Abstract:
In the spectrometer, heavy loads are arranged centrally inside a case having a height smaller than a width, and having a depth smaller than the height. The heavy loads include a vacuum chamber, a vacuum pump which evacuates the vacuum chamber, a sample introduction unit which introduces a sample to be measured and evaporates the sample, an ionization unit which ionizes the evaporated sample and provides it to the vacuum chamber, and an ion detection unit which is connected to the vacuum chamber. Circuit board storage units which store a plurality of circuit boards with a predetermined space therebetween are formed on both sides along a width direction of the case.

Description:
CLAIM OF PRIORITY 
     The present application claims priority from Japanese patent application JP 2011-079623 filed on Mar. 31, 2011, the content of which is hereby incorporated by reference into this application. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a small mass spectrometer. 
     2. Description of the Related Arts 
     Well-known mass spectrometers ionize a small volume of samples and electomagnetically separate the ions, thereby reliably measuring molecular weights. The mass spectrometry includes a liquid chromatography mass spectrometry and a chromatography mass spectrometry. The liquid chromatography mass spectrometry includes mass spectrometry after separating components of a target material to be analyzed in liquid chromatograph, while the chromatograph mass spectrometry includes qualitative analysis of the same component separated in gas chromatograph by performing the mass spectrometry measuring, so as to determine the quantitation of the components based on the intensity of the ion detected by the mass spectrometry. 
     In recent years, introduction of mass spectrometers has been demanded for the sake of safety, in some kinds of environments, such as the industry, the non-official entities, and military environment. This is because it is necessary to quickly determine the level or kind of contamination due to unknown chemical goods as quickly as possible. 
     Particularly, in some well-known cases, the introduction of the mass spectrometer has been demanded as a countermeasure for terrorism using chemical weapons (for example, poisonous gas) or for maintaining strict control of drugs. However, the conventional mass spectrometers are too large to be carried. 
     Some conventional techniques have been proposed. One technique (Japanese Patent Application Laid-Open Publication No. 2003-294619(hereinafter referred to as Patent Document 1)) proposes a portable compound analyzing system having a portable case containing at least an optical spectrometer and a mass spectrometer. Another technique (Japanese Unexamined Patent Application Publication No. 2003-527563 (hereinafter referred to as Patent Document 2)) proposes a gas chromatograph mass spectrometer whose entire weight including the entire vacuum system is light to be carried (approximately 25 kg). 
     SUMMARY OF THE INVENTION 
     The conventional technique discloses a method for improving the portability by storing internal implementation units inside a rectangular parallelepiped. However, such conventional techniques make no attention to the weight balance nor a problem about heat exhaustion at the implementation. This weight balance is an important matter to be considered in carriage. 
     For example, the first conventional example (Patent Document 1) has a layout in which entrances/exits respectively for an optical analyzing unit, a mass spectrometer, and an optical sound analyzing unit are about to face each other in adjacent positions, in consideration that the total length of the piping for conducting sample gas to each analyzing unit. Therefore, the disclosure contents make no attention to the weight balance, and do not disclose heat exhaustion. 
     The second conventional example (Patent Document 2) discloses a technique: for specifying various units included in the mass spectrometer; for setting the inside measurement of approximately 0.09 cubic meter; and for decreasing the inside measurement by having a suitable layout. However, no disclosure has been made to a basic layout or specific contents therefor and to heat exhaustion. 
     An object of the present invention is to provide a small size mass spectrometer which realizes excellent heat exhaustion efficiency and which is weight balanced in carriage. 
     In order to attain the above object, according to an aspect of the present invention, there is provided a mass spectrometer including a case and circuit board storage units which store plural circuit boards on both sides of the case, the case having heavy loads including a vacuum chamber, a vacuum pump which evacuates the vacuum chamber, an ion detection unit which is connected to the vacuum chamber, and a battery. 
