JP5147246B2 - camera - Google Patents

Description

The present invention relates to a camera using an image sensor such as a CCD or a CMOS, and more particularly to a camera having a system that reduces noise generated during imaging by cooling the image sensor.

  In an imaging device (particularly a digital still camera) using an image sensor such as a CCD or CMOS, noise may occur in an image due to the influence of dark current.

  Although current image pickup devices have advanced noise countermeasures, this dark current noise becomes conspicuous even when the signal gain is increased (gain-up imaging for increasing the ISO value).

  Since this noise increases as the temperature of the image sensor increases, a technique for suppressing the noise by cooling the image sensor using an electronic cooling element such as a Peltier element has also been proposed.

For example, Patent Document 1 discloses a mechanism that absorbs heat generated by an imaging element by disposing an electronic cooling element on the back surface of the imaging element and dissipates the heat with a heat dissipation member provided on the back surface of the electronic cooling element. Yes.
JP 2006-033031 A

  In Patent Document 1, although the cooling efficiency of the image sensor is large, the entire device becomes thick in the thickness direction (the direction of the photographing optical axis), resulting in a large-sized image pickup device that is difficult to handle as a consumer product. There are drawbacks to say.

An object of the present invention is to provide a camera that is thin and has a high cooling effect.

In order to achieve the above object, a camera according to claim 1 is in contact with the imaging element, a heat conduction member provided on the back surface of the imaging surface of the imaging element, the thermal conduction member, and a planar direction of the imaging element. It has a flat surface in a direction aligned with, provided on the heat conducting member and the imaging device based on the electronic cooling element provided at different positions on the same plane, flush with the imaging element based on the heat conducting member And a heat dissipating member that is in contact with the upper surface of the electronic cooling element.

According to the present invention, a thin solid-state imaging device with a high cooling effect can be realized, and a captured image with less noise can be obtained in a consumer product.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a side cross-sectional view of a photographing apparatus including a solid-state imaging device according to the first embodiment of the present invention when preparing for photographing.

  Hereinafter, the configuration will be described together with the operation.

  In FIG. 1, a lens barrel 12 is detachably provided on a camera body 11 via a mount 14. The lens barrel 12 is provided with a photographing optical system 13.

  The subject image captured by the photographing optical system 13 is reflected by the quick return mirror 15 and incident on the pentaprism 16 when the subject is observed, and then becomes a photographer observation image via the eyepiece optical system 17.

  A finder optical system is formed by the pentaprism 16 and the eyepiece optical system 17. The quick return mirror 15 is a half mirror, and the subject luminous flux that has passed through the quick return mirror 15 is reflected by the sub mirror 18, passes through the field lens 19, the AF mirror 110, and the eyeglass lens 111 and is connected to the surface of the AF sensor 112. Image.

  The AF sensor 112 detects defocus based on the phase difference between the two images via the eyeglass lens 111. The field lens 19, the AF mirror 110, the eyeglass lens 111, and the AF sensor 112 constitute a known focus detection device.

  FIG. 2 shows a state at the time of photographing. When a release button (not shown) is operated, the quick return mirror 15 is flipped up, and the sub mirror 18 is stored in the quick return mirror 15. At the same time, the shutter film of the shutter 113 is retracted, and the subject light flux passes through the low-pass filter 114 and enters the image sensor 115.

  The subject image captured by the image sensor 115 is recorded on a recording medium (not shown) and displayed on the liquid crystal screen 116, so that the photographer can observe the captured image.

  A series of operations including the focus detection and the quick return mirror 15 jumping up are controlled by the camera microcomputer 118 disposed on the main board 117.

  A heat conducting member such as a graphite sheet is in contact with the back side of the imaging surface of the imaging element 115 (the surface facing the imaging optical system 13). The heat conducting member is configured by at least two planes of a first heat conducting member 119a in contact with the back surface of the image sensor 115 and a second heat conducting member 119b facing the side surface of the image sensor 115.

  First and second electronic cooling elements 120a and 120b such as Peltier elements are in contact with the second heat conducting member 119b and the third heat conducting member 119c, respectively. The second electronic cooling element 120 a is in contact with the bottom surface (camera bottom surface) 121 of the camera body 11.

  The bottom surface 121 of the camera body 11 is formed of a member having high thermal conductivity, and the opposite surface of the electronic cooling element 120a to the contact surface of the heat conductive member is in contact. The bottom surface 121 of the camera body serves as a heat radiating member that radiates heat generated by the first electronic cooling element 120a. Similarly, the second electronic cooling element 120b is also in contact with the camera body 11, and the camera body 11 radiates heat from the second electronic cooling element 120b.

