Cooling device, control method, program, and storage medium

Abstract

To efficiently cool a cooling target by preventing dew condensation in a housing while reducing a power consumption of a dehumidifying element.SOLUTION: A cooling device is a cooling device for cooling a cooling target in a housing, and includes: cooling means for cooling the cooling target; dehumidifying means for dehumidifying the inside of the housing; first obtaining means for obtaining an internal temperature of the housing; second obtaining means for obtaining an internal humidity of the housing; third obtaining means for obtaining a cooling surface temperature of the cooling means; and control means for controlling activation and deactivation of the dehumidifying means. The control means calculates a dew point temperature in the housing based on the internal temperature and the internal humidity, activates the dehumidifying means when a difference between a dew point temperature and a cooling surface temperature is smaller than a threshold value, and adjusts the threshold value based on an output of the cooling means.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cooling device, a control method, a program, and a storage medium. [Background technology]

[0002] Conventionally, cooling devices with built-in Peltier elements are known. Because the cooling elements of these devices can cool to temperatures below ambient temperature, condensation can occur inside the housing of the cooling device. Condensation inside the housing of the cooling device can cause problems such as short circuits in electrical components.

[0003] As a countermeasure, Patent Document 1 discloses a technology for preventing condensation in an imaging device equipped with a cooling element and a dehumidifying element by supplying power to the cooling element so that the target temperature is reached after the time when the limit humidity, which is the dehumidification limit of the dehumidifying element, is reached. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2009-152971 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in Patent Document 1, the dehumidifying element is constantly operating, so it continues to dehumidify even after the inside of the housing has been dehumidified to a humidity level where condensation does not occur, resulting in the dehumidifying element consuming more power than necessary. This consumption of more power than necessary can be a factor in raising the temperature inside the housing.

[0006] Therefore, the problem to be solved by the present invention is to reduce the power consumption of the dehumidifying element while preventing condensation inside the housing and efficiently cooling the object to be cooled. [Means for solving the problem]

[0007] In order to solve the above problem, a cooling device according to one embodiment of the present invention is a cooling device for cooling a cooling object inside a housing, and includes a cooling means for cooling the cooling object, a dehumidifying means for dehumidifying the inside of the housing, a first acquisition means for acquiring the internal temperature of the housing, a second acquisition means for acquiring the internal humidity of the housing, a third acquisition means for acquiring the cooling surface temperature of the cooling means, and a control means for controlling the start and stop of the dehumidifying means, wherein the control means calculates a dew point temperature inside the housing based on the internal temperature and the internal humidity, starts the dehumidifying means when the difference between the dew point temperature and the cooling surface temperature is smaller than a threshold value, and adjusts the threshold value based on the output of the cooling means. [Effects of the Invention]

[0008] According to the present invention, it is possible to reduce the power consumption of the dehumidifying element while preventing condensation on the housing, and to efficiently cool the object to be cooled. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a diagram showing the device configuration of a camera housing. [Figure 2] 10 is a flowchart showing a cooling process by a cooling element of the camera housing and a dehumidifying process by a dehumidifying element. [Figure 3] 10 is a graph showing the relationship between cooling surface temperature and dew point temperature for different threshold Z values ​​of the camera housing and the output of the cooling element. [Figure 4] FIG. 1 is a diagram showing the configuration of an imaging apparatus. [Figure 5] 5 is a flowchart showing a cooling process by a cooling element and a dehumidifying process by a dehumidifying element of the imaging device. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments described below are examples of means for realizing the present invention, and should be appropriately modified or changed depending on the configuration of the device to which the present invention is applied and various conditions. The present invention is not limited to the following embodiments. Furthermore, a configuration may be made by appropriately combining parts of each embodiment described below.

[0011] <Embodiment 1> (Device configuration) The camera housing according to this embodiment will now be described. FIG. 1 is a diagram showing the device configuration of the camera housing according to this embodiment. The camera housing 20 includes a housing 2 that contains a substantially sealed internal space 15. The internal space 15 of the housing 2 houses an imaging device 30, which is protected from raindrops and dust in outdoor environments. The imaging device 30 is fixed to a camera stand 22, and captures an external space 18 through a light-transmitting front window 21.

[0012] The camera housing 20 further includes a cooling element 3 (cooling means), a dehumidifying element 4 (dehumidifying means), an internal heat sink 23, an internal fan 24, a duct 25, an external heat sink 10, and an external fan 11.

[0013] The cooling element 3 is, for example, a Peltier element, and is arranged so that the cooling surface of the cooling element 3 abuts against the internal heat sink 23 and the heat dissipation surface of the cooling element 3 abuts against the external heat sink 10. Note that a heat conductor with high thermal conductivity, such as a heat dissipation sheet or heat dissipation grease, may be interposed between the cooling element 3 and the internal heat sink 23 and between the cooling element 3 and the external heat sink 10. The desired cooling temperature can be set for the cooling surface of the cooling element 3 by adjusting the amount of power supplied to the cooling element 3, and the temperature of the cooling surface can be lowered by increasing the output of the cooling element 3.