     According to this invention, it is possible to provide a small mass spectrometer which realizes excellent heat exhaustion efficiency and good weight balance, because the weight balance is adjusted, by setting the circuit board storage units as exhaust passage, by centrally arranging the heavy loads, and by arranging two groups of light weighted boards on both sides thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a schematic block diagram of a mass spectrometer according to the present invention; 
         FIG. 1B  is a schematic block diagram of the mass spectrometer according to the present invention; 
         FIG. 2A  is an internal layout diagram of the mass spectrometer according to the present invention; 
         FIG. 2B  is an internal layout diagram of the mass spectrometer according to the present invention; 
         FIG. 2C  is an internal layout diagram of the mass spectrometer according to the present invention; 
         FIG. 3  is an appearance diagram of the mass spectrometer when it is carried, according to the present invention; 
         FIG. 4  is an appearance diagram of the mass spectrometer when it is used, according to the present invention; 
         FIG. 5A  to  FIG. 5F  are screen transition diagrams of the mass spectrometer according to the present invention; 
         FIG. 6A  is a diagram of a mass spectrometer according to another embodiment of the present invention; and 
         FIG. 6B  is a diagram of the mass spectrometer according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Descriptions will now specifically be made to a mass spectrometer according to this invention, with reference to  FIGS. 1A to 6B .  FIGS. 1A to 5F  illustrate the mass spectrometer according to a first embodiment, while  FIGS. 6A and 6B  illustrate a mass spectrometer according to another embodiment. In the descriptions below, the same components and arrows are identified by the same symbols, and will be described once. 
     First Embodiment 
     The schematic configuration of the mass spectrometer according to this invention will now be described with reference to  FIGS. 1A and 1B .  FIG. 1A  shows the appearance diagram of the mass spectrometer, while  FIG. 1B  shows the layout of the component parts inside the spectrometer. 
     In  FIGS. 1A and 1B , the symbolical numeral  1  generally identifies the portable mass spectrometer which ionizes a small volume of sample and detects components of the sample by electromagnetically separating the ions. 
     This mass spectrometer  1  includes some mounted components, such as a vacuum chamber  10  and a vacuum pump  15 , that are contained inside a box-type case  100 . The appearance diagram of  FIG. 1A  shows a usage state (detection state) of the spectrometer which can be carried by a user holding a handle unit  110 . The case  100  of this embodiment has a height H smaller than a width W, and has a depth D smaller than the height H. In addition, the case  100  has a size of a small bag, thus is excellent in carriage. That is, the user holding the handle unit  110  can carry the mass spectrometer  1  without a sense of discomfort. 
     As illustrated in  FIG. 1A , at the usage, on this case  100 , one wide surface  111  comes into contact with the installation surface, and an operation unit  120  is provided on the other wide surface  112  as the upper surface. This operation unit  120  is used for executing a detection operation. Thus, the user can use the securely installed mass spectrometer to perform the detection. 
     One major characteristic of the mass spectrometer of this embodiment is that the heavy loads, such as the vacuum chamber  10  and the vacuum pump  15 , are arranged centrally inside the case  100 , and plural circuit boards  50  are arranged on both right and left sides thereof. 
     In the example of  FIG. 1B , three circuit boards are arranged on the left side of the illustration paper, while two circuit boards are arranged on the right side thereof. 
     That is, when the small size mass spectrometer  1  is carried, it is preferred that it be weight balanced. It is also preferred that the heavy loads be arranged near and right under the handle unit. For example, when to carry a bag having the heavy loads put aside to one side of the bag, this bag is not weight balanced, thus is not easily handled. In this case, a large moment is applied to the handle in carriage. This requires large power just to carry the bag. 
     The above problems are applicable to a bag having one single handle in the center of the top surface of the bag and also to a bag having handles on both sides thereof. That is, as a small size mass spectrometer, it is preferred that the spectrometer be weight balanced with the center of gravity near the center of the base  100 . 
     In consideration of the above, inventors of the present invention paid their attention to a point that the mass spectrometer  1  needs plural circuit boards  50  and a point that the circuit boards  50  are used as a unit for improving the weight balance. The weight of the circuit boards  50  is very small in relation to their packaging space inside the case  100 . On the contrary, the vacuum chamber  10 , the vacuum pump  15 , and a battery  20  are the heavy loads. Therefore, their arrangement has a great effect on the weight balance. 
     According to the given layout of this embodiment, the vacuum chamber  10  and the vacuum pump  15  are centrally arranged in the case  100 , and the plural circuit boards  50  are arranged on both sides thereof.
         In general, in relatively large bags (business case) that are carried with a single hand, the width W along the front and rear direction of the user when holding the bag with one single hand is greater than the height H along the vertical direction when holding the bag with one hand. This setting is made for not bothering about obstacle on the floor, in order that the width direction (width W) while walking coincides with the direction in which the user swings his/her arms as he/she walks, and in order to notice any obstacle on the front. Further, when holding the bag with one single hand, it is easy to hold the bag having the center of gravity right under the shoulder. Based on this, the width direction (depth W) of the user should be made thin so that the user can easily hold the bag. That is, it can be said that the portability can be maintained even if the width W is made large, in this type of one-hand-holding bag.       