  Here, the first and second electronic cooling elements 120a and 120b have different heat absorption capacities, and a large amount of heat is absorbed by the first electronic cooling element 120a and dissipated from the camera bottom surface 121. The electronic cooling element 120b is used.

  As in the conventional example, generally, the electronic cooling element and the heat radiating member are arranged on the back surface of the imaging surface of the imaging element. However, as described above, in such a layout, the dimension in the thickness direction of the imaging element becomes too large, and the imaging device becomes large as a consumer product and difficult to handle.

  In the present embodiment, like the graphite sheet, a heat conduction member having high heat conduction efficiency is arranged in the thickness direction, and the first electronic cooling element 120a is arranged on the side surface side of the imaging element 115, whereby the cooling device is arranged. Thinning of the solid-state imaging device is achieved.

  In addition, the operation member and the display member are not provided, and the first electronic cooling element 120a can dissipate heat on the camera bottom surface 121 having a large surface area, whereby efficient cooling can be performed.

  First and second temperature sensors 122a and 122b are provided on the back surface of the first heat conducting member 119a on the contact surface of the image sensor 115.

  FIG. 3 is a control block diagram including the image sensor and its cooling unit in FIG.

  In FIG. 3, the first and second temperature sensors 122a and 122b for detecting the respective temperatures are provided above and below the image sensor 115 and on the back surface of the first heat conducting member 119a as described above. Yes.

  The detection outputs of the first and second temperature sensors 122a and 122b are input to the camera microcomputer 118, and the camera microcomputer 118 controls the drive of the first and second electronic cooling elements 120a and 120b based on the signals. Is going.

  As described above, the first electronic cooling element 120a is in contact with the camera bottom surface 121 having a large heat dissipation capacity, and the cooling efficiency is high. Therefore, most of the heat generated by the image sensor 115 flows in the direction of the first electronic cooling element 120a, and only the heat flowing in the direction opposite to the camera bottom surface 121 is cooled by the second electronic cooling element 120b. It is configured to do.

  Specifically, when the outputs of the first temperature sensor 122a and the second temperature sensor 122b are the same (equal temperature), the cooling capacity of the first electronic cooling element 120a is increased (the drive voltage is increased or the drive current is increased). More).

  Alternatively, when the outputs of the first temperature sensor 122a and the second temperature sensor 122b are the same (equal temperature), the cooling capacity of the second electronic cooling element 120b is lowered (lowering the driving voltage or reducing the driving current). cut back).

  Accordingly, the temperature distribution of the first heat conducting member 119a is given a gradient so that the temperature detected by the first temperature sensor 122a is slightly lower than the temperature detected by the second temperature sensor 122b, and heat is applied to the bottom surface 121 of the camera. It is configured to flow a lot on the side.

  The present electronic apparatus may be configured with only the first electronic cooling element 120a without the second electronic cooling element 120b, but in this case, the heat remaining on the second electronic cooling element 120b side is accumulated. As a result, the temperature of the image sensor 115 is increased. For this reason, the second electronic cooling element 120 b is provided to dissipate the remaining heat to the camera body 11.

  The temperature rise of the image sensor 115 is detected by the first and second temperature sensors 122a and 122b, and the drive control of the first and second electronic cooling elements 120a and 120b is performed based on the result. However, a delay time occurs until the cooling effect for detecting the temperature rise and suppressing it is obtained. Therefore, noise cannot be sufficiently reduced until the cooling capacity is exhibited.

  In this embodiment, in order to shorten this delay time, a temperature rise prediction means for predicting a temperature rise is provided. When a temperature rise is predicted, the electronic cooling element is driven in advance according to the predicted temperature. In addition, the temperature rise is prevented.

The temperature rise prediction means predicts a temperature rise according to the photographing conditions of the photographing apparatus. Specifically, the temperature rise predicting means predicts a temperature rise based on the following conditions, the ambient temperature and the usage time of the photographing apparatus.
Whether the shooting mode of the shooting device is the moving image shooting mode or the still image shooting mode, whether the shooting mode of the shooting device is the continuous shooting mode, the exposure time of the shooting device, whether the device is being held in FIG. The microcomputer (CPU) 118 includes a usage time measuring unit 31 of the image sensor 115, a moving image still image mode determining unit (switching operation) 32, a continuous single shooting mode determining unit (switching operation) 33, and a shooting exposure time calculating unit 34. A signal is input. Similarly, signals from the vibration detection means 35 and the outside air temperature detection means 36 are input.