[0014] The air cooled by the cooling element 3 through the internal heat sink 23 is blown by the internal fan 24 through the duct 25 to cool the internal space 15. The heat conducted to the external heat sink 10 by the cooling element 3 is dissipated to the external space 18 by the external fan 11. This protects the imaging device 30 from raindrops and dust, and also suppresses a temperature rise in the internal space 15 due to heat exhaust from the imaging device 30.

[0015] The dehumidifying element 4 is a component that uses a solid polymer electrolyte membrane to electrolyze and remove water vapor from the air. When a voltage is applied to the anode and cathode of the dehumidifying element 4, water molecules are decomposed into hydrogen ions and oxygen on the anode side, reducing humidity. The decomposed hydrogen ions react with oxygen in the air on the cathode side to form water molecules, which are then released. By dehumidifying the internal space 15 using the dehumidifying element 4, condensation is prevented when the internal space 15 is cooled by the cooling element 3. When no voltage is applied, the dehumidifying element 4 allows water vapor to pass through it, so that the humidity in the internal space 15 and the external space 18 are in equilibrium. Therefore, when the dehumidifying element 4 is turned off after dehumidifying the internal space 15, water vapor enters the internal space 15 from the external space 18 over time, causing the humidity in the internal space 15 to rise until it reaches equilibrium.

[0016] The camera housing 20 further includes an external temperature sensor 8, an internal temperature sensor 5, an internal humidity sensor 6, a cooling surface temperature sensor 7, and a control board 9.

[0017] The external temperature sensor 8 (fourth acquisition means) is a temperature sensor that measures the temperature of the external space 18 (hereinafter referred to as the external temperature), and the internal temperature sensor 5 (first acquisition means) is a temperature sensor that measures the temperature of the internal space 15 (hereinafter referred to as the internal temperature).

[0018] The internal humidity sensor 6 (second acquisition means) is a humidity sensor that measures the humidity in the internal space 15 (hereinafter referred to as internal humidity), and the cooling surface temperature sensor 7 (third acquisition means) is a temperature sensor that measures the temperature of the cooling surface of the cooling element 3 (hereinafter referred to as cooling surface temperature). The cooling surface temperature sensor 7 may measure a temperature correlated with the cooling surface temperature, such as the temperature near the cooling surface of the cooling element 3, and acquire an estimated value from the measured value. In other words, the cooling surface temperature sensor 7 may be disposed near the cooling surface.

[0019] The control board 9 (control means) is a control board that comprehensively controls the cooling process by the cooling element 3 and the dehumidifying process by the dehumidifying element 4. The control board 9 is connected to each sensor and each element as shown by the dashed lines, and comprehensively controls mainly the cooling element 3, the dehumidifying element 4, the internal fan 24, and the external fan 11. The control board 9 has a CPU (Central Processing Unit) such as a microcontroller or microprocessor (not shown). The CPU executes programs for controlling each element that are stored in RAM (Random Access Memory) or ROM (Read Only Memory), not shown. The output of the cooling element 3 is controlled by, for example, a PWM control method or a constant current control method.

[0020] (Operation description) The cooling and dehumidifying operations of the camera housing 20 according to this embodiment will now be described. FIG. 2 is a flowchart showing the cooling process by the cooling element 3 and the dehumidifying process by the dehumidifying element 4. Each operation shown in the flowchart in FIG. 2 is realized by a control program being executed by a microcontroller or microprocessor on the control board 9. When the power supply (not shown) of the camera housing 20 is turned on, the processing of this flowchart begins. The processing of this flowchart can be executed repeatedly while the power supply of the main body is on.

[0021] In step S101, the internal fan 24 is started. Next, in step S102, temperature information is acquired from each of the external temperature sensor 8, the internal temperature sensor 5, the internal humidity sensor 6, and the cooling surface temperature sensor 7. That is, the internal temperature, external temperature, internal humidity, and cooling surface temperature are acquired. Then, in step S103, the dew-point temperature of the internal space 15 is calculated from the internal temperature and internal humidity acquired in step S102.

[0022] In step S104, it is determined whether the internal space 15 needs to be cooled. If the difference between the internal temperature acquired from the internal temperature sensor 5 and the target temperature pre-stored in a storage medium such as a ROM is greater than 0 (if the internal temperature is higher than the target temperature), it is determined that the internal space 15 needs to be cooled, and the process proceeds to step S105. For example, this may be the case when the outside temperature is high and the internal cooling is insufficient. On the other hand, if the difference between the internal temperature and the target temperature is 0 or less (if the internal temperature is equal to or lower than the target temperature), it is determined that the internal space 15 does not need to be cooled, the output of the cooling element 3 is reduced (S110), and the process proceeds to step S111. For example, this may be the case when the outside temperature is low and the internal temperature is also low, or when the outside temperature is high but the internal temperature is sufficiently cooled. This prevents the internal space from being cooled more than necessary, and reduces power consumption by the cooling element 3. Note that if the output of the cooling element 3 is 0% (OFF) in step S110, it is maintained at 0%. The target temperature may be set in advance to, for example, the upper limit temperature of the environment in which the image capture device 30 is used.

