JPH099116A - Cooled ccd camera - Google Patents

Abstract

PURPOSE: To provide the cooled CCD camera with excellent handling performance by preventing disturbance of image pickup for a long time. CONSTITUTION: The cooled CCD camera is made up of an air-tight chamber 30 consisting of housings 4a, 4b and having a getter 5, a CCD 6 and Peltier elements 8, 9 cooling the CCD 6. The getter 5 is a porous substance made of a metallic element of the group 4A of the periodic table or an alloy including the metallic element as the major component and has a heating means in its inside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooled CCD camera, and more particularly to a cooled CCD camera suitable for astronomical observation.

[0002]

2. Description of the Related Art As a camera for observing celestial bodies such as nebulae with low luminosity, a cooled charge-coupled device (ChargeC) is used.
Cooled CCD using oupled device (hereinafter abbreviated as CCD)
I have a camera. In the case of astronomical observation, the exposure time is as long as several minutes, so the temperature of the CCD built into the camera is 0-40
In the range of ° C, for example, the dark current becomes large at 100 e- / sec or more, and there is a problem that imaging is disturbed. On the other hand, in order to reduce the dark current to 10 e- / sec or less, a method of cooling the CCD to a constant temperature with a Peltier element using the Peltier effect to reduce the disturbance of imaging was studied.

However, when the CCD is cooled in a dry atmosphere having a relative humidity of 7 to 10% RH, the moisture in the atmosphere which is in direct contact with the surface of the CCD is CC at a temperature of -10 to -15 ° C.
Condensation freezes on the surface of D, and a part of the energy for cooling the CCD is consumed for the condensation or freezing, so that C
There is a problem that not only the CD is not sufficiently cooled but also the energy consumption is increased.

Therefore, the dew point in the airtight chamber in which the CCD is housed is lowered, and there are the following methods for lowering the dew point.

The first method is to replace the air-tight chamber with a commercially available high-purity gas such as nitrogen gas. In the second method, silica gel is vacuum-sealed in an airtight chamber to minimize the absolute amount of gas. That is, the gas released from each substance in the airtight chamber and the water vapor content adhering to the inner surface of the airtight chamber are adsorbed on the silica gel in which the gas has been put in advance. The third method is a method of maintaining the initial degree of vacuum in the airtight chamber in which the CCD is housed for a long period of time, in which a vacuum is regularly evacuated using a vacuum pump.

[0006]

However, the above-mentioned prior art has the following problems. That is, the first gas replacement method is
A part of the cooling heat of the CCD escapes to the enclosed gas that is in contact with the CCD surface, resulting in a large energy loss and a dew point in the airtight chamber where the outside air is not completely entrapped when the replacement gas is introduced. There was a point to rise.

In the second moisture absorption method, for example, the moisture absorption rate of silica gel is 30% in relative humidity of 50% RH.
It became 8% in 0% RH, and the moisture absorption property of silica gel deteriorated as the water vapor pressure decreased, and complete dehumidification was difficult. That is, in the extremely low humidity region (in a low temperature vacuum), there is a point that the steam gas, which increases with time, cannot be adsorbed. That is, in the first and second methods, the dew point is not sufficiently lowered, and the imaging disorder occurs in a relatively short time.

In the third vacuum method, the user himself has a vacuum degree of 1
There has been a problem that a vacuum pump capable of achieving a pressure of Pa or less must be prepared and the vacuum must be regularly drawn. Therefore, there are problems that it is necessary to secure a storage place for the vacuum pump, and it is necessary to consider leakage from a dedicated valve provided for evacuation. That is, the third method had a difficulty in handling.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a cooled CCD camera which is capable of preventing image disturbance for a long period of time and is excellent in handleability.

[0010]

An object of the present invention is to provide a CCD for imaging, a cooling means for cooling the CCD, and the CC.
A cooling CCD camera configured to include D and an airtight chamber that seals a cooling means, and which receives light by the CCD and takes an image,
This can be achieved by installing a gas adsorbent made of a metal element of Group 4A of the periodic table or an alloy containing it as a main component in the hermetic chamber.

Further, heating means for heating the gas adsorbent may be provided.

