Patent Publication Number: US-2021161410-A1

Title: Blood pressure related information display apparatus

Description:
This is a Continuation of U.S. application Ser. No. 15/986,088 filed on May 22, 2018, which in turn is a Continuation of PCT/JP2016/079313 filed on Oct. 3, 2016, which claims the benefit of Japanese Patent Application No. 2015-257064 filed on Dec. 28, 2015. The disclosure of the prior applications is hereby incorporated by reference herein in its entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a blood pressure related information display apparatus, and more specifically relates to a blood pressure related information display apparatus for displaying information relating to the blood pressure of a measurement subject on a display screen. 
     BACKGROUND ART 
     Conventionally, as this type of blood pressure related information display apparatus, a blood pressure related information display apparatus has been known which obtains an altitude difference between a blood pressure measurement site and a heart using an altitude sensor, an acceleration sensor, or the like, corrects the measured blood pressure values based on the altitude difference, and displays, on a display device, information relating to the altitude difference and whether or not it is appropriate, as disclosed in Patent Document 1 (JP 2014-68825A) and Patent Document 2 (JP 2014-54648A), for example. Accordingly, the accuracy of measuring the blood pressure values is increased, and measurement in an appropriate orientation is prompted. 
     CITATION LIST 
     Patent Literature 
     Patent Document 1: JP 2014-68825A 
     Patent Document 2: JP 2014-54648A 
     SUMMARY OF INVENTION 
     Technical Problem 
     Incidentally, in recent years, the importance of measuring night-time blood pressure for treatment of hypertension has been receiving attention. In night-time blood pressure measurement, blood pressure measurement is generally performed automatically using a timer setting during a sleep period of the measurement subject, and therefore the measurement subject cannot consciously correct his or her orientation during blood pressure measurement. For this reason, blood pressure values measured in various orientations are stored and these blood pressure values may be influenced by the orientations. Accordingly, it is convenient if a user (includes a medical professional such as a doctor or a nurse, for example, in addition to the measurement subject; the same applies in the description hereinafter) can intuitively understand the orientation of the measurement subject during blood pressure measurement on a display screen afterward. 
     However, as far as the applicant of the present invention knows, conventionally, there has been no apparatus that performs display such that a user can intuitively understand the orientation of the measurement subject during blood pressure measurement. 
     In view of this, the object of the present invention is to provide a blood pressure related information display apparatus that displays information relating to the blood pressure of a measurement subject on a display screen, and can perform display such that a user can intuitively understand the orientation of the measurement subject during blood pressure measurement. 
     Solution to the Problem 
     In order to solve the above-described problem, the blood pressure related information display apparatus of the present invention is 
     a blood pressure related information display apparatus configured to display information relating to blood pressure of a measurement subject on a display screen, including: 
     a blood pressure measurement cuff configured to be worn by being wrapped around a measurement site of the measurement subject; 
     an acceleration sensor attached integrally to the blood pressure measurement cuff; 
     an orientation detection unit configured to detect an orientation of the measurement subject during blood pressure measurement based on an output of the acceleration sensor; and 
     a display control unit configured to perform control for displaying the orientation of the measurement subject detected by the orientation detection unit as an illustration on the display screen, 
     wherein a plurality of torso patterns corresponding to torso angles varied with respect to a bed surface in a view along a body height direction of a person lying on the bed surface, and a plurality of arm patterns corresponding to arm positions varied with respect to the plurality of torso patterns are prepared in advance as materials for creating the illustration, and 
     from among the plurality of torso patterns, the display control unit selects a torso pattern corresponding to the orientation of the measurement subject detected by the orientation detection unit, and from among combinations of the plurality of torso patterns and the plurality of arm patterns, the display control unit selects a combination that corresponds to the orientation of the measurement. 
     In the present specification, “information relating to blood pressure” includes blood pressure values, the orientation of the measurement subject during blood pressure measurement, and information indicating whether or not there is body movement and whether or not there is external compression on the cuff. 
     “During blood pressure measurement” does not indicate the entire period in which the blood pressure measurement cuff is worn for night-time blood pressure measurement and the like, for example, and indicates a timing during which the blood pressure values of the measurement subject are measured by actually performing pressure increase or pressure reduction on the above-described blood pressure measurement cuff. 
     Also, “illustration” means a diagram illustrated schematically. 
     A “bed surface” broadly indicates a surface on which a measurement subject can lie, such as the upper surface of a bed or a futon. 
     “Torso angle” means the angle by which a flat torso rotates about a center (roughly matches the backbone) in a view along the body height direction (e.g., in a view from the head to the feet) of a person lying on a bed surface. 
     With the blood pressure related information display apparatus of the present invention, the blood pressure measurement cuff is worn by being wrapped around a measurement site of the measurement subject in a state in which the acceleration sensor is integrally attached. The orientation detection unit detects the orientation of the measurement subject during blood pressure measurement based on the output of the acceleration sensor. The display control unit performs control for displaying, as an illustration, the orientation of the measurement subject detected by the orientation detection unit, on a display screen. Accordingly, the orientation of the measurement subject during blood pressure measurement is displayed as an illustration on the display screen as information relating to the blood pressure of the measurement subject. Accordingly, the user can intuitively understand the orientation of the measurement subject during blood pressure measurement by viewing the illustration displayed on the display screen. 
     Moreover, with this blood pressure related information display apparatus, a plurality of torso patterns corresponding to torso angles varied with respect to a bed surface in a view along a body height direction of a person lying on the bed surface, and a plurality of arm patterns corresponding to arm positions varied with respect to the plurality of torso patterns are prepared in advance as materials for creating the illustration. From among the plurality of torso patterns, the display control unit selects a torso pattern corresponding to the orientation of the measurement subject detected by the orientation detection unit, and from among combinations of the plurality of torso patterns and the plurality of arm patterns, the display control unit selects a combination that corresponds to the orientation of the measurement. By using the selected combination of the torso pattern and the arm pattern, the display control unit can, through simple processing, rapidly create image data including an illustration indicating the orientation of the measurement subject. 
     With the blood pressure related information display apparatus according to an embodiment, 
     the orientation detection unit detects the orientation of the measurement subject during each blood pressure measurement in a predetermined period, and 
     the display control unit performs control for displaying the orientations of the measurement subject detected by the orientation detection unit during each blood pressure measurement as illustrations in alignment with the passage of time on the display screen. 
     With the blood pressure related information display apparatus of this embodiment, the orientation detection unit detects the orientation of the measurement subject during each blood pressure measurement in a predetermined period. The display control unit performs control for displaying the orientations of the measurement subject detected by the orientation detection unit during each blood pressure measurement as illustrations in alignment with the passage of time on the display screen. Accordingly, the user can intuitively understand the orientations of the measurement subject during blood pressure measurement according to the passage of time by viewing the illustrations displayed on the display screen. 
     With the blood pressure related information display apparatus according to an embodiment, the orientation detection unit detects the orientation of the measurement subject during blood pressure measurement according to a direction of a gravity acceleration vector with respect to an XYZ orthogonal coordinate system set in the acceleration sensor. 
     With the blood pressure related information display apparatus of this embodiment, the orientation detection unit detects the orientation of the measurement subject during blood pressure measurement according to a direction of a gravity acceleration vector with respect to an XYZ orthogonal coordinate system set in the acceleration sensor. Accordingly, the orientation of the measurement subject can be detected easily. 
     Note that the data of various illustrations obtained by combining the plurality of torso patterns and the plurality of arm patterns is desirably stored in a storage unit such as a memory. 
     The blood pressure related information display apparatus according to an embodiment includes 
     a blood pressure measurement unit configured to measure a blood pressure value of the measurement subject using the blood pressure measurement cuff, 
     wherein the display control unit performs control for displaying, as a graph, the blood pressure values of the measurement subject measured by the blood pressure measurement unit, along with the illustrations of the orientations of the measurement subject, on the display screen. 
     With the blood pressure related information display apparatus of this embodiment, the blood pressure measurement unit measures the blood pressure value of the measurement subject using the blood pressure measurement cuff. The display control unit performs control for displaying, as a graph, the blood pressure values of the measurement subject measured by the blood pressure measurement unit, along with the illustrations of the orientations of the measurement subject, on the display screen. Accordingly, by viewing the graph, a user can intuitively understand the blood pressure values of the measurement subject according to the passage of time. Also, by viewing both the illustration of the orientations and the graph of the blood pressure values displayed on the display screen, the user can intuitively understand the influence of the orientation on the blood pressure value of the measurement subject. 
     The blood pressure related information display apparatus according to an embodiment includes: 
     a blood pressure measurement unit configured to measure a blood pressure value of the measurement subject using the blood pressure measurement cuff; and 
     a blood pressure correction unit configured to correct the blood pressure value of the measurement subject measured by the blood pressure measurement unit according to the orientation of the measurement subject detected by the orientation detection unit, 
     wherein the display control unit performs control for displaying, as a graph, the blood pressure values of the measurement subject corrected by the blood pressure correction unit, along with the illustrations of the orientations of the measurement subject, on the display screen. 