[0023] In step S105, it is determined whether condensation will occur even if the cooling surface temperature is reduced by increasing the output of the cooling element 3. If the difference between the current cooling surface temperature acquired from the cooling surface temperature sensor 7 and the dew-point temperature calculated in step S103 is greater than threshold Y, it is determined that condensation is unlikely to occur even if the cooling surface temperature is reduced, and the process proceeds to step S106. For example, if the interior has been sufficiently dehumidified and the dew-point temperature has reduced, the difference between the cooling surface temperature and the dew-point temperature will be large, and there is a possibility that this difference will exceed threshold Y.

[0024] On the other hand, if the difference between the current cooling surface temperature acquired from the cooling surface temperature sensor 7 and the dew-point temperature calculated in step S103 is equal to or less than the threshold Y, it is determined that a decrease in the cooling surface temperature is likely to result in condensation, and the output of the cooling element 3 is reduced (S109), and the process proceeds to step S111. For example, if the cooling element 3 is providing sufficient cooling and the cooling surface temperature is decreasing, the difference between the cooling surface temperature and the dew-point temperature will become smaller, potentially making the difference smaller than the threshold Y. Note that if the output of the cooling element 3 is already at 0% in step S109, the output cannot be further reduced and is therefore maintained at 0%. Note that in this embodiment, an example has been shown in which the output of the cooling element is controlled based on the difference between the cooling surface temperature, which is likely to be the lowest temperature in the internal space 15, and the dew-point temperature. However, it is also possible to control the output of the cooling element based on the difference between the internal temperature and the dew-point temperature. Because the cooling surface of the cooling element 3 is most likely to cause condensation, this embodiment will describe an example in which the difference between the cooling surface temperature and the dew-point temperature is used as a preferred example.

[0025] Here, the threshold value Y will be explained. The threshold value Y is a value indicating the margin of the cooling surface temperature relative to the dew point temperature so that condensation does not occur on the cooling surface of the cooling element 3, and is, for example, Y=1. The smaller the value of the threshold value Y, the easier it is to determine in step S105 that condensation is unlikely to occur, and therefore the easier it is to increase the output of the cooling element 3. However, because the margin of the cooling surface temperature relative to the dew point temperature is small, the possibility of condensation occurring before it is determined that condensation is likely to occur (NO in step S105) increases.

[0026] On the other hand, the larger the value of threshold Y, the more likely it is that condensation will occur in step S105, so the output of the cooling element is more likely to decrease, and the actual possibility of condensation occurring becomes smaller. However, since it is difficult to increase the output of cooling element 3, it may take a long time to cool the inside.

[0027] In step S106, it is determined whether the output of the cooling element 3 needs to be increased. Generally, it is difficult to configure a camera housing so that the internal space is insulated from the external space. If the internal temperature drops below the external temperature, heat from the external space is transferred to the internal space, potentially reducing the internal cooling efficiency. Therefore, it is desirable not to cool the internal temperature below the external temperature. In step S106, if the difference between the internal temperature acquired from the internal temperature sensor 5 and the external temperature acquired from the external temperature sensor 8 is greater than 0, the output of the cooling element 3 is increased (step S107), and the process proceeds to step S111. This may be due, for example, to insufficient cooling of the internal space or a low-temperature external environment. However, if the output of the cooling element 3 is 100% in step S107, the output cannot be increased any further, and therefore the output is maintained at 100%.

[0028] On the other hand, if the difference between the internal temperature acquired from the internal temperature sensor 5 and the external temperature acquired from the external temperature sensor 8 is 0 or less, it is determined that there is no need to increase the output of the cooling element 3, so the output of the cooling element 3 is maintained (S108), and the process proceeds to step S111. For example, this may be the case when the inside is sufficiently cooled or the outside has become hot.

[0029] In step S111, it is determined whether it is necessary to dehumidify the interior using the dehumidifying element 4. If the difference between the cooling surface temperature acquired from the cooling surface temperature sensor 7 and the dew-point temperature calculated in step S103 is smaller than the threshold Z, it is determined that it is necessary to dehumidify the interior using the dehumidifying element 4, and the dehumidifying element 4 is activated (step S112). If the dehumidifying element 4 is already activated, its operation is continued. On the other hand, if the difference between the cooling surface temperature acquired from the cooling surface temperature sensor 7 and the dew-point temperature calculated in step S103 is equal to or greater than the threshold Z, it is determined that it is not necessary to dehumidify the interior using the dehumidifying element 4, and the dehumidifying element 4 is deactivated (step S113). For example, it may be that the interior has been sufficiently dehumidified and the dew-point temperature has dropped. In determining whether to activate or deactivate the dehumidifying element 4, similar to the control of the output of the cooling element 3, it may be determined whether to activate or deactivate the dehumidifying element 4 based on the difference between the internal temperature and the dew-point temperature.