[0012]

According to the above structure, the getter as a gas adsorbent made of a metal element of Group 4A of the periodic table or an alloy containing it as a main component, which is installed in the airtight chamber, has a long time even in an extremely low humidity region. Since it absorbs water vapor gas that increases with the passage of time, compared with the conventional getter made of silica gel,
The airtight chamber is maintained at a predetermined dew point or lower or a predetermined vacuum degree or lower for a long period of time to prevent image disturbance.

In particular, energy is applied from the outside to heat the getter enclosed in the airtight chamber, the gas once adsorbed on the surface of the getter is diffused inside, and the surface of the getter is activated again. Therefore, the gas existing or generated in the airtight chamber can be repeatedly adsorbed. As a result, for a considerably long period of time, the airtight chamber can be maintained at a temperature below the predetermined dew point or below the predetermined vacuum degree.

On the other hand, the vacuum pump is not used, and the getter having the adsorption ability is still installed in the airtight chamber, so that the handleability is good. Furthermore, a method of applying electricity to the electric heater incorporated in the getter to reactivate and adsorb it is easy to handle.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a cooled CCD camera according to an embodiment of the present invention. FIG. 2 is a diagram showing a configuration of an astronomical telescope having the cooled CCD camera shown in FIG. FIG. 3 is a diagram showing an image signal processing configuration of the cooled CCD camera of FIG. First, FIG. 2 shows a cooling C according to the present invention.
This is an example in which a CD camera is applied to an astronomical telescope, and a cooling CCD camera 3 is fixed to the eyepiece side 2 of the astronomical telescope 1 with a screw or the like.
In this configuration, the personal computer 14 and the television 15 are connected.

As shown in FIG. 3, the image signal received by the CCD for capturing an image is passed through the control circuit 11 including the drive circuit 12 and the A / D converter 13, and the personal computer 14 is driven. The image data is sent to the TV, and the celestial object is displayed on the television 15 by the processing for making the image clear. Returning to FIG. 1, the illustrated cooling C
The CD camera 3 includes a housing 4, getter 5, CCD
6, a mechanical shutter 7, Peltier elements 8 and 9, a thermistor 10, a drive circuit 12, an A / D converter 13, and the like. The housing 4 includes housings 4a, 4b,
Divided into 4c and 4d, an airtight chamber 30 formed by the housings 4a and 4b and a storage chamber 40 formed by the housings 4b, 4c and 4d are configured. The more detailed structure will be described below.

Inside the airtight chamber 30, a getter 5, a CCD 6 as a charge-coupled device, a mechanical shutter 7, Peltier devices 8 and 9 as cooling means for cooling the CCD 6, a thermistor 10 for temperature detection, etc. Is built in. The evacuation of the airtight chamber 30 is performed only when the product is manufactured by inserting the special cap of the vacuum pump into the passage 25 of the housing 4a. Then, at the stage when the evacuation to a predetermined degree of vacuum is completed, the passage 25 is sealed with a dedicated valve formed of an O-ring 26 and a sealing plug 27.

The drive circuit 1 constituting the control circuit 11
2, the A / D converter 13, the drive circuit, the power supply circuit, and the like are divided into a plurality of printed circuit boards, and are supported by a plurality of columns at predetermined intervals. Further, the control circuit 11 is a CCD
It has a control micro-computer, which processes signals obtained from the getter 5, CCD 6, mechanical shutter 7, Peltier elements 8 and 9, thermistor 10, and the like. Then, it is housed in a storage chamber 40 adjacent to the airtight chamber 30 that does not require an airtight structure. The housing 4a has a tubular portion 21 fixed to the astronomical telescope 1,
An optical glass 22 is fixed to the bottom of the tubular portion 21 with an O-ring 26 for maintaining airtightness.

FIG. 4 is an enlarged view showing the peripheral portion of the getter 5 shown in FIG. A peripheral portion of the getter 5 includes the getter 5, housings 4a and 4b, an O-ring 26, a hermetic seal terminal 24, a shield plate 20, and the like. As shown in the figure, the getter 5 as a gas adsorbent has an electric heater 18 as a heating means for heating the getter 5, and the heater leads 16 and 16 'for supplying electric power are the electric heaters. Heater 1
It is a structure connected to 8. The hermetic seal terminal 24 has two leads 17, 17 'which are fixed to the housing 4b by tegu welding or the like and are airtightly insulated and supported by an insulating material such as glass. And lead 17,
Heater leads 16 and 16 'are fixed to the tip of 17' by spot welding or the like. The electric heater 18 is made of, for example, molybdenum, tungsten, molybdenum-manganese, or an alloy thereof.