     With the blood pressure related information display apparatus of this embodiment, the blood pressure measurement unit measures the blood pressure value of the measurement subject using the blood pressure measurement cuff. The blood pressure correction unit corrects the blood pressure values of the measurement subject measured by the blood pressure measurement unit, according to the orientation of the measurement subject detected by the orientation detection unit. The display control unit performs control for displaying, as a graph, the blood pressure values of the measurement subject corrected by the blood pressure correction unit, along with the illustrations of the orientations of the measurement subject, on the display screen. Accordingly, by viewing the illustrations of the orientations and the graph of the corrected blood pressure values displayed on the display screen, the user can intuitively understand whether or not the blood pressure values of the measurement subject have been corrected appropriately according to the orientations of the measurement subject during blood pressure measurement. 
     Also, the display control unit may display, as a graph, both the blood pressure values of the measurement subject measured by the blood pressure measurement unit and the blood pressure values of the measurement subject corrected by the blood pressure correction unit, on the display screen. In this case, by viewing the illustrations of the orientations and the graphs of the non-corrected and corrected blood pressure values displayed on the display screen, the user can more intuitively understand whether or not the blood pressure values of the measurement subject have been corrected appropriately according to the orientations of the measurement subject during blood pressure measurement. 
     The blood pressure related information display apparatus according to an embodiment includes 
     an external compression detection unit configured to detect whether or not there is external compression on the cuff during the blood pressure measurement, 
     wherein the display control unit performs control for displaying compression information indicating the result of detection performed by the external compression detection unit, along with the illustrations of the orientations of the measurement subject, on the display screen. 
     Here, “external compression” refers to compression from outside of the outer circumferential surface of the blood pressure measurement cuff wrapped around the measurement site. In other words, “external compression” does not encompass compression from the measurement site (inner circumferential surface side of the cuff) around which the blood pressure measurement cuff is wrapped. Typically, external compression occurs when the measurement subject lying on the bed surface places the cuff worn on the measurement site under the torso in the case of night-time blood pressure measurement. 
     With the blood pressure related information display apparatus of this embodiment, the external compression detection unit detects whether or not there is external compression on the cuff during blood pressure measurement. The display control unit performs control for displaying, on the display screen, compression information indicating the result of detection performed by the external compression detection unit, along with the illustrations of the orientations of the measurement subject. Accordingly, the user can intuitively understand whether or not there is external pressure on the cuff during blood pressure measurement by viewing the illustrations and the compression information displayed on the display screen. 
     The blood pressure related information display apparatus according to an embodiment includes a bodily movement detection unit configured to detect whether or not there is bodily movement of the measurement subject during blood pressure measurement performed by the blood pressure measurement unit, based on the output of the acceleration sensor. 
     The display control unit performs control for displaying bodily movement information indicating the result of detection performed by the bodily movement detection unit, along with the illustrations of the orientations of the measurement subject, on the display screen. 
     With the blood pressure related information display apparatus of this embodiment, the bodily movement detection unit detects whether or not there is bodily movement of the measurement subject during blood pressure measurement based on the output of the acceleration sensor. The display control unit performs control for displaying bodily movement information indicating the result of detection performed by the bodily movement detection unit, along with the illustrations of the orientations of the measurement subject, on the display screen. Accordingly, the user can intuitively understand whether or not there is bodily movement of the measurement subject during blood pressure measurement by viewing the illustrations and the bodily movement information displayed on the display screen. 
     In another aspect, the blood pressure related information display apparatus according to the present invention is 
     a blood pressure related information display apparatus configured to display information relating to blood pressure of a measurement subject on a display screen, including: 
     a blood pressure measurement cuff configured to be worn by being wrapped around a measurement site of the measurement subject; 
     an acceleration sensor attached integrally to the blood pressure measurement cuff; 
     an orientation detection unit configured to detect an orientation of the measurement subject during blood pressure measurement based on an output of the acceleration sensor; 
     an external compression detection unit configured to detect whether or not there is external compression on the cuff during the blood pressure measurement; and 
     a display control unit configured to perform control for displaying the orientation of the measurement subject detected by the orientation detection unit as an illustration, as well as displaying compression information indicating the result of detection performed by the external compression detection unit, on the display screen. 
     With the blood pressure related information display apparatus of this embodiment, the blood pressure measurement cuff is worn by being wrapped around a measurement site of the measurement subject in a state in which the acceleration sensor is integrally attached. The orientation detection unit detects the orientation of the measurement subject during blood pressure measurement based on the output of the acceleration sensor. The external compression detection unit detects whether or not there is external compression on the cuff during blood pressure measurement. The display control unit performs control for displaying compression information indicating the result of detection performed by the external compression detection unit, along with an illustration of the orientation of the measurement subject, on the display screen. Accordingly, the user can intuitively understand whether or not there is external compression on the cuff during blood pressure measurement by viewing the illustration and the compression information displayed on the display screen. 
     Advantageous Effects of the Invention 
     As is evident from the description above, with the blood pressure related information display apparatus of the present invention, it is possible to perform display such that a user can intuitively understand the orientation of the measurement subject during blood pressure measurement. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic view showing an exterior of a blood pressure monitor in which the cuff and the main body are integrated, and in which a blood pressure related information display apparatus according to an embodiment of the invention is included. 
         FIG. 2  is a diagram showing a block configuration of the blood pressure monitor. 
         FIG. 3  is a diagram showing a block configuration of a hospital terminal that can communicate with the blood pressure monitor via a network. 
         FIG. 4(A)  is a diagram showing a state in which the measurement subject wears the blood pressure monitor on a left upper arm serving as a measurement site and is in a supine orientation (supine position) on a bed surface.  FIG. 4(B)  is a diagram showing a state in which the measurement subject has changed the torso angle with respect to the bed surface from the state of  FIG. 4(A) . 
         FIG. 5  is a diagram showing an overall operation flow of the blood pressure monitor. 
         FIG. 6A  is a diagram illustrating a cuff pressure signal, a pulse wave signal, a pump driving signal, and a cuff compliance during blood pressure measurement (pressure increase process) in the case where there is no external compression on the cuff of the blood pressure monitor. 
         FIG. 6B  is a diagram illustrating a cuff pressure signal, a pulse wave signal, a pump driving signal, and a cuff compliance during blood pressure measurement (pressure increase process) in the case where there is external compression on the cuff of the blood pressure monitor (here, a case in which the cuff is placed under the torso of the measurement subject). 
         FIG. 7  is a diagram illustrating the output of an acceleration sensor built in the main body, during blood pressure measurement performed by the blood pressure monitor. 
         FIG. 8A  is a diagram showing a correspondence relationship between the orientation (torso angle and arm position) of the measurement subject during blood pressure measurement and the outputs (XZ coordinates and XY coordinates) of the acceleration sensor. 
         FIG. 8B  is a diagram showing a correspondence relationship between the orientation (torso angle and arm position) of the measurement subject during blood pressure measurement and the outputs (XZ coordinates and XY coordinates) of the acceleration sensor. 
         FIG. 8C  is a diagram showing a correspondence relationship between the orientation (torso angle and arm position) of the measurement subject during blood pressure measurement and the outputs (XZ coordinates and XY coordinates) of the acceleration sensor. 
         FIG. 8D  is a diagram showing a correspondence relationship between the orientation (torso angle and arm position) of the measurement subject during blood pressure measurement and the outputs (XZ coordinates and XY coordinates) of the acceleration sensor. 
         FIG. 8E  is a diagram showing a correspondence relationship between the orientation (torso angle and arm position) of the measurement subject during blood pressure measurement and the outputs (XZ coordinates and XY coordinates) of the acceleration sensor. 
         FIG. 8F  is a diagram showing a correspondence relationship between the orientation (torso angle and arm position) of the measurement subject during blood pressure measurement and the outputs (XZ coordinates and XY coordinates) of the acceleration sensor. 
         FIG. 8G  is a diagram showing a correspondence relationship between the orientation (torso angle and arm position) of the measurement subject during blood pressure measurement and the outputs (XZ coordinates and XY coordinates) of the acceleration sensor. 
         FIG. 8H  is a diagram showing a correspondence relationship between the orientation (torso angle and arm position) of the measurement subject during blood pressure measurement and the outputs (XZ coordinates and XY coordinates) of the acceleration sensor. 
         FIGS. 9(A) and 9(B)  are diagrams illustrating images to be displayed on a display device of the blood pressure monitor. 
         FIGS. 10(A) and 10(B)  are diagrams illustrating images to be displayed on the display device of the blood pressure monitor. 
         FIG. 11  is a diagram illustrating an image to be displayed on the display device of the hospital terminal. 
         FIG. 12  is a diagram illustrating another image to be displayed on the display device of the hospital terminal. 
         FIG. 13  is a diagram illustrating yet another image to be displayed on the display device of the hospital terminal. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the invention will be described in detail with reference to the drawings. 
     Configuration of Blood Pressure Monitor 
       FIG. 1  shows an exterior of a blood pressure monitor (indicated overall by reference numeral  1 ) that constitutes a blood pressure related information display apparatus according to an embodiment of the invention. 
     The blood pressure monitor  1  mainly includes a blood pressure measurement cuff  20  that is to be wrapped around a measurement site of a measurement subject, and a main body  10  that is integrally attached to the cuff  20 . 
     The cuff  20  has a shape that is elongated so as to wrap around the measurement site along the circumferential direction, and includes a band-shaped inner cloth  20   a  that is to come into contact with the measurement site, and an outer cloth  20   b  that opposes the inner cloth  20   a . The inner cloth  20   a  and the outer cloth  20   b  are formed into a bladder shape by having their peripheral edges sewn together. The cuff  20  contains a fluid bladder  22  (see  FIG. 2 ) for compressing a measurement site. 