[0030] Here, the threshold value Z will be explained. The threshold value Z is a threshold value for determining whether or not to activate the dehumidifying element 4, and is a threshold value for the difference between the cooling surface temperature and the dew point temperature. In this embodiment, the threshold value Z is determined so that it increases as the output of the cooling element 3 decreases, and so that it decreases as the output of the cooling element 3 increases. The threshold value Z is expressed, for example, as in equation (1). Z = Y + B × (100 - P) / 100 (B is a constant, P is a variable) (1)

[0031] The constant B is a value corresponding to the temperature difference of the cooling surface temperature when the output of the cooling element 3 changes from 0% to 100%, for example, B=20. The variable P is the output (0 to 100) of the cooling element 3. By changing the threshold Z according to the output of the cooling element 3 as in formula (1), it is possible to accommodate rapid cooling, and to efficiently cool the inside without condensation while preventing the dehumidifying element 4 from consuming more power than necessary.

[0032] FIG. 3 shows the relationship between the cooling surface temperature and dew point temperature with respect to the output of the cooling element 3 at threshold Z of the camera housing 20. FIGS. 3(a), 3(b), and 3(c) show the relationship between the cooling surface temperature and dew point temperature with respect to the output of the cooling element 3 when threshold Z is Y, Y+B, and Y+B(100-P) / 100, respectively. The vertical axis represents temperature, and the horizontal axis represents time. That is, the threshold Z in this embodiment is shown in FIG. 3(c).

[0033] First, consider the case where threshold value Z is set to the same value as threshold value Y described above (see FIG. 3(a)). According to the flowchart shown in FIG. 2, if the output of cooling element 3 rises to P% while dehumidifying the internal space, the temperature difference between the cooling surface temperature and the dew point temperature will be Z (= Y) in step S111. If the external temperature rises suddenly from this state, the internal temperature will also rise, and it will be necessary to increase the output of cooling element 3 to cool the internal space.

[0034] However, the decrease in dew point temperature due to dehumidification by the dehumidifying element 4 is small compared to the decrease in cooling surface temperature of the cooling element 3. Therefore, as shown in FIG. 3(a), the cooling surface temperature is gradually decreased from time T1 to time T2 while maintaining the difference Y from the dew point temperature. Normally, when the output of the cooling element 3 changes from 0% to 100%, the cooling surface temperature changes approximately linearly. However, the dew point temperature response of the dehumidifying element 4 is small compared to the response of the cooling surface temperature. To prevent condensation, the cooling surface temperature must be kept higher than the dew point temperature. Therefore, the output of the cooling element 3 must be adjusted to match the dehumidification (decrease in dew point temperature) by the dehumidifying element 4. Unlike the cooling element 3, the dehumidifying performance of the dehumidifying element 4 cannot be increased in response to the output, and therefore the dew point temperature cannot follow a sudden decrease in the cooling surface temperature of the cooling element 3. Therefore, if the threshold value Z is set to the same value as the threshold value Y, it is difficult to rapidly cool the interior space.

[0035] Next, consider the case where threshold Z is the sum of the aforementioned threshold Y and the aforementioned constant B, Y+B (see FIG. 3(b)). When cooling progresses while dehumidifying the internal space according to the flowchart shown in FIG. 2 and the output of cooling element 3 rises to P%, the temperature difference between the cooling surface temperature and the dew-point temperature becomes Z (=Y+B) in step S111. In other words, when the temperature difference between the cooling surface temperature and the dew-point temperature falls below Y+B, dehumidifying element 4 starts up, and the margin of Y+B is maintained. If the external temperature rises suddenly from this state, the internal temperature will also rise, and it will be necessary to increase the output of cooling element 3 to cool the internal space.

[0036] Since there is a difference of Y + B between the cooling surface temperature and the dew point temperature, even if the output of the cooling element 3 is increased in step S105, the state where the difference between the cooling surface temperature and the dew point temperature is greater than Y will continue for some time. In other words, since a sufficient margin is ensured between the cooling surface temperature and the dew point temperature, even if the output of the cooling element 3 is rapidly increased, it is unlikely that the dew point temperature will be lower than the cooling surface temperature. For example, by setting the constant B to a value corresponding to the temperature difference of the cooling surface temperature when the output of the cooling element 3 changes from 0% to 100% as described above, it becomes possible to rapidly increase the output of the cooling element 3 from 0 to 100%. Therefore, as shown in Fig. 3(b), between time T1 and T3 (T3 < T2), the cooling surface temperature can be rapidly decreased, and the internal space can be rapidly cooled.