     The inventors of the present invention have employed a layout in which the circuit boards  50  are arranged on both sides of the width W as the width direction, when holding the bag with one hand. Besides, the circuit boards  50  can easily be divided in the unit of several boards  50  and in the unit of functions. The plural separated circuit boards  50  can easily be arranged on both sides in consideration of the weight balance, thus capable of easily adjusting the center of gravity in the center of the case  100 . 
     Another major characteristic of the mass spectrometer of this embodiment is that the heavy loads are arranged in the center of the case  100  round the vacuum chamber  10 . 
     That is, in the mass spectrometer  1 , a sample insertion unit  30 , the vacuum pump  15 , and the ion detection unit  25  are connected to the vacuum chamber  10  (see  FIGS. 2A to 2C ). According to an employed layout of this embodiment, the vacuum chamber  10  is arranged in the center of the case  100 , and various units are arranged therearound. In this configuration, the heavy loads can easily be arranged in the center of the case  100 . Besides, the length of the electrical wiring can be made short, because the circuit boards  50  are arranged on both sides thereof. 
     In this embodiment, the vacuum chamber  10  is put aside to one wide surface  112  of the case  100 , as its upper surface at the usage state shown in  FIG. 1A . In addition, the sample insertion unit  30  and an RF oscillation circuit unit  11  are arranged to face each other, and a first vacuum pump (turbo pump)  15   a  and a vacuum gage unit  12  are arranged to face each other, on the side surface around the chamber. Further, the ion detection unit  25  (see  FIGS. 2A to 2C ) is arranged on the bottom surface. With this configuration, the sample insertion unit  30  connected to the vacuum chamber  10  can be arranged near the wide surface  112 , thus easily attaching a sample insertion adapter  70  to the sample insertion unit  30 . 
     Further, the weight balance is improved by arranging a heavy second pump (roughing vacuum pump)  15   b  on the opposite side of a heavy first vacuum pump  15   a , through the vacuum chamber  10 . A liquid crystal display unit  40  is arranged on the upper surface of the second vacuum pump  15   b , and this liquid crystal display unit  40  is arranged adjacent to the sample insertion unit  30 . As a result, an operation unit  120  including the sample insertion unit  30  and the liquid crystal display unit  40  is arranged on the upper wide surface  112 . 
     Still another major characteristic of the mass spectrometer according to this embodiment is that the circuit boards  50  with high consumption power and generating heat are arranged near the right and left ends of the case, and circuit board storage units  60  on both sides thereof are exhaust heat passages. 
     That is, if each unit included in the mass spectrometer  1  is made compact, it is necessary to exhaust heat generated from each unit efficiently outside the case  100 . In this embodiment, therefore, the circuit board storage units  60  are used as an exhaust heat passage of the circuit boards  50  arranged on both sides of the case  100 . The circuit board storage units  60  as the exhaust heat passage are provided on both sides of the case  100 . Thus, the heat generated by the circuit boards  50  can efficiently be exhausted using the two circuit board storage units  60 . Because the circuit boards  50  are arranged along the exhaust passages, the heat generated by the circuit boards  50  is not conducted to the vacuum chamber or RF circuit, thus restraining the change in the performance of each unit due to temperature rise. 
     Still yet another major characteristic of the mass spectrometer  1  of this embodiment is that the circuit boards  50  provided in the circuit board storage units  60  are aligned along an exhaust passage direction Z. 
     That is, in this embodiment, in the configuration of the circuit boards  50 , they are divided in the unit of several circuit boards  50  and arranged on both sides of the case  100 , so as to improve the weight balance. However, the circuit boards  50  to be divided in the unit of several circuit boards needs to have certain sizes, otherwise the efficiency decreases. In this embodiment, one single circuit board  50  is rectangular, in which one side (long side) is equal to or smaller than the height H, another side (short side) is equal to or smaller than the depth D, and the thin thickness direction is parallel to the width direction W. 
     According to the arrangement of the circuit boards  50  in the circuit board storage units  60 , one sheet of circuit board  50  can be made large, and each of the circuit board storage units  60  may be an aggregation of the plural circuit boards  50 . In this case, each of the circuit board storage units  60  has spaces that are long along the height H and separated by the circuit boards  50 . Therefore, in this embodiment, an exhaust passage along the exhaust passage direction Z (same as the height H) is formed inside the unit  60 . 
