Abstract:
A cerebral function measuring apparatus houses a light detector in a package that can be set on the head of the subject examinee with light detection elements, amplifiers, and high voltage power supplies sealed in the package. Each amplifier and each high voltage power supply are united into one and covered with a high polymer material with high dielectric strength, and further enclosed by a metallic shield so as to be insulated. The high voltage power supply consists of a very small coil and an integrated circuit to generate a voltage required to drive the light detection element in the package. A removable and safe module type light detector is thus realized.

Description:
CLAIM OF PRIORITY 
       [0001]    The present application claims priority from Japanese application JP 2007-006524 filed on Jan. 16, 2007, the content of which is hereby incorporated by reference into this application. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to a biological optical measuring apparatus that checks the internal state of a living body with use of a light, more particularly to a compact module type light detection apparatus excellent in portability and capable of measuring the cerebral function of a subject examinee by analyzing the intensity of a light transmitted through the head of the examinee. 
       BACKGROUND OF THE INVENTION 
       [0003]    As means for measuring the human&#39;s cerebral function, there is a well known topography technique. The technique irradiates a near-infrared light to part of the head of the subject examinee, analyzes the intensity of the reflected light, and displays the distribution of blood kinetics in the cerebral cortex two-dimensionally. This light topography apparatus includes a light source, a detector, and a signal processor. A probe is fixed at the subject human&#39;s head and the probe is connected to the apparatus through plural optical fibers for measuring the distribution of blood kinetics in the brain. This method clarifies the correspondence between the human&#39;s motor function and the respective brain&#39;s localized regions, thereby providing new clues of mental and medical treatments. In recent years, this localized cerebral function is used to develop interface techniques for controlling external units and devices such as computers, games, environmental control units, etc., by utilizing signals measured from the brain. JP-A No. 07 (1995)-314195 proposes a method for facilitating such a development. According to the method, a biological optical measuring apparatus is used to measure the intensity of a light transmitted through the head of the subject examinee to compute an amount of oxidized and reduced hemoglobin with use of a computing device, thereby driving an object external device according to the computed data. On the other hand, JP-A No. 10 (1998)-346450 proposes a method for determining a history of changes of measured signals obtained from a biological optical measuring apparatus with use of a computing device, a storage device, a controller, etc. and applies the determination result to certain rules, thereby making switching among TV channels. JP-A No. 2000-373292 also proposes an interface technique for controlling an object on a screen according to the intensity of a light signal obtained by setting a light irradiator and a light detector on the skin of the subject examinee. 
         [0004]    Those techniques provide welfare information units and devices for mainly supporting bedridden patients, as well as interface techniques applied to information home electric appliances that are different from conventional ones. 
       SUMMARY OF THE INVENTION 
       [0005]    However, in any of the above described conventional techniques, each of the cerebral function measuring apparatuses is complicated in configuration and large in scale, so that they are difficult to be carried. This has been a problem. Particularly, the light irradiator and the light detector are manufactured with a state-of-the-art semiconductor technology, so that its effect of mass production has not been expected. In addition, the light irradiator and the light detector are limited in operating life and services must stop during their parts exchanges. Furthermore, in any of the conventional biological optical measuring apparatuses, the cerebral function measuring unit and the head probe are connected to each other through plural optical fibers, so that it has been difficult to increase those optical fibers to increase measuring spots, since a long time measurement is often refused by the examinee due to the weight of those optical fibers. The distance between the measuring apparatus and the examinee&#39;s body is also limited by the lengths of the optical fibers, so that measurement of the cerebral function is impossible while the examinee is walking or in motion. 
         [0006]    Under such circumstances, it is an object of the present invention to provide a structure of a removable module type light detector to realize a compact and portable biological optical measuring apparatus. It is another object of the present invention to provide a structure of an easy-to-handle and safe shield type light detector to achieve the same. 
         [0007]    In order to achieve the above objects, the light detector of the present invention is housed in a package having a size for enabling the light detector to be easily put on the examinee&#39;s head and a light detection element, an amplifier, and a high voltage power supply thereof are shielded in the package. And the amplifier and the high voltage power supply are united into one and covered with a high insulation high polymer material and enclosed again by a metal shield material, thereby insulating the package from external. The high voltage power supply is composed of a very compact coil and an integrated circuit, thereby generating a voltage required to drive the light detection element in the package. As a result, a removable and safety module type light detector has been realized. The high polymer with a high insulation property is just required to satisfy a condition that those elements are electrically insulated from each another. In this case, the high polymer material means a material having a volume resistivity of 1 teraohmmeter or over and an electrical breakdown voltage of 10 kV or over. For example, it may be any of resin, silicon rubber, etc. 