[0037] However, as shown in Fig. 3(b), even after the output of the cooling element 3 reaches 100% at time T3, the dehumidifying element 4 continues to operate until time T4 so that the difference between the cooling surface temperature and the dew point temperature becomes a fixed value of Y + B. Since the output of the cooling element 3 has reached the maximum value, a large margin between the cooling surface temperature and the dew point temperature is unnecessary, and ideally, a difference of the threshold value Y between the cooling surface temperature and the dew point temperature is sufficient. Nevertheless, since the threshold value Z is set to Y + B, the dehumidifying element 4 continues to operate and dehumidification is performed more than necessary. This may lead to an increase in the power consumption of the dehumidifying element 4.

[0038] In view of the above problems at Y and Y + B of the threshold value Z, in this embodiment, the threshold value Z is determined to increase as the output of the cooling element 3 decreases and to decrease as the output of the cooling element 3 increases. For example, let Z = Y + B(100 - P) / 100 (see Fig. 3(c)). P is the output of the cooling element 3 and varies between 0 and 100%. In this embodiment, since the control board 9 also controls the output of the cooling element 3, it is possible to acquire the current output of the cooling element 3.

[0039] Along the flowchart shown in FIG. 2, when cooling progresses while dehumidifying the internal space and the output of the cooling element 3 rises to P%, the temperature difference between the cooling surface temperature and the dew point temperature becomes Z = Y + B(100 - P) / 100. For example, when the output of the cooling element is 50%, the threshold value Z becomes Z = Y + B / 2, and the dehumidifying element 4 is activated so that the difference between the cooling surface temperature and the dew point temperature becomes Z = Y + B / 2 (steps S111, S112). When the temperature of the external space rises rapidly from this state, the temperature of the internal space also rises, so it is necessary to increase the output of the cooling element 3 to cool the internal space.

[0040] Therefore, when increasing the output of the cooling element 3, since a margin of Y + B / 2 is ensured for the cooling surface temperature with respect to the dew point temperature, the output of the cooling element 3 can be increased rapidly. As shown in FIG. 3(c), between time T1 and time T3 (T3 < T2), the cooling surface temperature can be rapidly decreased, and the internal space can be rapidly cooled.

[0041] Also, as shown in FIG. 3(c), even after the output of the cooling element 3 reaches the maximum 100% at time T3, the state where the cooling surface temperature is only Y higher than the dew point temperature is maintained, the occurrence of condensation is suppressed, and the dehumidifying element 4 does not activate. Therefore, compared with the case of FIG. 3(b), the power consumption by the dehumidifying element 4 can be suppressed. When the output of the cooling element 3 is 20%, Z = Y + B*4 / 5, and a larger margin is ensured compared to when the output of the cooling element 3 is 50%. Thus, the margin ensured is adjusted according to the output of the cooling element 3. This is because the assumed decrease in the cooling surface temperature when the output of the cooling element 3 rises from 50% to 100% is different from when it rises from 20% to 100%. By setting the margin considering the increase width from the current output of the cooling element 3 in this way, it is possible to suppress the activation of the dehumidifying element 4 at a timing when dehumidification is unnecessary, and reduce the power consumption by the dehumidifying element 4.

[0042] In step S114, it is determined whether it is necessary to dissipate heat using the external fan 11. If the cooling element 3 is operating, heat is conducted to the external heat sink 10 by the cooling element 3, and therefore it is determined that it is necessary to dissipate heat using the external fan 11. Then, the external fan 11 is started (step S115), and the process proceeds to step S117. Note that if the external fan 11 is already operating, it continues to operate.

[0043] On the other hand, if the cooling element 3 is not operating, the cooling element 3 does not conduct heat to the external heat sink 10, so it is determined that there is no need to dissipate heat using the external fan 11, and the external fan 11 is stopped (step S116), and the process proceeds to step S117.

[0044] In step S117, it is determined whether to turn off the power supply to the main body of the camera housing 20. If the power supply to the main body of the camera housing 20 is to be turned off, the process proceeds to step S118, where the cooling element 3, the dehumidifying element 4, the internal fan 24, and the external fan 11 are stopped, and this control flow ends.

[0045] On the other hand, if the power supply of the camera housing 20 is not turned off, the process returns to step S102 after a certain period of time (cycle time of the control flow) has elapsed, and the operations of this flowchart are repeatedly executed.

[0046] As described above, the camera housing according to this embodiment can prevent condensation on the housing and efficiently cool the object to be cooled while reducing the power consumption of the dehumidifying element 4. Note that in the camera housing 20 according to this embodiment, the object to be cooled is the internal space 15, but for example, the heat of the image capture device 30 may be conducted to the cooling element 3 by a thermally conductive member, and the image capture device 30 may be the object to be cooled.

[0047] <Embodiment 2> The imaging device according to this embodiment will be described. Note that, in the configuration of the imaging device 40 according to this embodiment, components that have substantially the same functions and actions as those of the camera housing 20 according to embodiment 1 are assigned the same reference numerals, and descriptions thereof will be omitted. Also, in the operation of the imaging device 40 according to this embodiment, descriptions of the same flow as the operation of the camera housing 20 according to embodiment 1 will be omitted.

