis cell 4 to the space in the cooling camera 1 and an opening for exposing the cathode 4b to the outside. Further, a pilot lamp 15 described later is provided outside the heat radiating housing 8. The heat dissipating casing 8 having such a configuration is desirably made of a metal material such as aluminum having good thermal conductivity.
With the above configuration, the inside of the housing 6 is always kept airtight.

The substrate 3 is installed in the heat radiating housing 8 at a predetermined interval by being fixed to the heat radiating housing 8 with screws 17 with the sleeve 16 interposed therebetween.
The substrate 3 includes a power supply circuit 18 for supplying power input from an external device such as a camera control unit to each element such as the CCD 5, the Peltier element 2, and the electrolysis cell 4, and the elements and the power supply circuit 18. A control circuit 20 that performs control and processing of an image signal obtained by the CCD 5 is mounted. A CCD 5 is mounted on the opposite surface of the substrate 3 by soldering, and a humidity sensor 21 is mounted near the CCD 5. The humidity sensor 21 can be provided at other positions inside the cooling camera 1, but is preferably provided near the contact surface between the Peltier element 2 and the CCD 5 that are most likely to condense inside the cooling camera 1.
A square through hole 3a is formed at the center of the substrate 3, and the Peltier element 2 is disposed in the through hole 3a.

The Peltier element 2 is a plate-like electronic cooling element for cooling the CCD 5, and the first surface 2 a, which is the lower surface in FIG. 1, is bonded to the back surface of the CCD 5 via the heat conductive double-sided tape 22. The second surface 2 b, which is the upper surface in FIG. 1, is in contact with the convex portion 8 a of the heat radiating housing 8 through the heat conductive sheet 23.
The heat conductive sheet 23 is a sheet made of resin such as silicone, and the thickness dimension thereof is larger than the gap dimension between the Peltier element 2 and the convex portion 8a of the heat radiating housing 8, and the heat conductive sheet 23 is deformed when assembled. By doing so, adhesion is secured. Specifically, in the present embodiment, a 0.5 mm thick heat conductive sheet 23 is inserted into a gap dimension of 0.4 mm. With such a heat conductive sheet 23, it is possible to ensure adhesion between the second surface 2 b of the Peltier element 2 and the convex portion 8 a of the heat radiating housing 8 and to ensure heat conductivity.

  As shown in FIG. 2A, the Peltier element 2 is connected with two power sources 26a and 26b in different directions as a power circuit 25. The power sources 26a and 26b are provided with switches 27a and 27b, respectively. It has been. These switches 27a and 27b are configured to open and close in conjunction so that when one is connected, the other is not connected. Such a power supply circuit 25 is included in the power supply circuit 18 on the substrate 3 described above. With such a configuration, the control circuit 20 controls the operation of the switches 27a and 27b to control the voltage applied to the Peltier element 2. The polarity can be reversed.

Under the above configuration, when the control circuit 20 on the substrate 3 controls the power supply circuit 18 to open the switch 27a of the power supply circuit 25 and connect the switch 27b as shown in FIG. A voltage is applied to the Peltier element 2 by 26b, and heat is transferred from the first surface 2a toward the second surface 2b. Thereby, the 1st surface 2a can act as a cooling surface, and the 2nd surface 2b can be made to act as a thermal radiation surface (after-mentioned normal operation).
On the other hand, when the control circuit 20 connects the switch 27a of the power supply circuit 25 and opens the switch 27b as shown in FIG. 2B, a voltage is applied to the Peltier element 2 by the power supply 26a, that is, FIG. A voltage opposite to (a) is applied to the Peltier element 2. Therefore, the first surface 2a can act as a heat dissipation surface, and the second surface 2b can act as a cooling surface (forced dehumidification operation described later).
Although the power sources 26a and 26b are constant voltage sources, the power source is not limited to this, and may be a variable voltage type power source. In this case, the voltage may be appropriately controlled while measuring the cooling temperature or heating temperature of the CCD 5.

  The electrolysis cell 4 is a dehumidifying element using a solid polymer electrolyte membrane. By applying a predetermined voltage to the anode 4a and the cathode 4b of the electrolysis cell 4, the electrolysis cell 4 on the anode side of the solid polymer electrolyte membrane. Water molecules are decomposed to lower the humidity, and some of the water molecules decomposed on the cathode side appear to generate water vapor. The electrolysis cell 4 is connected to the above-described power supply circuit 18 on the substrate 3 by an electric wire (not shown), and thereby, power can be supplied to the electrolysis cell 4.