     In this embodiment, to improve the exhaust efficiency, a blast fan  13  is arranged on one of the circuit board storage units  60  as the exhaust passage. In this embodiment, exhaust ports  150  are provided on both side surfaces of the case  100  as both sides of the handle unit  110 , while an inlet port  151  is provided on the back surface side (bottom surface side) of the case  100  facing the handle unit  110 . 
     Further major characteristic of the mass spectrometer  1  of this embodiment is the compact appearance structure in accordance with the internal configuration. 
     That is, in the appearance of the case  100  of this embodiment, both ends of the case  100  covering the circuit board storage unit  60  are projected in the forward direction, and the bar-like handle unit  110  is formed to connect the both ends of projecting units  115 . According to this configuration, the bar-like handle unit  110  can be incorporated with the case  100  so as to enhance the strength. 
     In this embodiment, exhaust wind-direction plates  116  are provided inside the pair of projecting units  115 , thereby refracting the exhaust. This avoids the exhaust from striking on the user. However, the present invention is not limited to the above configuration. For example, the space of the projecting units  115  may be used for storing attachments, or may be used as a packaging space for arranging the blast fan  13  or the circuit board  50 . The directions of the exhaust passage direction Z may be changed by switching the exhaust port  150  and the inlet port  151  from one to the other. 
     Still further major characteristic of the mass spectrometer  1  of this embodiment is that an opening/closing cover  121  is provided on the operation unit  120 , a non-illustrative manual is put on an internal surface  121   a  of the opening/closing cover, or the internal surface  121   a  is used as a storage space for the operation manual. 
     That is, the mass spectrometer  1  of this embodiment may frequently be carried outside. Thus, it is necessary to prevent dust from entering a sample insertion port  31  of the sample insertion unit  30  arranged inside the operation unit  120 , and to prevent any attacks on a display screen  41  of the liquid crystal display unit  40 . Hence, in the configuration of this embodiment, the operation unit  120  is covered with the opening/closing cover  121 . This opening/closing cover  121  includes a hinge  122  on a side facing the handle unit  110 , as illustrated in  FIG. 1 . At the usage state, the opening/closing cover  121  may turn backward. 
     According to this configuration, the opening/closing cover  121  may be used not only as a protection unit for the spectrometer, but also as an attachment space for the operation manual on the internal surface  121   a.    
     Descriptions will now further be made to the mass spectrometer according to this embodiment with reference to  FIGS. 1A to 5F .  FIGS. 2A to 2C  are internal layout diagrams of the mass spectrometer according to the present invention. In particular,  FIG. 2A  is a plane view of the mass spectrometer,  FIG. 2B  is a front view of the mass spectrometer, and  FIG. 2C  is a front view of the mass spectrometer.  FIG. 3  is an appearance diagram of the mass spectrometer when it is carried.  FIG. 4  is an appearance diagram of the mass spectrometer, at the usage.  FIG. 5  are screen transmission diagrams of the mass spectrometer. 
       FIGS. 2A to 2C  show the layout of the main constituent parts of the mass spectrometer according to this embodiment. In  FIG. 2A , the handle unit  110  is arranged in the lower part of the illustration. The internal constituent parts are attached to a non-illustrative chassis. 
     According to the configuration of this embodiment, the internal constituent parts are covered with a resin-formed outer case. In this embodiment, descriptions will be made to a configuration in which the internal constituent parts are covered with an outer case including the handle unit  110 . Instead of this outer case, the mass spectrometer may be carried while being stored in an attaché case including a hard case or may be stored in a soft (soft member) case including a handle part and a shoulder belt for holding the mass spectrometer contained in a box-type case. 
     In the descriptions of  FIGS. 2A to 2C , to clarify the arrangement relationship of the units, the arrangement of each illustration will be described based on  FIG. 2B , on the assumption that the upper part of the illustration corresponds to the upper surface of the spectrometer. 
     As described above, in this embodiment, the heavy loads are concentrated in the center of the case  100 , and the circuit board storage units  60  including the circuit boards  50  are provided on both sides thereof. The main unit of the heavy loads is the vacuum chamber  10 . This vacuum chamber  10  is arranged in the upper central part of the case  100 . 