[0048] (Device configuration) 4 is a diagram showing the device configuration of an imaging device 40 according to this embodiment. The imaging device 40 includes a housing 2 containing a substantially sealed internal space 15, an imaging element 42 housed inside the housing 2, and captures an image of an external space 18 through a translucent cover glass 41 and a detachable interchangeable lens 43. The imaging device 40 further includes a cooling element 3, a dehumidifying element 4, an external heat sink 10, and an external fan 11.

[0049] The cooling element 3 is arranged so that its cooling surface abuts against the imaging element 42, and its heat dissipation surface abuts against the external heat sink 10. Note that a heat conductor with high thermal conductivity, such as a heat dissipation sheet or heat dissipation grease, may be interposed between the cooling element 3 and the imaging element 42, and between the cooling element 3 and the external heat sink 10.

[0050] Cooling the imaging element 42 with the cooling element 3 can prevent deterioration in image quality due to an excessive rise in temperature of the imaging element 42. The heat conducted to the external heat sink 10 by the cooling element 3 is dissipated into the external space 18 by the external fan 11.

[0051] By dehumidifying the internal space 15 with the dehumidifying element 4, it is possible to prevent condensation from occurring inside the housing 2 when the imaging element 42 is cooled by the cooling element 3.

[0052] The imaging device 40 further includes an internal temperature sensor 5, an internal humidity sensor 6, a cooling surface temperature sensor 7, and a control board 9.

[0053] The internal temperature sensor 5 is a temperature sensor that measures the temperature of the internal space 15 (hereinafter referred to as the internal temperature). The internal humidity sensor 6 is a humidity sensor that measures the humidity of the internal space 15 (hereinafter referred to as the internal humidity), and the cooling surface temperature sensor 7 is a temperature sensor that measures the temperature of the cooling surface of the cooling element 3 (hereinafter referred to as the cooling surface temperature). In this embodiment, the cooling surface of the cooling element 3 abuts against the imaging element 42. Therefore, when the imaging element 42 and the cooling element 3 reach a state of thermal equilibrium due to thermal conduction, the temperature of the cooling surface of the cooling element 3 can be said to be substantially the same as that of the imaging element 42.

[0054] The control board 9 is a control board that comprehensively controls the cooling process by the cooling element 3 and the dehumidification process by the dehumidifying element 4. The control board 9 is connected to each sensor, each element, and external fan 11 as shown by the dashed lines. The control board 9 acquires the internal temperature, internal humidity, and cooling surface temperature from the internal temperature sensor 5, internal humidity sensor 6, and cooling surface temperature sensor, and comprehensively controls mainly the cooling element 3, dehumidifying element 4, and external fan 11. The control board 9 has a CPU (not shown) such as a microcontroller or microprocessor. The CPU executes programs for controlling each element and external fan 11, which are stored in RAM or ROM (not shown).

[0055] (Operation description) The cooling and dehumidifying processes of the imaging device 40 according to this embodiment will be described. Fig. 5 is a flowchart showing the cooling and dehumidifying processes of the imaging device 40 according to this embodiment. Each operation shown in the flowchart of Fig. 2 is realized by the microcontroller or microprocessor in the control board 9 executing a control program.

[0056] First, in step S202, the internal temperature is acquired from the internal temperature sensor 5, the internal humidity from the internal humidity sensor 6, and the cooling surface temperature from the cooling surface temperature sensor 7. Next, in step S203, the dew-point temperature of the internal space 15 is calculated from the internal temperature and internal humidity acquired in step S202.

[0057] Next, in step S204, it is determined whether it is necessary to cool the image sensor 42. If the difference between the cooling surface temperature acquired from the cooling surface temperature sensor 7 and the preset target temperature of the image sensor 42 is greater than 0, it is determined that it is necessary to cool the image sensor 42, and the process proceeds to step S205. For example, it may be that the outside temperature is high and the image sensor 42 is not being sufficiently cooled.

[0058] On the other hand, if the difference between the cooling surface temperature acquired from the cooling surface temperature sensor 7 and the preset target temperature of the image sensor 42 is 0 or less, it is determined that cooling of the image sensor 42 is not necessary, and the output of the cooling element 3 is reduced (step S210). Then, the process proceeds to step S211. For example, there may be a case where the outside temperature is low and the image sensor 42 is also low, or there may be a case where the outside temperature is high but the image sensor 42 is sufficiently cooled. This prevents excessive cooling of the image sensor 42 and reduces unnecessary power consumption of the cooling element 3. However, if the output of the cooling element 3 is already 0% at the stage of proceeding to step S210, it is maintained at 0%. The target temperature of the image sensor 42 is preset to a value determined, for example, based on the tolerance for image quality of the imaging device 40.