     In order to form a surface fastener, the surface (inner circumferential surface that is to come into contact with the measurement site) of the inner cloth  20   a  is provided with many minute hooks (not shown). On the other hand, many minute loops (not shown) that engage with the above-described hooks are formed on the surface (outer circumferential surface) of the outer cloth  20   b.    
     The main body  10  is integrally attached to a site between one end (end portion that is to serve as the inner circumferential end when worn)  20   e  and another end (end portion that is to serve as the outer circumferential end when worn)  20   f  with respect to the lengthwise direction (circumferential direction) of the cuff  20 . 
     When the blood pressure monitor  1  is worn on the left upper arm  90   a  (see  FIG. 4(A) ) serving as the measurement site, the left upper arm  90   a  is arranged in the orientation indicated by the arrow A in  FIG. 1  and the cuff  20  is arranged along with the main body  10  on the front surface of the left upper arm  90   a . Next, the cuff  20  is wrapped in the form of a left-handed spiral as viewed by the measurement subject. Then, the corresponding surface of the inner cloth  20   a  is pressed onto and fixed to a site near the inner circumferential end  20   e  compared to the main body  10  of the outer cloth  20   b . The extra portion near the other end  20   f  in the lengthwise direction (circumferential direction) of the cuff  20  is folded over so as to prevent the main body  10  from being hidden. 
       FIG. 2  shows a schematic block configuration of the cuff  20  and the main body  10  of the blood pressure monitor  1 . The blood pressure monitor  1  includes a CPU (Central Processing Unit)  100  serving as a control unit, a display device  50 , an operation unit  52 , a memory  51  serving as a storage unit, a communication unit  59 , a power source unit  53 , a pump  32 , a valve  33 , a pressure sensor  31 , and an acceleration sensor  34 , all of which are mounted in the main body  10 . Furthermore, the main body  10  includes an oscillation circuit  310  that converts the output from the pressure sensor  31  into a frequency, a pump driving circuit  320  that drives the pump  32 , a valve driving circuit  330  that drives the valve  33 , and an AD converter  340  that performs AD (Analog to Digital) conversion on the output from the acceleration sensor  34 , all of which are mounted in the main body  10 . 
     In this example, the display device  50  is composed of an LCD (Liquid Crystal Display) and displays information relating to blood pressure, such as a blood pressure measurement result, in accordance with a control signal from the CPU  100 . 
     The operation unit  52  includes a power source switch  52 A for turning on and off the power source of the main body  10 , a measurement start switch  52 B for receiving an instruction to start blood pressure measurement, and a memory switch  52 C for calling a blood pressure measurement result stored in the memory. The switches  52 A,  52 B, and  52 C input operation signals corresponding to instructions performed by a user to the CPU  100 . 
     As shown in  FIG. 1 , the display device  50  and the operation unit  52  are provided on the front surface (upper surface in  FIG. 1 ) or the side surface of the main body  10 . 
     The memory  51  shown in  FIG. 2  stores data of programs for controlling the blood pressure monitor  1 , data to be used to control the blood pressure monitor  1 , setting data for setting various functions of the blood pressure monitor  1 , data of measurement results of blood pressure values, data indicating whether or not there is later-described external compression on the cuff  20 , whether or not there is bodily movement of a measurement subject, and the orientation of the measurement subject, and the like. Also, the memory  51  is used as a work memory or the like for when a program is executed. 
     In accordance with a program for controlling the blood pressure monitor  1  that is stored in the memory  51 , the CPU  100  performs control for driving the pump  32  and the valve  33  according to the operation signal from the operation unit  52 . Also, based on a signal from the pressure sensor  31 , the CPU  100  performs control for calculating the blood pressure values and control for detecting whether or not there is external compression on the cuff  20 . Furthermore, based on the output of the acceleration sensor  34 , the CPU  100  performs control for detecting whether or not there is bodily movement of the measurement subject and the orientation of the measurement subject. These controls will be described in detail later. 
     The communication unit  59  is controlled by the CPU  100  to transfer predetermined information to an external apparatus via the network  900 , and to receive information from the external apparatus via the network  900  and transfer it to the CPU  100 . Communication via the network  900  may be performed wirelessly or using a wire. In this embodiment, the network  900  is the Internet, but there is no limitation to this, and it is also possible to use another type of network such as an in-hospital LAN (Local Area Network), or one-to-one communication using a USB cable or the like. 
     The power source unit  53  supplies power to the units, namely the CPU  100 , the pressure sensor  31 , the pump  32 , the valve  33 , the acceleration sensor  34 , the display device  50 , the memory  51 , the communication unit  59 , the oscillation circuit  310 , the pump driving circuit  320 , the valve driving circuit  330 , and the AD converter  340 . 
     The pump  32 , the valve  33 , and the pressure sensor  31  are connected to the fluid bladder  22  contained in the cuff  20  via a common air tube  39  serving as a tube system. The pump  32  supplies air to the fluid bladder  22  through the air tube  39  in order to increase the pressure (cuff pressure) in the fluid bladder  22  contained in the cuff  20 . The valve  33  is a solenoid valve that is controlled so as to open and close through application of a current, and is used to control the cuff pressure by discharging the air in the air bladder  22  through the air tube  39  or sealing the air in the air bladder  22 . The pump driving circuit  320  drives the pump  32  based on the control signal provided by the CPU  100 . The valve driving circuit  330  opens and closes the valve  33  based on the control signal provided from the CPU  100 . 
     In this example, the pressure sensor  31  is a piezoresistance pressure sensor that detects the pressure of the cuff  20  (fluid bladder  22 ) through the air tube  39 , and in this example, the pressure sensor  31  detects a pressure obtained with reference to atmospheric pressure (with atmospheric pressure being set to zero) and outputs the detected pressure as a cuff pressure signal Pc in a time series. The oscillation circuit  310  oscillates based on an electricity signal value that is based on a change in the electric resistance caused by a piezoresistance effect from the pressure sensor  31 , and outputs a frequency signal having a frequency corresponding to the electricity signal value of the pressure sensor  31  to the CPU  100 . 
     In this example, the output of the pressure sensor  31  is used to calculate the blood pressure values (includes systolic blood pressure and diastolic blood pressure; the same applies in the description hereinafter) of the measurement subject  90  through an oscillomertic method. In addition to this, the output of the pressure sensor  31  is used to determine whether or not there is external compression on the cuff  20  by calculating the cuff compliance (amount of air needed to change the cuff pressure by a unit pressure 1 mmHg). Typically, in the case of night-time blood pressure measurement, external compression occurs when the cuff  20  and the left upper arm  90   a  serving as the measurement site are placed under the torso of the measurement subject who is lying down, and are compressed by the torso and the bed surface. 
     The acceleration sensor  34  is composed of a triaxial acceleration sensor that is integrally built into the main body  10 . The acceleration sensor  34  outputs an acceleration signal indicating acceleration in three mutually orthogonal directions of the main body  10  and accordingly, of the cuff  20  integrally attached to the main body  10 , to the CPU  100  via the AD converter  340 . 
     In this example, as shown in  FIG. 4(A) , an XYZ orthogonal coordinate system is set with the position of the acceleration sensor  34  in the main body  10  serving as the origin. The Z axis is set facing outward orthogonally to the front surface of the main body  10 . The Y axis is set in an orientation facing from the knee to the shoulder along the left upper arm  90   a  of the measurement subject  90  in a state in which the blood pressure monitor  1  is worn on the left upper arm  90   a  serving as the measurement site as described above. Also, the X axis is set orthogonally to the Y axis and the Z axis (the X axis faces approximately leftward as viewed by the measurement subject  90 , but this depends on the orientation of the measurement subject  90  as well). Note that in  FIG. 4(A) , the measurement subject  90  is in a supine orientation (supine position) on the bed surface  99 , but in actuality, especially in the case of night-time blood pressure measurement, the measurement subject  90  can be in various orientations. For example, as shown in  FIG. 4(B) , the measurement subject can be in an orientation in which the angle θ of the torso is changed with respect to the bed surface  99 . 
     In this example, the output of the acceleration sensor  34  is used to detect whether or not there is bodily movement of the measurement subject  90 . In addition, the output of the acceleration sensor  34  is used to detect the orientation of the measurement subject  90  according to the direction (e.g., in  FIGS. 4(A) and 4(B) , the directions of the gravity acceleration vectors G with respect to the XYZ orthogonal coordinate system are different) of a gravity acceleration vector G with respect to the above-described XYZ orthogonal coordinate system. 
     Method of Detecting External Compression 
       FIG. 6A  shows a cuff pressure signal Pc, a pulse wave signal SM, a pump driving signal Vout, and a cuff compliance CL during blood pressure measurement (pressure increase process) in the case where there is no external compression on the cuff  20 . On the other hand,  FIG. 6B  shows a cuff pressure signal Pc, a pulse wave signal SM, a pump driving signal Vout, and a cuff compliance CL during blood pressure measurement (pressure increase process) in the case where there is external compression on the cuff  20  (here, a case in which the cuff  20  is placed under the torso of the measurement subject  90 ). The cuff pressure signal Pc indicates the pressure of the cuff  20  (fluid bladder  22 ) that is detected via the air tube  39  and the oscillation circuit  310  by the pressure sensor  31 . The pulse wave signal SM indicates a signal extracted through a filter (not shown) as a fluctuation component of the cuff pressure signal Pc (the pulse wave signal SM is used to calculate the blood pressure values through an oscillometric method). The pump driving signal Vout indicates a square wave signal (pulse width modulation signal) output from the CPU  100  to the pump driving circuit  320  in order to increase the pressure of the cuff  20 . The cuff compliance CL is obtained as values (calculated for each predetermined pressure segment) CMa, CMb, CMc, CMd, . . . , which are obtained by integrating the duty of the pump driving signal Vout over time. In order to facilitate understanding, in  FIGS. 6A and 6B , an envelope EV is added to the sequence formed by the values CMa, CMb, CMc, CMd, . . . of the cuff compliance CL. 