     In the plane view of  FIG. 2A , the sample insertion unit  30  and the RF oscillation circuit  11  are arranged to face each other on both sides of the vacuum chamber  10 . The vacuum gate unit  12  and the first vacuum pump  15   a  arranged to face each other in front and in rear of the vacuum chamber  10 . As illustrated in  FIG. 2B , an ion detection unit  25  is provided in the lower part of the vacuum chamber  10 . Accordingly, in this embodiment, the units are arranged on the five surfaces of the vacuum chamber except the top surface thereof having approximately a rectangular parallelepiped, thus improving the accuracy and realizing the compact size of the mass spectrometer. Further, in this arrangement, because the sample insertion unit  30  to be attached to the vacuum chamber  10  is arranged near the upper surface of the mass spectrometer, the sample insertion port  31  of the sample insertion unit  30  is arranged near the upper surface so as to desirably attach/detach the sample insertion adapter  70  to/from the sample insertion port  31 , as illustrated in  FIG. 1A . 
     In this embodiment, the heaviest unit is the vacuum pump  15 , and occupies one fourth of the entire weight. In this embodiment, the vacuum pump  15  includes two stages: that are a first vacuum pump (turbo molecular pump)  15   a  to be attached to the vacuum chamber  10  and a second vacuum pump (roughing pump)  15   b  to be attached to the first vacuum pump  15   a.    
     In this embodiment, the second vacuum pump (roughing pump)  15   b  is arranged in the front part of the case  100 . In particular, the second vacuum pump  15   b  is arranged to face the first vacuum pump  15   a  arranged in the rear part of the case  100 . This attempts to obtain the weight balance of the case  100  along the front and rear direction. 
     The second vacuum pump  15   b  is arranged in the lower part of the case  100 , thereby maintaining an arrangement space for the liquid crystal display unit  40  in the upper part thereof. As a result, the sample insertion port  31  of the sample insertion unit  30  is arranged near the liquid crystal display unit  40 . Therefore, the operation unit  120  may be made compact. 
     Another heavy load may be a battery  20 . In this embodiment, the battery  20  is arranged in the rear part of the case  100  in a position next to the first vacuum pump  15   a  in a side-by-side manner. By so doing, the center of gravity G will slightly be lowered approximately in the rear of the case  100 , that is, in a carriage posture having the handle unit  110 . 
     A backboard substrate  51  is provided on the bottom surface of the circuit board storage units  60  arranged on both sides of the case  100 . Provided on this backboard substrate  51  are circuit board installation units  52  for aligning the circuit boards  50  in the front and rear direction. According to this configuration, the rectangular circuit boards  50  are put side by side respectively on the circuit board installation units  52 , in the front and rear direction. 
     As described above, in this embodiment, the circuit boards  50  are processed as parts for adjusting the center of gravity G. Thus, the circuit board storage unit  60   a  on the left side stores a larger number of circuit boards  50  than the number of circuit boards  50  in the circuit board storage unit  60   b  on the right side, and has a larger storage space than that of the circuit board storage unit  60   b . This is based on the weight and an amount of generated heat of each circuit board and an effect of electric noise. 
     In this embodiment, a circuit board for controlling electricity are digital circuit board and arranged in the circuit board storage unit  60   a  on the left side near the battery  20 , while an analog circuit board having a high voltage is arranged in the circuit board storage unit  60   b  on the right side. 
     The above-described layout is applied to the mass spectrometer  1  according to this embodiment. As a result, the center of gravity G may be set approximately in the center along the right and left direction, approximately in the rear part along the front and rear direction, and approximately in the lower part of the vertical direction. With this center of gravity, the center of gravity G is approximately in a lower center position, thus enabling to realize the analyzing process in a stable posture. In the carriage posture in which the handle unit  110  is held with one hand, the center of gravity is the center and slightly in the lower part along the right and left direction of the case  100 , thus enabling to realize the carriage operation. In a normal carriage posture, the spectrometer is held while the operation unit  120  is set in the nearest part to the outer periphery. In other words, the center of gravity may be set in a position near the user side, that is, in a position right below the shoulder of the bearer. Therefore, it is possible to easily carry the spectrometer. 
     In this embodiment, the blast fan  13  is provided in the rear parts on both sides of the circuit board storage units  60 . However, it is not limited to this configuration. That is, the exhaust systems inside the case  100  include a system for pushing the outside air into the case  100  with the blast fan  13  and a system for taking out the heat inside the case  100  with the blast fan  13 . In consideration of the weight balance, the blast fan  13  may adequately be arranged. 