The surface of the heater wire of the electric heater 18 is covered with a thin film of alumina or the like for electrical insulation and embedded in the getter 5. The shield plate 20 has a Peltier element 8 for cooling the radiant heat (radiant heat rays) of the getter 5.
Or other parts to prevent burning, or C
It is provided so as to cover the getter 5 so that light (infrared ray) at the time of activation, which will be described later, does not reach the window portion of the CD 6 and erroneous imaging is performed. That is, the shield plate 20 is provided as a means for covering the gas adsorbent so as to block the heat rays (radiant heat rays and infrared rays) emitted from the gas adsorbent when the gas adsorbent is heated.

The main body of the getter 5 is a metal element of Group 4A of the periodic table or an alloy containing it as a main component, that is, a zirconium or titanium alone, or a zirconium or titanium aluminum. It is made of an alloy with added elements such as aluminum. It is preferably a porous body. The getter 5 having a strong porous body can be manufactured by arbitrarily changing the mixing ratio of the binder, the binder, the solvent, etc., which are mixed at the time of firing the powder raw material, the firing time, the firing temperature and the like. These can be adjusted in size and density of micropores, which will be described later, of the porous body by raising or lowering the activation temperature according to the type of gas to be adsorbed and removed, and by arbitrarily changing the mixing ratio of raw materials. Then you can make it.

Next, referring to FIGS. 5 to 7 at the same time, a method of repeatedly activating the getter 5 (a method of maintaining the airtight chamber below a predetermined dew point or a predetermined vacuum degree for a considerably long time ( The getter reactivation) will be described. FIG. 5 is an enlarged view showing the adsorption states of the getter before and after gas adsorption. FIG. 6 is an enlarged view showing the concentration distribution state inside the getter of atoms or molecules constituting the gas after gas adsorption. FIG.
FIG. 6 is an enlarged view showing a concentration distribution state inside the getter of atoms or molecules constituting the gas after reactivation.

First, the getter before gas adsorption is in a state where gas atoms are not adsorbed by the getter mass as shown in FIG. 5 (a). The getter in this state adsorbs various gases existing in the hermetic chamber, for example, active gases such as oxygen, nitrogen, carbon dioxide, and carbon monoxide in the atmosphere, and the getter gas as shown in FIG. It becomes the state after adsorption. That is, in the getter, the surface of the porous body having innumerable fine pores 19 captures gas atoms, forms oxides, nitrides, and carbides with the bulk of the getter and chemically adsorbs them. At this time, the adsorbed gas atoms are concentrated on the surface of the porous body.

FIG. 6 shows the gas atom concentration inside the getter (inside the getter mass) after gas adsorption. From the expected concentration distribution in the figure, it can be seen that gas atoms are concentrated on the surface. And since it concentrates on the surface, the adsorption ability on the surface is significantly reduced. Since these gas atoms once adsorbed form oxides, nitrides, and carbides, they are chemically stable and will not be released again.

Although the getter 5 is chemically stable at room temperature as described above, when it is heated to, for example, 400 to 1000 ° C., the reduced adsorption capacity is restored and reactivated. That is, if the getter 5 is heated to a high temperature to activate it again,
The already adsorbed gas atoms diffuse to the central portion where the partial pressure is low, as shown in FIG. In other words, the gas atom concentration in the bulk after activation is averaged. Therefore, the gas atoms intensively adsorbed near the surface diffuse to the central portion after activation, and the gas atom concentration near the surface becomes diluted. That is, the state becomes as shown in FIG. 5C, and the gas atom concentration on the surface becomes small as shown in FIG. In other words, since the surface is in a cleaned state, it becomes possible to adsorb a new gas again after activation. That is,
The getter 5 having the electric heater 18 built therein is heated by the jule heat of the electric heater 18, recovers its adsorption ability, and is reactivated.