         [0008]    Concretely, the present invention provides a biological optical measuring apparatus that includes a light irradiation module for irradiating a light to an examinee; a light detection module for detecting the light irradiated from the light irradiation module and transmitted through the examinee; and a computing device for computing blood kinetics of the brain of the examinee from a detection result of the light detection module. The light detection module includes a first circuit substrate having a high voltage power supply, a second circuit substrate having a signal amplification circuit, and a light detection element for detecting the light. The first and second circuit substrates and the light detection element are disposed in three dimensions in the light detection module in the order of the first circuit substrate, the second circuit substrate, and the light detection element or in the order of the second circuit substrate, the first circuit substrate, and the light detection element. The first and second circuit substrates are enclosed by a housing material and the housing material has a hole for guiding the light irradiated from the light irradiation module and transmitted through the examinee to the light detection element. 
         [0009]    Outside the housing material is exposed a power supply terminal and another terminal for guiding signals detected by the light detection element to external. 
         [0010]    According to an embodiment of the present invention, the portability is therefore improved because the light detection module can be set on the examinee&#39;s head. Because a high voltage generated in the module is shielded so as not to be leaked to external, the safety is excellent. Furthermore, the light detection module can be replaced in units of a module, the maintenance cost is reduced and the reliability is improved. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is an explanatory drawing for showing a system configuration in a first embodiment of the present invention; 
           [0012]      FIG. 2  is a configuration of the probe shown in  FIG. 1 ; 
           [0013]      FIG. 3  is a cross sectional view of the configuration of the detector shown in  FIG. 1 ; 
           [0014]      FIG. 4  is a block diagram for showing a structure of the detector shown in  FIG. 1 ; 
           [0015]      FIG. 5  is another block diagram for showing the structure of the detector shown in  FIG. 1 ; 
           [0016]      FIG. 6  is a cross sectional view for showing the configuration of the detector shown in  FIG. 1 ; 
           [0017]      FIG. 7  is another cross sectional view for showing the configuration of the detector shown in  FIG. 1 ; 
           [0018]      FIG. 8  is still another cross sectional view for showing the configuration of the detector shown in  FIG. 1 ; 
           [0019]      FIG. 9  is a cross sectional view for showing disposition of the electrodes of the detector shown in  FIG. 1 ; 
           [0020]      FIG. 10  is another cross sectional view for showing disposition of the electrodes of the detector shown in  FIG. 1 ; 
           [0021]      FIG. 11  is still another cross sectional view for showing disposition of the electrodes of the detector shown in  FIG. 1 ; 
           [0022]      FIG. 12  is still another cross sectional view for showing disposition of the electrodes of the detector shown in  FIG. 1 ; 
           [0023]      FIG. 13  is a block diagram for showing a circuit of the detector shown in  FIG. 1 ; 
           [0024]      FIG. 14  is a system configuration diagram in a second embodiment of the present invention; and 
           [0025]      FIG. 15  is a system configuration diagram in a third embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0026]    Hereunder, the preferred embodiments of the present invention will be described with reference to the accompanying drawings. In those drawings, the same reference numerals will be used for the same components, avoiding redundant description. 
       First Embodiment 
       [0027]      FIG. 1  shows an explanatory drawing of how the present invention applies to a biological optical measuring apparatus. A probe  70  is set on the head of an examinee  80  to measure the state of blood kinetics. The probe  70  includes plural light sources  9   n  and plural detectors  10   n . Those light sources  9   n  and detectors  10   n  are connected to a measuring apparatus installed separately from the examinee  80  through a send cable  50  and a receive cable  60 . The measuring apparatus consists of a transmitter  10 , a receiver  20 , a computing device  30 , and a storage device  40 . The transmitter  10  sends electrical signals converted to those having a specific frequency or light signals converted to those having a wavelength of a near-infrared region respectively to the plurality of light sources  9   n . Each of the detectors  10   n  detects a light scattered on the surface of the cerebral cortex and converts the detected light to an electrical signal to be sent to the receiver  20 . The receiver  20  processes information exchanged between the computing device  30  and the storage device  40  to compute an amount of hemoglobin in the brain from the electrical signal. Thus changes of the blood amount in the cerebral cortex can be displayed in a two-dimensional space. 