     In this embodiment, because the laminar circuit boards  50  can be arranged separately on both sides of the circuit board storage units  60 , the exhaust passage direction Z can be formed along the laminar circuit boards  50 . The heat generated from each unit arranged in the center of the case  100  is taken into the circuit board storage units  60  on both sides so as to be exhausted, thus improving the heat exhaustion efficiency. 
     The external appearance of the mass spectrometer  1  according to this embodiment will be described with reference to  FIGS. 3 to 4 . 
     In  FIG. 3 , the mass spectrometer  1  according to this embodiment is made thin in the form of a business attaché case, and has a compact outer appearance without a bulky body to carry. In the periphery form of the handle unit  110  which is a matter of public exposure in carriage, the pair of projecting units  115  are rounded toward the head end. The projecting units  115  are formed continuously from the box-shaped end parts. The bar-like handle unit  110  is provided to connect the pair of projecting units  115 . Accordingly, a simple configuration without a concave-convex surface is realized with the handle unit  110  introduced into the case  100 . The bar-like handle unit  110  is supported by the pair of projecting units  115 , thus making an appeal to user about the strong configuration. 
     As seen from the illustration, the outer appearance of the case  100  has a form covered with a thick cover body  113  connecting from the pair of rounded projecting units  115  to the pair of wide surfaces  111  and  112 , with minimized concave-convex irregularities thereon, so as to be easily mounted into vehicles or the like. The periphery of the cover body  113  has corner parts  114  that are rounded, thus reducing the impression of the bulky body. With this appearance, the rain or dusts can easily be wiped out in carriage. Further, the side surface wall  115  of both sides along the width W is lower than the end part of the cover body  113  by one step. Inside that, the exhaust port  150  and an external terminal unit  152  are provided. Thus, the exhaust port  150  and the external terminal unit  152  are unlikely subject to external attacks. 
     The external terminal unit  152  is covered with the opening/closing cover, in which a non-illustrative main power switch or an external connection terminal is arranged. The external terminal unit  152  is provided adjacent to the circuit board storage unit  60 . Thus, the main power switch or the external connection terminal is directly connected to the circuit boards  50  provided in the circuit board storage unit  60 . Therefore, this configuration does not need new wiring. 
     In  FIG. 3 , the lower part of the case  100 , as the bottom surface, has one down step so as to form a pair of side surface walls  117  in a continuous form, and includes four projecting leg parts  118  on the four corners. As a result, the case  100  can stably be put on the floor, thus preventing the entrance of water into the inlet port  151  formed on this bottom surface, when the case  100  is put on the floor. 
     Further, the wide surface  112  has the opening/closing cover  121  that is flat with respect to the surrounding wide surface  112 , in a state where the cover  121  is closed as shown in  FIG. 3 . On this opening/closing cover  121 , an indicator  153  for indicating “charge” or “power ON” is provided. This indicator  153  is not limited to be provided on the opening-closing cover  121 , but may be provided on the case  100 . 
     Descriptions will now be made to the operation unit  120  with reference to  FIG. 4 . In  FIG. 4 , the opening/closing cover  121  of this embodiment has an L-like shape in cross section, has the head end part bent toward the handle unit  110 , and has an opening/closing mechanism  154  on its head end. With this configuration, the opening/closing mechanism  154  is the upper surface in posture of carriage shown in  FIG. 3 , thus preventing unintentional operation of the opening/closing mechanism  154 . This minimizes the opening/closing cover  121  kept open in carriage. 
     In this embodiment, the opening/closing cover  121  is in an L-like form. The opening/closing mechanism  154  has an inclined surface, and includes the display screen  41  arranged thereon. With this configuration, it is possible to improve the visibility and operability of the display screen  41  arranged on the inclined surface (opening/closing cover  154 ) and a liquid crystal operation switch  155  arranged in the front part thereof. 
     In this embodiment, the inclining opening/closing cover  154  is formed on the left front side of the operation unit  120 , and an operation surface  156  is formed along a horizontal surface at the back and right side thereof. A sample insertion port  31  is provided at the back and left side of the horizontal operation surface  156 . An analysis start switch  157  and a sub-main power switch  158  are arranged side by side at the back and right side of the operation surface  156 . A detection lamp  159  is arranged at the right forefront part of the operation surface  156 . 