FIG. 8 is a diagram showing the relationship between the elapsed time of adsorption and the average atomic concentration of adsorbed gas in the getter. That is, when activated repeatedly, the concentration of the adsorbed gas atom inside the getter increases, and the activated gas approaches the critical line each time it is reactivated once or twice. Similarly, in FIG.
The dotted line shows the expected concentration distribution after the third and third activations. In this way, the gas atoms are adsorbed on the getter surface including the inner walls of the micropores, diffused inside the getter by activation by heating, and until the gas atom concentration in the getter bulk reaches the gas atom-containing critical line. Is repeatedly adsorbed on. For example, in the case of a getter made of Zr, as shown by the chain double-dashed line in FIG. 8, the gas accumulated in the hermetic chamber can be repeatedly adsorbed until the critical line containing the allowable adsorbed gas atom of 30 at% of oxygen is reached. It is possible. It has been found that vanadium, which is a metal element of Group 5A of the periodic table, or an alloy containing it, can be similarly reactivated and can be used as the getter 5.

In order to deepen the understanding of the present invention, supplementary problems and ideas of the invention will be described below. First, a supplementary explanation will be given regarding the problem. Products such as CCD cameras are manufactured by giving priority to making the product inexpensive. Therefore, for the parts stored in the airtight chamber (vacuum housing),
It contains hygroscopic materials and materials with high porosity, the degree of vacuum drops during use, and over a long period of 5 to 8 years, even though it is 2 to 3 years, for example, dew point -30 ° C. It is difficult to secure the following (vacuum degree of 10 Pa or less).
That is, in the vacuum sealing method, even if the degree of vacuum in the airtight chamber is initially 1 Pa, for example, after a period of about 3 months to 1 year, various conditions such as a cooling / heating cycle overlap, and the airtight chamber has an extremely small amount of air. Although the amount was small, atmospheric air entered from the outside, gas was generated from the organic substance contained inside, and the gas gradually increased to 50 Pa.

For this reason, it was decided to put silica gel in the airtight chamber in advance and to adsorb the minute amount of water vapor in the invading air, but as mentioned above, under extremely low water vapor pressure,
The water vapor adsorption capacity of silica gel is almost lost. Therefore, as time passes, the water vapor content in the air becomes 200 PPM.
There is a problem in that the CCD cannot be cooled at -30 ° C. after about three months depending on the amount of silica gel in the hermetic chamber.

Next, the idea of the present invention will be described. As a getter used to adsorb gas and maintain a predetermined degree of vacuum, there is an evaporating type mainly containing Ba. However, in the case of a cooled CCD camera that can be combined with an astronomical telescope to magnify nebulae and capture images as an image, the internal CCD
It can be said that the evaporative getter is not a good idea considering that the evaporative substance from the evaporative getter adheres to the window into which the light enters as dust or dirt. Considering the heat activation method of the getter as described above, in particular, the use of the evaporation type getter should be avoided. Therefore, it can be said that it is desirable to use a non-evaporable getter that does not generate an evaporated substance that evaporates from the getter itself and interferes with the light reception of the CCD.

The non-evaporable getter is composed of a metal element of Group 4A in the periodic table (such as Zr or Ti) or an alloy containing it as a main component. The shape is a cylindrical shape or a hollow cylindrical shape. The size of the getter of the above type depends on the gas accumulation rate (invasion or generation rate) in the airtight chamber, but for example, if the airtight chamber is about 100cc, the weight can be about 1 to 3 gr. The size of the getter occupying the volume of the airtight chamber is as small as several%. In particular, it is advantageous that the airtight chamber is relatively narrow, such as a CCD camera, and the inside of a container in which various materials are incorporated is small in size. Then, it can be used in a relatively low temperature range without adversely affecting other parts at the time of heating, and if a small amount of Zr or Ti is easily available, it is possible to reduce the manufacturing cost. Getters are best. In addition, getters are CC
It is housed together with D in an airtight chamber, and when the user activates the getter at a proper time, for example, when using a cooled CCD camera, it is possible to maintain a finite but effective degree of vacuum.