     As can be understood from  FIG. 6A , if there is no external compression on the cuff  20 , air is supplied to the cuff  20 , and the cuff compliance CL gradually decreases and is saturated as pressure increase from the low pressure range (0 mmHg to less than 40 mmHg) to the high pressure range (over 120 mmHg) is performed. The reason for this is because if there is no external compression on the cuff  20 , the volume of the cuff easily expands in the low pressure region (0 mmHg to less than 40 mmHg), and therefore a large amount of air is needed to raise the cuff pressure, but the volume of the cuff  20  is substantially less likely to increase when the tensile force of the cuff  20  increases due to the cuff pressure rising by a certain degree. On the other hand, as can be understood from  FIG. 6B , if there is external compression on the cuff  20 , the cuff compliance CL has a maximum value in the pressure increase process. In this case, in the low pressure region (0 mmHg to less than 40 mmHg), the volume of the cuff  20  increases due to the cuff  20  pressing back on the torso of the measurement subject  90 . Accordingly, the cuff compliance CL changes gradually from a low value (varies due to the influence of the tensile force of wrapping the cuff around the measurement site) to a high value. On the other hand, in the high pressure region (over 120 mmHg), the torso is pushed away by the top of the cuff  20  due to the inflation of the cuff  20 , and therefore the cuff compliance CL gradually decreases and is saturated, similarly to the case shown in  FIG. 6A  (the case in which there is no external compression). As a result, in the intermediate range (40 mmHg or more, 120 mmHg or less), the cuff compliance CL has a maximum value accompanying the rising of the cuff pressure. 
     Accordingly, it is possible to detect whether or not there is external compression on the cuff  20  according to whether or not the cuff compliance CL has a maximum value in the intermediate pressure range (40 mmHg or more and 120 mmHg or less) in the pressure increase process. 
     Method of Detecting Bodily Movement 
       FIG. 7  illustrates the outputs (acceleration signals) of the acceleration sensor  34  during blood pressure measurement. During blood pressure measurement, and especially during night-time blood pressure measurement, the measurement subject  90  is essentially in a resting state, and therefore an output α x  in the X-axis direction of the acceleration sensor  34 , an output α y  in the Y-axis direction, and an output α z  in the Z-axis direction have approximately constant values. However, if the measurement subject  90  temporarily moves by turning over or the like, the outputs α x , α y , and α z  change as indicated by α x   1 , α y   1 , and α z   1 . 
     In this example, the CPU  100  functions as a bodily movement detection unit, and during blood pressure measurement, obtains average values &lt;α x &gt;, &lt;α y &gt;, and &lt;α z &gt; of the outputs α x , α y , and α z  of the acceleration sensor  34  in each unit period (e.g., one second or several seconds). Furthermore, the CPU  100  obtains fluctuation amounts (α x −&lt;α x &gt;), (α y −&lt;α y &gt;), and (α 2 −&lt;α z &gt;) by which the acceleration outputs α x , α y , and α z  of the times in the unit period fluctuate with respect to the average values &lt;α x &gt;, &lt;α y &gt;, and &lt;α z &gt;. Also, when the square root of the sum of squares of these fluctuation amounts {(α x −&lt;α x &gt;) 2 +(α y −&lt;α y &gt;) 2 +(α z −&lt;α z &gt;) 2 } 1/2  exceeds a predetermined threshold (denoted as Δa), it is determined that there is bodily movement. On the other hand, if the square root of the sum of the squares is less than or equal to the threshold Δa, it is determined that there is no bodily movement. 
     Accordingly, it is possible to detect whether or not there is bodily movement of the measurement subject  90  based on changes in the outputs of the acceleration sensor  34 . 
     Method of Detecting Orientation 
       FIGS. 8A to 8H  show correspondence relationships between the orientation (torso angle and arm position) of the measurement subject  90  during blood pressure measurement and the normalized outputs (XZ coordinates and XY coordinates) of the acceleration sensor  34 . 
     Specifically,  FIGS. 8A to 8H  show eight types of “torso angles” as torso patterns in the first rows (top rows). “Torso angle” means the angle (indicated by reference numeral θ in  FIG. 4(B) ) by which the flat torso  90   b  is rotated about a center (approximately matches the spine) in a view along the body height direction (in this example, in a view from head to feet) of a person lying on a bed surface. In  FIG. 8A , the torso  90   b  is in the supine position and the torso angle is 0 degrees. In  FIG. 8B , the torso  90   b  is between the supine position and the right side position, and the torso angle is 20 degrees. In  FIG. 8C , the torso  90   b  is in the right side position and the torso angle is 90 degrees. In  FIG. 8D , the torso  90   b  is between the right side position and the prone position, and the torso angle is 160 degrees. In  FIG. 8E , the torso  90   b  is in the prone position and the torso angle is 180 degrees. In  FIG. 8F , the torso  90   b  is between the prone position and the left side position, and the torso angle is 200 degrees. In  FIG. 8G , the torso  90   b  is in the left side position and the torso angle is 270 degrees. In  FIG. 8H , the torso  90   b  is between the left side position and the supine position, and the torso angle is 340 degrees. 
     Also, in  FIGS. 8A to 8H , the second rows each show four or three types of representative arm positions serving as arm patterns corresponding to arm positions that are varied with respect to a person&#39;s torso. In  FIG. 8A , in the first column (leftmost column), the left upper arm  90   a  is at a “body-lateral” position of extending along the lateral side of the torso  90   b , in the second column, the left upper arm  90   a  is at a “body-side separated” position of being separated laterally from the torso  90   b , in the third column, the left upper arm  90   a  is at an “on-chest” position of being placed on the torso  90   b , and in the fourth column (rightmost column), the left upper arm  90   a  is in a “hurrah” position of being raised toward the head. In  FIGS. 8B, 8C, and 8D , in the first columns (leftmost columns), the left upper arm  90   a  is at a “back-side” position of being rotated rearward of the torso  90   b , in the second columns, the left upper arm  90   a  is at a “body-lateral” position of extending along the lateral side of the torso  90   b , in the third columns, the left upper arm  90   a  is at a “chest-side” position of being rotated frontward of the torso  90   b , and in the fourth columns (rightmost columns), the left upper arm  90   a  is at a “hurrah” position of being raised toward the head. In  FIG. 8E , in the first column (leftmost column), the left upper arm  90   a  is at a “body-lateral” position of extending along the lateral side of the torso  90   b , in the second column, the left upper arm  90   a  is at a “body-side separated” position of being separated laterally from the torso  90   b , and in the third column, (rightmost column), the left upper arm  90   a  is in a “hurrah” position of being raised toward the head. In  FIG. 8F , in the first column (leftmost column), the left upper arm  90   a  is at a “back-side” position of being rotated rearward of the torso  90   b , in the second column, the left upper arm  90   a  is at a “body-lateral” position of extending along the lateral side of the torso  90   b , and in the third column (rightmost column), the left upper arm  90   a  is at a position of being rotated frontward of the torso  90   b . In  FIG. 8G , in the first column (leftmost column), the left upper arm  90   a  is at a “chest-front separated” position of being separated frontward from the torso  90   b , in the second column, the left upper arm  90   a  is at a “body-lateral” position of extending along the lateral side of the torso  90   b , and in the third column (rightmost column), the left upper arm  90   a  is at a “hurrah” position of being raised toward the head. Also, in  FIG. 8H , in the first column (leftmost column), the left upper arm  90   a  is at a “chest-front” position of being rotated frontward from the torso  90   b , in the second column, the left upper arm  90   a  is at a “body-lateral” position of extending along the lateral side of the torso  90   b , and in the third column (rightmost column), the left upper arm  90   a  is at a “hurrah” position of being raised toward the head. 
     The orientations of the measurement subject  90  during blood pressure measurement (in particular, during night-time blood pressure measurement) are specified using combinations of the “torso angles” in the first rows (top rows) and the “arm positions” in the second rows corresponding thereto in  FIGS. 8A to 8H . 
     In the third rows and the fourth rows (bottom rows) in  FIGS. 8A to 8H , the normalized (normalized to 1) outputs of the acceleration sensor  34  in cases where the measurement subject  90  is in orientations specified using combinations of the “torso angles” in the first rows and the “arm positions” in the second rows are indicated in XZ coordinate planes and XY coordinate planes. Here, the measurement subject  90  is substantially in a resting state, and the outputs (the above-described average values &lt;α x &gt;, &lt;α y &gt;, and &lt;α z &gt;) of the acceleration sensor  34  correspond to the direction of the gravity acceleration vector G corresponding to the XYZ orthogonal coordinate system set in the main body  10 . 
     For example, if the measurement subject  90  is in an orientation specified using a combination in which the “torso angle” is 0 degrees and the “arm position” is “body-lateral” in the first column (leftmost column) of  FIG. 8A , the normalized outputs of the acceleration sensor  34  are detected as point a xz  where X=0 and Z=1 in the XZ coordinate plane in the third row, and as point a xy  where X=0 and Y=0 in the XY coordinate plane in the fourth row. Also, when the measurement subject  90  is in an orientation specified using the combination in which the “torso angle” is 0 degrees and the “arm position” is “body-side separated” in the second column of  FIG. 8A , the normalized outputs of the acceleration sensor  34  are detected as point a xz  where −1&lt;X&lt;0 and 0&lt;Z&lt;1 (second quadrant) in the XZ coordinate plane in the third row, and as point a xy  where −1&lt;X&lt;0 and Y=0 in the XY coordinate plane in the fourth row. When the measurement subject  90  is in an orientation specified using the combination in which the “torso angle” is 0 degrees and the “arm position” is “on-chest” in the third column of  FIG. 8A , the normalized outputs of the acceleration sensor  34  are detected as point a xz  where 0&lt;X&lt;1 and 0&lt;Z&lt;1 (first quadrant) in the XZ coordinate plane in the third row, and as point a xy  where 0&lt;X&lt;1 and −1&lt;Y&lt;0 (fourth quadrant) are satisfied in the XY coordinate plane in the fourth row. When the measurement subject  90  is in an orientation specified using the combination in which the “torso angle” is 0 degrees and the “arm position” is “hurrah” in the fourth column (rightmost column) of  FIG. 8A , the normalized outputs of the acceleration sensor  34  are detected as point a xz  where −1&lt;X&lt;0 and −1&lt;Z&lt;0 (third quadrant) in the XZ coordinate plane in the third row, and as point a xy  where −1&lt;X&lt;0 and −1&lt;Y&lt;0 (third quadrant) in the XY coordinate plane in the fourth row. 
     Also, for example, if the measurement subject  90  is in an orientation specified using the combination in which the “torso angle” is 270 degrees and the “arm position” is “chest-front separated” in the first column (leftmost column) in  FIG. 8G , the normalized outputs of the acceleration sensor  34  are detected as point a xz  where X=−1 and Z=0 in the XZ coordinate plane in the third row, and as point a xy  where X=−1 and Y=0 in the XY coordinate plane in the fourth row. Also, if the measurement subject  90  is in an orientation specified using the combination in which the “torso angle” is 270 degrees and the “arm position” is “body-lateral” in the second column in  FIG. 8G , the normalized outputs of the acceleration sensor  34  are detected as point a xz  where X=−1 and Z=0 in the XZ coordinate plane in the third row, and as point a xy  where X=−1 and Y=0 in the XY coordinate plane in the fourth row. If the measurement subject  90  is in an orientation specified using the combination in which the “torso angle” is 270 degrees and the “arm position” is “hurrah” in the third column (rightmost column) in  FIG. 8G , the normalized output of the acceleration sensor  34  is detected as point a xz  where 0&lt;X&lt;1 and 0&lt;Z&lt;1 (first quadrant) in the XZ coordinate plane in the third row, and as point a xy  where 0&lt;X&lt;1 and Y=0 in the XY coordinate plane in the fourth row. 
     As can be understood from the examples above, in  FIGS. 8A to 8H , when the measurement subject  90  is in an orientation specified using a combination of a “torso angle” in a first row and an “arm position” in a second row, the orientation and the normalized output (combination of XZ coordinates and XY coordinates) of the acceleration sensor  34  are in a one-to-one correspondence. Accordingly, if the normalized outputs (combination of the XZ coordinates and the XY coordinates) of the acceleration sensor  34  are specified, the orientation of the measurement subject  90 , that is, the combination of the “torso angle” and the “arm position” is specified. In other words, the orientation of the measurement subject  90  is determined. In this example, the CPU  100  functions as an orientation detection unit and determines the orientation of the measurement subject  90  based on the outputs (the above-described average values &lt;α x &gt;, &lt;α y &gt;, and &lt;α z &gt; are desirable) of the acceleration sensor  34 . Accordingly, the orientation of the measurement subject can be detected easily. 