[0059] In step S205, it is determined whether condensation will occur even if the cooling surface temperature is reduced by increasing the output of the cooling element 3. If the difference between the cooling surface temperature acquired from the cooling surface temperature sensor 7 and the dew-point temperature calculated in step S203 is greater than threshold Y, it is determined that condensation will not occur even if the cooling surface temperature is reduced by increasing the output of the cooling element 3, and the output of the cooling element 3 is increased (step S207). Then, the process proceeds to step S211. For example, it is possible that the interior has been sufficiently dehumidified and the dew-point temperature has decreased. However, if the output of the cooling element 3 is already 100% at the stage of proceeding to step S207, it is maintained at 100%.

[0060] On the other hand, if the difference between the cooling surface temperature acquired from the cooling surface temperature sensor 7 and the dew point temperature calculated in step S203 is equal to or less than threshold Y, it is determined that condensation will occur if the cooling surface temperature decreases as the output of the cooling element 3 is increased, and the output of the cooling element 3 is decreased (step S209). Then, the process proceeds to step S211. For example, it is possible that the cooling surface temperature has decreased as the cooling of the image sensor 42 progresses. However, if the output of the cooling element 3 is already 0% at the stage of proceeding to step S209, it is maintained at 0%.

[0061] Here, the aforementioned threshold value Y is, as in embodiment 1, the margin value of the cooling surface temperature relative to the dew point temperature so that condensation does not occur on the cooling surface, which is the coldest inside the housing 2, regardless of the output of the cooling element 3, and is, for example, Y=1.

[0062] In step S211, it is determined whether it is necessary to dehumidify the interior using the dehumidifying element 4. If the difference between the cooling surface temperature and the dew point temperature is smaller than the threshold Z, it is determined that it is necessary to dehumidify the interior using the dehumidifying element 4, and the dehumidifying element 4 is activated (step S212). Then, the process proceeds to step S214. If the dehumidifying element 4 is already operating, it continues to operate. For example, it may be that the cooling surface temperature of the imaging element 42 is decreasing as the cooling progresses.

[0063] On the other hand, if the difference between the cooling surface temperature acquired from the cooling surface temperature sensor 7 and the dew-point temperature calculated in step S203 is equal to or greater than threshold Z, it is determined that there is no need to dehumidify the interior using the dehumidifying element 4, and the dehumidifying element 4 is stopped (step S213). Then, the process proceeds to step S214. For example, it may be that the interior has been sufficiently dehumidified and the dew-point temperature has dropped.

[0064] Here, as in the first embodiment, the threshold value Z is determined so that it increases as the output of the cooling element 3 decreases and decreases as the output of the cooling element 3 increases. For example, Z=Y+B×(100-P) / 100 (B is a constant, and P is a variable). The constant B is a value corresponding to the temperature difference of the cooling surface temperature when the output of the cooling element 3 changes from 0% to 100%, and is, for example, B=20. The variable P is the output of the cooling element 3 (0 to 100).

[0065] As in the first embodiment, by changing the threshold Z according to the output of the cooling element 3, it is possible to accommodate rapid cooling, and it is possible to efficiently cool the image sensor 42 without condensation while preventing the dehumidifying element 4 from consuming more power than necessary.

[0066] In step S214, it is determined whether heat needs to be dissipated by the external fan 11. If the cooling element 3 is operating, heat is conducted to the external heat sink 10 by the cooling element 3, so it is determined that heat needs to be dissipated by the external fan 11, and the external fan 11 is started (step S215). Then, the process proceeds to step S217. If the external fan 11 is already operating, it continues to operate.

[0067] On the other hand, if the cooling element 3 is not operating, the cooling element 3 does not conduct heat to the external heat sink 10, so it is determined that there is no need to dissipate heat using the external fan 11, and the process proceeds to step S216 to stop the external fan 11, and then to step S217.

[0068] In step S217, it is determined whether to turn off the power supply of the main body of the imaging device 40. If the power supply of the main body of the imaging device 40 is to be turned off, the process proceeds to step S218, in which the cooling element 3, the dehumidifying element 4, and the external fan 11 are stopped, and the operational flow of this flowchart ends.

[0069] On the other hand, if the power supply of the main body of the imaging device 40 is not turned off, the process returns to step S202 after a certain period of time (cycle time of the operation flow) has elapsed.

[0070] With the above configuration and operation flow, in an imaging device that can prevent condensation by controlling the cooling element and dehumidifying element, it is possible to reduce the power consumption of the dehumidifying element while efficiently cooling the imaging element without causing condensation.

[0071] In the camera housing 20 according to the first embodiment, the object to be cooled is the internal space 15, and therefore cooling is required across the entire area. On the other hand, the object to be cooled in the imaging device 40 according to the present embodiment is the imaging element 42, and therefore localized cooling is required, and therefore the internal fan 24 is not provided.

[0072] Furthermore, the camera housing 20 according to the first embodiment determines in step S106 whether it is necessary to increase the output of the cooling element 3 based on the difference between the internal and external temperatures so as not to cool the temperature of the internal space 15 (internal temperature) below the temperature of the external space 18 (external temperature). On the other hand, the imaging device 40 according to the present embodiment assumes that the temperature of the imaging element 42 will be cooled to the temperature of the external space 18 (external temperature) or below, and does not include a process equivalent to step S106. Furthermore, the imaging device 40 does not include an external temperature sensor 8 that measures the external temperature.