That is, the above-mentioned non-evaporable getter does not have a reversible action of adsorption and desorption of gas unlike silica gel, the gas is captured in a chemically stable state, and the gas adsorbed by the getter is released again. It can be used stably for a long period of time. Therefore, even in the extremely low humidity range,
Since it absorbs water vapor gas that increases with the passage of time, the state of the hermetic chamber can be maintained below a predetermined dew point or below a predetermined vacuum degree for a long time, as compared with a conventional getter made of silica gel. Further, since there is no need to prepare a vacuum pump, there is no need for a storage place for the vacuum pump, and there is no need for a dedicated valve for connecting the vacuum pump and drawing a vacuum.

The airtight chamber that houses the CCD at the stage of assembling as a product is evacuated to a predetermined degree of vacuum using a vacuum pump, and then sealed with a sealing stopper. Cooling CCD cameras cannot be expected to expand sales unless they provide users with inexpensive products. In addition, the high degree of vacuum initially secured was maintained for several years.
There is no affordable price for adopting internal structures and parts that do not have to worry about gas intrusion and generation of internal gas. Therefore, during long-term use with a structure that cannot be said to be sufficient, gas emitted from various substances in the airtight chamber or gas emitted from the inner wall of the airtight chamber is generated due to some cause such as a thermal cycle, or the atmosphere is released. It may penetrate inside and the vacuum level may drop.

In such a case, the getter is made of a porous material. That is, since the getter adsorbs gas on its surface, it is better to use a getter as a porous body to increase the surface area per unit weight. If the porous body is used, the adsorption capacity is increased, the adsorption speed is increased, the weight is reduced, and the product is easily incorporated into the product. The getter made of this porous body can be manufactured by applying the sintering method of metal powder. Then, the gas is chemically adsorbed and captured on the wide surface of the porous body to maintain the degree of vacuum. From the above, compared with the conventional getter made of silica gel,
It is possible to use it for 3 years)
In order to withstand use for 5 to 8 years, it is effective to provide a heating means for heating the gas adsorbent. This will be described below.

By energizing an electric heater as a heating means incorporated in the getter to generate a jule heat to heat the getter, the temperature of the bulk of the getter is increased and the molecular motion is activated (activated). Gas atoms near the surface, the concentration of which increased due to gas adsorption (atoms that made up the gas)
Is diffused inside and the adsorbed gas atoms in the bulk of the getter are averaged. That is, the getter adsorbs gas even at room temperature, but is chemically relatively stable. However, it is activated at 400 to 1000 ° C, and active gases that are generally present in the atmosphere such as oxygen, nitrogen, and carbon monoxide in the airtight chamber are decomposed on the surface, and getter bulk, oxides, and nitrides are decomposed. It forms substances and carbides and is chemically adsorbed. Once adsorbed, these gases become chemically stable and will not be released again.

For example, when the bulk of the Zr getter adsorbs oxygen gas, the adsorbed oxygen gas is decomposed on the surface of the getter into Zr oxide (ZrO), and the oxygen concentration in ZrO is higher as it is closer to the surface. For example, if ZrO is partially 20
The internal oxygen concentration with a small amount of adsorbed gas is at%.
For example, it is a relatively low value of 1 at%. When the getter is heated to a high temperature for activation, the molecular motion inside the getter bulk becomes chemically active, and the oxygen near the surface that has become highly concentrated due to gas adsorption has a low oxygen concentration and oxygen partial pressure. Has the property of diffusing into the interior. The oxygen concentration in the bulk of the getter after activation is, for example, 3 a for ZrO.
It is averaged to about t%. Even if a large amount of gas is adsorbed with the passage of time and the adsorption capacity is significantly reduced, the getter is activated again, so that oxygen and other adsorbed gas atoms on the densified surface gettered as described above. Since it diffuses inside, the concentration of adsorbed gas atoms near the surface becomes low,
Adsorption of new gas is efficiently performed. In this way, gas adsorption is repeatedly performed, and the adsorbed gas atoms are accumulated in the getter bulk.

For example, in the case of oxygen, the gas can be adsorbed repeatedly until the average oxygen concentration in the bulk of the getter reaches about 30 at%. According to the phase diagram of metal, zirconium that has adsorbed more than 30 at% oxygen.
It is known that the metal structure of ceramics changes and becomes ceramic. In general, in addition to zirconium (alloy containing), titanium (alloy containing) is known to be a metal capable of adsorbing gas without causing a phase change up to a relatively high temperature. It can be said that it can be used similarly. Regarding the type of adsorbed gas, it can be said that nitrogen, carbon dioxide, and other gases can be adsorbed by the same idea in addition to oxygen.