     The sample insertion port  31  has an attachment lever  32  for fixing the sample insertion adapter  70  shown in  FIG. 1A . In this embodiment, on the spot of analysis, this sample insertion port  31 , the analysis start switch  157 , and the sub-main power switch  158  are simply operated so as to perform an analysis process. In this embodiment, visible parts, such as the display screen  41  and the detection lamp  159 , are arranged in the front part of the operation unit  120 , while operation parts, such as the sample insertion port  31 , the analysis start switch  157 , and the sub-main power switch  158  are arranged in the back part thereof. In this arrangement, the operation parts can be operated while checking the visible parts, or while acquiring the guidance about the visible parts. 
     In this embodiment, an adapter preparation unit  160  for preparing a sample insertion adapter  70  is provided using the space between the detection lamp  159  and the analysis start switch  157 . As shown in  FIG. 1A , the sample insertion adapter  70  includes a sample container  71  for putting sample pieces and an attachment case  72  for attaching this sample container  71  to the sample insertion unit  30 . 
     With this adapter preparation unit  160 , the sample container  70  having the sample put therein is set in a hollow part. The attachment case  72  can be attached downward from up into the stably set sample container  71 . This coupled sample insertion adapter  70  can be attached to the sample insertion port  31 . 
     The opening/closing cover  121  of this embodiment can be open backward through the hinge  122  which is provided in the rear part of the operation unit  120 . Thus, the internal surface  121   a  of the opening/closing cover  121  is visible to the users. In this embodiment, non-illustrative guidance representing the operation procedures of the mass spectrometer  1  is illustrated on the internal surface  121   a . In accordance with this guidance, easy operations can be achieved without reading an operations manual. 
     The use of and operational method of this mass spectrometer  1  will now be described with reference to  FIGS. 1A , B and  5 A to  5 F. 
     In the mass spectrometer  1 , a non-illustrative control circuit included in the circuit boards  50  generally controls the mass spectrometer  1 . The mass spectrometer  1  is activated upon operation of a non-illustrative main power switch provided on the external terminal unit  152 . Upon operation of the sub-main power switch  158 , the control circuit starts to prepare the operations, and displays a screen  200  on the display screen  41 , as shown in  FIG. 5A   
     This screen  200  includes a confirmation display unit  201  in the uppermost row, a first status display unit  202  in the second row, a second status display unit  203  in the third row, and a guidance unit  204  in the lowest row. The confirmation display unit  201  shows the analysis date/time and a status of the sample insertion unit  30 . The first status display unit  202  shows the status of examination step. The second status display unit  203  shows guidance additional information and the examination result. The guidance unit  204  shows the operations guidance in written form. No change will be made in the basic layout of the screen  200 . This screen  200  has been described only by way of example, and is not limited to this. 
     The screen  200  of  FIG. 5A  shows the present time, and also shows that no sample has been set into the sample insertion port  30 . The control circuit may display this screen  200 , and also may output voice data stored in a memory unit provided in the circuit board  50 , through a non-illustrative speaker. In this case, the output contents correspond to the guidance on the screen  200 . For example, the user can confirm that the sample can be loaded now, and also that he/she is instructed to load the sample based on the guidance contents and the voice, by watching the screen  200 . Now, the user can understand the operational method based on the guidance screen of the second status display unit  203 . 
     Upon reception of the screen  200 , the user can set the sample insertion adapter  70  (including the sample container  71  and the attachment case  72  as shown in  FIG. 1A ) to the sample insertion port  31 , and executes an operation for fixing the adapter by operating the attachment lever  32 . 
     The control circuit displays the screen  210  shown in  FIG. 5B , upon detection that the sample insertion adapter  70  is set to the sample insertion port  31  by operation of the attachment lever  32  based on a non-illustrative sensor. This screen  210  shows the guidance that the sample insertion adapter  70  can be taken out now, informs that it is possible to perform measurement, and instructs the user to press the start button. In this status, the control circuit starts the analyzing when the analysis start switch  157  is operated. 
     The control circuit displays the screen  220  shown in  FIG. 5C , when the analysis start switch  157  is operated. This screen  220  shows that the sample insertion adapter  70  cannot be taken out, and shows also the remaining detection time. Upon detection of one kind of target material, the control circuit displays the screen  230  shown in  FIG. 5D . Upon detection of several kinds of target materials, the control circuit displays the screen  240  shown in  FIG. 5E . When no target material has been detected, the circuit displays the screen  250  shown in  FIG. 5F . 