     With the blood pressure monitor  1 , in order to express the orientation of the measurement subject  90  specified based on the output of the acceleration sensor  34 , illustrations A- 1  to A- 4  shown in the first row in  FIG. 8A , illustrations B- 1  to B- 4  shown in the first row in  FIG. 8B , illustrations C- 1  to C- 4  shown in the first row in  FIG. 8C , illustrations D- 1  to D- 4  shown in the first row in  FIG. 8D , illustrations E- 1  to E- 3  shown in the first row in  FIG. 8E , illustrations F- 1  to F- 3  shown in the first row in  FIG. 8F , illustrations G- 1  to G- 3  shown in the first row in  FIG. 8G , and illustrations H- 1  to H- 3  shown in the first row in  FIG. 8H  are prepared in advance. These illustrations A- 1  to A- 4 , B- 1  to B- 4 , C- 1  to C- 4 , D- 1  to D- 4 , E- 1  to E- 3 , F- 1  to F- 3 , G- 1  to G- 3 , and H- 1  to H- 3  correspond to combinations obtained using the torso patterns and arm patterns as materials. 
     In these illustrations A- 1  to A- 4 , B- 1  to B- 4 , C- 1  to C- 4 , D- 1  to D- 4 , E- 1  to E- 3 , F- 1  to F- 3 , G- 1  to G- 3 , and H- 1  to H- 3 , the torso  90   b  of the measurement subject  90  is expressed as an elongated circle. In the approximate center in the long axis direction of the elongated circle indicating the torso  90   b , the head  90   h  of the measurement subject  90  is indicated by a circle and a small triangle corresponding to the nose, in a state of being overlaid slightly shifted in the short axis direction. Also, the left upper arm  90   a  around which the cuff  20  is wrapped is indicated by a circle on the left side of the elongated circle indicating the torso  90   b . The main body  10  attached integrally to the cuff  20  is indicated by a rectangle. 
     For example, in the illustration A- 1  shown in  FIG. 8A , the elongated circle indicating the torso  90   b  is extended in the horizontal direction so as to indicate that the torso angle is 0 degrees (supine position). The circle indicating the head  90   h  of the measurement subject  90  is overlaid shifted upward of the elongated circle indicating the torso  90   b  (note that up, down, left, and right in this paragraph indicate up, down, left, and right in  FIG. 8A ). The circle indicating the left upper arm  90   a  is adjacent to the left of the elongated circle indicating the torso  90   b  so as to indicate “body-lateral”. The rectangle indicating the main body  10  is located on the upper portion of the circle indicating the left upper arm  90   a  so as to indicate that the main body  10  is on the front surface of the left upper arm  90   a . In the illustration A- 2 , the circle indicating the left upper arm  90   a  is separated from the elongated circle indicating the torso  90   b  so as to indicate “body-side separated”. In the illustration A- 3 , the circle indicating the left upper arm  90   a  is located above and to the left of the elongated circle indicating the torso  90   b  so as to indicate “on-chest”. In the illustration A- 4 , the circle indicating the left upper arm  90   a  is located above and to the left of the elongated circle indicating the torso  90   b  and the rectangle indicating the main body  10  is located below the circle indicating the left upper arm  90   a  so as to indicate “hurrah”. The other portions of the illustrations A- 2  to A- 4  are drawn in the same manner as those of the illustration A- 1 . 
     Also, for example, in the illustration G- 1  shown in  FIG. 8G , the elongated circle indicating the torso  90   b  is elongated in the vertical direction so as to indicate that the torso angle is 270 degrees (left side position). The circle indicating the head  90   h  of the measurement subject  90  is overlaid shifted to the left of the elongated circle indicating the torso  90   b  (note that up, down, left, and right in this paragraph indicate up, down, left, and right in  FIG. 8G ). The circle indicating the left upper arm  90   a  is separated from the elongated circle indicating the torso  90   b  so as to indicate “chest-front separated”. The rectangle indicating the main body  10  is located on the left portion of the circle indicating the left upper arm  90   a  so as to indicate that the main body  10  is on the front surface of the left upper arm  90   a . In the illustration G- 2 , the circle indicating the left upper arm  90   a  is adjacent to the bottom of the elongated circle indicating the torso  90   b  so as to indicate “body-lateral”. In the illustration G- 3 , the circle indicating the left upper arm  90   a  is located downward and to the left of the elongated circle indicating the torso  90   b  and the rectangle indicating the main body  10  is located on the right portion of the circle indicating the left upper arm  90   a  so as to indicate “hurrah”. The other portions of the illustrations G- 2  to G- 3  are drawn in the same manner as those of the illustration G- 1 . 
     In this manner, the orientation of the measurement subject  90  can be schematically indicated using the illustrations A- 1  to A- 4 , B- 1  to B- 4 , C- 1  to C- 4 , D- 1  to D- 4 , E- 1  to E- 3 , F- 1  to F- 3 , G- 1  to G- 3 , and H- 1  to H- 3 , that is, as a combination of a torso pattern indicating the “torso angle” and an arm pattern indicating the “arm position”. 
     With the blood pressure monitor  1 , the normalized outputs (XZ coordinates and XY coordinates) of the acceleration sensor  34  in the third rows and the fourth rows in  FIGS. 8A to 8H  and the illustrations A- 1  to A- 4 , B- 1  to B- 4 , C- 1  to C- 4 , D- 1  to D- 4 , E- 1  to E- 3 , F- 1  to F- 3 , G- 1  to G- 3 , and H- 1  to H- 3  in the first rows are stored in a one-to-one correspondence as an orientation table in the memory  51 . Thus, by preparing various illustrations indicating orientations of the measurement subject  90  in advance, image data including an illustration of an orientation of the measurement subject  90  can be created rapidly with simple processing during later-described display processing (step ST 110  in  FIG. 5 ). 
     Overall Operation 
       FIG. 5  illustrates an overall operation flow of the blood pressure monitor  1 . 
     If the measurement start switch  52 B is pressed in a state in which the power source switch  52 A is on, or if a predetermined measurement timing is reached in the case of night-time blood pressure measurement, the blood pressure monitor  1  starts the blood pressure measurement. At the start of blood pressure measurement, the CPU  100  initializes a memory region for processing and outputs a control signal to the valve driving circuit  330 . Based on the control signal, the valve driving circuit  330  opens the valve  33  to discharge the air in the fluid bladder  22  of the cuff  20 . Next, control for adjusting the pressure sensor  31  to 0 mmHg is performed. 
     When the blood pressure measurement is started, first, the CPU  100  closes the valve  33  via the valve driving circuit  330 , and thereafter drives the pump  32  via the pump driving circuit  320  while monitoring the cuff pressure signal Pc using the pressure sensor  31  (and the air tube  39  and the oscillation circuit  310 ), and thus performs control for sending air to the fluid bladder  22 . Accordingly, the fluid bladder  22  is inflated and the cuff pressure gradually increases (step ST 101 ). 
     In the pressure increase process, in order to detect whether or not there is external compression on the cuff  20 , the CPU  100  integrates the pump driving signal Vout for the pump driving circuit  320  to acquire data indicating the cuff compliance CL, as illustrated in  FIGS. 6A and 6B  (step ST 102 ). 
     Also, in the pressure increase process, in order to detect whether or not there is bodily movement of the measurement subject  90  and the orientation of the measurement subject  90 , the CPU  100  acquires the outputs of the acceleration sensor  34  (step ST  103 ). 
     Also, in this example, in the pressure increase process, in order to calculate the blood pressure values, the CPU  100  acquires the pulse wave signal SM serving as a fluctuation component through a filter (not shown) from the cuff pressure signal Pc (step ST 104 ). 
     Next, the CPU  100  functions as a blood pressure measurement unit and attempts calculation of the blood pressure values (systolic blood pressure SBP and diastolic blood pressure DBP) and the pulse by applying a known algorithm through the oscillometric method based on the pulse wave signal SM acquired at this time point (step ST 105 ). 
     At this time point, if the blood pressure values cannot yet be calculated due to insufficient data (NO in step ST 105 ), the processing of steps ST 101  to ST 105  are repeated as long as the cuff pressure has not reached the upper limit pressure (in the interest of safety, the upper limit pressure is set in advance to 300 mmHg, for example) (NO in step ST 106 ). 
     When the blood pressure values and pulse can be thus calculated (YES in step ST 105 ), the processing advances to step ST 107 , and the CPU  100  detects whether or not there is external compression on the cuff  20 , whether or not there is bodily movement of the measurement subject  90 , and the orientation of the measurement subject  90 . 
     Here, the CPU  100  functions as an external compression detection unit and detects whether or not there is external compression on the cuff  20  based on whether or not the cuff compliance CL is at a maximum value in the pressure increase process. Specifically, when the cuff compliance CL decreases monotonically as illustrated in FIG.  6 A in the pressure increase process, it is determined that there is no external compression. On the other hand, when the cuff compliance CL has a maximum value as illustrated in  FIG. 6B  in the pressure increase process, it is determined that there is external compression. 
     Also, the CPU  100  functions as a bodily movement detection unit and detects whether or not there is bodily movement of the measurement subject  90  based on changes in the output of the acceleration sensor  34 . Specifically, in each unit period (e.g., one second or multiple seconds) in the pressure increase process, the CPU  100  obtains the average values &lt;α x &gt;, &lt;α y &gt;, and &lt;α z &gt; of the outputs α x , α y , and α z  of the acceleration sensor  34  illustrated in  FIG. 7 . Then, when the square root of the sum of squares of the fluctuation amounts of the acceleration outputs α x , α y , and α z  in the unit period {(α x −&lt;α x &gt;) 2 +(α y −&lt;α y &gt;) 2 +(α z −&lt;α z &gt;) 2 } 1/2  exceeds a predetermined threshold Δa, it is determined that there is bodily movement. On the other hand, if the square root of the sum of the squares is less than or equal to the threshold Δa, it is determined that there is no bodily movement. 
     Also, the CPU  100  functions as an orientation detection unit and detects the orientation of the measurement subject  90  based on the outputs (the above-described average values &lt;α x &gt;, &lt;α y &gt;, &lt;α z &gt;) of the acceleration sensor  34  in the pressure increase process. Specifically, the CPU  100  determines whether or not the orientation of the measurement subject  90  corresponds to an orientation in an illustration in one of the first rows (top rows) in  FIGS. 8A to 8H  based on the correspondence relationship between the normalized outputs (XZ coordinates and XY coordinates) of the acceleration sensor  34  in the third rows and fourth rows of  FIGS. 8A to 8H  and the illustrations A- 1  to A- 4 , B- 1  to B- 4 , C- 1  to C- 4 , D- 1  to D- 4 , E- 1  to E- 3 , F- 1  to F- 3 , G- 1  to G- 3 , and H- 1  to H- 3  in the first rows, which are stored in the orientation table in the memory  51 . 
     Next, in step ST 108  in  FIG. 5 , the CPU  100  stores the measurement number, measurement time, measured blood pressure values (systolic blood pressure SBP and diastolic blood pressure DBP), pulse, whether or not there is external compression on the cuff  20 , whether or not there is bodily movement of the measurement subject  90 , and the orientation of the measurement subject  90 , in association with each other in the memory  51 . 
     Here, the data stored in the memory  51  is accumulated for each measurement of the blood pressure, as shown in the following data table (Table 1) for example. In this example, the night-time blood pressure measurement is performed every 30 seconds. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Data table 
               