In the following conditions, the driving capacity of the electronic cooling element is increased.
・ Longer usage time of imaging device (temperature rise of circuit board)
・ Movie mode (temperature rise of image sensor)
-Continuous shooting mode (temperature rise of image sensor)
・ Long exposure time (temperature rise of image sensor)
・ The output of the vibration detection means is large (the imaging device is held by hand and heat builds up)
・ The outside air temperature is high (the camera is hot)
Not only the above conditions, but also the driving capability of the electronic cooling element is controlled based on the rate of temperature rise of the first and second temperature sensors 122a and 122b. This is because the responsiveness is improved by predictive temperature control and temperature fluctuation is reduced by feedback control using a temperature sensor.

  FIG. 4 is a flowchart showing the procedure of the photographing operation process executed by the photographing apparatus of FIG.

  This flow starts when the main power of the photographing apparatus is turned on. This flow is executed by the camera microcomputer (CPU) 118 in FIG.

  In FIG. 4, in step S401, it is determined whether the shooting mode is a still image mode or a moving image mode. This is determined based on the output to the camera microcomputer 118 of the moving image still image mode determination means 32 of FIG. Then, the process proceeds to step S402 in the still image mode, and to step S403 in the moving image mode.

  Here, the difference in driving of the first and second electronic cooling elements 120a and 122b (hereinafter sometimes simply referred to as an electronic cooling element) due to the difference in the photographing mode will be described.

  First, in the video mode, you don't know how long you will continue to shoot. For this reason, if the electronic cooling element continues to function as much as possible, the power consumption cannot be predicted. Since this photographing apparatus gives priority to the image quality of still images, it is necessary to retain power when performing still image photographing after moving image photographing.

  Therefore, at the time of video shooting, the ability of the electronic cooling element is reduced to save power.

  Specifically, the camera microcomputer 118 drives the first and second electronic cooling elements 120a and 120b with 1v (step S403).

  In step S402, it is determined whether or not the continuous shooting mode is used for still images. When the process proceeds to step S404, a single shooting mode is set (a mode in which one image can be shot with a single camera operation, and a camera operation is performed each time shooting is performed). In this mode, for example, when the exposure time is found to be 6 minutes (exposure time used in astronomical photography or the like), the camera microcomputer 118 drives the first and second electronic cooling elements 120a and 120b with 3v.

  More specifically, the driving voltage is increased every time the exposure time becomes longer, such as 0.5 V driving for an exposure time of 1 minute and 1 v driving for 2 minutes.

  When the continuous shooting mode is selected (multiple images can be shot continuously with one camera operation), the process proceeds to step S405. When still image shooting is continuously performed, the image sensor 115 has a high temperature because there is no period for cooling compared to shooting only once. Therefore, in the case of continuous shooting, the capacity of the electronic cooling element is raised. For example, when the exposure time is found to be 6 minutes, the camera microcomputer 118 drives the first and second electronic cooling elements 120a and 120b with 6v.

  More specifically, the drive voltage is increased every time the exposure time becomes longer, such as 1 V drive for an exposure time of 1 minute, 2 v drive for 2 minutes, and so on. That is, in the continuous shooting mode, the ability of the electronic cooling element with respect to the exposure time is made higher than in the single shooting mode.

  After setting the driving voltage of the electronic cooling element in steps S403, S404, and S405, the process proceeds to step S406. In step S406, the driving capacity of the electronic cooling element is set according to the outside air temperature.

  This is determined based on the output to the camera microcomputer 118 of the outside air temperature detection means 36 in FIG. More specifically, when the outside air temperature is 60 ° C., the electronic cooling element is driven by 4 v, the outside air temperature is 50 ° C., 3 v, 40 ° C. is 2 v, 30 ° C. is 1 v, 20 ° C. is 0 v, 10 ° C. is −1 v, 0 ° C. is − At 2 v and −10 ° C., the electronic cooling element is driven at −3 v.

  When the drive voltage is negative, the electronic cooling element is not actually driven. In order to drive the electronic cooling element by subtracting the drive setting voltage in steps S403, S404, and S405, a negative voltage is set.

  That is, when the electronic cooling element is driven at 1v in step S403, the electronic cooling element is not driven if the outside air temperature is 10 ° C. or lower in step S406.