[0073] <Other embodiments> The present invention can be realized by a process of reading and executing a program that realizes one or more functions of the above-described first embodiment. This program is supplied to a system or device via a network or a storage medium, and is read and executed by one or more processors in the computer of the system or device. The present invention can also be realized by a circuit (e.g., ASIC) that realizes one or more functions. [Explanation of symbols]

[0074] 2. Case 3 Cooling element 4 Dehumidifying element 5 Internal temperature sensor 6 Internal humidity sensor 7 Cooling surface temperature sensor 8 External Temperature Sensor 9 Control board 10 External Heatsink 11 External Fan 15 Interior Space 18 Exterior Space 20 Camera Housing 21 Front window

Claims

1. A cooling device for cooling an object to be cooled in a housing, a cooling means for cooling the object to be cooled; a dehumidifying means for dehumidifying the inside of the housing; a first acquisition means for acquiring an internal temperature of the housing; a second acquisition means for acquiring the internal humidity of the housing; a third acquisition means for acquiring a cooling surface temperature of the cooling means; a control means for controlling the start and stop of the dehumidifying means, The control means calculating a dew point temperature inside the enclosure based on the internal temperature and the internal humidity; activating the dehumidifying means when a difference between the dew point temperature and the cooling surface temperature is smaller than a threshold value; A cooling device that adjusts the threshold value based on the output of the cooling means.

2. 2. The cooling device according to claim 1, wherein the control means reduces the threshold value as the output of the cooling means increases.

3. 2. The cooling device according to claim 1, wherein the control means increases the threshold value as the output of the cooling means decreases.

4. Further, a fourth acquisition means for acquiring an external temperature of the housing is provided, 2. The cooling device according to claim 1, wherein the control means reduces the output of the cooling means when the internal temperature is lower than the external temperature.

5. further comprising a fan for radiating heat from the heat radiation surface of the cooling means; 2. The cooling device according to claim 1, wherein the fan is stopped when the cooling means is not operating.

6. 2. The cooling device according to claim 1, wherein the first acquisition means is an internal temperature sensor arranged inside the housing, the second acquisition means is an internal humidity sensor arranged inside the housing, and the third acquisition means is a cooling surface temperature sensor arranged on or near the cooling surface of the cooling means.

7. 5. The cooling device according to claim 4, wherein the fourth acquisition means is an external temperature sensor disposed outside the housing.

8. 2. The cooling device according to claim 1, wherein the cooling means is a cooling element, and the dehumidifying means is a dehumidifying element.

9. 2. The cooling device according to claim 1, wherein the control means controls the output of the cooling means based on a difference between the cooling surface temperature and a target temperature.

10. 10. The cooling device according to claim 9, wherein the control means increases the output of the cooling means when the cooling surface temperature is higher than the target temperature.

11. A cooling device for cooling an object to be cooled in a housing, a cooling means for cooling the object to be cooled; a dehumidifying means for dehumidifying the inside of the housing; a first acquisition means for acquiring an internal temperature of the housing; a second acquisition means for acquiring the internal humidity of the housing; a control means for controlling the start and stop of the dehumidifying means, The control means calculating a dew point temperature inside the enclosure based on the internal temperature and the internal humidity; activating the dehumidifying means when the difference between the dew point temperature and the internal temperature is smaller than a threshold value; A cooling device that adjusts the threshold value based on the output of the cooling means.

12. A control method for a cooling device for cooling an object to be cooled in a housing, comprising: a first acquisition step of acquiring an internal temperature of the housing; a second acquisition step of acquiring an internal humidity of the housing; a third acquisition step of acquiring a cooling surface temperature of a cooling means for cooling the object to be cooled; a control step of controlling the start and stop of the dehumidifying means, In the control step, calculating a dew point temperature inside the enclosure based on the internal temperature and the internal humidity; activating the dehumidifying means when a difference between the dew point temperature and the cooling surface temperature is smaller than a threshold value; A method for controlling a cooling device, comprising: adjusting the threshold value based on the output of the cooling means.

13. A control method for a cooling device for cooling an object to be cooled in a housing, comprising: a first acquisition step of acquiring an internal temperature of the housing; a second acquisition step of acquiring an internal humidity of the housing; a control step of controlling the start and stop of the dehumidifying means, In the control step, calculating a dew point temperature inside the enclosure based on the internal temperature and the internal humidity; activating the dehumidifying means when the difference between the dew point temperature and the internal temperature is smaller than a threshold value; A method for controlling a cooling device, comprising: adjusting the threshold value based on an output of a cooling means for cooling the object to be cooled.

14. A program for causing a computer to execute the control method according to claim 12 or 13.

15. A computer-readable storage medium storing the program according to claim 14.

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