Next, the normal operation of the Peltier device 2 and the electrolysis cell 4 in the cooling camera 1 according to this embodiment and the forced dehumidification operation for evaporating water droplets generated in the cooling camera 1 will be described.
(Normal operation)
In the cooling camera 1 according to the present embodiment having the above configuration, light from a subject (not shown) guided to the cooling camera 1 is projected onto the imaging surface 5a of the CCD 5 to form a subject image. This subject image is photoelectrically converted by the CCD 5, converted to image data by the control circuit 20 on the substrate 3, and then output to an external device such as a camera control unit.

Here, when the operating CCD 5 generates heat and its temperature rises, the image quality of the photographed image deteriorates due to dark current noise caused by this. In order to prevent this, in the present cooling camera 1, the control circuit 20 controls the power supply circuit 18 to apply the voltage of the power supply 26b to the Peltier element 2 as shown in FIG. Thereby, the CCD 5 can be cooled by the first surface 2a acting as the cooling surface to suppress the generation of dark current, and heat is conducted from the second surface 2b acting as the heat radiating surface to the heat radiating housing 8 to allow outside air to flow. Can be released.
At the same time, in the cooling camera 1, the control circuit 20 controls the power supply circuit 18 to apply a predetermined voltage to the electrolysis cell 4 to operate the electrolysis cell 4. As a result, water vapor originally present in the inside of the cooling camera 1 (in the sealed space formed by the heat radiating housing 8, the front housing 7, and the glass plate 11) and the O-rings 9, 12 and the like are transmitted by cooling. Thus, a very small amount of water vapor that intrudes can be discharged to the outside by the electrolysis action of the electrolysis cell 4, thereby preventing condensation on the glass surface 5 b of the CCD 5.

(Forced dehumidification operation)
In the cooling camera 1, when the above-described normal operation is repeatedly performed particularly in a high humidity environment, the inside of the cooling camera 1 passes through the O-rings 9, 12, etc. from the outside rather than the amount of water vapor released from the electrolysis cell 4. The amount of water vapor entering the water increases, and water droplets may be generated inside the cooling camera 1, particularly in the vicinity of the first surface 2 a of the Peltier element 2. In such a case, the humidity inside the cooling camera 1 rises, and if the normal operation described above is performed in this state, condensation occurs on the glass surface 5b of the CCD 5, leading to deterioration of the image quality of the photographed image. End up.

Therefore, in order to avoid such a problem, in the present cooling camera 1, the control circuit 20 controls the power supply circuit 18 to apply the voltage of the power source 27a to the Peltier element 2 as shown in FIG. Accordingly, since the first surface 2a acts as a heat dissipation surface, the first surface 2a and the CCD 5 in contact with the first surface 2a are heated, and water vapor in the vicinity thereof is evaporated into the atmosphere in the cooling camera 1. be able to. At this time, the second surface 2b acts as a cooling surface. However, since the heat capacity of the heat dissipating casing 8 is larger than the heat capacity of the CCD 5, no significant temperature drop of the heat dissipating casing 8 occurs and no dew condensation occurs.
At the same time, in the cooling camera 1, the control circuit 20 controls the power supply circuit 18 to apply a predetermined voltage to the electrolysis cell 4 to operate the electrolysis cell 4. Thereby, the water vapor evaporated into the atmosphere in the cooling camera 1 as described above can be released to the outside by the electrolysis action of the electrolysis cell 4, thereby preventing condensation on the glass surface 5 b of the CCD 5. be able to.

In the cooling camera 1 according to the present embodiment, the normal operation and the forced dehumidification operation described above are performed according to the control routine described below.
FIG. 3 is a flowchart showing a control routine of the cooling camera 1 according to the first embodiment of the present invention.
This control routine is started when the cooling camera 1 is turned on.
Step S <b> 1: The control circuit 20 on the substrate 3 acquires the relative humidity value X detected by the humidity sensor 21 from the humidity sensor 21.

Step S2: The control circuit 20 determines whether or not the relative humidity value X acquired in Step S1 is equal to or less than a reference humidity value X0 described later. If the relative humidity value X is less than or equal to the reference humidity value X0, the process proceeds to step S3, and if the relative humidity value X is greater than the reference humidity value X0, the process proceeds to step S4.
Here, the reference humidity value X0 is a humidity at which condensation does not occur when the CCD 5 is cooled under a humidity condition equal to or lower than the reference humidity value X0, and is a value depending on the cooling temperature of the CCD 5 by the Peltier element 2. is there. The reference humidity value X0 is a value that also depends on the location of the humidity sensor 21, and is preferably set by experiment.

Step S3: The normal operation of the Peltier element 2 and the electrolysis cell 4 is performed, and the process returns to Step S1.
Step S4: The forced dehumidification operation of the Peltier element 2 and the electrolysis cell 4 is performed, and the process returns to Step S1. During the forced dehumidifying operation, the control circuit 20 lights the pilot lamp 15 provided in the heat radiating housing 8 to display to the user that the forced dehumidifying operation is currently being performed.
The above control routine is repeatedly executed after the cooling camera 1 is turned on until the power is turned off.