         [0028]      FIG. 2  shows a cross sectional view of the probe  70 , as well as the plurality of light sources  9   n  and the plurality of detectors  10   n  disposed on the probe  70  shown in  FIG. 1 . The probe  70  includes plural sockets  11   n  disposed regularly. Each light source  9   n  or detector  10   n  is inserted in one of the sockets  11   n . Each light source  9   n  or detector  10   n  is structured as a module and this module is inserted/removed in/from its socket  11   n , thereby realizing arrangement of a variety of detection patterns. And when a light source  9   n  or detector  12   n  goes wrong, it is easily replaced with a normal one. 
         [0029]      FIG. 3  shows a cross sectional view of a configuration of a detector  10   n  of the present invention. The detector  10   n  consists of a light detection element  150 , a high voltage power supply  180 , and an amplifier  190  housed in a package. Those components are covered by a case  130  and then by a high polymer material  160  with higher electric insulation. Plural electrodes  20   n  for sending/receiving signals to/from the high voltage power supply  180 , the amplifier  190 , and external are disposed on the surface of the case  130 . Under the high polymer material  160  with high electric insulation is provided an aperture  170  for guiding an external light. The aperture  170  has a filter  260  at its inlet to remove unnecessary wavelengths. The use of this filter  260  depends on the ambient conditions; it is not necessarily required. In  FIG. 3 , the high voltage power supply  180  is disposed in the upper portion while the amplifier  190  is disposed in the lower portion. However, their disposition places can be inverted up and down with no problem. 
         [0030]      FIG. 4  shows a block diagram for showing a structure of the detector  10   n . The detector  10   n  consists of a light detection element  150 , a module of a high voltage power supply circuit and a temperature compensation circuit  220 , and a module of an amplification circuit and a temperature compensation circuit  230 . The high voltage power supply circuit generates a voltage of around 200V, so that it must be insulated from external. This is why the present invention encloses the module  220  and the module  230  with a shield  210  respectively. Consequently, the safety is more improved even when handing a module of the detector  10   n  manually. In addition, because the magnetic waves are prevented from leaking to external, influences of the magnetic waves to human bodies are reduced. 
         [0031]      FIG. 5  shows an example in which the modules  220  and  230  are enclosed by one shield  210 . Also in this case, it is possible to obtain the same effect as that shown in  FIG. 4 . 
         [0032]      FIG. 6  shows a cross sectional view of a structure of the detector  10   n  shown in  FIG. 1 . The detector  10   n  consists of a light detection element  150  housed in a package  140 , an amplification circuit  27   n  disposed on a printed-circuit board  250 , and a high voltage power supply  180  disposed on a printed-circuit board  251 . Those boards  250  and  251  and circuits  27   n  are made of high electric insulation silicon or the like respectively. The detector  10   n  is covered entirely by a metallic shield  210 . This module of the detector  10   n  is sealed in a case  130  made of a high insulation polymer material. Under this case  130  is provided an aperture  170  for guiding an external light. And the aperture  170  has a filter for eliminating unnecessary lights. Around the bottom of the case  130  is disposed plural electrodes  29   n , each having a spring in itself. This secures the electrical connections of those electrodes  29   n  inserted respectively in the sockets  11   n  shown in  FIG. 2 . In this example, the electrode  290  is connected to the printed-circuit board  250  in the metallic shield  210  and the electrode  291  is connected to the case  130 . Consequently, a dielectric strength test can be carried out by applying a voltage between the electrodes  290  and  291 . 
         [0033]      FIG. 7  shows an example in which the electrodes  29   n  shown in  FIG. 6  are disposed on the top surface of the case  130 . In this example, the high voltage power supply  180  is disposed under the board  250  and the boards  250  and  251  are connected to each other by a wire. The high voltage power supply  180  and the amplification circuit  27   n  are covered by a metallic shield  210  and furthermore, all the detectors  10   n  are housed in the case  130 . Consequently, the detectors  10   n  are insulated perfectly to assure the safety when in handing the detectors  10   n . In addition, this structure is not connected to any of the sockets  11   n  and the case  130  mechanically and electrically, the structure never affects the electrical signals even when the positional relationship between the sockets  11   n  and the detectors  10   n  is varied. This is a merit of the structure. 