On the other hand, heating means other than the electric heater can be used. For example, as a heating means, an airtight chamber accommodating a CCD is made of a material capable of penetrating a magnetic field, a magnetic field generated in a coil outside the airtight chamber is passed through a getter inside the airtight chamber, and an induction current is generated inside the getter. Means for generating and heating can be considered. Further, if the getter housed in the airtight chamber can be seen through a transparent glass window fixed to the airtight chamber, a means for irradiating the getter with light from a laser or an infrared lamp to heat the getter through this window is also available. It is possible. However, as the heating means, an electric heater that can be easily heated and has a simple structure is used.
It can be said that it is the most suitable.

By the way, the gas adsorption rate of the getter during activation is high, and the adsorption capacity is also large. Therefore, although it is desired that the getter be adsorbed during reactivation of the getter, that is, during heating, the life of the getter may be shortened depending on the activation timing. It is also advisable to avoid activating the getter while the cooled CCD camera is capturing images. This is because the getter emits light due to the temperature rise during activation, which adversely affects the image. Therefore, it can be said that it is desirable for the getter to perform activation (supply of power or irradiation of light) at the preparatory stage for photographing or after completion of image capturing, avoiding the time of capturing an image. However, considering the effective use of the cooled CCD camera and the shortening of the operating time and the shooting time, there is a seal around the getter.
With a cold plate attached, the heat and light when the getter temperature rises is C
It is better to have a structure that does not leak to the CD side so that activation is possible even during image capture.

Further, the activation timing of the getter is previously incorporated in the computer software, and the activation operation is performed at least once every use as one of a series of operations when the cooled CCD camera is used. It is possible to adsorb the gas accumulated by internal generation or external invasion to recover the degree of vacuum. As for the activation timing of the getter, there is a method in which the user stores the usage time and the like and performs the activation operation as necessary, but when it is left to human operation, it may be forgotten. The built-in microcomputer is used to issue the drive command and other control commands. That is, it is a good idea to store it in the microcomputer and to activate it periodically when the cooling CCD camera is operated, that is, when the power source or the like is turned on based on the command.

Further, it is possible to carry out the activation continuously, but this is not a good idea because the energy consumption for heating the heater is large. Accumulation of gas in one hermetic chamber is for a long period of time, and the adsorption rate of the getter and diffusion rate of gas atoms are relatively faster than those of the other gas. Therefore, continuous activation is not necessary, and intermittent or periodic activation may be more efficient. Specifically, based on the internal volume of the airtight chamber and the type of adsorbed gas, the accumulation time of the generated gas and the adsorption rate are set, and the microcomputer determines the calculation based on the settings, and the heating by the heating means is performed. For example, the control circuit 11 is provided with means for performing the operation intermittently or periodically.

On the other hand, a sealing plug for evacuation formed in the side wall of the airtight chamber, for example, in the vertical direction of the right-angled bent hole, is previously inserted by inserting a passage so that the right-angled hole is electrically connected. After the vacuum pump has evacuated through this passage, when the predetermined degree of vacuum has been secured, the conical bottom of this sealing stopper is pressed against the valve seat with an O-shaped cross section to keep it airtight while vacuuming is continued. The degree of vacuum in the room can be maintained. Another method of closing the passage after evacuation is to use a copper pipe. The copper pipe is fixed on the side of the airtight chamber, and is previously installed as a part of the evacuation passage. The stage when the specified vacuum level is reached
The airtightness can be maintained by sandwiching the middle of the copper pipe from the right-angled side face (while vacuuming is continued) and crushing and then locally heating and welding. After that, the welded portion is cut while leaving the airtight chamber side.

[0042]

According to the present invention, the non-evaporable getter is placed in advance in the airtight chamber of the cooled CCD camera at the manufacturing stage, and with the passage of time thereafter, the invasion of the external gas and the gas from the internal material. The user can periodically activate the getter to adsorb and remove the gas slightly accumulated due to the generation of the gas. Therefore, the CCD can be stably cooled to a predetermined temperature and controlled for a long period of time, so that the dark current of the CCD is reduced and reliable image quality can be guaranteed. It also has the following effects.