            
           
           
               
               
            
               
                   
                 Correction according to altitude 
               
               
                   
                 difference 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                   
                   
                 Systolic 
                 Diastolic 
                   
                   
                   
                   
                   
                 Systolic 
                 Diastolic 
               
               
                   
                   
                 blood 
                 blood 
                   
                   
                   
                   
                   
                 blood 
                 blood 
               
               
                   
                   
                 pressure 
                 pressure 
                   
                   
                   
                   
                 Correction 
                 pressure 
                 pressure 
               
               
                 Measurement 
                 Measurement 
                 SBP 
                 DBP 
                 Pulse 
                 External 
                 Bodily 
                   
                 amount 
                 SBP′ 
                 DBP′ 
               
               
                 number 
                 time 
                 [mmHg] 
                 [mmHg] 
                 [BPM] 
                 compression 
                 movement 
                 Orientation 
                 [mmHg] 
                 [mmHg] 
                 [mmHg] 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 0 
                 23:00  
                 125 
                 93 
                 64 
                 0 
                 0 
                 K-1 
                 0 
                 125 
                 93 
               
               
                 1 
                 23:30  
                 117 
                 81 
                 55 
                 0 
                 0 
                 A-1 
                 0 
                 117 
                 81 
               
               
                 2 
                 0:00 
                 111 
                 77 
                 55 
                 0 
                 0 
                 A-1 
                 0 
                 111 
                 77 
               
               
                 3 
                 0:30 
                 107 
                 71 
                 62 
                 0 
                 0 
                 C-2 
                 16 
                 123 
                 87 
               
               
                 4 
                 1:00 
                 99 
                 71 
                 55 
                 0 
                 1 
                 C-2 
                 16 
                 115 
                 87 
               
               
                 5 
                 1:30 
                 103 
                 65 
                 57 
                 0 
                 0 
                 B-2 
                 8 
                 111 
                 73 
               
               
                 6 
                 2:00 
                 105 
                 69 
                 54 
                 0 
                 0 
                 B-2 
                 8 
                 113 
                 77 
               
               
                 7 
                 2:30 
                 111 
                 68 
                 62 
                 1 
                 0 
                 G-2 
                 0 
                 111 
                 68 
               
               
                 8 
                 3:00 
                 131 
                 85 
                 55 
                 0 
                 1 
                 A-1 
                 0 
                 131 
                 85 
               
               
                 9 
                 3:30 
                 105 
                 71 
                 47 
                 0 
                 0 
                 A-3 
                 10 
                 115 
                 81 
               
               
                 10 
                 4:00 
                 119 
                 81 
                 55 
                 0 
                 0 
                 A-1 
                 0 
                 119 
                 81 
               
               
                 11 
                 4:30 
                 119 
                 81 
                 50 
                 0 
                 0 
                 B-2 
                 8 
                 127 
                 89 
               
               
                 12 
                 5:00 
                 118 
                 82 
                 54 
                 0 
                 0 
                 C-2 
                 16 
                 134 
                 98 
               
               
                 13 
                 5:30 
                 114 
                 79 
                 55 
                 0 
                 0 
                 C-2 
                 16 
                 130 
                 95 
               
               
                 14 
                 6:00 
                 121 
                 83 
                 53 
                 0 
                 0 
                 B-2 
                 8 
                 129 
                 91 
               
               
                 . . . 
                 . . . 
                 . . . 
                 . . . 
                 . . . 
                 . . . 
                 . . . 
                 . . . 
                 . . . 
                 . . . 
                 . . . 
               
               
                   
               
            
           
         
       
     