         [0034]      FIG. 8  shows an example in which the plural electrodes  29   n  shown in  FIG. 6  are disposed at the periphery of the case  130 . In this example, a counter electrode is also disposed at the side face of each socket  11   n . And because this counter electrode and a spring electrode  296  come in contact with each other at a certain elastic force, the electrical connection between them is assured. The same effect can also be obtained by using a spring electrode at the counter electrode side and a fixed electrode at the side of the case  130 . 
         [0035]      FIG. 9  shows a cross sectional view of the structure shown in  FIG. 8 . In this example, the plural electrodes  30   n  are disposed at equal intervals in a concentric circle pattern. Consequently, the distance between each socket  11   n  and the case  130  can be kept constantly. If the number of electrodes  30   n  is less, the electrodes  30   n  may be disposed at one side of the case  130 . 
         [0036]      FIG. 11  shows an example in which the shape of the electrodes  29   n  shown in  FIG. 8  is varied. In  FIG. 11 , the shape of the electrodes  32   n  is rectangular. Consequently, the rectangular detectors  10   n  are inserted in the sockets  11   n , thereby the electrical connection between them is assured even when the positional relationship between the detectors  10   n  and the sockets  11   n  is shifted slightly up and down. Thus the user can use the apparatus more easily. 
         [0037]      FIG. 12  shows an example in which the cross sectional shape of the case  1300  shown in  FIG. 9  is polygonal. In this example, the case  130  is octagonal. The electrodes  33   n  are disposed at the eight sides of the octagon respectively. Consequently, the detectors  10   n  having such a shape can be inserted in the sockets  11   n  so as to prevent each detector  10   n  from shifting in the rotating direction, thereby the electrical connection between each of the detectors  10   n  and each of the sockets  11   n  can be stabilized. 
         [0038]      FIG. 13  shows a block diagram for showing a circuit of the detector  10   n  shown in  FIG. 1 . A light detector  150  catches incident signals and converts the signals to electrical signals. A light detection circuit  372  detects a weak current and an amplification circuit  373  amplifies the current. Then, an output circuit changes the current to a voltage to be assumed as an external voltage. The light detection element  150  is supplied a high driving voltage from a step-up circuit  371 . A coil  360  generates this high voltage. At first, a DC voltage  340  is applied to an oscillation circuit  370  to generate a pulse voltage. This pulse voltage is applied to the primary side  361  of the coil  360  to generate an AC voltage higher than the pulse voltage at the secondary side  362  of the coil  360 . This AC voltage is applied to the step-up circuit  371  to generate a driving high supply voltage. The temperature detection element  350  is connected to the step-up circuit  317  and the detected signal is fed back to the oscillation circuit  370 . Consequently, a stable supply voltage is realized. 
       Second Embodiment 
       [0039]      FIG. 14  shows a second embodiment of the present invention. Each of measuring systems  400  and  401  includes plural light sources  38   n  and plural detectors  39   n  that are disposed at equal intervals in an array pattern. Each detector  39   n  is structured as a module according to the present invention to improve the portability. The use of one unit of this measuring system  400  enables measurement of the freshness, etc. of food, since the light irradiated from a light source  380  is reflected at the surface of the subject living sample  410  and caught by the detector  390 . If two units of this measuring system  400  are used to measure a living sample set therebetween, for example, the light irradiated from a light source is caught by the detectors  393 , so that the distribution of the water contained in any of the examinee&#39;s organs can be measured. 
       Third Embodiment 
       [0040]      FIG. 15  shows a third embodiment of the present invention. In this example, a module type detector is used for part of a head band. A human body  45   n  puts on a band  46   n  wound around his/her head to measure blood kinetic changes in the brain. The band  46   n  includes a measuring system  40   n  and a transmitter  47   n . The measuring system includes plural light sources  50   n  and plural detectors  51   n . The transmitter  470  exchanges measured signals with an external cerebral function analyzer  420  wirelessly  49   n . The cerebral function analyzer  420  is connected to a controller  430  and generates a signal in accordance with changes of blood kinetics. This signal is used to control the operations of the cursor and animations displayed, for example, on a display screen  440 . Each of two players who control the changes of blood kinetics in his/her brain, moves a character on the screen to play, for example, a combat game. The players can also observe character movements on the screen to obtain visual biofeedback  480  respectively, thereby controlling the character movements more accurately.