As described above, in the cooling camera 1 according to the present embodiment, the normal operation and the forced dehumidification operation of the Peltier element 2 and the electrolysis cell 4 can be automatically and appropriately switched by executing the above-described control routine. Condensation can be effectively prevented.
In step S4 of the control routine, since the CCD 5 is heated, the output of image data from the control circuit 20 to an external device such as a camera control unit is stopped, and the cooling camera 1 is set in a shooting pause state. Also good.
Similarly, in step S4, the information indicating that the forced dehumidifying operation is being performed is not limited to the lighting of the pilot lamp 15, and superimposed information is displayed on the monitor that displays the captured image, or an audio output means is provided. It can also be set as the structure output by an audio | voice.

In the cooling camera 1 according to the present embodiment, it is desirable to provide a temperature / humidity sensor capable of measuring temperature simultaneously with humidity instead of the humidity sensor 21. In such a case, a reference humidity value X0 is set in advance for each temperature inside the cooling camera 1 and stored in a storage device (not shown) on the substrate 3. As a result, the control circuit 20 can read out the reference humidity value X0 corresponding to the temperature measured by the temperature / humidity sensor from the storage device and execute the control routine based on the reference humidity value X0. Condensation on the glass surface 5b can be prevented.
Further, in the cooling camera 1 according to the present embodiment, the user can manually switch between the normal operation and the forced dehumidification operation as described above.

  As described above, the cooling camera 1 according to this embodiment is configured to forcibly evaporate water droplets generated in the camera with the Peltier element 2 in a short time as described above by the forced dehumidifying operation of the Peltier element 2 and the electrolysis cell 4. The evaporated water vapor can be discharged to the outside of the cooling camera 1 by the electrolysis cell 4 and effectively dehumidified. For this reason, the forced dehumidifying operation is completed in a short time and the normal operation is performed, that is, the cooling camera 1 can be returned to the normal use state in a short time. Further, it is possible to effectively prevent a failure of the Peltier element 2 due to water droplets generated on the Peltier element 2 or the like which is most likely to condense in the cooling camera 1 or a short circuit due to water droplets adhering to the electronic components on the substrate 3. You can also.

In the cooling camera 1 according to the present embodiment, the electrolysis cell 4 is always operated through normal operation and forced dehumidification operation. Thereby, dehumidification inside the cooling camera 1 can be effectively performed and the occurrence of condensation can be more effectively suppressed. However, the present invention is not limited to this, and the life of the electrolysis cell 4 can be extended as a configuration in which the operation of the electrolysis cell 4 is suspended during normal operation.
Since the cooling camera 1 according to the present embodiment employs the electrolysis cell 4 as a dehumidifying element, the water absorption amount of the water absorbing sheet reaches a saturated state as in a conventional cooling camera using a water absorbing sheet, and the imaging element. Of course, no condensation will occur.

(Second Embodiment)
In the present embodiment and a third embodiment to be described later, parts having the same configurations as those of the first embodiment are denoted by the same reference numerals, description thereof is omitted, and different parts are described in detail.
FIG. 4 is a cross-sectional view showing a configuration of a cooling camera according to the second embodiment of the present invention.
As shown in FIG. 4, the cooling camera 30 according to the present embodiment includes a heat conduction plate 31 made of aluminum between the Peltier element 2 and the CCD 5, and the upper surface of the heat conduction plate 31 and the second Peltier element 2. One surface 2a, the lower surface of the heat conductive plate 31, and the CCD 5 are bonded by a heat conductive double-sided tape 32, respectively. In order to dispose the heat conducting plate 31 between the Peltier element 2 and the CCD 5, the heat radiating housing 8 is not formed with the convex portion 8a as in the first embodiment.

The cooling camera 30 according to the present embodiment having such a configuration can achieve the same effects as those of the first embodiment. Further, the heat conduction plate 31 can make the temperature uniform when the CCD 5 is cooled and heated by the Peltier element 2.
The material of the heat conductive plate 31 is not limited to aluminum, and other materials such as a metal having high heat conductivity can be used.

(Third embodiment)
FIG. 5 is a cross-sectional view showing a configuration of a cooling camera according to the third embodiment of the present invention.
As shown in FIG. 5, the cooling camera 40 according to the present embodiment is adhered to the back surface of the CCD 5 in the vicinity of the contact position between the back surface of the CCD 5 and the first surface 2 a of the Peltier element 2 with an adhesive tape or the like. A water absorbing sheet 41 is provided.
The water absorbent sheet 41 has a property of absorbing moisture in a temperature environment equal to or lower than a predetermined temperature T0 and releasing the absorbed moisture as water vapor in a temperature environment exceeding the predetermined temperature T0. Specifically, the water absorbing sheet 41 of the present embodiment absorbs moisture when the internal temperature of the cooling camera 40 becomes a predetermined temperature T0 or less during normal operation of the Peltier element 2 and the electrolytic cell 4, and the cooling camera during forced dehumidification operation. The internal temperature of 40 exceeds the predetermined temperature T0, and the water that has been absorbed during normal operation is discharged as water vapor.