     Here, in the “external compression” column, “1” indicates that there is external compression and “0” indicates that there is no external compression. In the “bodily movement” column, “1” indicates that there is bodily movement and “0” indicates that there is no bodily movement. In the “orientation” column, the orientation of the measurement subject  90  is indicated by the reference sign specifying an illustration in a first row (top row) of  FIGS. 8A to 8H . Note that the reference sign “K- 1 ” in the “orientation” column indicates an orientation (e.g., an orientation corresponding to the first illustration K- 1  in later-described  FIG. 11 ) in which the measurement subject  90  is in a sitting position and the left upper arm  90   a  serving as the measurement site naturally hangs downward. Although not shown in the third and fourth rows of  FIGS. 8A to 8H , the orientation K- 1  is detected as the point at which X=0 and Z=0 in the XZ coordinate plane and is detected as the point at which X=0 and Y=1 in the XY coordinate plane. The “correction using altitude difference” column will be described later. 
     Next, in step ST 109  in  FIG. 5 , the CPU  100  functions as a blood pressure correction unit and corrects the measured blood pressure values according to the obtained orientation of the measurement subject  90 . 
     As is known, the measured blood pressure values are shifted from the actual values (values in the case where the heart and the measurement site are at the same height level) according to an altitude difference between the heart and the measurement site (in this example, the left upper arm  90   a ) of the measurement subject  90 . In view of this, a correction amount that is thought to be suitable due to experience is set in advance according to the obtained orientation of the measurement subject  90 , as shown in the “correction amount” column in “correction according to altitude difference” of the data table (Table 1). For example, with the orientation “A- 1 ”, the heart and the left upper arm  90   a  of the measurement subject  90  are at the same height level, and therefore the correction amount is set to 0 [mmHg]. With the orientation “C- 2 ”, the left upper arm  90   a  is at a higher level than the heart of the measurement subject  90 , and therefore the correction amount is set to 16 [mmHg]. Also, with the orientation “B- 2 ”, the altitude difference between the heart and the left upper arm  90   a  of the measurement subject  90  is at a level between that of the orientation “A- 1 ” and that of the orientation “C- 2 ”, and therefore the correction amount is set to 8 [mmHg]. 
     Then, the CPU  100  adds the pre-set correction amount to the measured blood pressure value according to the obtained orientation of the measurement subject  90 . For example, if the obtained orientation is “C- 2 ”, 16 [mmHg] is added as the correction amount when the measurement blood pressure values are systolic blood pressure SBP=107 [mmHg] and diastolic blood pressure DBP=71 [mmHg], for example. As a result, the corrected blood pressure values are systolic blood pressure SBP′=123 [mmHg] and diastolic blood pressure DBP′=87 [mmHg]. Also, if the obtained orientation is “B- 2 ”, 8 [mmHg] is added as the correction amount when the measurement blood pressure values are systolic blood pressure SBP=103 [mmHg] and diastolic blood pressure DBP=65 [mmHg], for example. As a result, the corrected blood pressure values are systolic blood pressure SBP′=111 [mmHg] and diastolic blood pressure DBP′=73 [mmHg]. Note that if the obtained orientation is “A- 1 ”, the correction amount is 0 [mmHg], and therefore values that are the same as those of the systolic blood pressure SBP and the diastolic blood pressure DBP go in the “systolic blood pressure SBP′” and “diastolic blood pressure DBP′” columns of the data table (Table 1). 
     In this example, the CPU  100  additionally stores the correction amount corresponding to the orientation and the corrected blood pressure values (systolic blood pressure SBP′ and diastolic blood pressure DBP′) in the data table (Table 1) in the memory  51  in association with the measurement number, the measurement time, the measured blood pressure values (systolic blood pressure SBP and diastolic blood pressure DBP), the pulse, whether or not there is external compression on the cuff  20 , whether or not there is bodily movement of the measurement subject  90 , and the orientation of the measurement subject  90 . 
     Next, in step ST 110  in  FIG. 5 , the CPU  100  refers to the data table (Table 1) in the memory  51 , functions as a display control unit, and displays the blood pressure values (systolic blood pressure SBP and diastolic blood pressure DBP) measured in this instance of measurement, the pulse, whether or not there is external compression on the cuff  20 , whether or not there is bodily movement of the measurement subject  90 , and the orientation of the measurement subject  90  on the display screen of the display device  50 . 
     Finally, in step ST 111  in  FIG. 5 , the CPU  100  performs control for opening the valve  33  via the valve driving circuit  330  and discharging the air in the fluid bladder  22  of the cuff  20 . 
     Note that in the flow shown in  FIG. 5 , the acquisition of the cuff compliance data, the acquisition of the output of the acceleration sensor, the acquisition of the pulse wave signal, and the calculation of the blood pressure values are performed in the process of increasing the pressure of the cuff  20 , but there is no limitation to this. The acquisition of the output of the acceleration sensor, the acquisition of the pulse wave signal, and the calculation of the blood pressure values may be performed in the pressure decrease process. 
     Example of Display in Blood Pressure Monitor Main Body 
     As shown in  FIGS. 9(A), 9(B), 10(A) , and  10 (B), a “systolic blood pressure” region  50   a  for displaying the measured systolic blood pressure SBP as a numerical value, a “diastolic blood pressure” region  50   b  for displaying the measured diastolic blood pressure DBP as a numerical value, a “pulse” region  50   c  for displaying the pulse as a numerical value, a “bodily movement” region  50   d  for displaying whether or not there is bodily movement of the measurement subject as an illustration as bodily movement information, a “compression” region  50   e  for displaying whether or not there is external compression on the cuff  20  as an illustration as compression information, and an orientation region  50   f  for displaying the orientation of the measurement subject  90  as an illustration are set on the display screen of the display device  50 . An illustration J- 1  indicating that there is bodily movement is composed of a circle m 1  indicating the head of the measurement subject  90 , a rounded-corner rectangle (a rectangle with rounded corners) m 2  indicating the torso of the measurement subject  90 , and a waveform mark m 3  indicating motion of the body. Also, the illustration J- 2  indicating that there is external compression is obtained approximately by adding a waveform mark m 4  indicating the bed surface to the illustration G- 2 . The illustrations J- 1  and J- 2  are stored in advance in the memory  51 . Note that when there is no bodily movement, the “bodily movement” region  50   d  is blank (empty) and when there is no external compression, the “compression” region  50   e  is blank (empty). The illustration corresponding to the content (reference numeral specifying the illustration) of the “orientation” column of the data table (Table 1) is selected from among the multiple illustrations A- 1  to A- 4 , B- 1  to B- 4 , C- 1  to C- 4 , D- 1  to D- 4 , E- 1  to E- 3 , F- 1  to F- 3 , G- 1  to G- 3 , and H- 1  to H- 3  in the first rows (top rows) in  FIGS. 8A to 8H , and is displayed in the orientation region  50   f  Accordingly, the image data including the illustration indicating the orientation of the measurement subject  90  can be rapidly created with simple processing. 
     In the example shown in  FIG. 9(A) , a systolic blood pressure SBP of 115 mmHg, a diastolic blood pressure DBP of 87 mmHg, and a pulse of 70 BPM that were measured in this instance of measuring are displayed as numerical values in the “systolic blood pressure” region  50   a , the “diastolic blood pressure” region  50   b , and the “pulse” region  50   c . Also, the fact that there is bodily movement is displayed as an illustration J- 1  in the “bodily movement” region  50   d . The fact that there is external compression is displayed as an illustration J- 2  in the “compression” region  50   e . Furthermore, the orientation of the measurement subject  90  is displayed as the illustration G- 2  in the orientation region  50   f.    
     In the example shown in  FIG. 9(B) , a systolic blood pressure SBP of 117 mmHg, a diastolic blood pressure DBP of 81 mmHg, and a pulse of 70 BPM that were measured in the current instance of measurement are displayed as numerical values in the “systolic blood pressure” region  50   a , the “diastolic blood pressure” region  50   b , and the “pulse” region  50   c , similarly to the example above. Also, the fact that there is no bodily movement is displayed as a blank in the “bodily movement” region  50   d . The fact that there is no external compression is displayed as a blank in the “compression” region  50   e . Furthermore, the orientation of the measurement subject  90  is displayed as an illustration A- 1  in the orientation region  50   f.    
     In the example shown in  FIG. 10(A) , similarly to the example above, a systolic blood pressure SBP of 111 mmHg, a diastolic blood pressure DBP of 68 mmHg, and a pulse of 70 BPM that were measured in the current instance of measurement are displayed as numerical values in the “systolic blood pressure” region  50   a , the “diastolic blood pressure” region  50   b , and the “pulse” region  50   c . Also, the fact that there is no bodily movement is displayed as a blank in the “bodily movement” region  50   d . The fact that there is external compression is displayed as the illustration J- 2  in the “compression” region  50   e . Furthermore, the orientation of the measurement subject  90  is displayed as the illustration G- 2  in the orientation region  50   f.    
     In the example shown in  FIG. 10(B) , similarly to the example above, a systolic blood pressure SBP of 131 mmHg, a diastolic blood pressure DBP of 85 mmHg, and a pulse of 70 BPM that were measured in the current instance of measurement are displayed as numerical values in the “systolic blood pressure” region  50   a , the “diastolic blood pressure” region  50   b , and the “pulse” region  50   c . Also, the fact that there is bodily movement is displayed as the illustration J- 1  in the “bodily movement” region  50   d . The fact that there is no external compression is displayed as a blank in the “compression” region  50   e . Furthermore, the orientation of the measurement subject  90  is displayed as the illustration A- 1  in the orientation region  50   f.    
     Accordingly, the user can find out the blood pressure values (systolic blood pressure SBP and diastolic blood pressure DBP) and the value of the pulse that were measured in this instant of measurement by viewing the numerical values in the “systolic blood pressure” region  50   a , the “diastolic blood pressure” region  50   b , and the “pulse” region  50   c  on the display screen of the display device  50 . In addition to this, by viewing the illustrations in the “bodily movement” region  50   d , the “compression” region  50   e , and the orientation region  50   f , the user can intuitively understand whether or not there is bodily movement of the measurement subject  90 , whether or not there is external compression on the cuff  20 , and the orientation of the measurement subject  90  during blood pressure measurement. 
     Note that in the pressure increase process shown in  FIG. 5 , if the cuff pressure reaches the upper limit value while the blood pressure values cannot be calculated (YES in step ST 106 ), the fact that an error occurred is stored in the memory  51  in association with the measurement time (step ST 112 ). In this example, “Error” is stored in the columns for the measured blood pressure values (systolic blood pressure SBP and diastolic blood pressure DBP) in the data table (Table 1) in the memory  51 . Even if this error is present, it is desirable to store the detection results in the “external compression” column, the “bodily movement” column, and the “orientation” column of the data table (Table 1), if possible. The reason for this is that there is a possibility that the cause of the error is due to the external compression, bodily movement, or orientation. Also, in step ST 110  in  FIG. 5 , “Error” is displayed as character strings in the “systolic blood pressure” region  50   a  and the “diastolic blood pressure” region  50   b  on the display screen of the display device  50  in this example, and illustrations indicating the detection results are displayed in the “bodily movement” region  50   d , the “compression” region  50   e , and the orientation region  50   f  In this type of case, the user can infer the cause of the error by viewing the illustrations in the “bodily movement” region  50   d , the “compression” region  50   e , and the orientation region  50   f.    