     On the screens of  FIGS. 5D and 5E , the control circuit outputs a voice signal for informing that the target material has been detected, or informs the user about the detection of the target material by flashing or turning on a specific light of light on the detection lamp  159 . This specific color represents the detection of a target material. Similarly, if no target material has been detected, the control circuit outputs the same voice signal together with the screen of  FIG. 5F , and turns on or flashes another specific color of light on the detection lamp  159 . 
     In each of  FIGS. 5D to 5F , the screen shows the guidance for instructing the user to take out the sample insertion adapter  70 , upon complete examination. Then, the control circuit displays the screen  200  of  FIG. 5A , when it is detected that the sample insertion adapter  70  has been taken out, upon user operation of the attachable lever  32 . 
     Another Embodiment 
     Another layout of the operation unit will now be described with reference to  FIGS. 6A and 6B . 
       FIG. 6A  shows a layout of another embodiment, in which the operation unit  120  is divided into two parts left and right. One divided part includes the sample insertion port  31 , which needs to be covered with the opening/closing cover  121 , and sub-main power switch  157  related to this sample insertion port  31 . The other divided part includes the display screen  41 , the detection lamp  159 , and the sub-main power switch  158 . This embodiment is suitable when a large display screen  41  is applied. Even if the opening/closing cover is not open, the display screen is operable with using the liquid crystal operation switch  155 . Therefore, unnecessary exposure of the sample insertion port and/or analysis start switch can be prevented, at the operations the maintenance or at the confirmation of analysis history. 
     In the embodiment of  FIG. 6B , the analysis start switch  157  and the sub-main power switch  158  are arranged in the front part of the operation unit  120 , while the sample insertion port  31  is arranged in the rear part of them, and further the display screen  41  is arranged compact in the rear part of that. This embodiment is suitable for the operation unit of a further compact mass spectrometer. The display screen may be arranged in the rear part of the sample insertion port. In other words, the screen is kept away from the user. In this arrangement, even if a solution is unexpectedly spilt when the sample insertion adapter  70  is inserted into the sample insertion port, the possibility that the spilt solution reaches the display screen may be reduced. 
     Accordingly, the mass spectrometer of this embodiment includes the case and circuit board storage units on both sides of the case. Inside the case, heavy loads are arranged in the center thereof, and include the vacuum chamber, the vacuum pump, the sample insertion unit, and the ion detection unit. Specifically, the vacuum pump evacuating air from the vacuum chamber. The sample insertion unit provides ionized sample into the vacuum chamber. The ion detection unit is connected to the vacuum chamber. Each of the circuit board storage units stores plural circuit boards. 
     In this case, the case has the height larger than its width and the depth smaller than the height. The above-described circuit board storage units are provided on both sides along the width direction. The plural boards arranged inside the circuit board storage units are aligned along the height direction. Further, each of the circuit board storage units includes exhaust/inlet ports at both terminal ends along the height direction. 
     In the mass spectrometer of this embodiment, a case has heavy loads including a vacuum chamber, a vacuum pump evacuating air from the vacuum chamber, a sample insertion unit for providing ionized sample into the vacuum chamber, and an ion detection unit connected to the vacuum chamber, in the center thereof. Exhaust passages for exhausting heat generated from the heavy loads are formed on both sides thereof, and plural circuit boards are separately stored along the exhaust passages. 
     In this case, the case has the height larger than the width, and has the depth smaller than the height. The exhaust passages are formed on both sides along the width direction. The plural boards arranged inside the exhaust passages are aligned along the height direction. Further, the exhaust passages include the exhaust/inlet ports on both side ends along the height direction. 
     In the mass spectrometer of this embodiment, the case having a height smaller than a width and having a depth smaller than the height centrally have: heavy loads including a vacuum chamber; a vacuum pump evacuating air from this vacuum chamber; a sample insertion unit which provides an ionized sample to the vacuum chamber; an ion detection unit which is connected to the vacuum chamber; and a battery, wherein circuit board storage units for separately storing plural circuit boards are formed on both sides along a width direction, both ends of the case including the pair of circuit board storage units have a pair of projecting units which project in one height direction and are connected with a bar-like handle unit, and widest surface of the case has an operation unit including an injection port for injecting a sample into the sample insertion unit. 
     In this case, the circuit board storage unit is an exhaustive passage along which the plural circuit boards are aligned along the height direction, and includes an exhaust/inlet port on both ends along the height direction. Further, the operation unit is covered with the opening/closing cover, and includes a driving status display unit and an examination start button.