  In step S407, the driving capability of the electronic cooling element is changed in accordance with the usage time since the main power supply of the camera is turned on. When the main power supply of the camera is turned on, the temperature inside the camera gradually rises due to the heat generated by the current flowing through the main board 117.

  This temperature change is actually not linear with respect to time, and the temperature change rate increases with time. That is, the difference between the temperature 60 minutes after the main power-on and the temperature 5 minutes after the main power-on is larger than the difference between the temperature 10 minutes after the main power-on and the temperature 5 minutes after the main power-on. Therefore, the elapsed time since the main power is turned on is known, and the subsequent temperature rise is predicted.

  The elapsed time from the main power-on is determined based on the output to the camera microcomputer 118 of the usage time measuring means 31 in FIG. For example, when 60 minutes have passed since the main power is turned on, the electronic cooling element is set to be driven at 2V, and when it is 30 minutes, it is set at 1V to cope with the subsequent temperature rise.

  In step S408, it is determined whether or not the camera is held. If it is grasped, the camera microcomputer 118 sets the first and second electronic cooling elements 120a and 120b to 6v when the exposure time is found to be 6 minutes in step S409 as in step S405. To drive.

  More specifically, the drive voltage is increased every time the exposure time becomes longer, such as 1 V drive for an exposure time of 1 minute, 2 v drive for 2 minutes, and so on. This is because when the camera is in the gripping state, heat from the camera is blocked by the photographer and becomes insufficient. Whether or not the camera is in the gripping state is determined based on the output to the camera microcomputer 118 of the vibration detecting means 35 in FIG.

  In step S410, the sum of the driving voltages of the electronic cooling elements set in steps S403, S404, S405, S406, S407, and S409 is obtained. Here, when the sum is 6V or more, it is 6V, and when the sum is negative, it is 0V.

  In step S411, the electronic cooling element is driven with the total driving voltage to cool the imaging element 115, and the process returns to step S401.

  In this way, by accurately detecting imaging conditions, thereby predicting future temperature rise and driving the electronic cooling element with a suitable capacity in advance, highly responsive cooling control can be performed efficiently.

  As described above, in the present embodiment, an electronic cooling element is arranged on the side surface of the imaging element 115, and heat radiation of the electronic cooling element is performed on the bottom surface or the front surface instead of the back surface of the imaging device 115. The company is trying to make it thinner.

  In order to effectively use the thin cooling mechanism, the temperature rise of the image sensor 115 is predicted, and the image sensor 115 is cooled in advance before the temperature rises.

  FIG. 5 is a side cross-sectional view of an imaging device including a solid-state imaging device according to the second embodiment of the present invention when preparing for imaging.

  A difference from the first embodiment of FIG. 1 is that the heat radiation member 21 is in contact with the back surface of the contact surface of the first electronic cooling element 120a with the second heat conducting member 119b, and a part of the heat radiation member 21 Is a point that penetrates the camera bottom surface 121 and is exposed to the outside.

  In the first embodiment of FIG. 1, the camera bottom surface 121 also serves as a heat dissipation member. However, since the camera bottom surface 121 is also an exterior surface, it is often formed of resin or the like. In such a case, the bottom surface 121 cannot be effectively used as a heat radiating member.

  In the second embodiment, a dedicated heat radiating member 21 is provided and brought into contact with the camera bottom surface 121, and a part of the heat radiating member 21 is exposed to the outside through the bottom surface 121. Therefore, the camera bottom surface 121 can perform heat dissipation while maintaining the appearance as an exterior member.

  As described above, in the present embodiment, an electronic cooling element is arranged on the side surface of the imaging element 115, and heat radiation of the electronic cooling element is performed on the bottom surface or the front surface instead of the back surface of the imaging device 115. The company is trying to make it thinner.

  FIG. 6 is a side cross-sectional view of the photographing apparatus including the solid-state imaging device according to the third embodiment of the present invention when preparing for photographing.

  In the third embodiment, the first and second electronic cooling elements 120a and 120b are arranged side by side with the imaging element 115 so that the plane direction is along. The bent first and second heat radiating members 21a and 21b are in contact with the surfaces opposite to the contact surfaces of the first and second electronic cooling elements 120a and 120b with the heat conducting member 119.

  As in the second embodiment of FIG. 5, the first heat radiating member 21 a is in contact with the camera bottom surface 121, and a part thereof penetrates the bottom surface 121 and is exposed to the outside. The second heat radiating member 21b is in contact with the inner wall of the photographing apparatus.