  In the cooling camera 40 according to the present embodiment having such a configuration, the water absorbing sheet 41 absorbs moisture inside the cooling camera 40 during normal operation of the Peltier element 2 and the electrolysis cell 4. When the water absorption amount of the water absorbing sheet 41 reaches a saturated state, the humidity inside the cooling camera 40 increases, and the relative humidity value X detected by the humidity sensor 21 exceeds the reference humidity value X0. The decomposition cell 4 shifts to the forced dehumidification operation. During the forced dehumidifying operation, the water absorbing sheet 41 can release moisture absorbed during normal operation into the cooling camera 40 as water vapor, and can return from a saturated state to a water absorbing state. At this time, the water vapor released to the inside of the cooling camera 40 is released to the outside of the cooling camera 40 by the electrolysis cell 4.

The cooling camera 40 according to the present embodiment having such a configuration can achieve the same effects as those of the first embodiment. Further, the water absorbing sheet 41 can more effectively dehumidify the Peltier element 2 and the CCD 5 in the vicinity of the cooling camera 40 where condensation is most likely to occur, and more effectively prevent condensation on the glass surface 5b of the CCD 5. Can do.
In addition, in this embodiment, although the water absorbing sheet 41 is used, it is not restricted to this, For example, it is also possible to use other desiccants, such as a silica gel.

  According to each of the embodiments described above, it is possible to realize a cooling camera that can evaporate water droplets generated in the camera in a short time and prevent condensation of the image sensor.

It is sectional drawing which shows the structure of the cooling camera 1 which concerns on 1st Embodiment of this invention. It is a figure which shows the structure of the power supply circuit 25 connected to the Peltier device 2 of the cooling camera 1 which concerns on 1st Embodiment of this invention. It is a flowchart which shows the control routine of the cooling camera 1 which concerns on 1st Embodiment of this invention. It is sectional drawing which shows the structure of the cooling camera 1 which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the structure of the cooling camera 1 which concerns on 3rd Embodiment of this invention.

Explanation of symbols

1,30,40 Cooling camera 2 Peltier element 2a Peltier element first surface 2b Peltier element second surface 3 Substrate 4 Electrolysis cell 5 CCD
6 Housing 15 Pilot lamp 20 Control circuit 21 Humidity sensor 22, 32 Thermally conductive double-sided tape 23 Thermal conductive sheet 31 Thermal conductive plate 41 Water absorbing sheet

Claims (9)

An image sensor;
A housing for airtightly storing the image sensor;
An electronic cooling element that is disposed in the housing and cools the imaging element;
A dehumidifying element using a solid polymer electrolyte membrane, provided on the wall of the housing;
The first surface of the electronic cooling element is in contact with the imaging element, and the second surface is in contact with the wall surface of the housing;
A first operation in which the first surface of the electronic cooling element acts as a cooling surface, and the second surface acts as a heat dissipation surface; and the first surface of the electronic cooling element acts as a heat dissipation surface; A cooling camera characterized in that the surface is operated as a cooling surface and the second operation of dehumidifying the inside of the housing by the dehumidifying element is switched. Having humidity detecting means for detecting humidity in the housing;
The cooling camera according to claim 1, wherein the first operation and the second operation are switched in accordance with a detection result of the humidity detection means.   The cooling camera according to claim 2, further comprising a control unit that automatically switches between the first operation and the second operation based on a detection result of the humidity detection unit.   4. The cooling camera according to claim 2, wherein the humidity detection unit is disposed in the vicinity of the first surface of the electronic cooling element. 5.   5. The cooling camera according to claim 1, wherein at least one kind of heat conducting member is provided between the first surface of the electronic cooling element and the imaging element. 6.   6. The cooling according to claim 1, wherein at least one type of heat conducting member is provided between the second surface of the electronic cooling element and a wall surface of the housing. camera.   In the vicinity of the contact position between the first surface of the electronic cooling element and the imaging element, there is a water absorbing means for absorbing moisture during the first operation and releasing moisture as water vapor during the second operation. The cooling camera according to any one of claims 1 to 6, wherein:   The information output means for outputting the information that said 2nd operation is being implemented at the time of said 2nd operation | movement is provided, The information output means as described in any one of Claim 1-7 characterized by the above-mentioned. Cooling camera.   In the first operation, the first surface of the electronic cooling element acts as a cooling surface, the second surface acts as a heat radiating surface, and the dehumidifying element dehumidifies the housing. The cooling camera according to any one of claims 1 to 8.

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