Since the getter for recovering the degree of vacuum can be built in the cooled CCD camera body, the user does not need to purchase and prepare a vacuum pump specially like the conventional cooled CCD camera, which is inexpensive. The getter incorporated in the cooled CCD camera can automatically set the operation timing from the outside by computer software, and the operation for recovering the vacuum degree is simple. The handling of the user becomes easy. Since there is no need for a special valve for vacuuming to the outside as in the conventional case, there is no problem of leakage from the valve and it can be used for a long time. If it is a getter such as Zr or Ti having an adsorption ability, for example, 100 cc
The volume of the airtight chamber is about 3 g, and the size and weight can be reduced. Since the shield plate for shielding the radiant heat is installed on the outer periphery of the getter, the internal parts can be prevented from being heated and melted or burned, and the reliability can be secured.

[Brief description of drawings]

FIG. 1 is a sectional view showing a cooled CCD camera according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an astronomical telescope including the cooled CCD camera of FIG.

FIG. 3 is a diagram showing an image signal processing configuration of the cooled CCD camera of FIG.

FIG. 4 is an enlarged view showing a peripheral portion of the getter 5 in FIG.

FIG. 5 is an enlarged view showing the adsorption state of the getter before and after gas adsorption.

FIG. 6 is an enlarged view showing the concentration distribution state inside the getter of atoms or molecules constituting the gas after gas adsorption.

FIG. 7 is an enlarged view showing a concentration distribution state inside the getter of atoms or molecules constituting the gas after reactivation.

FIG. 8 is a diagram showing a relationship between an adsorption elapsed time and an average concentration of an adsorbed gas atom in a getter.

[Explanation of symbols]

1 ... Astronomical telescope, 2 ... Eyepiece side, 3 ... Cooled CCD camera, 4, 4a, 4b 4c, 4d ... Housing, 5 ... Getter, 6 ... CCD, 7 ... Mechanical shutter, 8, 9 ... Peltier element, 10 ... Thermistor, 11 ... Control circuit, 12 ...
Drive circuit, 13 ... A / D converter, 14 ... Personal computer, 15 ... Television, 16, 16 '... Heater lead, 17, 17' ... Lead, 18 ... Electric heater 1
9 ... Fine holes, 20 ... Shield plate, 21 ... Cylindrical part, 22 ... Optical glass, 24 ... Hermetic seal terminal, 25 ... Passage, 26 ... O ring, 27 ... Sealing plug, 30 ... Airtight chamber, Four
0 ... storage room

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaaki Fukuhara 2477, Kashima Yatsu Kashima Yatsu, Hitachinaka City, Ibaraki Prefecture 3 Hitachi Automotive Engineering Co., Ltd.

Claims (8)

[Claims] 1. A cooling CC configured to include an image pickup CCD, a cooling unit for cooling the CCD, and an airtight chamber for sealing the CCD and the cooling unit, and which receives light by the CCD and picks up an image.
In the D camera, a cooling CCD camera, wherein a gas adsorbent made of a metal element of Group 4A of the periodic table or an alloy containing it as a main component is installed in the hermetic chamber. 2. A cooled CCD camera according to claim 1, further comprising heating means for heating the gas adsorbent. 3. The non-evaporable adsorbent according to claim 1 or 2, wherein the gas adsorbent is a non-evaporable adsorbent that does not generate an evaporant that evaporates from the gas adsorbent itself and interferes with light reception by the CCD. A characteristic cooled CCD camera. 4. The cooling C according to claim 1, wherein the gas adsorbent is made of a porous material.
CD camera. 5. The cooled CCD camera according to claim 1 or 2, wherein the gas adsorbent is a zirconium or a titanium. 6. The cooled CCD camera according to claim 2, wherein the heating means is an electric heater. 7. The cooling according to claim 2, wherein means for covering the gas adsorbent is provided so as to block heat rays emitted from the gas adsorbent when the gas adsorbent is heated. CCD camera. 8. A cooled CCD camera according to claim 2, further comprising means for intermittently or periodically performing heating by said heating means.