  As described above, when the first and second electronic cooling elements 120a and 120b are arranged along the imaging element plane, the first and second electronic cooling elements 120a and 120b, the heat conduction member 119, the first and second elements are provided. The entire cooling mechanism composed of the heat radiating members 21a and 21b can be reduced in thickness, and can be incorporated into a small photographing apparatus.

  As described above, in the present embodiment, an electronic cooling element is arranged on the side surface of the imaging element 115, and heat radiation of the electronic cooling element is performed on the bottom surface or the front surface instead of the back surface of the imaging device 115. The company is trying to make it thinner.

  As described above, the description has been continued by taking the image stabilization system of the digital camera as an example. However, since the apparatus of the present invention is thin and can cool the image pickup device efficiently, the present invention is not limited to the digital camera. It can also be deployed to surveillance cameras, web cameras, mobile phones and the like.

It is side surface sectional drawing at the time of the preparation for imaging | photography of the imaging device containing the solid-state imaging device which concerns on the 1st Embodiment of this invention. It is side surface sectional drawing at the time of imaging | photography of the imaging device containing the solid-state imaging device which concerns on the 1st Embodiment of this invention. FIG. 2 is a control block diagram including the image sensor and its cooling unit in FIG. 1. 3 is a flowchart illustrating a procedure of imaging operation processing executed by the imaging apparatus of FIG. 1. It is side surface sectional drawing at the time of the preparation for imaging | photography of the imaging device containing the solid-state imaging device which concerns on the 2nd Embodiment of this invention. It is side surface sectional drawing at the time of the preparation for imaging | photography of the imaging device containing the solid-state imaging device which concerns on the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Camera main body 12 Lens barrel 21 Heat radiation member 115 Image pick-up element 119 Thermal conduction member 120 Electronic cooling element 121 Camera bottom face

Claims (12)

An image sensor;
A heat conducting member provided on the back surface of the imaging surface of the imaging element;
Contact with the heat conducting member, and the electronic cooling element and the have a plane in a direction aligned with the plane direction of the imaging device, which is provided at different positions on the image pickup device and the same plane relative to the heat conducting member,
A heat dissipating member that is provided on the same surface as the imaging element with respect to the heat conducting member and is in contact with the upper surface of the electronic cooling element;
A camera comprising:   The camera according to claim 1, wherein a plurality of the electronic cooling elements are arranged in a direction aligned with a planar direction of the imaging element.   The camera according to claim 1, wherein the heat radiating member is in contact with or forms a bottom surface including the imaging element. A plurality of temperature detection elements arranged in the vicinity of the imaging element;
An electronic cooling element control means for individually controlling the plurality of electronic cooling elements based on the output of each of the plurality of temperature detection elements;
2. The camera according to claim 1, wherein the electronic cooling element control means controls the electronic cooling element and the temperature detection element to give a gradient to a temperature distribution in the vicinity of the imaging element.   The camera according to claim 4, wherein the temperature distribution has a gradient toward a heat radiating member disposed in the vicinity of the image pickup device. A temperature detection element for detecting the temperature of the imaging element or the vicinity thereof;
A temperature rise prediction means for predicting a temperature rise in the machine containing the image sensor;
An electronic cooling element control means for driving and controlling the electronic cooling element based on the output of the temperature rise prediction means and the output of the temperature detection element;
The camera according to claim 1, further comprising:   The camera according to claim 6, wherein the temperature rise predicting unit predicts a temperature rise of the image sensor according to a photographing condition.   The camera according to claim 7, wherein the temperature increase prediction unit predicts a temperature increase of the image sensor based on whether a shooting mode is a moving image capturing mode or a still image capturing mode.   The camera according to claim 7, wherein the temperature increase prediction unit predicts a temperature increase of the image sensor based on whether or not the shooting mode is a continuous shooting mode.   The camera according to claim 7, wherein the temperature increase prediction unit predicts a temperature increase of the image sensor based on an exposure time.   The camera according to claim 7, wherein the temperature increase prediction unit predicts a temperature increase of the image sensor based on whether or not the device is held. Having a gripping discriminating means for discriminating whether or not the device is gripped based on the output of the vibration detecting means for detecting the vibration of the device;
The camera according to claim 11, wherein the temperature increase predicting unit predicts a temperature increase of the image pickup device based on an output of the grip determining unit.

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