     Example of Display on Hospital Terminal 
       FIG. 3  shows a block configuration of a hospital terminal  200  that can communicate with the blood pressure monitor  1  via a network  900 . The hospital terminal  200  is composed of a commercially-available personal computer, includes a main body  200 M, and includes a control unit  210  composed of a CPU, a memory  220  including a RAM (Random Access Memory) and a ROM (Read Only Memory), an operation unit  230  including a keyboard and a mouse, a display device  240  composed of an LCD, and a communication unit  290  for performing communication via the network  900 , all of which are mounted in the main body  200 M. 
       FIGS. 11 to 13  illustrate images displayed on the display screen of the display device  240  based on the image data received by the hospital terminal  200  from the blood pressure monitor  1  via the communication unit  290 . 
     For example, as shown in  FIG. 11 , the “measurement orientation” region  240   a  indicating the orientation of the measurement subject  90  during blood pressure measurement, the “bodily movement/compression” region  240   b  indicating whether or not there is bodily movement of the measurement subject  90  or compression, a blood pressure/pulse region  240   c  indicating the measured blood pressure values or the corrected blood pressure values, and a legend region  240   d  indicating a legend of reference signs displayed on the blood pressure/pulse region  240   c  are set on the display screen of the display device  240 . 
     In the “measurement orientation” region  240   a , the illustrations K- 1 , A- 1 , C- 2 , . . . , which correspond to the reference numerals “K- 1 ”, “A- 1 ”, “C- 2 ”, . . . stored in the above-described “orientation” column of the data table (Table 1) are displayed in alignment with the passage of time (measurement time shown on the horizontal axis in the blood pressure/pulse region  240   c ). By viewing the illustrations of the orientations displayed in the “measurement orientation” region  240   a , a doctor serving as a user can intuitively understand the orientations of the measurement subject  90  during blood pressure measurement according to the passage of time. In the example shown in  FIG. 11 , it can be understood intuitively that the orientation of the measurement subject  90  changes from K- 1  to A- 1 , A- 1 , C- 2 , C- 2 , B- 2 , B- 2 , G- 2 , A- 1 , A- 3 , A- 1 , B- 2 , C- 2 , C- 2 , and B- 2  in the period of measurement times 23:00 to 6:00. 
     In the “bodily movement/compression” region  240   b , the bodily movement information that is stored in the “bodily movement” column of the data table (Table 1) and indicates that there is bodily movement is indicated by a mark M- 1  at the positions in the horizontal direction corresponding to the measurement times when there was bodily movement. In addition, the compression information that is stored in the “external compression” column of the data table (Table 1) and indicates that there is external compression is indicated by a mark M- 2  at the position on the horizontal axis corresponding to the measurement time when there was external compression. The mark M- 1  is constituted by the words “BOD. MVMT.” being included in a rectangle with rounded corners. The mark M- 2  is constituted by the word “COMP.” being included in a rectangle with rounded corners. By viewing the marks M- 1  and M- 2  displayed in the “bodily movement/compression” region  240   b , a doctor serving as a user can intuitively understand that there was bodily movement of the measurement subject  90  and that there was external compression on the cuff  20  at a specific blood pressure measurement time. In the example shown in  FIG. 11 , it can be understood intuitively that there was bodily movement during blood pressure measurement at the blood pressure measurement times 1:00 and 3:00, and that there was external compression during blood pressure measurement at the blood pressure measurement time 2:30. 
     In the blood pressure/pulse region  240   c , the measured blood pressure values (systolic blood pressure SBP and diastolic blood pressure DBP) in the data table (Table 1) and the pulse value PR stored in the “pulse” column are displayed as line graphs in this example. By viewing these line graphs, a user can intuitively understand the passage of time of the blood pressure values and the pulse of the measurement subject  90 . Also, by viewing both the illustrations of the orientations displayed in the “measurement orientation” region  240   a  and the line graph of the blood pressure values displayed in the blood pressure/pulse region  240   c , the user can intuitively understand the influence that the orientation, bodily movement, and external compression have on the blood pressure value of the measurement subject  90 . 
     Accordingly, for example, in the case of diagnosing the health state of the measurement subject  90 , a doctor serving as a user can make a diagnosis giving consideration to the influence that the orientation, bodily movement, and external compression have on the blood pressure value of the measurement subject  90 . Specifically, for example, if the orientation has a large influence on the blood pressure value of the measurement subject  90 , the doctor can make a diagnosis based only on the blood pressure values measured at times when the measurement subject  90  was in a specific orientation (e.g., A- 1 ). Also, if the bodily movement or the external compression has a large influence on the blood pressure value of the measurement subject  90 , it is possible to ignore the blood pressure values measured when there is bodily movement and the blood pressure values measured when there is external compression, and to make a diagnosis based only on the blood pressure values measured when there is no bodily movement and no external compression. 
     As shown in  FIG. 12 , in the blood pressure/pulse region  240   c , the corrected blood pressure values (systolic blood pressure SBP′ and diastolic blood pressure DBP′) in the data table (Table 1) may be displayed as line graphs instead of the measured blood pressure values (systolic blood pressure SBP and diastolic blood pressure DBP) in the data table (Table 1). Accordingly, by viewing both the illustrations of the orientations displayed in the “measurement orientation” region  240   a  and the line graph of the corrected blood pressure values displayed in the blood pressure/pulse region  240   c , a doctor serving as a user can intuitively understand whether or not the blood pressure values of the measurement subject  90  have been appropriately corrected according to the orientations of the measurement subject  90  during blood pressure measurement. 
     Also, as shown in  FIG. 13 , the corrected blood pressure values (systolic blood pressure SBP′ and diastolic blood pressure DBP′) in the data table (Table 1) may be displayed along with the measured blood pressure values (systolic blood pressure SBP and diastolic blood pressure DBP) in the data table (Table 1) as line graphs in the blood pressure/pulse region  240   c . Accordingly, by viewing the illustrations of the orientations displayed in the “measurement orientation” region  240   a  and the line graphs of the uncorrected and corrected blood pressure values displayed in the blood pressure/pulse region  240   c , a doctor serving as a user can more intuitively understand whether or not the blood pressure values of the measurement subject  90  were corrected appropriately according to the orientation of the measurement subject  90  during blood pressure measurement. 
     Modified Examples 
     In the example above, as shown in  FIGS. 8A to 8H , the orientations of the measurement subject  90  are detected as combinations of eight types of “torso angles” and four or three types of “arm positions”. Furthermore, in correspondence to this, the orientations of the measurement subject  90  are indicated using the illustrations A- 1  to A- 4 , B- 1  to B- 4 , C- 1  to C- 4 , D- 1  to D- 4 , E- 1  to E- 3 , F- 1  to F- 3 , G- 1  to G- 3 , and H- 1  to H- 3 , which are obtained by combining eight types of torso patterns and four or three types of arm patterns. However, there is no limitation to this, and for example, the torso angle may be detected roughly as four types, namely 0 degrees (supine position), 90 degrees (right side position), 180 degrees (prone position), and 270 degrees (left side position), and in correspondence to this, the torso angle may be displayed as four types of torso patterns. 
     Also, the “arm position” of the measurement subject  90  may be at a special arm position other than the four or three types of representative “arm positions” in  FIGS. 8A to 8H . In this case, it is desirable that with regard to this special arm position, the points that are to be detected in the XZ coordinate plane in the third rows in  FIGS. 8A to 8H  and in the XY coordinate plane in the fourth rows are defined, and the arm pattern that indicates the special arm position is prepared. For example, as shown in the “measurement orientation” region  240   a , at the measurement time 3:30 shown in  FIG. 13 , the torso angle of the measurement subject  90  is 0 degrees (supine position). In this case, the left upper arm  90   a  is in an arm position of being separated frontward with respect to the torso  90   b  of the measurement subject  90  (being extended approximately vertically upward). In response to this, it is desirable that the points that are to be detected in the XZ coordinate plane in the third row and in the XY coordinate plane in the fourth row in  FIG. 8A  are defined and the arm pattern indicating this arm position (in this example, illustration A- 3 ′) is prepared. 
     Also, in the example above, the orientation of the measurement subject  90  is indicated using the illustrations A- 1  to A- 4 , B- 1  to B- 4 , C- 1  to C- 4 , D- 1  to D- 4 , E- 1  to E- 3 , F- 1  to F- 3 , G- 1  to G- 3 , and H- 1  to H- 3  in the first rows (top rows) of  FIGS. 8A to 8H . However, there is no limitation to this, and the orientation of the measurement subject  90  may be indicated using illustrations of another type, for example, the illustrations in the second rows of  FIGS. 8A to 8H . The illustrations in the second rows in  FIGS. 8A to 8H  indicate schematic views of the orientations of the measurement subject  90  from above in the vertical direction. In the illustrations shown in the second rows, the head  90   h  of the measurement subject  90  is indicated by an oval, the torso  90   b  is indicated by a half-oval, and the left upper arm  90   a  is indicated by a rounded-corner rectangle. With this kind of illustration as well, the user can intuitively understand the orientations of the measurement subject  90  during blood pressure measurement according to the passage of time. 
     Also, with the blood pressure monitor  1 , the cuff  20  and the main body  10  are constituted integrally, but there is no limitation to this. Instead, the cuff  20  and the main body  10  may be constituted separately, and may be connected via an elongated tube corresponding to the air tube  39 . In this case, the acceleration sensor  34  is preferably mounted in (built in) the cuff  20  so as to be able to detect the orientation of the measurement subject  90 . 
     The above-described embodiments are exemplary and various modifications are possible without departing from the scope of the invention. The above-described multiple embodiments can be established separately, but combinations of the embodiments are also possible. Also, the various characteristics of the different embodiments can be established separately, but combinations of the characteristics in the different embodiments are also possible. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1  Blood pressure monitor 
               10  Cuff 
               31  Pressure sensor 
               34  Acceleration sensor 
               50 ,  240  Display device 
               51 ,  220  Memory 
               100  CPU 
               200  Hospital terminal 
             A- 1  to A- 4 , B- 1  to B- 4 , C- 1  to C- 4 , D- 1  to D- 4 , E- 1  to E- 3 , F- 1  to F- 3 , G- 1  to G- 3 , H- 1  to H- 3 , J- 1 , J- 2  Illustration 
             M- 1 , M- 2  Mark